Krishna Prasad

for people in hurry, here is the code and some steps to run few demo samples . disclaimer: i am still learning play 2.0, please point to me if something is incorrect. play 2.0 is a web application stack that bundled with netty for http server , akka for loosely coupled backend processing and comet / websocket for asynchronous browser rendering. play 2.0 itself does not do any session state management, but uses cookies to manage user sessions and flash data . play 2.0 advocates reactive model based on iteratee io . please also see my blog on how play 2.0 pits against spring mvc . in this blog, i will discuss some of these points and also discuss how akka and comet complement play 2.0. the more i understand play 2.0 stack the more i realize that scala is better suited to take advantages of capabilities of play 2.0 compared to java. there is a blog on how web developers view of play 2.0 . you can understand how akka’s actor pits against jms refer this stackoverflow writeup . a good documentation on akka’s actor is here . play 2.0, netty, akka, commet: how it fits play 2.0, netty, akka, comet: how it fits servlet container like tomcat blocks each request until the backend processing is complete. play 2.0 stack will help in achieving the usecase like, you need to web crawl and get all the product listing from various sources in a non-blocking and asynchronous way using loosely coupled message oriented architecture. for example, the below code will not be scalable in play 2.0 stack, because play has only 1 main thread and the code blocks other requests to be processed. in play 2.0/netty the application registers with callback on a long running process using frameworks like akka when it is completed, in a reactive pattern. public static result index() { //here is where you can put your long running blocking code like getting // the product feed from various sources return ok("hello world"); } the controller code to use akka to work in a non-blocking way with async callback is as below, public static result index() { return async( future(new callable() { public integer call() { //here is where you can put your long running blocking code like getting //the product feed from various sources return 4; } }).map(new function() { public result apply(integer i) { objectnode result = json.newobject(); result.put("id", i); return ok(result); } }) ); } and more cleaner and preferred way is akka’s actor model is as below, public static result sayhello(string data) { logger.debug("got the request: {}" + data); actorsystem system = actorsystem.create("mysystem"); actorref myactor = system.actorof(new props(myuntypedactor.class), "myactor"); return async( akka.aspromise(ask(myactor, data, 1000)).map( new function() { public result apply(object response) { objectnode result = json.newobject(); result.put("message", response.tostring()); return ok(result); } } ) ); } static public class myuntypedactor extends untypedactor { public void onreceive(object message) throws exception { if (message instanceof string){ logger.debug("received string message: {}" + message); //here is where you can put your long running blocking code like getting //the product feed from various sources getsender().tell("hello world"); } else { unhandled(message); } } } f you want to understand how we can use comet for asynchronously render data to the browser using play, akka and comet refer the code in github . here is some good writeup comparing comet and websocket in stackoverflow .

In continuation of my earlier blogs on Introduction to Spring MVC and Testing DAO layer in Spring MVC, in this blog I will demonstrate how to test Service layer in Spring MVC. The objective of this demo is 2 fold, to build the Service layer using TDD and increase the code coverage during JUnit testing of Service layer. For people in hurry, get the latest code from Github and run the below command mvn clean test -Dtest=com.example.bookstore.service.AccountServiceTest Since in my earlier blog, we have already tested the DAO layer, in this blog we only need to focus on testing service layer. We need to mock the DAO layer so that we can control the behavior in Service layer and cover various scenarios. Mockito is a good framework which is used to mock a method and return known data and assert that in the JUnit. As a first step we define the AccountServiceTestContextConfiguration class with AccountServiceTest class. If you notice there are 2 beans defined in that class and we marked the as a @Configuration which shows that it is a Spring Context class. In the JUnit test we @Autowired AccountService class. And AccountServiceImpl @Autowired the AccountRepository class. When creating the Bean in the configuration file we also stubbed the AccountRepository class using Mockito, @RunWith(SpringJUnit4ClassRunner.class) @ContextConfiguration public class AccountServiceTest { @Configuration static class AccountServiceTestContextConfiguration { @Bean public AccountService accountService() { return new AccountServiceImpl(); } @Bean public AccountRepository accountRepository() { return Mockito.mock(AccountRepository.class); } } //We Autowired the AccountService bean so that it is injected from the configuration @Autowired private AccountService accountService; @Autowired private AccountRepository accountRepository; During the setup of the JUnit we use Mockito mock findByUsername method to return a predefined account object as below @Before public void setup() { Account account = new AccountBuilder() { { address("Herve", "4650", "Rue de la gare", "1", null, "Belgium"); credentials("john", "secret"); name("John", "Doe"); } }.build(true); Mockito.when(accountRepository.findByUsername("john")).thenReturn(account); } Now we write the tests as below and test both the positive and negative scenarios, @Test(expected = AuthenticationException.class) public void testLoginFailure() throws AuthenticationException { accountService.login("john", "fail"); } @Test() public void testLoginSuccess() throws AuthenticationException { Account account = accountService.login("john", "secret"); assertEquals("John", account.getFirstName()); assertEquals("Doe", account.getLastName()); } } Finally we verify if the findByUsername method is called only once successfully as below in the teardown, @After public void verify() { Mockito.verify(accountRepository, VerificationModeFactory.times(1)).findByUsername(Mockito.anyString()); // This is allowed here: using container injected mocks Mockito.reset(accountRepository); } AccountService class looks as below, @Service @Transactional(readOnly = true) public class AccountServiceImpl implements AccountService { @Autowired private AccountRepository accountRepository; @Override public Account login(String username, String password) throws AuthenticationException { Account account = this.accountRepository.findByUsername(username, password); } else { throw new AuthenticationException("Wrong username/password", "invalid.username"); } return account; } } I hope this blog helped you. In my next blog, I will demo how to build a controller JUnit test. Reference: Pro Spring MVC: With Web Flow by by Marten Deinum, Koen Serneels

