If you used earlier versions of Neo4j via its Java API with Java 6 you probably have code similar to the following to ensure write operations happen within a transaction: public class StylesOfTx { public static void main( String[] args ) throws IOException { String path = "/tmp/tx-style-test"; FileUtils.deleteRecursively(new File(path)); GraphDatabaseService db = new GraphDatabaseFactory().newEmbeddedDatabase( path ); Transaction tx = db.beginTx(); try { db.createNode(); tx.success(); } finally { tx.close(); } } } In Neo4j 2.0 Transaction started extending AutoCloseable which meant that you could use ‘try with resources’ and the ‘close’ method would be automatically called when the block finished: public class StylesOfTx { public static void main( String[] args ) throws IOException { String path = "/tmp/tx-style-test"; FileUtils.deleteRecursively(new File(path)); GraphDatabaseService db = new GraphDatabaseFactory().newEmbeddedDatabase( path ); try ( Transaction tx = db.beginTx() ) { Node node = db.createNode(); tx.success(); } } } This works quite well although it’s still possible to have transactions hanging around in an application when people don’t use this syntax – the old style is still permissible. In Venkat Subramaniam’s Java 8 book he suggests an alternative approach where we use a lambda based approach: public class StylesOfTx { public static void main( String[] args ) throws IOException { String path = "/tmp/tx-style-test"; FileUtils.deleteRecursively(new File(path)); GraphDatabaseService db = new GraphDatabaseFactory().newEmbeddedDatabase( path ); Db.withinTransaction(db, neo4jDb -> { Node node = neo4jDb.createNode(); }); } static class Db { public static void withinTransaction(GraphDatabaseService db, Consumer fn) { try ( Transaction tx = db.beginTx() ) { fn.accept(db); tx.success(); } } } } The ‘withinTransaction’ function would actually go on GraphDatabaseService or similar rather than being on that Db class but it was easier to put it on there for this example. A disadvantage of this style is that you don’t have explicit control over the transaction for handling the failure case – it’s assumed that if ‘tx.success()’ isn’t called then the transaction failed and it’s rolled back. I’m not sure what % of use cases actually need such fine grained control though. Brian Hurt refers to this as the ‘hole in the middle pattern‘ and I imagine we’ll start seeing more code of this ilk once Java 8 is released and becomes more widely used.

What is It Query by example is an alternative querying technique supported by the main JPA vendors but not by the JPA specification itself. QBE returns a result set depending on the properties that were set on an instance of the queried class. So if I create an Address entity and fill in the city field then the query will select all the Address entities having the same city field as the given Address entity. The typical use case of QBE is evaluating a search form where the user can fill in any search fields and gets the results based on the given search fields. In this case QBE can reduce code size significantly. When to Use · Using many fields of an entity in a query · User selects which fields of an Entity to use in a query · We are refactoring the entities frequently and don’t want to worry about breaking the queries that rely on them Limitations · QBE is not available in JPA 1.0 or 2.0 · Version properties, identifiers and associations are ignored · The query object should be annotated with @Entity Test Data I used the following entities to test the QBE feature of Hibernate: · Address (long id, String city, String street, String countryISO2Code, AddressType addressType) · AddressType (Integer type, String description) Imports The examples will refer to the following classes: import org.hibernate.Criteria; import org.hibernate.Session; import org.hibernate.criterion.Example; import org.hibernate.criterion.Restrictions; import org.junit.Test; import java.util.List; Utility Methods I also made two utility methods to present a list of the two entity types: private void listAddresses(List addresses) { for (Address address : addresses) { System.out.println(address.getId() + ", " + address.getCountryISO2Code() + ", " + address.getCity() + ", " + address.getStreet() + ", " + address.getAddressType().getType() + ", " + address.getAddressType().getDescription()); } } private void listAddressTypes(List addressTypes) { for (AddressType addressType : addressTypes) { System.out.println(addressType.getType() + ", " + addressType.getDescription()); } } Example 1: Equals This example code returns the Address entities matching the given CountryISO2Code and City. Method: @Test public void testEquals() throws Exception { Session session = (Session) entityManager.getDelegate(); Address address = new Address(); address.setCountryISO2Code("US"); address.setCity("CHICAGO"); Example addressExample = Example.create(address); Criteria criteria = session.createCriteria(Address.class).add(addressExample); listAddresses(criteria.list()); } Result: 75, US, CHICAGO, Los Angeles Way2, 6, Customer 170, US, CHICAGO, Jackson Blvd 33a, 4, Delivery 63, US, CHICAGO, Main Avenue 1, 5, Bill to 37, US, CHICAGO, Jackson Blvd 33a, 4, Delivery 36, US, CHICAGO, Jackson Blvd 33a, 4, Delivery Example 2: Id Limitation This example presents that id fields in the query object are ignored. Method: @Test public void testIdLimitation() throws Exception { Session session = (Session) entityManager.getDelegate(); Address address = new Address(); address.setCountryISO2Code("US"); address.setCity("CHICAGO"); address.setId(100); // setting id is ignored Example addressExample = Example.create(address); Criteria criteria = session.createCriteria(Address.class).add(addressExample); listAddresses(criteria.list()); } Result: 75, US, CHICAGO, Los Angeles Way2, 6, Customer 170, US, CHICAGO, Jackson Blvd 33a, 4, Delivery 63, US, CHICAGO, Main Avenue 1, 5, Bill to 37, US, CHICAGO, Jackson Blvd 33a, 4, Delivery 36, US, CHICAGO, Jackson Blvd 33a, 4, Delivery Example 3: Association Limitation Associations of the query object are ignored, too. Method: @Test public void testAssociationLimitation() throws Exception { Session session = (Session) entityManager.getDelegate(); Address address = new Address(); address.setCountryISO2Code("US"); address.setCity("CHICAGO"); AddressType addressType = new AddressType(); addressType.setType(5); address.setAddressType(addressType); // setting an association is ignored Example addressExample = Example.create(address); Criteria criteria = session.createCriteria(Address.class).add(addressExample); listAddresses(criteria.list()); } Result: 75, US, CHICAGO, Los Angeles Way2, 6, Customer 170, US, CHICAGO, Jackson Blvd 33a, 4, Delivery 63, US, CHICAGO, Main Avenue 1, 5, Bill to 37, US, CHICAGO, Jackson Blvd 33a, 4, Delivery 36, US, CHICAGO, Jackson Blvd 33a, 4, Delivery Example 4: Like QBE supports like in the query object if we enable it with Example.enableLike(). Method: @Test public void testLike() throws Exception { Session session = (Session) entityManager.getDelegate(); Address address = new Address(); address.setCountryISO2Code("US"); address.setCity("AT%"); Example addressExample = Example.create(address).enableLike(); Criteria criteria = session.createCriteria(Address.class).add(addressExample); listAddresses(criteria.list()); } Result: 83, US, ATLANTA, null, 6, Customer 184, US, ATLANTA, null, 1, Shipper 25, US, ATLANTA, null, 1, Shipper Example 5: ExcludeProperty We can exclude a property with Example.excludeProperty(String propertyName). Method: @Test public void testExcludeProperty() throws Exception { Session session = (Session) entityManager.getDelegate(); Address address = new Address(); address.setCountryISO2Code("US"); address.setCity("AT%"); Example addressExample = Example.create(address).enableLike() .excludeProperty("countryISO2Code"); // countryISO2Code is a property of Address Criteria criteria = session.createCriteria(Address.class).add(addressExample); listAddresses(criteria.list()); } Result: 154, GR, ATHENS, BETA ALPHA Street 5, 2, Consignee 83, US, ATLANTA, null, 6, Customer 25, US, ATLANTA, null, 1, Shipper 184, US, ATLANTA, null, 1, Shipper Example 6: IgnoreCase Case-insensitive search is supported by Example.ignoreCase(). Method: @Test public void testIgnoreCase() throws Exception { Session session = (Session) entityManager.getDelegate(); AddressType addressType = new AddressType(); addressType.setDescription("customer"); Example addressTypeExample = Example.create(addressType).ignoreCase(); Criteria criteria = session.createCriteria(AddressType.class) .add(addressTypeExample); listAddressTypes(criteria.list()); } Result: 6, Customer Example 7: ExcludeZeroes We can ignore 0 values of the query object by Example.excludeZeroes(). Method: @Test public void testExcludeZeroes() throws Exception { Session session = (Session) entityManager.getDelegate(); AddressType addressType = new AddressType(); addressType.setType(0); addressType.setDescription("Customer"); Example addressTypeExample = Example.create(addressType) .excludeZeroes(); Criteria criteria = session.createCriteria(AddressType.class) .add(addressTypeExample); listAddressTypes(criteria.list()); } Result: 6, Customer Example 8: Combining with Criteria QBE can be combined with criteria query. In this example we add further restriction to the query object using criteria query. Method: @Test public void testCombiningWithCriteria() throws Exception { Session session = (Session) entityManager.getDelegate(); AddressType addressType = new AddressType(); addressType.setDescription("Customer"); Example addressTypeExample = Example.create(addressType); Criteria criteria = session .createCriteria(AddressType.class).add(addressTypeExample) .add(Restrictions.eq("type", 6)); listAddressTypes(criteria.list()); } Result: 6, Customer Example 9: Association With criteria query we can filter both sides of an association, using two query objects. Method: @Test public void testAssociation() throws Exception { Session session = (Session) entityManager.getDelegate(); Address address = new Address(); address.setCountryISO2Code("US"); AddressType addressType = new AddressType(); addressType.setType(6); Example addressExample = Example.create(address); Example addressTypeExample = Example.create(addressType); Criteria criteria = session.createCriteria(Address.class).add(addressExample) .createCriteria("addressType").add(addressTypeExample); // addressType is a property of Address listAddresses(criteria.list()); } Result: 84, US, BOSTON, null, 6, Customer 83, US, ATLANTA, null, 6, Customer 82, US, SAN FRANCISCO, null, 6, Customer 75, US, CHICAGO, Los Angeles Way2, 6, Customer EclipseLink EclipseLink QBE uses QueryByExamplePolicy, ReadObjectQuery and JpaHelper: QueryByExamplePolicy qbePolicy =newQueryByExamplePolicy(); qbePolicy.excludeDefaultPrimitiveValues(); Address address =newAddress(); address.setCity("CHICAGO"); ReadObjectQuery roq =newReadObjectQuery(address, qbePolicy); Query query =JpaHelper.createQuery(roq, entityManager); OpenJPA OpenJPA uses OpenJPAQueryBuilder: CriteriaQuery cq = openJPAQueryBuilder.createQuery(Address.class); Address address =newAddress(); address.setCity("CHICAGO"); cq.where(openJPAQueryBuilder.qbe(cq.from(Address.class), address); References Hibernate: · Srinivas Guruzu and Gary Mak: Hibernate Recipes: A Problem-Solution Approach (Apress) · http://docs.jboss.org/hibernate/core/3.3/reference/en/html/querycriteria.html#querycriteria-examples · http://www.java2s.com/Code/Java/Hibernate/CriteriaQBEQueryByExampleCriteria.htm · http://www.dzone.com/snippets/hibernate-query-example · http://gal-levinsky.blogspot.de/2012/01/qbe-pattern.html Hibernate associations: · http://stackoverflow.com/questions/9309884/query-by-example-on-associations · http://stackoverflow.com/questions/8236596/hibernate-query-by-example-equivalent-of-association-criteria-query JPA: · http://stackoverflow.com/questions/2880209/jpa-findbyexample EclipseLink: · http://www.coderanch.com/t/486528/ORM/databases/findByExample-JPA-book OpenJPA: · http://www.ibm.com/developerworks/java/library/j-typesafejpa/#N10C18

