DZone
Thanks for visiting DZone today,
Edit Profile
  • Manage Email Subscriptions
  • How to Post to DZone
  • Article Submission Guidelines
Sign Out View Profile
  • Post an Article
  • Manage My Drafts
Over 2 million developers have joined DZone.
Log In / Join
Refcards Trend Reports
Events Video Library
Refcards
Trend Reports

Events

View Events Video Library

The Latest Databases Topics

article thumbnail
Extending Java APIs: Add Missing Features Without the Hassle
Do you ever pull your hair out in frustration, asking why isn't this part of the Java API? Thanks to Manifold, you can solve that problem for everyone.
May 24, 2023
by Shai Almog DZone Core CORE
· 7,132 Views · 7 Likes
article thumbnail
Auditing Tools for Kubernetes
These tools explain how they can help maintain security and compliance by identifying and mitigating vulnerabilities within a Kubernetes environment.
May 24, 2023
by Vasilii Kulazhenkov
· 11,721 Views · 4 Likes
article thumbnail
Observability Architecture: Financial Payments Introduction
Explore an open-source, standards-based, cloud-native observability platform that helps control the speed, scale, and complexity of a cloud-native financial payments architecture.
May 24, 2023
by Eric D. Schabell
· 10,385 Views · 6 Likes
article thumbnail
Auto-Scaling Kinesis Data Streams Applications on Kubernetes
This guide explores how to auto-scale your Kinesis Data Streams consumer applications on Kubernetes so you can save on costs and improve resource efficiency.
May 23, 2023
by Abhishek Gupta DZone Core CORE
· 15,722 Views · 5 Likes
article thumbnail
Security Challenges for Microservice Applications in Multi-Cloud Environments
Multi-cloud strategies bring new security concerns. As a result, organizations need to address them at every stage of their security measures.
May 23, 2023
by Pascal Tene
· 6,145 Views · 3 Likes
article thumbnail
A Complete Guide to AWS File Handling and How It Is Revolutionizing Cloud Storage
Learn about the world of AWS file handling, how it is revolutionizing cloud storage, and discover the different ways you can manage your files.
May 23, 2023
by Satrajit Basu DZone Core CORE
· 5,434 Views · 5 Likes
article thumbnail
Redefining DevOps: The Transformative Power of Containerization
Discover how containerization is revolutionizing software development and deployment in the era of DevOps. Enhanced business agility with this technology.
May 23, 2023
by Samir Hazra
· 8,448 Views · 3 Likes
article thumbnail
MongoDB: 5 Syntactic Weirdnesses to Keep in Mind
People like to complain about MongoDB. For instance, maybe they feel that it ruined their social network, or any number of other less recent complaints. The debate gets so heated, though, that sometimes valid criticisms - and nothing is above criticism - are dismissed as bandwagon hatred. It's a problem that Slava Kim seems very aware of in this recent blog post on some of the syntactic weirdnesses of MongoDB. It's not bashing, Kim stresses. For developers to effectively use any technology, they need to understand the "sharp edges." Kim goes into detail for each warning, covering five general areas: "Keys order in a hash object" "undefined, null and undefined" "Soft limits, hard limits and no limits" "Special treatment for arrays" "$near geo-location operator" Check out the full article for all the details on what aspects of MongoDB may cause some problems or frustration down the line.