In continuation of my blog JUnit testing of Spring MVC application – Introduction, in this blog, I will show how to design and implement DAO layer for the Bookstore Spring MVC web application using Test Driven development. For people in hurry, get the latest code from Github and run the below command mvn clean test -Dtest=com.example.bookstore.repository.JpaBookRepositoryTest As a part of TDD, Write a basic CRUD (create, read, update, delete) operations on a Book DAO class com.example.bookstore.repository.JpaBookRepository. Don’t have the database wiring yet in this DAO class. Once we build the JUnit tests, we use JPA as a persistence layer. We also use H2 as a inmemory database for testing purpose. Create Book POJO class Create the JUnit test as below, public class JpaBookRepositoryTest { @Test public void testFindById() { Book book = bookRepository.findById(this.book.getId()); assertEquals(this.book.getAuthor(), book.getAuthor()); assertEquals(this.book.getDescription(), book.getDescription()); assertEquals(this.book.getIsbn(), book.getIsbn()); } @Test public void testFindByCategory() { List books = bookRepository.findByCategory(category); assertEquals(1, books.size()); for (Book book : books) { assertEquals(this.book.getCategory().getId(), category.getId()); assertEquals(this.book.getAuthor(), book.getAuthor()); assertEquals(this.book.getDescription(), book.getDescription()); assertEquals(this.book.getIsbn(), book.getIsbn()); } } @Test @Rollback(true) public void testStoreBook() { Book book = new BookBuilder() { { description("Something"); author("JohnDoe"); title("John Doe's life"); isbn("1234567890123"); category(category); } }.build(); bookRepository.storeBook(book); Book book1 = bookRepository.findById(book.getId()); assertEquals(book1.getAuthor(), book.getAuthor()); assertEquals(book1.getDescription(), book.getDescription()); assertEquals(book1.getIsbn(), book.getIsbn()); } } If you notice since the JpaBookRepository is only a skeleton class without implementation, all the tests will fail. As a next step, we need to create a Configuration and wire a datasource, and for the test purpose we will be using H2 database. And we also need to wire this back to JUnit test as below, @Configuration public class InfrastructureContextConfiguration { @Autowired private DataSource dataSource; //some more configurations.. @Bean public DataSource dataSource() { EmbeddedDatabaseBuilder builder = new EmbeddedDatabaseBuilder(); builder.setType(EmbeddedDatabaseType.H2); return builder.build(); } } //JUnit test wiring is as below @RunWith(SpringJUnit4ClassRunner.class) @ContextConfiguration(classes = { InfrastructureContextConfiguration.class, TestDataContextConfiguration.class }) @Transactional public class JpaBookRepositoryTest { //the test methods } Next step is to setup and teardown sample data in the JUnit test case as below, public class JpaBookRepositoryTest { @PersistenceContext private EntityManager entityManager; private Book book; private Category category; @Before public void setupData() { EntityBuilderManager.setEntityManager(entityManager); category = new CategoryBuilder() { { name("Evolution"); } }.build(); book = new BookBuilder() { { description("Richard Dawkins' brilliant reformulation of the theory of natural selection"); author("Richard Dawkins"); title("The Selfish Gene: 30th Anniversary Edition"); isbn("9780199291151"); category(category); } }.build(); } @After public void tearDown() { EntityBuilderManager.clearEntityManager(); } } Once we do the wiring, we need to implement the com.example.bookstore.repository.JpaBookRepository and use JPA to do the CRUD on the database and run the tests. The tests will succeed. Finally if you run Cobertura for this example from STS, we will get over 90% of line coverage for com.example.bookstore.repository.JpaBookRepository. In case you want to try few exercises you can implement repository for Account and User. I hope this blog helped you. In my next blog I will talk about Mochito and Implementing the Service layer.