Within this post we will have a deeper look into the new Date/Time API we get with Java 8 (JSR 310). Please note that this post is mainly driven by code examples that show the new API functionality. I think the examples are self-explanatory so I did not spent much time writing text around them :-) Let's get started! Working with Date and Time Objects All classes of the Java 8 Date/Time API are located within the java.time package. The first class we want to look at is java.time.LocalDate. A LocalDate represents a year-month-day date without time. We start with creating new LocalDate instances: // the current date LocalDate currentDate = LocalDate.now(); // 2014-02-10 LocalDate tenthFeb2014 = LocalDate.of(2014, Month.FEBRUARY, 10); // months values start at 1 (2014-08-01) LocalDate firstAug2014 = LocalDate.of(2014, 8, 1); // the 65th day of 2010 (2010-03-06) LocalDate sixtyFifthDayOf2010 = LocalDate.ofYearDay(2010, 65); LocalTime and LocalDateTime are the next classes we look at. Both work similar to LocalDate. ALocalTime works with time (without dates) while LocalDateTime combines date and time in one class: LocalTime currentTime = LocalTime.now(); // current time LocalTime midday = LocalTime.of(12, 0); // 12:00 LocalTime afterMidday = LocalTime.of(13, 30, 15); // 13:30:15 // 12345th second of day (03:25:45) LocalTime fromSecondsOfDay = LocalTime.ofSecondOfDay(12345); // dates with times, e.g. 2014-02-18 19:08:37.950 LocalDateTime currentDateTime = LocalDateTime.now(); // 2014-10-02 12:30 LocalDateTime secondAug2014 = LocalDateTime.of(2014, 10, 2, 12, 30); // 2014-12-24 12:00 LocalDateTime christmas2014 = LocalDateTime.of(2014, Month.DECEMBER, 24, 12, 0); By default LocalDate/Time classes will use the system clock in the default time zone. We can change this by providing a time zone or an alternative Clock implementation: // current (local) time in Los Angeles LocalTime currentTimeInLosAngeles = LocalTime.now(ZoneId.of("America/Los_Angeles")); // current time in UTC time zone LocalTime nowInUtc = LocalTime.now(Clock.systemUTC()); From LocalDate/Time objects we can get all sorts of useful information we might need. Some examples: LocalDate date = LocalDate.of(2014, 2, 15); // 2014-06-15 boolean isBefore = LocalDate.now().isBefore(date); // false // information about the month Month february = date.getMonth(); // FEBRUARY int februaryIntValue = february.getValue(); // 2 int minLength = february.minLength(); // 28 int maxLength = february.maxLength(); // 29 Month firstMonthOfQuarter = february.firstMonthOfQuarter(); // JANUARY // information about the year int year = date.getYear(); // 2014 int dayOfYear = date.getDayOfYear(); // 46 int lengthOfYear = date.lengthOfYear(); // 365 boolean isLeapYear = date.isLeapYear(); // false DayOfWeek dayOfWeek = date.getDayOfWeek(); int dayOfWeekIntValue = dayOfWeek.getValue(); // 6 String dayOfWeekName = dayOfWeek.name(); // SATURDAY int dayOfMonth = date.getDayOfMonth(); // 15 LocalDateTime startOfDay = date.atStartOfDay(); // 2014-02-15 00:00 // time information LocalTime time = LocalTime.of(15, 30); // 15:30:00 int hour = time.getHour(); // 15 int second = time.getSecond(); // 0 int minute = time.getMinute(); // 30 int secondOfDay = time.toSecondOfDay(); // 55800 Some information can be obtained without providing a specific date. For example, we can use the Year class if we need information about a specific year: Year currentYear = Year.now(); Year twoThousand = Year.of(2000); boolean isLeap = currentYear.isLeap(); // false int length = currentYear.length(); // 365 // sixtyFourth day of 2014 (2014-03-05) LocalDate date = Year.of(2014).atDay(64); We can use the plus and minus methods to add or subtract specific amounts of time. Note that these methods always return a new instance (Java 8 date/time classes are immutable). LocalDate tomorrow = LocalDate.now().plusDays(1); // before 5 houres and 30 minutes LocalDateTime dateTime = LocalDateTime.now().minusHours(5).minusMinutes(30); TemporalAdjusters are another nice way for date manipulation. TemporalAdjuster is a single method interface that is used to separate the process of adjustment from actual date/time objects. A set of common TemporalAdjusters can be accessed using static methods of the TemporalAdjusters class. LocalDate date = LocalDate.of(2014, Month.FEBRUARY, 25); // 2014-02-25 // first day of february 2014 (2014-02-01) LocalDate firstDayOfMonth = date.with(TemporalAdjusters.firstDayOfMonth()); // last day of february 2014 (2014-02-28) LocalDate lastDayOfMonth = date.with(TemporalAdjusters.lastDayOfMonth()); Static imports make this more fluent to read: import static java.time.temporal.TemporalAdjusters.*; ... // last day of 2014 (2014-12-31) LocalDate lastDayOfYear = date.with(lastDayOfYear()); // first day of next month (2014-03-01) LocalDate firstDayOfNextMonth = date.with(firstDayOfNextMonth()); // next sunday (2014-03-02) LocalDate nextSunday = date.with(next(DayOfWeek.SUNDAY)); Time Zones Working with time zones is another big topic that is simplified by the new API. The LocalDate/Time classes we have seen so far do not contain information about a time zone. If we want to work with a date/time in a certain time zone we can use ZonedDateTime or OffsetDateTime: ZoneId losAngeles = ZoneId.of("America/Los_Angeles"); ZoneId berlin = ZoneId.of("Europe/Berlin"); // 2014-02-20 12:00 LocalDateTime dateTime = LocalDateTime.of(2014, 02, 20, 12, 0); // 2014-02-20 12:00, Europe/Berlin (+01:00) ZonedDateTime berlinDateTime = ZonedDateTime.of(dateTime, berlin); // 2014-02-20 03:00, America/Los_Angeles (-08:00) ZonedDateTime losAngelesDateTime = berlinDateTime.withZoneSameInstant(losAngeles); int offsetInSeconds = losAngelesDateTime.getOffset().getTotalSeconds(); // -28800 // a collection of all available zones Set allZoneIds = ZoneId.getAvailableZoneIds(); // using offsets LocalDateTime date = LocalDateTime.of(2013, Month.JULY, 20, 3, 30); ZoneOffset offset = ZoneOffset.of("+05:00"); // 2013-07-20 03:30 +05:00 OffsetDateTime plusFive = OffsetDateTime.of(date, offset); // 2013-07-19 20:30 -02:00 OffsetDateTime minusTwo = plusFive.withOffsetSameInstant(ZoneOffset.ofHours(-2)); Timestamps Classes like LocalDate and ZonedDateTime provide a human view on time. However, often we need to work with time viewed from a machine perspective. For this we can use the Instant class which represents timestamps. An Instant counts the time beginning from the first second of January 1, 1970 (1970-01-01 00:00:00) also called the EPOCH. Instant values can be negative if they occured before the epoch. They followISO 8601 the standard for representing date and time. // current time Instant now = Instant.now(); // from unix timestamp, 2010-01-01 12:00:00 Instant fromUnixTimestamp = Instant.ofEpochSecond(1262347200); // same time in millis Instant fromEpochMilli = Instant.ofEpochMilli(1262347200000l); // parsing from ISO 8601 Instant fromIso8601 = Instant.parse("2010-01-01T12:00:00Z"); // toString() returns ISO 8601 format, e.g. 2014-02-15T01:02:03Z String toIso8601 = now.toString(); // as unix timestamp long toUnixTimestamp = now.getEpochSecond(); // in millis long toEpochMillis = now.toEpochMilli(); // plus/minus methods are available too Instant nowPlusTenSeconds = now.plusSeconds(10); Periods and Durations Period and Duration are two other important classes. Like the names suggest they represent a quantity or amount of time. A Period uses date based values (years, months, days) while a Duration uses seconds or nanoseconds to define an amount of time. Duration is most suitable when working with Instants and machine time. Periods and Durations can contain negative values if the end point occurs before the starting point. // periods LocalDate firstDate = LocalDate.of(2010, 5, 17); // 2010-05-17 LocalDate secondDate = LocalDate.of(2015, 3, 7); // 2015-03-07 Period period = Period.between(firstDate, secondDate); int days = period.getDays(); // 18 int months = period.getMonths(); // 9 int years = period.getYears(); // 4 boolean isNegative = period.isNegative(); // false Period twoMonthsAndFiveDays = Period.ofMonths(2).plusDays(5); LocalDate sixthOfJanuary = LocalDate.of(2014, 1, 6); // add two months and five days to 2014-01-06, result is 2014-03-11 LocalDate eleventhOfMarch = sixthOfJanuary.plus(twoMonthsAndFiveDays); // durations Instant firstInstant= Instant.ofEpochSecond( 1294881180 ); // 2011-01-13 01:13 Instant secondInstant = Instant.ofEpochSecond(1294708260); // 2011-01-11 01:11 Duration between = Duration.between(firstInstant, secondInstant); // negative because firstInstant is after secondInstant (-172920) long seconds = between.getSeconds(); // get absolute result in minutes (2882) long absoluteResult = between.abs().toMinutes(); // two hours in seconds (7200) long twoHoursInSeconds = Duration.ofHours(2).getSeconds(); Formatting and Parsing Formatting and parsing is another big topic when working with dates and times. In Java 8 this can be accomplished by using the format() and parse() methods: // 2014-04-01 10:45 LocalDateTime dateTime = LocalDateTime.of(2014, Month.APRIL, 1, 10, 45); // format as basic ISO date format (20140220) String asBasicIsoDate = dateTime.format(DateTimeFormatter.BASIC_ISO_DATE); // format as ISO week date (2014-W08-4) String asIsoWeekDate = dateTime.format(DateTimeFormatter.ISO_WEEK_DATE); // format ISO date time (2014-02-20T20:04:05.867) String asIsoDateTime = dateTime.format(DateTimeFormatter.ISO_DATE_TIME); // using a custom pattern (01/04/2014) String asCustomPattern = dateTime.format(DateTimeFormatter.ofPattern("dd/MM/yyyy")); // french date formatting (1. avril 2014) String frenchDate = dateTime.format(DateTimeFormatter.ofPattern("d. MMMM yyyy", new Locale("fr"))); // using short german date/time formatting (01.04.14 10:45) DateTimeFormatter formatter = DateTimeFormatter.ofLocalizedDateTime(FormatStyle.SHORT) .withLocale(new Locale("de")); String germanDateTime = dateTime.format(formatter); // parsing date strings LocalDate fromIsoDate = LocalDate.parse("2014-01-20"); LocalDate fromIsoWeekDate = LocalDate.parse("2014-W14-2", DateTimeFormatter.ISO_WEEK_DATE); LocalDate fromCustomPattern = LocalDate.parse("20.01.2014", DateTimeFormatter.ofPattern("dd.MM.yyyy")); Conversion Of course we do not always have objects of the type we need. Therefore, we need an option to convert different date/time related objects between each other. The following examples show some of the possible conversion options: // LocalDate/LocalTime <-> LocalDateTime LocalDate date = LocalDate.now(); LocalTime time = LocalTime.now(); LocalDateTime dateTimeFromDateAndTime = LocalDateTime.of(date, time); LocalDate dateFromDateTime = LocalDateTime.now().toLocalDate(); LocalTime timeFromDateTime = LocalDateTime.now().toLocalTime(); // Instant <-> LocalDateTime Instant instant = Instant.now(); LocalDateTime dateTimeFromInstant = LocalDateTime.ofInstant(instant, ZoneId.of("America/Los_Angeles")); Instant instantFromDateTime = LocalDateTime.now().toInstant(ZoneOffset.ofHours(-2)); // convert old date/calendar/timezone classes Instant instantFromDate = new Date().toInstant(); Instant instantFromCalendar = Calendar.getInstance().toInstant(); ZoneId zoneId = TimeZone.getDefault().toZoneId(); ZonedDateTime zonedDateTimeFromGregorianCalendar = new GregorianCalendar().toZonedDateTime(); // convert to old classes Date dateFromInstant = Date.from(Instant.now()); TimeZone timeZone = TimeZone.getTimeZone(ZoneId.of("America/Los_Angeles")); GregorianCalendar gregorianCalendar = GregorianCalendar.from(ZonedDateTime.now()); Conclusion With Java 8 we get a very rich API for working with date and time located in the java.time package. The API can completely replace old classes like java.util.Date or java.util.Calendar with newer, more flexible classes. Due to mostly immutable classes the new API helps in building thread safe systems. The source of the examples can be found on GitHub.