May 23, 2023
by Alec Noller
· 8,521 Views · 1 Like
article thumbnail
The Magic Testing Challenge: Part 2
My last article raised an interesting discussion whether you should see tests more as documentation or more as specification. I agree that they can contribute to both of them, but I still think tests are just - tests... There were also complaints about my statement that testing often becomes tedious work which nobody likes. Also here I agree, that techniques like TDD can help you to structure your code and make sure you code exactly what is needed by writing the tests, but the result of the process will still be a class which needs to be tested somehow. So I have set up another small challenge to show how the visual approach featured by MagicTest helps to make testing a breeze. As you know, traditional assertion-based test frameworks like TestNG or JUnit force us to include the expected results in the test code. Where this may be more or less suitable for simple tests (like in the previous article), it quickly becomes cumbersome if the test handles complex objects or voluminous data. The Task We must test the method createEvenOddTable() (see appended ) with the following functionality: Create HTML table (elements table, tr, td) with specified number of data rows and columns. An additional row will be added to store header information (element th). An additional column will be added which contains the row number (element th) The rows will have attribute class set to "head", "even", or "odd" for easy styling. Both the specification (the 4 lines above) and the source code itself (25 lines) are short and simple to understand, so any experienced developer will write this method in a few minutes. So what's the problem with testing this method? We will see if we look at how MagicTest handles this case. The Magic Test The MagicTest for this method looks like this: public class HtmlTableTest { @Trace public void testCreateEvenOddTable() { HtmlTable.createEvenOddTable(4, 3); } @Formatter(outputType=OutputType.TEXT) public static String formatElement(Element elem) { XMLOutputter serializer = new XMLOutputter(); serializer.setFormat(Format.getPrettyFormat()); return serializer.outputString(elem); } } Some details: We use the @Trace annotation to automatically capture information about calls to the method under test. We rely on naming conventions, so the method HtmlTable.createEvenOddTable() is tested by HtmlTableTest.testCreateEvenOddTable(). Per default, MagicTest uses the toString() method to report the parameter and return values. As the Element's toString() method returns only its name, we have to define a custom @Formatter to get the full XML tree. If we run the test, we get the following report: If we look at the XML element tree in the report, we can see all the details which a complete test should cover: correct nesting of elements (table, tr, td), correct header line, correct line numbers, correct number of rows, correct number of cells for each row, correct class attribute for each row, etc. But even if you end up with a bunch of lengthy assert statements like assert("head".equals(((Element) elem.getChildren("tr").get(0)).getAttributeValue("class"))); which tests for the correct class attribute, this will not be enough: you should also test the absence of the class attribute for all cells except the first ones in each row. So yes, for a sound test you must actually verify the whole XML tree - and this is exactly the information which MagicTest shows you for confirmation. Let the Challenge Begin To run the test yourself, you will need to download the MagicTest Eclipse plug-in. Copy it into the Eclipse dropins folder and restart Eclipse. Then download the attached Eclipse project and import it into your workspace. Run the test class TagsTest by executing Run As / MagicTest. After the first run, the test report will show up and all test steps will be red. This is the MagicTest way of telling you that a step has failed. In our case, the steps just fail because MagicTest simply does not know anything about the expected result. So we carefully check the output and confirm its correctness by clicking on the save button. Now all steps are green - and the test is successful. You have now seen how efficiently this test can be realized using MagicTest - it even looked like fun. Does your test tool accept the challenge? How many minutes and lines does it take you to write the test? I'm looking forward to your contributions! Appendix: Listing HtmlTable /** * Create HTML table (elements table, tr, td) with specified number of data rows and columns. * An additional row will be added to store header information (element th). * An additional column will be added which contains the row number (element th) * The rows will have attribute class set to "head", "even", or "odd" for easy styling. * * @param rows number of rows * @param cols number of column * @return XML element containing the HTML table */ public static Element createEvenOddTable(int rows, int cols) { Element table = new Element("table"); for (int r=0; r 0) { td.setText(Integer.toString(r)); } } } return table; }
May 23, 2023
by Thomas Mauch
· 5,190 Views · 1 Like