For people in hurry get the code from Github. In continuation of my earlier blog on spring-test-mvc junit testing Spring Security layer with InMemoryDaoImpl, in this blog I will discuss how to use achieve method level access control. Please follow the steps in this blog to setup spring-test-mvc and run the below test case. mvn test -Dtest=com.example.springsecurity.web.controllers.SecurityControllerTest The JUnit test case looks as below, @RunWith(SpringJUnit4ClassRunner.class) @ContextConfiguration(loader = WebContextLoader.class, value = { "classpath:/META-INF/spring/services.xml", "classpath:/META-INF/spring/security.xml", "classpath:/META-INF/spring/mvc-config.xml" }) public class SecurityControllerTest { @Autowired CalendarService calendarService; @Test public void testMyEvents() throws Exception { Authentication auth = new UsernamePasswordAuthenticationToken("user1@example.com", "user1"); SecurityContext securityContext = SecurityContextHolder.getContext(); securityContext.setAuthentication(auth); calendarService.findForUser(0); SecurityContextHolder.clearContext(); } @Test(expected = AuthenticationCredentialsNotFoundException.class) public void testForbiddenEvents() throws Exception { calendarService.findForUser(0); } } @Test(expected=AccessDeniedException.class) public void testWrongUserEvents() throws Exception { Authentication auth = new UsernamePasswordAuthenticationToken("user2@example.com", "user2"); SecurityContext securityContext = SecurityContextHolder.getContext(); securityContext.setAuthentication(auth); calendarService.findForUser(0); SecurityContextHolder.clearContext(); } If you notice, if the user did not login or if the user is trying to access another users information it will throw an exception. The interface access control is as below, public interface CalendarService { @PreAuthorize("hasRole('ROLE_ADMIN') or principal.id == #userId") List findForUser(int userId); } The PreAuthorize only works on interface so that any implementation that implements this interface has this access control. I hope this blog helps you.

In continuation with my earlier blog on Enabling SSL on Tomcat, in this blog I will go to next step and enable CLIENT-CERT based authorization on Tomcat. Again if you want to tryout the code go to my Github and download the code. For this sample, I assume that you have tried my earlier SSL example on Tomcat and have the setup. As per the SSL example I assume, You have setup Tomcat 6.0 version You have set the SSL Connector Configuration in Tomcat server.xml You have started the Tomcat server and run the SecureHttpClient0Test test In this blog, I will show you how to, Setup MemoryRealm In the server.xml comment the Realm tag and replace that with the code below, Setup user role setup In /conf/tomcat-users.xml Setup security-contraint Add access control in the individual application web.xml as below, Demo App /secure/* GET secureconn CLIENT-CERT Demo App secureconn Run JUnit test Open the class src/test/java/com/goSmarter/test/SecureHttpClient1Test.java file and change the below code to point to /conf folder public static final String path = "D:/apache-tomcat-6.0.36/conf/"; Start the Tomcat and run the JUnit test using “mvn test -Dtest=”com.goSmarter.test.SecureHttpClient1Test” If you want to debug the Realm, you need to increase the log level for Realm in /conf/logging.properties as below, org.apache.catalina.realm.level = ALL org.apache.catalina.realm.useParentHandlers = true org.apache.catalina.authenticator.level = ALL org.apache.catalina.authenticator.useParentHandlers = true If you notice there are 2 positive tests and 1 negative test, negative test will give a forbidden 403 return status when a wrong certificate is sent based on the security-constraint. I hope this blog helped you.

in continuation of my earlier blog jsoup: nice way to do html parsing in java, in this blog i will compare jsoup with other similar framework, htmlunit . apparently both of them are good html parsing frameworks and both can be used for web application unit testing and web scraping. in this blog, i will explain how htmlunit is better suited for web application unit testing automation and jsoup is better suited for web scraping. typically web application unit testing automation is a way to automate webtesting in junit framework. and web scraping is a way to extract unstructured information from the web to a structured format. i recently tried 2 decent web scraping tools, webharvy and mozenda . for any good html parsing tools to click, they should support either xpath based or css selector based element access. there are lot of blogs comparing each one like, why css locators are the way to go vs xpath , and css selectors and xpath expressions . htmlunit htmlunit is a powerful framework, where you can simulate pretty much anything a browser can do like click events, submit events etc and is ideal for web application automated unit testing. xpath based parsing is simple and most popular and htmlunit is heavily based on this. in one of my application, i wanted to extract information from the web in a structured way. htmlunit worked out very well for me on this. but the problem starts when you try to extract structured data from modern web applications that use jquery and other ajax features and use div tags extensively. htmlunit and other xpath based html parsers will not work with this. there is also a jsoup version that supports xpath based on jaxe n, i tried this as well, guess what? it also was not able to access the data from modern web applications like ebay.com. finally my experience with htmlunit was it was bit buggy or maybe i call it unforgiving unlike a browser, where in if the target web applications have missing javascripts, it will throw exceptions, but we can get around this, but out of the box it will not work. jsoup the latest version of jsoup goes extra length not to support xpath and will very well support css selectors . my experience was it is excellent for extracting structured data from modern web applications. it is also far forgiving if the web application has some missing javascripts. extracting xpath and css selector data in most of the browsers, if you point to an element and right click and click on “inspect element” it can extract the xpath information, i noticed firefox/firebug can also extract css selector path as shown below, htmlunit vs jsoup: extract css path and xpath in firebug i hope this blog helped.