We all write unit tests but the challenge we face at times is that the unit under test might be dependent on other components. And configuring other components for unit testing is definitely an overkill. Instead we can make use of Mocks in place of the other components and continue with the unit testing. To show how one can use mocks, I have a Data access layer(DAL), basically a class which provides an API for the application to access and modify the data in the data repository. I then unit test the DAL without actually the need to connect to the data repository. The data repository can be a local database or remote database or a file system or any place where we can store and retrieve the data. The use of a DAL class helps us in keeping the data mappers separate from the application code. Lets create a Java project using maven. mvn archetype:generate -DgroupId=info.sanaulla -DartifactId=MockitoDemo -DarchetypeArtifactId=maven-archetype-quickstart -DinteractiveMode=false The above creates a folder MockitoDemo and then creates the entire directory structure for source and test files. Consider the below model class for this example: package info.sanaulla.models; import java.util.List; /** * Model class for the book details. */ public class Book { private String isbn; private String title; private List authors; private String publication; private Integer yearOfPublication; private Integer numberOfPages; private String image; public Book(String isbn, String title, List authors, String publication, Integer yearOfPublication, Integer numberOfPages, String image){ this.isbn = isbn; this.title = title; this.authors = authors; this.publication = publication; this.yearOfPublication = yearOfPublication; this.numberOfPages = numberOfPages; this.image = image; } public String getIsbn() { return isbn; } public String getTitle() { return title; } public List getAuthors() { return authors; } public String getPublication() { return publication; } public Integer getYearOfPublication() { return yearOfPublication; } public Integer getNumberOfPages() { return numberOfPages; } public String getImage() { return image; } } The DAL class for operating on the Book model class is: package info.sanaulla.dal; import info.sanaulla.models.Book; import java.util.ArrayList; import java.util.Arrays; import java.util.Collections; import java.util.List; /** * API layer for persisting and retrieving the Book objects. */ public class BookDAL { private static BookDAL bookDAL = new BookDAL(); public List getAllBooks(){ return Collections.EMPTY_LIST; } public Book getBook(String isbn){ return null; } public String addBook(Book book){ return book.getIsbn(); } public String updateBook(Book book){ return book.getIsbn(); } public static BookDAL getInstance(){ return bookDAL; } } The DAL layer above currently has no functionality and we are going to unit test that piece of code (TDD). The DAL layer might communicate with a ORM Mapper or Database API which we are not concerned while designing the API. Test Driving the DAL Layer There are lot of frameworks for Unit testing and mocking in Java but for this example I would be picking JUnit for unit testing and Mockito for mocking. We would have to update the dependency in Maven’s pom.xml 4.0.0 info.sanaulla MockitoDemo jar 1.0-SNAPSHOT MockitoDemo http://maven.apache.org junit junit 4.10 test org.mockito mockito-all 1.9.5 test Now lets unit test the BookDAL. During the unit testing we will inject mock data into the BookDAL so that we can complete the testing of the API without depending on the data source. Initially we will have an empty test class: public class BookDALTest { public void setUp() throws Exception { } public void testGetAllBooks() throws Exception { } public void testGetBook() throws Exception { } public void testAddBook() throws Exception { } public void testUpdateBook() throws Exception { } } We will inject the mock BookDAL and mock data in the setUp() as shown below: public class BookDALTest { private static BookDAL mockedBookDAL; private static Book book1; private static Book book2; @BeforeClass public static void setUp(){ //Create mock object of BookDAL mockedBookDAL = mock(BookDAL.class); //Create few instances of Book class. book1 = new Book("8131721019","Compilers Principles", Arrays.asList("D. Jeffrey Ulman","Ravi Sethi", "Alfred V. Aho", "Monica S. Lam"), "Pearson Education Singapore Pte Ltd", 2008,1009,"BOOK_IMAGE"); book2 = new Book("9788183331630","Let Us C 13th Edition", Arrays.asList("Yashavant Kanetkar"),"BPB PUBLICATIONS", 2012,675,"BOOK_IMAGE"); //Stubbing the methods of mocked BookDAL with mocked data. when(mockedBookDAL.getAllBooks()).thenReturn(Arrays.asList(book1, book2)); when(mockedBookDAL.getBook("8131721019")).thenReturn(book1); when(mockedBookDAL.addBook(book1)).thenReturn(book1.getIsbn()); when(mockedBookDAL.updateBook(book1)).thenReturn(book1.getIsbn()); } public void testGetAllBooks() throws Exception {} public void testGetBook() throws Exception {} public void testAddBook() throws Exception {} public void testUpdateBook() throws Exception {} } In the above setUp() method I have: Created a mock object of BookDAL BookDAL mockedBookDAL = mock(BookDAL.class); Stubbed the API of BookDAL with mock data, such that when ever the API is invoked the mocked data is returned. //When getAllBooks() is invoked then return the given data and so on for the other methods. when(mockedBookDAL.getAllBooks()).thenReturn(Arrays.asList(book1, book2)); when(mockedBookDAL.getBook("8131721019")).thenReturn(book1); when(mockedBookDAL.addBook(book1)).thenReturn(book1.getIsbn()); when(mockedBookDAL.updateBook(book1)).thenReturn(book1.getIsbn()); Populating the rest of the tests we get: package info.sanaulla.dal; import info.sanaulla.models.Book; import org.junit.BeforeClass; import org.junit.Test; import static org.junit.Assert.*; import static org.mockito.Mockito.mock; import static org.mockito.Mockito.when; import java.util.Arrays; import java.util.List; public class BookDALTest { private static BookDAL mockedBookDAL; private static Book book1; private static Book book2; @BeforeClass public static void setUp(){ mockedBookDAL = mock(BookDAL.class); book1 = new Book("8131721019","Compilers Principles", Arrays.asList("D. Jeffrey Ulman","Ravi Sethi", "Alfred V. Aho", "Monica S. Lam"), "Pearson Education Singapore Pte Ltd", 2008,1009,"BOOK_IMAGE"); book2 = new Book("9788183331630","Let Us C 13th Edition", Arrays.asList("Yashavant Kanetkar"),"BPB PUBLICATIONS", 2012,675,"BOOK_IMAGE"); when(mockedBookDAL.getAllBooks()).thenReturn(Arrays.asList(book1, book2)); when(mockedBookDAL.getBook("8131721019")).thenReturn(book1); when(mockedBookDAL.addBook(book1)).thenReturn(book1.getIsbn()); when(mockedBookDAL.updateBook(book1)).thenReturn(book1.getIsbn()); } @Test public void testGetAllBooks() throws Exception { List allBooks = mockedBookDAL.getAllBooks(); assertEquals(2, allBooks.size()); Book myBook = allBooks.get(0); assertEquals("8131721019", myBook.getIsbn()); assertEquals("Compilers Principles", myBook.getTitle()); assertEquals(4, myBook.getAuthors().size()); assertEquals((Integer)2008, myBook.getYearOfPublication()); assertEquals((Integer) 1009, myBook.getNumberOfPages()); assertEquals("Pearson Education Singapore Pte Ltd", myBook.getPublication()); assertEquals("BOOK_IMAGE", myBook.getImage()); } @Test public void testGetBook(){ String isbn = "8131721019"; Book myBook = mockedBookDAL.getBook(isbn); assertNotNull(myBook); assertEquals(isbn, myBook.getIsbn()); assertEquals("Compilers Principles", myBook.getTitle()); assertEquals(4, myBook.getAuthors().size()); assertEquals("Pearson Education Singapore Pte Ltd", myBook.getPublication()); assertEquals((Integer)2008, myBook.getYearOfPublication()); assertEquals((Integer)1009, myBook.getNumberOfPages()); } @Test public void testAddBook(){ String isbn = mockedBookDAL.addBook(book1); assertNotNull(isbn); assertEquals(book1.getIsbn(), isbn); } @Test public void testUpdateBook(){ String isbn = mockedBookDAL.updateBook(book1); assertNotNull(isbn); assertEquals(book1.getIsbn(), isbn); } } One can run the test by using maven command: mvn test. The output is: ------------------------------------------------------- T E S T S ------------------------------------------------------- Running info.sanaulla.AppTest Tests run: 1, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.029 sec Running info.sanaulla.dal.BookDALTest Tests run: 4, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.209 sec Results : Tests run: 5, Failures: 0, Errors: 0, Skipped: 0 So we have been able to test the DAL class without actually configuring the data source by using mocks.

The WebLogic Server 12c has very nice support for Maven now. The doc for this is kinda hidden though, so here is a direct link http://docs.oracle.com/middleware/1212/core/MAVEN To summarize the doc, Oracle did not provide a public Maven repository manager hosting for their server artifacts. However they do now provide a tool for you to create and populate your own. You can setup either your local repository (if you are working mostly on your own in a single computer), or you may deploy them into your own internal Maven repository manager such as Archiva or Nexus. Here I would show how the local repository is done. First step is use a maven plugin provided by WLS to populate the repository. I am using a MacOSX for this demo and my WLS is installed in $HOME/apps/wls12120. If you are on Windows, you may install it under C:/apps/wls12120. $ cd $HOME/apps/wls12120/oracle_common/plugins/maven/com/oracle/maven/oracle-maven-sync/12.1.2/ $ mvn install:install-file -DpomFile=oracle-maven-sync.12.1.2.pom -Dfile=oracle-maven-sync.12.1.2.jar $ mvn com.oracle.maven:oracle-maven-sync:push -Doracle-maven-sync.oracleHome=$HOME/apps/wls12120 -Doracle-maven-sync.testingOnly=false The artifacts are placed under your local $HOME/.m2/repository/com/oracle. Now you may use Maven to build Java EE application with these WebLogic artifact as dependencies. Not only these are available, the push also populated some additional maven plugins that helps development more easy. For example, you can generate a template project using their archetype plugin. $ cd $HOME $ mvn archetype:generate \ -DarchetypeGroupId=com.oracle.weblogic.archetype \ -DarchetypeArtifactId=basic-webapp \ -DarchetypeVersion=12.1.2-0-0 \ -DgroupId=org.mycompany \ -DartifactId=my-basic-webapp-project \ -Dversion=1.0-SNAPSHOT Type 'Y' to confirm to finish. Notice that pom.xml it generated; it is using the "javax:javaee-web-api:6.0:provided" dependency. This is working because we setup the repository earlier. Now you may build it. $ cd my-basic-webapp-project $ mvn package After this build you should have the war file under the target directory.You may manually copy and deploy this into your WebLogic server domain. Or you may continue to configure the maven pom to do this all with maven. Here is how I do it. Edit the my-basic-webapp-project/pom.xml file and replace the weblogic-maven-plugin plugin like this: com.oracle.weblogic weblogic-maven-plugin 12.1.2-0-0 ${oracleMiddlewareHome} ${oracleServerUrl} ${oracleUsername} ${oraclePassword} ${project.build.directory}/${project.build.finalName}.${project.packaging} ${oracleServerName} true ${project.build.finalName} With this change, you may deploy the webapp into WebLogic server (well, assuming you already started your "mydomain" with "myserver" server running locally. See my previous blog for instructions) $ cd my-basic-webapp-project $ mvn weblogic:deploy -DoracleMiddlewareHome=$HOME/apps/wls12120 -DoracleServerName=myserver -DoracleUsername=admin -DoraclePassword=admin123 After the "BUILD SUCCESS" message, you may visit the http://localhost:7001/basicWebapp URL. Revisit the WLS doc again and you will find that they also provide other project templates (Maven calls these archetypes) for building EJB, MDB, or WebService projects. These should help you get your EE projects started quickly.