article thumbnail
Java EE 6 Pet Catalog with GlassFish and MySQL
This Pet Catalog app explains a web application that uses JSF 2.0, Java EE 6, GlassFish and MySQL. I took this example GlassFish and MySQL, Part 2: Building a CRUD Web Application With Data Persistence and modified it to use some of the new features of JSF 2.0 and Java EE 6. Download the sample code Explanation of the usage of JSF 2.0 and Java EE 6 in a sample Store Catalog Application The image below shows the Catalog Listing page, which allows a user to page through a list of items in a store. JSF 2.0 Facelets XHTML instead of JSP For JSF 2.0, Facelets XHTML is the preferred way to declare JSF Web Pages. JSP is supported for backwards compatibility, but not all JSF 2.0 features will be available for views using JSP as their page declaration language. JSF 2.0 Facelets has some nice features like templating (similar in functionality to Tiles) and composite components, which I'm not going to discuss here but you can read about that in this article: http://www.ibm.com/developerworks/java/library/j-jsf2fu2/index.html and in this Tech Tip Composite UI Components in JSF 2.0. The Catalog application's resources JSF 2.0 standardizes how to define web resources. Resources are any artifacts that a component may need in order to be rendered properly -- images, CSS, or JavaScript files. With JSF 2.0 you put resources in a resources directory or a subdirectory. In your Facelets pages, you can access css files with the , javascript files with the , and images with the JSF tags. The list.xhtml uses the The Catalog application uses a resource bundle to contain the static text and error messages used by the Facelets pages. Putting messages in a resource bundle makes it easier to modify and internationalize your Application text. The messages are in a properties file in a java package directory. Title=Pet Catalog Next=Next Previous=Prev Name=Name The resource bundle is configured in the faces-config.xml File (you don't need any other configuration in the faces-config.xml for JSF 2.0, as explained later you no longer have to configure managed beans and navigation with XML). web.WebMessages msgs The List.xhtml facelets page uses a JSF dataTable component to display a list of catalog items in an html table. The dataTable component is useful when you want to show a set of results in a table. In a JavaServer Faces application, the UIData component (the superclass of dataTable) supports binding to a collection of data objects. It does the work of iterating over each record in the data source. The HTML dataTable renderer displays the data as an HTML table. In the list.xhtml web page the dataTable is defined as shown below: (Note: Red colors are for Java EE tags, annotations code, and Green is for my code or variables) The value attribute of a dataTable tag references the data to be included in the table. The var attribute specifies a name that is used by the components within the dataTable tag as an alias to the data referenced in the value attribute of dataTable. In the dataTable tag from the List.jsp page, the value attribute points to a list of catalog items. The var attribute points to a single item in that list. As the dataTable component iterates through the list, each reference to dataTableItem points to the current item in the list. JSF 2.0 Annotations instead of XML configuration The dataTable's value is bound to the items property of the catalog managed bean. With JSF 2.0 managed beans do not have to be configured in the faces-config.xml file, you annotate the managed beans instead as shown below: @ManagedBean @SessionScoped public class Catalog implements Serializable { By convention, the name of a managed bean is the same as the class name, with the first letter of the class name in lowercase. To specify a managed bean name you can use the name attribute of the ManagedBean annotation, like this: @ManagedBean(name = "Catalog"). This Catalog ManagedBean items property is defined as shown below: private List items = null; public List getItems() { if (items == null) { getPagingInfo(); items = getNextItems(pagingInfo.getBatchSize(), pagingInfo.getFirstItem()); } return items; } The getItems() method returns a List of item objects. The JSF dataTable, supports data binding to a collection of data objects. The dataTable object is modeled as a collection of row objects that can be accessed by a row index. The APIs provide mechanisms to position to a specified row index, and to retrieve an object that represents the data that corresponds to the current row index. The Item properties name, imagethumburl, and priceare displayed with the column component: The column tags represent columns of data in a dataTable component. While the dataTable component is iterating over the rows of data, it processes the UIColumn component associated with each column tag for each row in the table. The dataTable component iterates through the list of items (catalog.items) and displays the item (var="row") attribute value. Each time UIData iterates through the list of items, it renders one cell in each column. The dataTable and column tags use facet to represent parts of the table that are not repeated