In this example I will show how to test Spring Integration flow using Mock SftpServer.

for people in hurry, get the latest code and the steps in github . to run the junit test, run “mvn test” and understand the test flow. introduction: fakeftpserver in this spring integration fakeftpserver example, i will demonstrate using spring fakeftpserver to junit test a spring integration flow. this is an interesting topic, and there are few articles on unit testing file transfers , which gives some insight on this topic. in this blog, we will test a spring integration flow which checks for a list of files, apply a splitter to separate each file and start downloading them into a local location. once the download is complete, it will delete the files on the ftp server. in my next blog, i will show how to do junit testing of spring integration flow with sftp server. spring integration flow spring integration fakeftpserver example in order to use fakeftpserver we need to have maven dependency as below, org.mockftpserver mockftpserver 2.3 test the first step to this is to create a fakeftpserver before every test runs as below, @before public void setup() throws exception { fakeftpserver = new fakeftpserver(); fakeftpserver.setservercontrolport(9999); // use any free port filesystem filesystem = new unixfakefilesystem(); filesystem.add(new fileentry(file, contents)); fakeftpserver.setfilesystem(filesystem); useraccount useraccount = new useraccount("user", "password", home_dir); fakeftpserver.adduseraccount(useraccount); fakeftpserver.start(); } @after public void teardown() throws exception { fakeftpserver.stop(); } finally run the junit test case as seen below, @autowired private filedownloadutil downloadutil; @test public void testftpdownload() throws exception { file file = new file("src/test/resources/output"); delete(file); ftpclient client = new ftpclient(); client.connect("localhost", 9999); client.login("user", "password"); string files[] = client.listnames("/dir"); client.help(); logger.debug("before delete" + files[0]); assertequals(1, files.length); downloadutil.downloadfilesfromremotedirectory(); logger.debug("after delete"); files = client.listnames("/dir"); client.help(); assertequals(0, files.length); assertequals(1, file.list().length); } i hope this blog helped.

for people in hurry, refer the steps and the demo . introduction control bus pattern is a enterprise integration pattern is used to control distributed systems in spring integration . in this blog, i will show you how a control bus can control your application or a component to start or stop listening to jms message . in this example, we are using jms queue to start and stop the jms inbound-channel-adapter , we can also do this with jdbc inbound-channel-adapter and control this thru an external application. the other way to do the same is by using mbean as in this example . in this use case, there is a spring integration flow. this spring integration flow can be controlled by sending start / stop message to inbound-channel-adapter from a activemq jms queue. details control bus with spring integration control bus spring integration jms to start implementing this use case, we write the junit test 1st. if you notice once the inboundadapter is started the message is received from the adapteroutchannel. once the inboundadapter is stopped no message is received. this is demonstrated as below, @test public void democontrolbus() { assertnull(adapteroutputchanel.receive(1000)); controlchannel.send(new genericmessage("@inboundadapter.start()")); assertnotnull(adapteroutputchanel.receive(1000)); controlchannel.send(new genericmessage("@inboundadapter.stop()")); assertnull(adapteroutputchanel.receive(1000)); } the test configuration looks as below, if you run the “mvn test” the tests work. in the main configuration, we will be configuring actual queues and jms inbound-channel-adapter as below, now when you start the component as “run on server” in sts ide and post a message on myqueue, you can see the subscribers received the messages on the console. you can issue “@inboundadapter.stop()” on the controlbusqueue, it will stop the inbound-channel-adapter, it will also throw java.lang.interruptedexception, it looks like a false alarm. to test if the inbound-channel-adapter is stopped, post a message on to myqueue, the component will not process the message. now issue “@inboundadapter.start()” on the controlbusqueue, it will process the earlier message and start listening for new messages. conclusion if you notice in this blog, we can control the component to listen to message using control bus. the other way to do the same is by using mbean as in this example .