This article deals with different approaches to load multiple versions of the same class. The problem: Many times during the development you will need to work with different libraries versions which not always backward compatible or from some reason you need to support multiple versions of the same library. Using standard Java classloaders will not solve this issue since they all use "loadClass" method to load a specific class only once. After that "loadClass" will return the reference of the existing Class instance. The solution: Using another classloader to load the library (or multiple classloaders). There are several approaches available to achieve that: Use a URLClassLoader: This class loader will allow you to load your jars via URLs, or specify a directory for your classes location. Here is an example: URLClassLoader clsLoader = URLClassLoader.newInstance(new URL[] {new URL("file:/C://Test/test.jar")}); Class cls = clsLoader.loadClass("test.Main"); Method method = cls.getMethod("main", String[].class); String[]params = new String[2]; method.invoke(null, (Object) params); 2. Write your own custom class loader. Since Java class loaders (including URLClassLoader) first ask to load classes from their parent class loader, you can encounter a situation where you will need your custom classloader to load the classes from your specified location first. In this case here is a sample of a custom class loader which do exactly that: import java.net.URL; import java.net.URLClassLoader; import java.util.List; public class CustomClassLoader extends ClassLoader { private ChildClassLoader childClassLoader; public CustomClassLoader(List classpath) { super(Thread.currentThread().getContextClassLoader()); URL[] urls = classpath.toArray(new URL[classpath.size()]); childClassLoader = new ChildClassLoader( urls, new DetectClass(this.getParent()) ); } @Override protected synchronized Class loadClass(String name, boolean resolve) throws ClassNotFoundException { try { return childClassLoader.findClass(name); } catch( ClassNotFoundException e ) { return super.loadClass(name, resolve); } } private static class ChildClassLoader extends URLClassLoader { private DetectClass realParent; public ChildClassLoader( URL[] urls, DetectClass realParent ) { super(urls, null); this.realParent = realParent; } @Override public Class findClass(String name) throws ClassNotFoundException { try { Class loaded = super.findLoadedClass(name); if( loaded != null ) return loaded; return super.findClass(name); } catch( ClassNotFoundException e ) { return realParent.loadClass(name); } } } private static class DetectClass extends ClassLoader { public DetectClass(ClassLoader parent) { super(parent); } @Override public Class findClass(String name) throws ClassNotFoundException { return super.findClass(name); } } }

Java is a minimalist language with deliberately less features than other languages, never the less it has edge cases which strange effects, and even some common cases with surprising effects to trip up the unwary. If you are used to reading another language you can easily read Java the wrong way leaving to confusion. Variables are only references or primitives That's right, variables are not Objects. This means when you see the following, s is not an object, it is not a String, it is a reference to a String String s = "Hello"; This answers many areas of confusion such as; Q: If String is immutable how can I change it. e g. s += "!"; A: You can't in normal Java, you can only change a reference to a String. == compares references, not their contents. To add to the confusion, using == some times works. If you have two immutable values which are the same, the JVM can try to make the references the same too. e.g. String s1 = "Hi", s2 = "Hi"; Integer a = 12, b = 12; In both these case, an object pool is used so the references end up being the same. s1 == s2 and a == b are both true as the JVM has made the references to the same object. However, vary the code a little so the JVM doesn't pool the objects, and == returns false, perhaps unexpectedly. In this case you need to use equals. String s3 = new String(s1); Integer c = -222, d = -222; s1 == s2 // is true s1 == s3 // is false s1.equals(s3) // is true a == b // is true c == d // is false (different objects were created) c.equals(d) // is true For Integer, the object pool starts at -128 up to at least 127 (possibly higher) Java passes references by value All variables are passed by value, even references. This means when you have a variable which is a reference to an object, this reference is copied, but not the object. e.g. public static void addAWord(StringBuilder sb) { sb.append(" word"); sb = null; } StringBuilder sb = new StringBuilder("first "); addWord(sb); addWord(sb); System.out.println(sb); // prints "first word word" The object referenced can be changed, but changes to the copied reference have no effect on the caller. In most JVMs, the Object.hashCode() doesn't have anything to do with memory location A hashCode() has to remain constant. Without this fact hash collections like HashSet or ConcurrentHashMap wouldn't work. However, the object can be anywhere in memory and can change location without your program being aware this has happened. Using the location for a hashCode wouldn't work (unless you have a JVM where objects are not moved) For OpenJDK and the HotSpot JVM, the hashCode() generated on demand and stored in the object's header. Using Unsafe you can see whether the hashCode() has been set and even change it by over Object.toString() does something surprising rather than useful The default behaviour of toString() is to print an internal name for a class and a hashCode(). As mentioned the hashCode is not the memory location, even though it is printed in hexi-decimal. Also the class name, especially for arrays is confusing. For example; a String[] is printed as [Ljava.lang.String; The [ signifies that it is an array, the L signifies it is a "language" created class, not a primitive like byte which BTW has a code of B. and the ;signifies the end of the class. For example say you have an array like String[] words = { "Hello", "World" }; System.out.println(words); print something like [Ljava.lang.String;@45ee12a7 Unfortunately you have to know that the class is an object array, e.g. if you have justObject words, you have a problem and you have to know to call Arrays.toString(words) instead. This break encapsulation in a rather bad way and a common source of confusion on StackOverflow. I have asked different developers at Oracle about this and the impression I got is that it's too hard to fix it now. :(

This article presents the usage of sripted data set in the eclipse's BIRT.

This morning an interesting topic was posted to the Apache ServiceMix user forum, asking the question: To ServiceMix or not ServiceMix. In my mind the short answer is: NO Guillaume Nodet one of the key architects and long time committer on Apache ServiceMix already had his mind set 3 years ago when he wrong this blog post - Thoughts about ServiceMix. What has happened on the ServiceMix project was that the ServiceMix kernel was pulled out of ServiceMix into its own project - Apache Karaf. That happened in spring 2009, which Guillaume also blogged about. So is all that bad? No its IMHO all great. In fact having the kernel as a separate project, and Camel and CXF as the integration and WS/RS frameworks, would allow the ServiceMix team to focus on building the ESB that truly had value-add. But that did not happen. ServiceMix did not create a cross product security model, web console, audit and trace tooling, clustering, governance, service registry, and much more that people were looking for in an ESB (or related to a SOA suite). There were only small pieces of it, but never really baked well into the project. That said its not too late. I think the ServiceMix project is dying, but if a lot of people in the community step up, and contribute and work on these things, then it can bring value to some users. But I seriously doubt this will happen. PS: 6 years ago I was working as a consultant and looked at the next integration platform for a major Danish organization, and we looked at ServiceMix back then and dismissed it due its JBI nature, and the new OSGi based architecture was only just started. And frankly it has taken a long long time to mature Apache Karaf / Felix / Aries and the other pieces in OSGi to what they are today to offer a stable and sound platform for users to build their integration applications. That was not the case 4-6 years ago. Okay No to ServiceMix - what are my options then? So what should use you instead of ServiceMix? Well in my mind you have at least these two options. 1) Use Apache Karaf and add the pieces you need, such as Camel, CXF, ActiveMQ and build your own ESB. These individual projects have regular releases, and you can upgrade as you need. The ServiceMix project only has the JBI components in additional, that you should NOT use. Only legacy users that got on the old ServiceMix 3.x wagon may need to use this in a graceful upgrade from JBI to Karaf based containers. 2) Take a look at fabric8. IMHO fabric8 is all that value-add the ServiceMix project did not create, and a lot more. James Strachan, just blogged today about some of his thoughts on fabric8, JBoss Fuse, and Karaf. I encourage you to take a read. For example he talks about how fabric becomes poly container, so you have a much wider choice of which containers/JVM to run your integration applications. OSGi is no longer a requirement. (IMHO that is very very existing and potentially a changer). I encourage you to check out fabric8 web-site, and also read the overview and motivation sections of the documentation. And then check out some of the videos. After the upcoming JBoss Fuse 6.1 release, the Fuse team at Red Hat will have more time and focus to bring the documentation at fabric8 up to date covering all the functionality we have (there is a lot more), and as well bring out a 1.0 community released using pure community releases. This gives end users a 100% free to use out of the box release. And users looking for a commercial release can then use JBoss Fuse. Best of both worlds. Summary Okay back to the question - to ServiceMix or not. Then NO. Innovation happens outside ServiceMix, and also more and more outside Apache. If you have thoughts then you can share those in comments to this blog, or better yet, get involved in the discussion forum at the ServiceMix user forum. PPS: The thoughts on this blog is mine alone, and are not any official words from my employer.

Background SPNego is RFC 4178 used for negotiation either NTLM or Kerberos based SSO. A typical use case is for web applications to reuse the authentication used by Desktops such as Windows or Linux. In this article, we will explore approaches for SPNego authentication with JBoss Enterprise Application Platform. JBoss Negotiation is the library that provides the SPNego authentication support in JBoss. This library has been integrated in JBoss EAP and WildFly Application Server. Checklist Obtain JBoss EAP from jboss.org. Enable your JavaEE Web Application for SPNego Authentication. Configure JBoss EAP for SPNego. Configure your Browsers for SPNego. Start JBoss EAP. Test your web application. Obtain JBoss EAP from jboss.org Download JBoss EAP 6.2 or newer from http://www.jboss.org/products/eap You can also use WildFly Application Server from http://www.wildfly.org. Your configuration may vary slightly. Enable your JavaEE Web Application for SPNego Authentication It is easier to use a demo web application as a starting point. You can then modify your web application for SPNego authentication. The demo web application we use for this article is called spnego-demo, by my colleague, Josef Cazek. The demo web application is available at https://github.com/kwart/spnego-demo . You can also download the spnego-demo.war from here . Fully configured web application spnego-demo.war can be obtained from this location . Copy the spnego-demo.war in your jboss-eap-6.2/standalone/deployments directory. Configure JBoss EAP for SPNego Authentication You will need to configure a couple of security domains and system properties in JBoss EAP6. There are two ways by which you can configure: either manual editing or using CLI tool. Manual Editing of configuration file standalone.xml in jboss-eap-6.2/standalone/configuration Add system properties to this file. Remember to put this block right after the extensions block (around line 25 of the configuration file). Add security domains to this file. Remember to put these blocks in the block. Using Command Line Interface to update JBoss EAP Go to the bin directory of JBoss EAP 6.2 and run the following. $ cat << EOT > $SPNEGO_TEST_DIR/cli-commands.txt /subsystem=security/security-domain=host:add(cache-type=default) /subsystem=security/security-domain=host/authentication=classic:add(login-modules=[{"code"=>"Kerberos", "flag"=>"required", "module-options"=>[ ("debug"=>"true"),("storeKey"=>"true"),("refreshKrb5Config"=>"true"),("useKeyTab"=>"true"),("doNotPrompt"=>"true"),("keyTab"=>"$SPNEGO_TEST_DIR/http.keytab"),("principal"=>"HTTP/[email protected]")]}]) {allow-resource-service-restart=true} /subsystem=security/security-domain=SPNEGO:add(cache-type=default) /subsystem=security/security-domain=SPNEGO/authentication=classic:add(login-modules=[{"code"=>"SPNEGO", "flag"=>"required", "module-options"=>[("serverSecurityDomain"=>"host")]}]) {allow-resource-service-restart=true} /subsystem=security/security-domain=SPNEGO/mapping=classic:add(mapping-modules=[{"code"=>"SimpleRoles", "type"=>"role", "module-options"=>[("[email protected]"=>"Admin"),("[email protected]"=>"User")]}]) {allow-resource-service-restart=true} /system-property=java.security.krb5.conf:add(value="$SPNEGO_TEST_DIR/krb5.conf") /system-property=java.security.krb5.debug:add(value=true) /system-property=jboss.security.disable.secdomain.option:add(value=true) :reload() EOT $ ./jboss-cli.sh -c --file=$SPNEGO_TEST_DIR/cli-commands.txt This is explained in https://github.com/kwart/spnego-demo/blob/master/README.md We will need a keytab file. In this example, we will use the Kerberos Server using ApacheDS (as explained in Appendix A). $ java -classpath kerberos-using-apacheds.jar org.jboss.test.kerberos.CreateKeytab HTTP/[email protected] httppwd http.keytab Note that the http.keytab has been configured in the security domain called "host" in standalone.conf. So place the keytab file appropriately while correcting the path defined in security domain. More information is available at https://github.com/kwart/kerberos-using-apacheds/blob/master/README.md JBoss EAP will need a keytab file. In this example we use a keytab called as http.keytab Different tools such as ktutil exist to create keytab files. Keytab files contain Kerberos Principals and encrypted keys. It is important to safeguard keytab files. It is very important that JBoss EAP configuration for keytab in the security domain "host" refers to the actual path of the keytab file. Configure your Browsers for SPNego The browsers such as Microsoft IE, Mozilla Firefox, Google Chrome, Apple Safari have different settings for enabling SPNego or Integrated Authentication. Start JBoss EAP Go to the bin directory of JBoss EAP 6.2 and either use standalone.sh (Unix/Linux) or standalone.bat to start your instance. Test your Web Application Assuming you have followed Appendix A steps to start the kerberos server and done kinit, you are ready to test the web application. In this article we have used spnego-demo, we can test that by going to http://localhost:8080/spnego-demo/ You can click on the "User Page" link and you should be able to see the principal name as "[email protected]" Appendix A Local Kerberos Server Download the zip file https://github.com/kwart/kerberos-using-apacheds/archive/master.zip Unzip the zip file into a directory. Build the package using maven. $ mvn clean package Start the Kerberos Server as $ java -jar target/kerberos-using-apacheds.jar test.ldif A krb5.conf file has been created. Login now using [email protected] $ kinit [email protected] Password for [email protected]: secret Launch Firefox via command line from where the kinit was run On MacOSX $open -a firefox http://localhost:8080/spnego-demo/ Appendix B Kerberos Command Line Utilities klist can be used to see the current kerberos tickets. $ klist Credentials cache: API:501:10 Principal: [email protected] Issued Expires Principal Feb 9 21:19:30 2014 Feb 10 07:19:27 2014 krbtgt/[email protected] kdestroy can be used to clear the current kerberos tickets. References SPNego Demo Web Application: https://github.com/kwart/spnego-demo Kerberos Server using ApacheDS: https://github.com/kwart/kerberos-using-apacheds JBoss EAP 6 http://www.jboss.org/products/eap PicketLink Open Source Project: http://www.picketlink.org Troubleshooting https://docs.jboss.org/author/display/PLINK/SPNego+Support+Questions Remember krb5.conf is important for client side kerberos interactions. You can use a environment variable on Unix/Linux/Mac systems called KRB5_CONFIG to point to your krb5.conf Acknowledgement Darran Lofthouse for the wonderful JBoss Negotiation Project and Josef Czacek for the SPNego-demo and Kerberos_using_Apache DS projects.