or updated. These include headers, footers, and captions. Java EE 6: JSF 2.0, EJB 3.1, and Java Persistence API (JPA) 2.0 The Catalog ManagedBean annotates the field private ItemFacade itemFacade; with @EJB , which causes an itemFacade EJB to be injected when the managed bean is instatiated. The Catalog getNextItems method calls the ItemFacade Stateless EJB which uses the Java Persistence API EntityManager Query object to return a list of items. @ManagedBean @SessionScoped public class Catalog implements Serializable { @EJB private ItemFacade itemFacade; public List getNextItems(int maxResults, int firstResult) { return itemFacade.findRange(maxResults, firstResult); } EJB 3.1 No-interface local client View With EJB 3.1, local EJBs do not have to a implement separate interface, that is, all public methods of the bean class are automatically exposed to the caller. Simplified Packaging With Java EE 6, EJBs can be directly packaged in a WAR file just like web components. The ItemFacade EJB uses the Java Persistence API EntityManager Query object to return a list of items. The ItemFacade EJB annotates the field private EntityManager em; with @PersistenceContext , which causes an entity manager to be injected when it is instatiated. @Stateless public class ItemFacade { @PersistenceContext(unitName = "catalogPU") private EntityManager em; public List findRange(int maxResults, int firstResult) { Query q = em.createQuery("select object(o) from Item as o"); q.setMaxResults(maxResults); q.setFirstResult(firstResult); return q.getResultList(); } The Java Persistence Query APIs are used to create and execute queries that can return a list of results. The JPA Query interface provides support for pagination via the setFirstResult() and setMaxResults() methods: q.setMaxResults(int maxResult) sets the maximum number of results to retrieve. q.setFirstResult(int startPosition) sets the position of the first result to retrieve. In the code below, we show the Item entity class which maps to the ITEM table that stores the item instances. This is a typical Java Persistence entity object. There are two requirements for an entity: annotating the class with an @Entity annotation. annotating the primary key identifier with @Id Because the fields name, description.... are basic mappings from the object fields to columns of the same name in the database table, they don't have to be annotated. The O/R relationships with Address and Product are also annotated. For more information on defining JPA entities see Pro EJB 3: Java Persistence API book. @Entity public class Item implements java.io.Serializable { @Id private Integer id; private String name; private String description; private String imageurl; private String imagethumburl; private BigDecimal price; @ManyToOne private Address address; @ManyToOne private Product product; public Item() { } public String getName() { return name; } public void setName(String name) { this.name = name; } ... } The Catalog ManagedBean pages through the list of Items by maintaining the PagingInfo.firstItem and PagingInfo.batchSize attributes and passing these as parameters to the getNextItems(firstItem, batchSize) method. The catalog's scope is defined with the annotation @SessionScoped, a JSF Managedbean with session scope will be stored in the session meaning that the bean's properties will stay alive for the life of the Http Session. A JSF commandButton is used to provide a button to click on to display the next page of items. The commandButton tag is used to submit an action event to the application. This commandButton action attribute references the catalog Managed bean next() method which calculates the next page's first row number and returns a logical outcome String, which causes the list.xhtml page to display the next page's list . The catalog next method is defined as shown below: public String next() { if (firstItem + batchSize < itemCount()) { firstItem += batchSize; } return "list"; } JSF 2.0 Simplified Navigation The JavaServer Faces 2.0 NavigationHandler convention adds .xhtml to the logical outcome of the action method (in this example list) and loads that file, in this case, it loads the list .xhtml page after this method returns. If the action doesn't begin with a forward slash (/), JSF assumes that it's a relative path. You can specify an absolute path by adding the slash like this "/items/list". A JSF commandLink is used to provide a link to click on to display a page with the item details. This commandLink action attribute references The catalog showDetail() method: With JSF 2.0 you can now specify parameters in method expressions. The dataTable row object associated with the selected link is passed as a parameter in the "#{catalog.showDetail(row)}" method expression. The Catalog showDetail() method gets the item data from the input parameter, and returns a string which causes the detail.xhtml page to display the item details : public String showDetail(Item item) { this.item = item; return "detail"; } The JavaServer Faces NavigationHandler adds .xhtml to the logical outcome of the action, detail and loads that file. In this case, the JavaServer Faces implementation loads the detail.xhtml