Lambda expressions are by far the most discussed and promoted feature of Java 8. While I agree that Lambdas are a large improvement I think that some other Java 8 feature go a bit short because of the Lambda hype. In this post I want to show a number of examples from another nice Java 8 feature: Type Annotations. Type Annotations are annotations that can be placed anywhere you use a type. This includes the new operator, type casts, implements clauses and throws clauses. Type Annotations allow improved analysis of Java code and can ensure even stronger type checking. In source code this means we get two new ElementTypes for annotations: @Target({ElementType.TYPE_USE, ElementType.TYPE_PARAMETER}) public @interface Test { } The enum value TYPE_PARAMETER allows an annotation to be applied at type variables (e.g. MyClass). Annotations with target TYPE_USE can be applied at any type use. Please note that the annotations from the following examples will not work out of the box when Java 8 is released. Java 8 only provides the ability to define these types of annotations. It is then up to framework and tool developers to actually make use of it. So this is a collection of annotations frameworks could give us in the future. Most of the examples are taken from the Type Annotations specification and various Java 8 presentations. Simple type definitions with type annotations look like this: @NotNull String str1 = ... @Email String str2 = ... @NotNull @NotBlank String str3 = ... Type annotations can also be applied to nested types Map.@NonNull Entry = ... Constructors with type annotations: new @Interned MyObject() new @NonEmpty @Readonly List(myNonEmptyStringSet) They work with nested (non static) class constructors too: myObject.new @Readonly NestedClass() Type casts: myString = (@NonNull String) myObject; query = (@Untainted String) str; Inheritance: class UnmodifiableList implements @Readonly List { ... } We can use type Annotations with generic type arguments: List<@Email String> emails = ... List<@ReadOnly @Localized Message> messages = ... Graph<@Directional Node> directedGraph = ... Of course we can nest them: Map<@NonNull String, @NonEmpty List<@Readonly Document>> documents; Or apply them to intersection Types: public & @Localized MessageSource> void foo(...) { ... } Including parameter bounds and wildcard bounds: class Folder { ... } Collection c = ... List<@Immutable ? extends Comparable> unchangeable = ... Generic method invocation with type annotations looks like this: myObject.<@NotBlank String>myMethod(...); For generic constructors, the annotation follows the explicit type arguments: 1 new @Interned MyObject() Throwing exceptions: void monitorTemperature() throws @Critical TemperatureException { ... } void authenticate() throws @Fatal @Logged AccessDeniedException { ... } Type annotations in instanceof statements: boolean isNonNull = myString instanceof @NonNull String; boolean isNonBlankEmail = myString instanceof @NotBlank @Email String; And finally Java 8 method and constructor references: @Vernal Date::getDay List<@English String>::size Arrays::<@NonNegative Integer>sort Conclusion Type annotations are an interesting addition to the Java type system. They can be applied to any use of a type and enable a more detailed code analysis. If you want to use Type annotations right now you should have a look at the Checker Framework.

If you are a programmer and have to deal with cryptography issues, you've surely heard about keywords such as encryption, decryption and key management. The last key word, key management, is defined as a group of operations such as generating, exchanging, storing and protecting security artifacts (i.e. keys and certificates). Security artifacts are essential parts of any cryptography operations. Without effective management of such valuable resources, the system can be easily compromised by attackers. Java supports key management by introducing two utilities; Java Keys Store or JKS as short and Java Keytool Utility. Java Key Store is a handy and safe storage to store keys and certificates. Java key store API describes methods and properties of Java keystore class which makes it possible to work with keystore file programmatically. To manage keys and certificates, Java provides a second utility named Java Keytool Utility. Keytool utility is included and delivered with JDK (Java Development Kit) distributions. The Keytool manual introduces and describes various commands and options that are available and provides by Java Keytool utility. Key management is feasible by services that are offered by both Java keystore and Java Keytool utility together. The Key management that Java provides is covering most of programming scenarios. Unfortunately there is only one limitation. Java Keytool utility as the main key management unit does not support any means to import custom created keys to Java keystore. It only supports key generation which results in auto generated keys. This is a major shortcoming in situations where there must be key exchange between application peers. In such situations key specifications are specific to the security models which are agreed between developers. Sometimes the keys are byte streams which are not accompanied with any certificates. These streams are defined as cryptography artifacts and must be protected and saved by Java keystore. One solution to this problem is to use third party utilities such as Openssl. Openssl utility offers a mechanism which is a hack to the unavailability of key import in Java Keytool utility. The trick is to save keys in PKCS12 format using the Openssl utility, and treating the created artifact as a new keystore. Fortunately Java Keytool utility supports key store merge option. The created keystore by Openssl utility then can be merged into any Java keystore by Java Keytool utility. Unfortunately I could not succeed in following this solution. One reason could be that my key had customized specifications such as size and value, plus there was no certificate available to accompany it as well. It seemed that there was no other way to overcome such limitation. I found a solution, pretty easy and quick that helped me achieving the result I wanted without being dependent on any third party tools. One advantage of this method is the use of current options that are offered by both Keytool and Java Keystore utilities. Let’s name this method “Key Replacement”. Firstly a new key must be created, for example, a secret key. The secret key will be auto generated by the Keytool utility and will be saved under a known ALIAS inside a new key store or in an existing one. Open your command prompt and issue the following command: keytool -genseckey -alias mykey -keyalg DES -keysize 56 -storetype jceks -keystore Make sure you have set your Java runtime environment correctly. Description and details of the above command and options can be found on Keytool manual. After issuing the above command, you will be asked to provide a password for the keystore. If the keystore already exists, provide its password; otherwise enter a password to be set for the newly created keystore. If the operation was successful, you can list the keystore entries by issuing the following command: keytool -list -v -storetype JCEKS -keystore The result of list command will be a list of keystore's entries. In our case, the record we seek is something like : Keystore type: JCEKS Keystore provider: SunJCE Your keystore contains 1 entry Alias name: mykey Creation date: Sep 30, 2013 Entry type: SecretKeyEntry As you can see the newly created key is represented by the alias we have set. This key is auto generated by Java Keytool utility. We are one step closer to what we needed. We have created a key entry with the alias we want. The final step is to change the key entry value with our customized value. Remaining steps consists of, locating the target key entry inside the keystore by its alias and change its value with our own value programmatically. The following simple java program will do the job. KeyStore ks = KeyStore.getInstance("JCEKS"); char[] password = "PASSWORD TO KEYSATORE".toCharArray(); java.io.FileInputStream fis = null; try { ks.load(new FileInputStream("PATH TO KEY STORE"), password); } finally { if (fis != null) { fis.close(); } } SecretKey mySecretKey = new SecretKeySpec(Util.hex2byte("5A5A5A5A5A5A5A5A"), 0, Util.hex2byte("5A5A5A5A5A5A5A5A").length, "DES"); KeyStore.SecretKeyEntry skEntry = new KeyStore.SecretKeyEntry(mySecretKey); ks.setEntry("mykey", skEntry, new KeyStore.PasswordProtection(password)); java.io.FileOutputStream fos = null; try { fos = new java.io.FileOutputStream("PATH TO KEYSTORE"); ks.store(fos, password); } finally { if (fos != null) { fos.close(); } } This java program will: · Open the keystore. · Load the key store prior to any operation. · Build a secret key with desired specs (Custom value and Custom length). · Replace the value of target key by using the setEntry() method of keystore object by providing its alias and a new key value. · Finally close and save the keystore object. To double check the modification, use the following code to locate and display the modified key value by loading the keystore object again. try { ks.load(new FileInputStream("PATH TO KEY SOTRE"), password); } finally { if (fis != null) { fis.close(); } } Key key = ks.getKey("mykey ", password); System.out.println("-----BEGIN PRIVATE KEY-----"); System.out.println(new BASE64Encoder().encode(key.getEncoded())); System.out.println("-----END PRIVATE KEY-----"); The steps are straight forward: · Load the key store object. · Load the target key by using the getKey() method and specifying its alias. · Fetch the key value and output its value in PEM format (Base 64 encoding). Voila! That’s our key. This article shows some simple steps which can be used to import a custom created secret key to java keystore. Hope this article will be helpful in cases where the tools such as Openssl utility has no use. Sam,

Every now and then we’ll come across a search problem that can’t simply be solved with plain Solr relevancy. This usually means a customer knows exactly how documents should be scored. They may have little tolerance for close approximations of this scoring through Solr boosts, function queries, etc. They want a Lucene-based technology for text analysis and performant data structures, but they need to be extremely specific in how documents should be scored relative to each other. Well for those extremely specialized cases we can prescribe a little out-patient surgery to your Solr install – building your own Lucene Query. This is the Nuclear Option Before we dive in, a word of caution. Unless you just want the educational experience, building a custom Lucene Query should be the “nuclear option” for search relevancy. It’s very fiddly and there are many ins-and-outs. If you’re actually considering this to solve a real problem, you’ve already gone down the following paths: You’ve utilized Solr’s extensive set of query parsers & features including function queries, joins, etc. None of this solved your problem You’ve exhausted the ecosystem of plugins that extend on the capabilities in (1). That didn’t work. You’ve implemented your own query parser plugin that takes user input and generates existing Lucene queries to do this work. This still didn’t solve your problem. You’ve thought carefully about your analyzers – massaging your data so that at index time and query time, text lines up exactly as it should to optimize the behavior of existing search scoring. This still didn’t get what you wanted. You’ve implemented your own custom Similarity that modifies how Lucene calculates the traditional relevancy statistics – query norms, term frequency, etc. You’ve tried to use Lucene’s CustomScoreQuery to wrap an existing Query and alter each documents score via a callback. This still wasn’t low-level enough for you, you needed even more control. If you’re still reading you either think this is going to be fun/educational (good for you!) or you’re one of the minority that must control exactly what happens with search. If you don’t know, you can of course contact us for professional services. Ok back to the action… Refresher – Lucene Searching 101 Recall that to search in Lucene, we need to get a hold of an IndexSearcher. This IndexSearcher performs search over an IndexReader. Assuming we’ve created an index, with these classes we can perform searches like in this code: Directory dir = new RAMDirectory(); IndexReader idxReader = new IndexReader(dir); idxSearcher idxSearcher = new IndexSearcher(idxReader) Query q = new TermQuery(new Term(“field”, “value”)); idxSearcher.search(q); Let’s summarize the objects we’ve created: Directory – Lucene’s interface to a file system. This is pretty straight-forward. We won’t be diving in here. IndexReader – Access to data structures in Lucene’s inverted index. If we want to look up a term, and visit every document it exists in, this is where we’d start. If we wanted to play with term vectors, offsets, or anything else stored in the index, we’d look here for that stuff as well. IndexSearcher — wraps an IndexReader for the purpose of taking search queries and executing them. Query – How we expect the searcher to perform the search, encompassing both scoring and which documents are returned. In this case, we’re searching for “value” in field “field”. This is the bit we want to toy with In addition to these classes, we’ll mention a support class exists behind the scenes: Similarity – Defines rules/formulas for calculating norms at index time and query normalization. Now with this outline, let’s think about a custom Lucene Query we can implement to help us learn. How about a query that searches for terms backwards. If the document matches a term backwards (like ananab for banana), we’ll return a score of 5.0. If the document matches the forwards version, let’s still return the document, with a score of 1.0 instead. We’ll call this Query “BackwardsTermQuery”. This example is hosted here on github. A tale of 3 classes – A Query, A Weight, and a Scorer Before we sling code, let’s talk about general architecture. A Lucene Query follows this general structure: A custom Query class, inheriting from Query A custom Weight class, inheriting from Weight A custom Scorer class inheriting from Scorer These three objects wrap each other. A Query creates a Weight, and a Weight in turn creates a Scorer. A Query is itself a very straight-forward class. One of its main responsibilities when passed to the IndexSearcher is to create a Weight instance. Other than that, there are additional responsibilities to Lucene and users of your Query to consider, that we’ll discuss in the “Query” section below. A Query creates a Weight. Why? Lucene needs a way to track IndexSearcher level statistics specific to each query while retaining the ability to reuse the query across multiple IndexSearchers. This is the role of the Weight class. When performing a search, IndexSearcher asks the Query to create a Weight instance. This instance becomes the container for holding high-level statistics for the Query scoped to this IndexSearcher (we’ll go over these steps more in the “Weight” section below). The IndexSearcher safely owns the Weight, and can abuse and dispose of it as needed. If later the Query gets reused by another IndexSearcher, a new Weight simply gets created. Once an IndexSearcher has a Weight, and has calculated any IndexSearcher level statistics, the IndexSearcher’s next task is to find matching documents and score them. To do this, the Weight in turn creates a Scorer. Just as the Weight is tied closely to an IndexSearcher, a Scorer is tied to an individual IndexReader. Now this may seem a little odd – in our code above the IndexSearcher always has exactly one IndexReader right? Not quite. See, a little hidden implementation detail is that IndexReaders may actually wrap other smaller IndexReaders – each tied to a different segment of the index. Therefore, an IndexSearcher needs to have the ability score documents across multiple, independent IndexReaders. How your scorer should iterate over matches and score documents is outlined in the “Scorer” section below. So to summarize, we can expand the last line from our example above… idxSearcher.search(q); … into this psuedocode: Weight w = q.createWeight(idxSearcher); // IndexSearcher level calculations for weight Foreach IndexReader idxReader: Scorer s = w.scorer(idxReader); // collect matches and score them Now that we have the basic flow down, let’s pick apart the three classes in a little more detail for our custom implementation. Our Custom Query What should our custom Query implementation look like? Query implementations always have two audiences: (1) Lucene and (2) users of your Query implementation. For your users, expose whatever methods you require to modify how a searcher matches and scores with your query. Want to only return as a match 1/3 of the documents that match the query? Want to punish the score because the document length is longer than the query length? Add the appropriate modifier on the query that impacts the scorer’s behavior. For our BackwardsTermQuery, we don’t expose accessors to modify the behavior of the search. The user simply uses the constructor to specify the term and field to search. In our constructor, we will simply be reusing Lucene’s existing TermQuery for searching individual terms in a document. private TermQuery backwardsQuery; private TermQuery forwardsQuery; public BackwardsTermQuery(String field, String term) { // A wrapped TermQuery for the reverse string Term backwardsTerm = new Term(field, new StringBuilder(term).reverse().toString()); backwardsQuery = new TermQuery(backwardsTerm); // A wrapped TermQuery for the Forward Term forwardsTerm = new Term(field, term); forwardsQuery = new TermQuery(forwardsTerm); } Just as importantly, be sure your Query meets the expectation of Lucene. Most importantly, you MUST override the following. createWeight() hashCode() equals() The method createWeight() we’ve discussed. This is where you’ll create a weight instance for an IndexSearcher. Pass any parameters that will influence the scoring algorithm, as the Weight will in turn be creating a searcher. Even though they are not abstract methods, overriding the hashCode()/equals() methods is very important. These methods are used by Lucene/Solr to cache queries/results. If two queries are equal, there’s no reason to rerun the query. Running another instance of your query could result in seeing the results of your first query multiple times. You’ll see your search for “peas” work great, then you’ll search for “bananas” and see “peas” search results. Override equals() and hashCode() so that “peas” != bananas. Our BackwardsTermQuery implements createWeight() by creating a custom BackwardsWeight that we’ll cover below: @Override public Weight createWeight(IndexSearcher searcher) throws IOException { return new BackwardsWeight(searcher); } BackwardsTermQuery has a fairly boilerplate equals() and hashCode() that passes through to the wrapped TermQuerys. Be sure equals() includes all the boilerplate stuff such as the check for self-comparison, the use of the super equals operator, the class comparison, etc etc. By using Lucene’s unit test suite, we can get a lot of good checks that our implementation of these is correct. @Override public boolean equals(Object other) { if (this == other) { return true; } if (!super.equals(other)) { return false; } if (getClass() != other .getClass()) { return false; } BackwardsTermQuery otherQ = (BackwardsTermQuery)(other); if (otherQ.getBoost() != getBoost()) { return false; } return otherQ.backwardsQuery.equals(backwardsQuery) && otherQ.forwardsQuery.equals(forwardsQuery); } @Override public int hashCode() { return super.hashCode() + backwardsQuery.hashCode() + forwardsQuery.hashCode(); } Our Custom Weight You may choose to use Weight simply as a mechanism to create Scorers (where the real meat of search scoring lives). However, your Custom Weight class must at least provide boilerplate implementations of the query normalization methods even if you largely ignore what is passed in: getValueForNormalization normalize These methods participate in a little ritual that IndexSearcher puts your Weight through with the Similarity for query normalization. To summarize the query normalization code in the IndexSearcher: float v = weight.getValueForNormalization(); float norm = getSimilarity().queryNorm(v); weight.normalize(norm, 1.0f); Great, what does this code do? Well a value is extracted from Weight. This value is then passed to a Similarity instance that “normalizes” that value. Weight then receives this normalized value back. In short, this is allowing IndexSearcher to give weight some information about how its “value for normalization” compares to the rest of the stuff being searched by this searcher. This is extremely high level, “value for normalization” could mean anything, but here it generally means “what I think is my weight” and what Weight receives back is what the searcher says “no really here is your weight”. The details of what that means depend on the Similarity and Weight implementation. It’s expected that the Weight’s generated Scorer will use this normalized weight in scoring. You can chose to do whatever you want in your own Scorer including completely ignoring what’s passed to normalize(). While our Weight isn’t factoring into the scoring calculation, for consistency sake, we’ll participate in the little ritual by overriding these methods: @Override public float getValueForNormalization() throws IOException { return backwardsWeight.getValueForNormalization() + forwardsWeight.getValueForNormalization(); } @Override public void normalize(float norm, float topLevelBoost) { backwardsWeight.normalize(norm, topLevelBoost); forwardsWeight.normalize(norm, topLevelBoost); } Outside of these query normalization details, and implementing “scorer”, little else happens in the Weight. However, you may perform whatever else that requires an IndexSearcher in the Weight constructor. In our implementation, we don’t perform any additional steps with IndexSearcher. The final and most important requirement of Weight is to create a Scorer. For BackwardsWeight we construct our custom BackwardsScorer, passing scorers created from each of the wrapped queries to work with. @Override public Scorer scorer(AtomicReaderContext context, boolean scoreDocsInOrder, boolean topScorer, Bits acceptDocs) throws IOException { Scorer backwardsScorer = backwardsWeight.scorer(context, scoreDocsInOrder, topScorer, acceptDocs); Scorer forwardsScorer = forwardsWeight.scorer(context, scoreDocsInOrder, topScorer, acceptDocs); return new BackwardsScorer(this, context, backwardsScorer, forwardsScorer); } Our Custom Scorer The Scorer is the real meat of the search work. Responsible for identifying matches and providing scores for those matches, this is where the lion share of our customization will occur. It’s important to note that a Scorer is also a Lucene DocIdSetIterator. A DocIdSetIterator is a cursor into a set of documents in the index. It provides three important methods: docID() – what is the id of the current document? (this is an internal Lucene ID, not the Solr “id” field you might have in your index) nextDoc() – advance to the next document advance(target) – advance (seek) to the target One uses a DocIdSetIterator by first calling nextDoc() or advance() and then reading the docID to get the iterator’s current location. The value of the docIDs only increase as they are iterated over. By implementing this interface a Scorer acts as an iterator over matches in the index. A Scorer for the query “field1:cat” can be iterated over in this manner to return all the documents that match the cat query. In fact, if you recall from my article, this is exactly how the terms are stored in the search index. You can chose to either figure out how to correctly iterate through the documents in a search index, or you can use the other Lucene queries as building blocks. The latter is often the simplest. For example, if you wish to iterate over the set of documents containing two terms, simply use the scorer corresponding to a BooleanQuery for iteration purposes. The first method of our scorer to look at is docID(). It works by reporting the lowest docID() of our underlying scorers. This scorer can be thought of as being “before” the other in the index, and as we want to report numerically increasing docIDs, we always want to chose this value: @Override public int docID() { int backwordsDocId = backwardsScorer.docID(); int forwardsDocId = forwardsScorer.docID(); if (backwordsDocId <= forwardsDocId && backwordsDocId != NO_MORE_DOCS) { currScore = BACKWARDS_SCORE; return backwordsDocId; } else if (forwardsDocId != NO_MORE_DOCS) { currScore = FORWARDS_SCORE; return forwardsDocId; } return NO_MORE_DOCS; } Similarly, we always want to advance the scorer with the lowest docID, moving it ahead. Then, we report our current position by returning docID() which as we’ve just seen will report the docID of the scorer that advanced the least in the nextDoc() operation. @Override public int nextDoc() throws IOException { int currDocId = docID(); // increment one or both if (currDocId == backwardsScorer.docID()) { backwardsScorer.nextDoc(); } if (currDocId == forwardsScorer.docID()) { forwardsScorer.nextDoc(); } return docID(); } In our advance() implementation, we allow each Scorer to advance. An advance() implementation promises to either land docID() exactly on or past target. Our call to docID() after we call advance will return either that one or both are on target, or it will return the lowest docID past target. @Override public int advance(int target) throws IOException { backwardsScorer.advance(target); forwardsScorer.advance(target); return docID(); } What a Scorer adds on top of DocIdSetIterator is the “score” method. When score() is called, a score for the current document (the doc at docID) is expected to be returned. Using the full capabilities of the IndexReader, any number of information stored in the index can be consulted to arrive at a score either in score() or while iterating documents in nextDoc()/advance(). Given the docId, you’ll be able to access the term vector for that document (if available) to perform more sophisticated calculations. In our query, we’ll simply keep track as to whether the current docID is from the wrapped backwards term scorer, indicating a match on the backwards term, or the forwards scorer, indicating a match on the normal, unreversed term. Recall docID() is always called on advance/nextDoc. You’ll notice we update currScore in docID, updating it every time the document advances. @Override public float score() throws IOException { return currScore; } A Note on Unit Testing Now that we have an implementation of a search query, we’ll want to test it! I highly recommend using Lucene’s test framework. Lucene will randomly inject different implementations of various support classes, index implementations, to throw your code off balance. Additionally, Lucene creates test implementations of classes such as IndexReader that work to check whether your Query correctly fulfills its contract. In my work, I’ve had numerous cases where tests would fail intermittently, pointing to places where my use of Lucene’s data structures subtly violated the expected contract. An example unit test is included in the github project associated with this blog post. Wrapping Up That’s a lot of stuff! And I didn’t even cover everything there is to know! As an exercise to the reader, you can explore the Scorer methods cost() and freq(), as well as the rewrite() method of Query used optionally for optimization. Additionally, I haven’t explored how most of the traditional search queries end up using a framework of Scorers/Weights that don’t actually inherit from Scorer or Weight known as “SimScorer” and “SimWeight”. These support classes consult a Similarity instance to customize calculation certain search statistics such as tf, convert a payload to a boost, etc. In short there’s a lot here! So tread carefully, there’s plenty of fiddly bits out there! But have fun! Creating a custom Lucene query is a great way to really understand how search works, and the last resort short in solving relevancy problems short of creating your own search engine. And if you have relevancy issues, contact us! If you don’t know whether you do, our search relevancy product, Quepid – might be able to tell you!

Since JBoss EAP 6.1 / AS 7.2.0 is modular and you can exclude what modules are visible to your webapp, you would expect it to be easy to ignore the built-in implementation of JAX-RS (Rest Easy 2.3.6) and use a custom one (3.0.6). However, sadly, this is not the case. You are stuck with what the official guide suggests, i.e.upgrading Rest Easy globally – provided that no other webapp running on the server becomes broken by the upgrade. This should be enough to exclude the built-in Rest Easy and be able to use a version included in the webapp: However it is far from working. This nearly does the job (though few of the exclusions might be unnecessary): However, only nearly. The problem is that the exclusion of javax.ws.rs.api has no effect. It seems as the core Java EE APIs cannot be excluded. Dead end. BTW, this are my final jax-rs related dependencies: // resteasyVersion = '3.0.6.Final' compile group: 'org.jboss.resteasy', name: 'jaxrs-api', version: resteasyVersion compile group: 'org.jboss.resteasy', name: 'resteasy-jaxrs', version: resteasyVersion compile group: 'org.jboss.resteasy', name: 'resteasy-jackson2-provider', version: resteasyVersion // JSONP compile group: 'org.jboss.resteasy', name: 'async-http-servlet-3.0', version: resteasyVersion // Required at runtime compile group: 'org.jboss.resteasy', name: 'resteasy-servlet-initializer', version: resteasyVersion // Required at runtime An approximate history of failed attempts I do not remember anymore exactly all the dead ends I went through but here is an approximate overview of the exceptions I got at deployment or runtime. java.lang.ClassNotFoundException: org.jboss.resteasy.plugins.server.servlet.HttpServlet30Dispatcher - fixed likely by adding org.jboss.resteasy:async-http-servlet-3.0:3.0.6.Final to the dependencies java.lang.ClassCastException: myapp.rs.RestApplication cannot be cast to javax.servlet.Servlet - fixed likely by adding org.jboss.resteasy:resteasy-servlet-initializer:3.0.6.Final to the dependencies java.lang.NoSuchMethodError: org.jboss.resteasy.spi.ResteasyProviderFactory.(Lorg/jboss/resteasy/spi/ResteasyProviderFactory;)V - fixed likely by adding more of the RestEasy/Jackson modules to the exclusion list java.lang.NoSuchMethodError: org.jboss.resteasy.specimpl.BuiltResponse.getHeaders()Ljavax/ws/rs/core/MultivaluedMap; - this is the ultimate one that cannot be fixed; the problem is that BuiltResponse from resteasy-jaxrs inherits from javax.ws.rs.core.Response however the version of this class from jaxrs-api-3.0.6.Final.jar is ignored in favour of Response from JAX-RS 1.1 from the javax.ws.rs.api module (/jboss-eap-6.1.0/modules/system/layers/base/javax/ws/rs/api/main/jboss-jaxrs-api_1.1_spec-1.0.1.Final-redhat-2.jar), which lacks the getHeaders method and, as mentioned, cannot be excluded. (Thanks to allprog for hinting at this confilct!) Conclusion The only way to use a newer JAX-RS is to upgrade the JBoss modules. If that would break some other webapps, you are stuck. Lessons learned: Application servers with the plenty of out-of-the-box, well-integrated (?) functionality seem attractive but when you run into conflicting libraries and classloading issues, their value diminishes rapidly. Starting with something simple that you control fully, such as Jettty, is perhaps in the long run a better solution. Also, running multiple webapps on the same server was perhaps smart in 2000 but is not worth the pain nowadays. We have plenty of disk space and memory so reuse of libraries is unimportant and the ability to manage global settings for all apps at one place has certainly better alternatives. Microservices FTW! Update: As Yannick has pointed out , the conclusion seems too general and unjustified. That is because I have arrived to it already before and this problem with JBoss serves only as another confirmation. Solution? Bill Burke has proposed a solution : I’ve lived through your pain and here’s a solution that works on AS7.1.1, EAP6.x, and Wildfly: https://github.com/keycloak/keycloak/blob/master/server/src/main/webapp/WEB-INF/jboss-deployment-structure.xml JBoss Modules don’t suck. The implicit dependencies do. The culprit is the “javaee.api” module which you have missing from your exclude. This module includes every single Java EE API. I haven’t tried, but I think if you reduce your excludes to just that module and the “resteasy” subsystem, it will work. ... FYI, I believe the “javaee.api” module problem is fixed in Wildfly so you won’t have to do the extra exclude.

At the end of last year I was playing around with running scheduled tasks to monitor a Neo4j cluster and one of the problems I ran into was that the monitoring would sometimes exit. I eventually realised that this was because a RuntimeException was being thrown inside the Runnable method and I wasn’t handling it. The following code demonstrates the problem: import java.util.ArrayList; import java.util.List; import java.util.concurrent.*; public class RunnableBlog { public static void main(String[] args) throws ExecutionException, InterruptedException { ScheduledExecutorService executor = Executors.newSingleThreadScheduledExecutor(); executor.scheduleAtFixedRate(new Runnable() { @Override public void run() { System.out.println(Thread.currentThread().getName() + " -> " + System.currentTimeMillis()); throw new RuntimeException("game over"); } }, 0, 1000, TimeUnit.MILLISECONDS).get(); System.out.println("exit"); executor.shutdown(); } } If we run that code we’ll see the RuntimeException but the executor won’t exit because the thread died without informing it: Exception in thread "main" pool-1-thread-1 -> 1391212558074 java.util.concurrent.ExecutionException: java.lang.RuntimeException: game over at java.util.concurrent.FutureTask$Sync.innerGet(FutureTask.java:252) at java.util.concurrent.FutureTask.get(FutureTask.java:111) at RunnableBlog.main(RunnableBlog.java:11) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:601) at com.intellij.rt.execution.application.AppMain.main(AppMain.java:120) Caused by: java.lang.RuntimeException: game over at RunnableBlog$1.run(RunnableBlog.java:16) at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:471) at java.util.concurrent.FutureTask$Sync.innerRunAndReset(FutureTask.java:351) at java.util.concurrent.FutureTask.runAndReset(FutureTask.java:178) at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$301(ScheduledThreadPoolExecutor.java:178) at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:293) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1110) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:603) at java.lang.Thread.run(Thread.java:722) At the time I ended up adding a try catch block and printing the exception like so: public class RunnableBlog { public static void main(String[] args) throws ExecutionException, InterruptedException { ScheduledExecutorService executor = Executors.newSingleThreadScheduledExecutor(); executor.scheduleAtFixedRate(new Runnable() { @Override public void run() { try { System.out.println(Thread.currentThread().getName() + " -> " + System.currentTimeMillis()); throw new RuntimeException("game over"); } catch (RuntimeException e) { e.printStackTrace(); } } }, 0, 1000, TimeUnit.MILLISECONDS).get(); System.out.println("exit"); executor.shutdown(); } } This allows the exception to be recognised and as far as I can tell means that the thread executing the Runnable doesn’t die. java.lang.RuntimeException: game over pool-1-thread-1 -> 1391212651955 at RunnableBlog$1.run(RunnableBlog.java:16) at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:471) at java.util.concurrent.FutureTask$Sync.innerRunAndReset(FutureTask.java:351) at java.util.concurrent.FutureTask.runAndReset(FutureTask.java:178) at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$301(ScheduledThreadPoolExecutor.java:178) at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:293) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1110) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:603) at java.lang.Thread.run(Thread.java:722) pool-1-thread-1 -> 1391212652956 java.lang.RuntimeException: game over at RunnableBlog$1.run(RunnableBlog.java:16) at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:471) at java.util.concurrent.FutureTask$Sync.innerRunAndReset(FutureTask.java:351) at java.util.concurrent.FutureTask.runAndReset(FutureTask.java:178) at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$301(ScheduledThreadPoolExecutor.java:178) at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:293) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1110) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:603) at java.lang.Thread.run(Thread.java:722) pool-1-thread-1 -> 1391212653955 java.lang.RuntimeException: game over at RunnableBlog$1.run(RunnableBlog.java:16) at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:471) at java.util.concurrent.FutureTask$Sync.innerRunAndReset(FutureTask.java:351) at java.util.concurrent.FutureTask.runAndReset(FutureTask.java:178) at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$301(ScheduledThreadPoolExecutor.java:178) at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:293) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1110) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:603) at java.lang.Thread.run(Thread.java:722) This worked well and allowed me to keep monitoring the cluster. However, I recently started reading ‘Java Concurrency in Practice‘ (only 6 years after I bought it!) and realised that this might not be the proper way of handling the RuntimeException. public class RunnableBlog { public static void main(String[] args) throws ExecutionException, InterruptedException { ScheduledExecutorService executor = Executors.newSingleThreadScheduledExecutor(); executor.scheduleAtFixedRate(new Runnable() { @Override public void run() { try { System.out.println(Thread.currentThread().getName() + " -> " + System.currentTimeMillis()); throw new RuntimeException("game over"); } catch (RuntimeException e) { Thread t = Thread.currentThread(); t.getUncaughtExceptionHandler().uncaughtException(t, e); } } }, 0, 1000, TimeUnit.MILLISECONDS).get(); System.out.println("exit"); executor.shutdown(); } } I don’t see much difference between the two approaches so it’d be great if someone could explain to me why this approach is better than my previous one of catching the exception and printing the stack trace.

Learn how to convert XML objects to Java, and vice versa.

Within this blog post I describe how you can use AspectJ to automatically translate one type of exception to another. The problem Sometimes we are in situations where we have to convert an exception (often thrown by a third-party library) to another type of exception. Assume you are using a persistence framework like hibernate and you do not want to leak hibernate specific exceptions out of a certain application layer. Maybe you are using more than one persistence technology and you want to wrap technology specific exceptions into a common base exception. In such situations, one can end with code like this: public class MyRepository { public Object getSomeData() { try { // assume hibernate is used to access some data } catch(HibernateException e) { // wrap hibernate specific exception into a general DataAccessException throw new DataAccessException(e); } } } Of course this becomes ugly if you have to do this every time you access a certain framework. The AspectJ way AspectJ is an aspect oriented programming (AOP) extension for Java. With AspectJ we can define Cross-cutting concerns that take care of the exception translation process for us. To get started we first have to add the AspectJ dependency to our project: org.aspectj aspectjrt 1.7.4 Next we have to set up ajc, the compiler and bytecode weaver for AspectJ. This step depends on the developing environment you are using, so I will not go into details here. Eclipse users should have a look at theAspectJ Development Tools (AJDT) for Eclipse. IntelliJ IDEA users should make sure the AspectJ plugin is enabled. There is also an AspectJ Maven plugin available (check this pom.xml for an example configuration). Now let's define our aspect using AspectJ annotations: @Aspect public class ExceptionTranslationAspect { @Around("execution(* com.mscharhag.exceptiontranslation.repository..*(..))") public Object translateToDataAccessException(ProceedingJoinPoint pjp) throws Throwable { try { return pjp.proceed(); } catch (HibernateException e) { throw new DataAccessException(e); } } } Using the @Aspect annotation we can declare a new aspect. Within this aspect we use the @Aroundannotation to define an advice that is always executed if the passed pointcut is matched. Here, the pointcut execution(* com.mscharhag.exceptiontranslation.repository..*(..)) tells AspectJ to call translateToDataAccessException() every time a method of a class inside thecom.mscharhag.exceptiontranslation.repository package is executed. Within translateToDataAccessException() we can use the passed ProceedingJoinPoint object to proceed the method execution we intercepted. In this example we just add a try/catch block around the method execution. Using the ProceedingJoinPoint instance we could also do more interesting things like analyzing the method signature using pjp.getSignature() or accessing method parameters withpjp.getArgs(). We can now remove the try/catch block from the example repository implementation shown above and use a simple test to verify our aspect is working: public class MyRepositoryTest { private MyRepository repository = new MyRepository(); @Test(expected = DataAccessException.class) public void testExceptionTranslation() { this.repository.getSomeData(); } } Conclusion Using AspectJ we can easily automate the conversion of Java runtime exceptions. This simplifies our code by removing try/catch blocks that would otherwise be required for exception translation. You can find the full source of the example project on GitHub.

Security has become a great topic of discussion in the last few years due to the recent releasing of documents from Edward Snowden and the explosion of hacking against online commerce stores like JC Penny, Sony andTarget. While this post will not give you all of the tools to help prevent the use of illegally sourced data, this post will provide a starting point for building a set of tools and tactics that will help prevent the use of data by other parties. This post will show how to adopt AES encryption for strings in a Java environment. It will talk about creating AES keys and storing AES keys in a JCEKS keystore format. A working example of the code in this blog is located athttps://github.com/mike-ensor/aes-256-encryption-utility It is recommended to read each section in order because each section builds off of the previous section, however, this you might want to just jump quickly jump to a particular section. Setup - Setup and create keys with keytool Encrypt - Encrypt messages using byte[] keys Decrypt - Decrypt messages using same IV and key from encryption Obtain Keys from Keystore - Obtain keys from keystore via an alias What is JCEKS? JCEKS stands for Java Cryptography Extension KeyStore and it is an alternative keystore format for the Java platform. Storing keys in a KeyStore can be a measure to prevent your encryption keys from being exposed. Java KeyStores securely contain individual certificates and keys that can be referenced by an alias for use in a Java program. Java KeyStores are often created using the "keytool" provided with the Java JDK. NOTE: It is strongly recommended to create a complex passcode for KeyStores to keep the contents secure. The KeyStore is a file that is considered to be public, but it is advisable to not give easy access to the file. Setup All encryption is governed by laws of each country and often have restrictions on the strength of the encryption. One example is that in the United States, all encryption over 128-bit is restricted if the data is traveling outside of the boarder. By default, the Java JCE implements a strength policy to comply with these rules. If a stronger encryption is preferred, and adheres to the laws of the country, then the JCE needs to have access to the stronger encryption policy. Very plainly put, if you are planning on using AES 256-bit encryption, you must install theUnlimited Strength Jurisdiction Policy Files. Without the policies in place, 256-bit encryption is not possible. Installation of JCE Unlimited Strength Policy This post is focusing on the keys rather than the installation and setup of the JCE. The installation is rather simple with explicit instructions found here (NOTE: this is for JDK7, if using a different JDK, search for the appropriate JCE policy files). Keystore Setup When using the KeyTool manipulating a keystore is simple. Keystores must be created with a link to a new key or during an import of an existing keystore. In order to create a new key and keystore simply type: keytool -genseckey -keystore aes-keystore.jck -storetype jceks -storepass mystorepass -keyalg AES -keysize 256 -alias jceksaes -keypass mykeypass Important Flags In the example above here are the explanations for the keytool's parameters: Keystore Parameters genseckey Generate SecretKey. This is the flag indicating the creation of a synchronous key which will become our AES key keystore Location of the keystore. If the keystore does not exist, the tool will create a new store. Paths can be relative or absolute but must be local storetype this is the type of store (JCE, PK12, JCEKS, etc). JCEKS is used to store symmetric keys (AES) not contained within a certificate. storepass password related to the keystore. Highly recommended to create a strong passphrase for the keystore Key Parameters keyalg algorithm used to create the key (AES/DES/etc) keysize size of the key (128, 192, 256, etc) alias alias given to the newly created key in which to reference when using the key keypass password protecting the use of the key Encrypt As it pertains to data in Java and at the most basic level, encryption is an algorithmic process used to programmatically obfuscate data through a reversible process where both parties have information pertaining to the data and how the algorithm is used. In Java encryption, this involves the use of a Cipher. A Cipher object in the JCE is a generic entry point into the encryption provider typically selected by the algorithm. This example uses the default Java provider but would also work with Bouncy Castle. Generating a Cipher object Obtaining an instance of Cipher is rather easy and the same process is required for both encryption and decryption. (NOTE: Encryption and Decryption require the same algorithm but do not require the same object instance) Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding"); Once we have an instance of the Cipher, we can encrypt and decrypt data according to the algorithm. Often the algorithm will require additional pieces of information in order to encrypt/decrypt data. In this example, we will need to pass the algorithm the bytes containing the key and an initial vector (explained below). Initialization In order to use the Cipher, we must first initialize the cipher. This step is necessary so we can provide additional information to the algorithm like the AES key and the Initial Vector (aka IV). cipher.init(Cipher.ENCRYPT_MODE, secretKeySpecification, initialVector); Parameters The SecretKeySpecification is an object containing a reference to the bytes forming the AES key. The AES key is nothing more than a specific sized byte array (256-bit for AES 256 or 32 bytes) that is generated by the keytool(see above). Alternative Parameteters There are multiple methods to create keys such as a hash including a salt, username and password (or similar). This method would utilize a SHA1 hash of the concatenated strings, convert to bytes and then truncate result to the desired size. This post will not show the generation of a key using this method or the use of a PBE key method using a password and salt. The password and/or salt usage for the keys is handled by the keytool using the inputs during the creation of new keys. Initialization Vector The AES algorithm also requires a second parameter called the Initialiation Vector. The IV is used in the process to randomize the encrypted message and prevent the key from easy guessing. The IV is considered a publicly shared piece of information, but again, it is not recommended to openly share the information (for example, it wouldn't be wise to post it on your company's website). When encrypting a message, it is not uncommon to prepend the message with the IV since the IV will be a set/known size based on the algorithm. NOTE: the AES algorithm will output the same result if using the same IV, key and message. It is recommended that the IV be randomly created each time an encryption takes place. With the newly initialized Cipher, encrypting a message is simple. Simply call: byte[] encryptedMessageInBytes = Cipher.doFinal((message.getBytes("UTF-8")); String base64EncodedEncryptedMsg = BaseEncoding.base64().encode(encryptedMessageInBytes); String base32EncodedEncryptedMsg = BaseEncoding.base32().encode(encryptedMessageInBytes); Encoding Results Byte arrays are difficult to visualize since they often do not form characters in any charset. The best recommendation to solve this is to represent the bytes in HEX (base-16), Double HEX (base-32) or Base64 format. If the message will be passed via a URL or POST parameter, be sure to use a web-safe Base64 encoding. Google Guava library provides a excellent BaseEncoding utility. NOTE: Remember to decode the encoded message before decrypting. Decrypt Decrypting a message is almost a reverse of the encryption process with a few exceptions. Decryption requires a known initialization vector as a parameter unlike the encryption process generating a random IV. Decryption When decrypting, obtain a cipher object with the same process as the encryption method. The Cipher object will need to utilize the exact same algorithm including the method and padding selections. Once the code has obtained a reference to a Cipher object, the next step is to initialize the cipher for decryption and pass in a reference to a key and the initialization vector. // key is the same byte[] key used in encryption SecretKeySpec secretKeySpecification = new SecretKeySpec(key, "AES"); cipher.init(Cipher.DECRYPT_MODE, secretKeySpecification, initialVector); NOTE: The key is stored in the keystore and obtained by the use of an alias. See below for details on obtaining keys from a keystore Once the cipher has been provided the key, IV and initialized for decryption, the cipher is ready to perform the decryption. byte[] encryptedTextBytes = BaseEncoding.base64().decode(message); byte[] decryptedTextBytes = cipher.doFinal(encryptedTextBytes); String origMessage = new String(decryptedTextBytes); Strategies to keep IV The IV used to encrypt the message is important to decrypting the message therefore the question is raised, how do they stay together. One solution is to Base Encode (see above) the IV and prepend it to the encrypted and encoded message: Base64UrlSafe(myIv) + delimiter + Base64UrlSafe(encryptedMessage). Other possible solutions might be contextual such as including an attribute in an XML file with the IV and one for the alias to the key used. Obtain Key from Keystore The beginning of this post has shown how easy it is to create new AES-256 keys that reference an alias inside of a keystore database. The post then continues on how to encrypt and decrypt a message given a key, but has yet shown how to obtain a reference to the key in a keystore. Solution // for clarity, ignoring exceptions and failures InputStream keystoreStream = new FileInputStream(keystoreLocation); KeyStore keystore = KeyStore.getInstance("JCEKS"); keystore.load(keystoreStream, keystorePass.toCharArray()); if (!keystore.containsAlias(alias)) { thrownew RuntimeException("Alias for key not found"); } Key key = keystore.getKey(alias, keyPass.toCharArray()); Parameters keystoreLocation String - Location to local keystore file location keypass String - Password used when creating or modifying the keystore file with keytool (see above) alias String - Alias used when creating new key with keytool (see above) Conclusion This post has shown how to encrypt and decrypt string based messages using the AES-256 encryption algorithm. The keys to encrypt and decrypt these messages are held inside of a JCEKS formatted KeyStore database created using the JDK provided "keytool" utility. The examples in this post should be considered a solid start to encrypting/decrypting symmetric keys such as AES. This should not be considered the only line of defense when encrypting messages, for example key rotation. Key rotation is a method to mitigate risks in the event of a data breach. If an intruder obtains data and manages to hack a single key, the data contained in multiple files should have used several keys to encrypt the data thus bringing down risk of a total exposure loss. All of the examples in this blog post have been condensed into a simple tool allowing for the viewing of keys inside of a keystore, an operation that is not supported out of the box by the JDK keytool. Each aspect of the steps and topics outlined in this post are available at: https://github.com/mike-ensor/aes-256-encryption-utility. NOTE: The examples, sample code and any reference is to be used at the sole implementers risk and there is no implied warranty or liability, you assume all risks.

Learn about using Mockito to create autowired fields.

Java SE 7 type inference I taught an introductory Java session on generics, and of course demonstrated the shorthand introduced in Java SE 7 for instantiating an instance of a generic type: // Java SE 6 List l = new ArrayList(); // Java SE 7 List l = new ArrayList<>(); This inference is very friendly, especially when we get into more complex collections: // This Map> m = new HashMap>(); // Becomes Map> m = new HashMap<>(); Not only the key and value type of the map, but the type of object stored in the collection used for the value type can be inferred. Of course, sometimes this inference breaks down. It so happens I ran across an interesting example of this. Imagine populating a set from a list, so as to speed up random access and remove duplicates. Something like this will work: List list = ...; // From somewhere Set nodup = new HashSet<>(list); However, this runs into trouble if the list could be null. The HashSetconstructor will not just return an empty set but will throwNullPointerException. So we need to guard against null here. Of course, like all good programmers, we seize the chance to use a ternary operator because ternary operators are cool. List list = ...; // From somewhere Set nodup = (null == list) ? new HashSet<>() : new HashSet<>(list); And here’s where inference breaks down. Because this is no longer a simple assignment, the statement new HashSet<>() can no longer use the left hand side in order to infer the type. As a result, we get that friendly error message, “Type mismatch: cannot convert from HashSet to Set”. What’s especially interesting is that inference breaks down even though the compiler knows that an object of typeSet is what is needed in order to gain agreement of types. The rules for inference are written to be conservative by doing nothing when an invalid inference might cause issues, while the compiler’s type checking is also conservative in what it considers to be matching types. Also interesting is that we only get that error message for the new HashSet<>(). The statement new HashSet<>(list) that uses the list to populate the set works just fine. This is because the inference is completed using the listparameter. Here’s the constructor: public class HashSet extends ... implements ... { ... public HashSet(Collection c) { ... } ... } The List that we pass in gets captured as Collection and this means that E is bound to String, so all is well. As a result, we wind up with the perfectly valid, if a little funny looking: List list = ...; // From somewhere Set nodup = (null == list) ? new HashSet() : new HashSet<>(list); Of course, I imagine most Java programmers do what I do, which is try to use the shortcut and then add the type parameter when the compiler complains. Following the rule about not meddling in the affairs of compilers (subtle; quick to anger), normally I would just fix it without trying very hard to understand why the compiler liked or didn’t like things done in a certain way. But this one was such a strange case I figured it was worth a longer look.