page after this method returns. The detail.xhtml uses the outputText component to display the catalog ManagedBean's item properties: GlassFish v3 is a lightweight server OSGi-based; Embedded API; RESTful admin API; Lightweight and fast startup; iterative development cycle "edit-save-refresh browser": Incremental compile of all JSF 2.0 artifacts when you save. Auto-deploy of all web or Java EE 6 artifacts Session retention: maintain sessions across re-deployments Conclusion This concludes the sample application which demonstrates a pet catalog web application which uses Java EE 6, GlassFish v3 and MySQL. Running the Sample Application Download and install NetBeans IDE 6.8 M1 with GlassFish v3 b57 (Glassfish v3 preview is Java EE 6 Preview) , and MySQL Community Server . Follow these instructions to set up a jdbc-driver for MySQL. (Normally this is already setup with Glassfish, but I got an errror message with Glassfish v3 b57 that it was missing) Download the sample code. Unzip the catalog.zip file which you downloaded, this will create a catalog directory with the project code. Create the Pet Catalog database In order to run the sample code you first have to create the Pet Catalog database and fill in the Item table. Start NetBeans IDE Ensure that GlassFish is registered in the NetBeans IDE, as follows: Click the Services tab in the NetBeans IDE. Expand the Servers node. You should see GlassFish v2 in the list of servers. If not, register GlassFish v2 as follows: Right-click the Servers node and select Add Server. This opens an Add Server Instance wizard. Select GlassFish v2 in the server list of the wizard and click the Next button. Enter the location information for the server and click the Next button. Enter the admin name and password and click the Finish button. Start the MySQL or Java DB database as follows: Click the Services tab in the NetBeans IDE. Expand the databases node. You should see the Java DB database in the list of databases. If you have installed the MySQL server database, you should also see the MySQL database in the list of databases.. Note: Java DB comes bundled with Netbeans, you can download MySQL separately. Right-mouse click on the Java DB or MySQL server database and select Start. If you installed MySQL, set the properties of the MySQL server database as follows: Right-click on the MySQL server database and select Properties. This opens the MySQL Server Properties dialog box, as shown in Figure 8. Figure 8. MySQL Server Basic Properties In the Basic Properties tab, enter the server host name and port number. The IDE specifies localhost as the default server host name and 3306 as the default server port number. Enter the administrator user name, if not displayed, and the administrator password -- the default administrator password is blank. Click the Admin Properties tab. Enter an appropriate path in the Path/URL to admin tool field. You can find the path by browsing to the location of a MySQL Administration application such as the MySQL Admin Tool. Enter an appropriate path in the Path to start command. You can find the path by browsing to the location of the MySQL start command. To find the start command, look for mysqld in the bin folder of the MySQL installation directory. Enter an appropriate path in the Path to stop command field. You can find the path by browsing to the location of the MySQL stop command. This is usually the path to mysqladmin in the bin folder of the MySQL installation directory. If the command is mysqladmin, in the Arguments field, type -u root stop to grant root permissions for stopping the server. The Admin Properties tab should look similar to Figure 9. Figure 9. MySQL Server Administration Properties Click the OK button. Right-click on the MySQL server or Java DB database and select Start. Create the petcatalog database as follows: Right-mouse click on the Java DB or MySQL server database and select Create Database. This will open a create Database window. Enter the database name catalog for Java DB or petcatalog for MySQL. For Java DB enter userid password app app as shown below: Click O.K. to accept the displayed settings. Create the tables in the catalog database as follows: Underneath Databases you should see a database connection for the petcatalog database. For example MySQL: or Java DB: Right-mouse click on the petcatalog connection and select Connect. Right-mouse click on the petcatalog connection and select Execute Command. This will open up a SQL command window. Copy the contents of the catalog.sql file in the catalog directory and paste the contents into the SQL command window, as shown in below: Click the Run SQL icon (Ctrl+Shift+E) above the SQL command window. Note: It is ok to see this: "Error code -1, SQL state 42Y55: 'DROP TABLE' cannot be performed on 'ITEM' because it does not exist. Line 2, column 1" . This just means you are deleting a table that does not exist. If you need to delete and recreate the tables you will not see this message the second time. View the data in the Pet Catalog database Item table as follows: Underneath Databases you should see a database connection for the petcatalog database. For example MySQL: or Java DB: If the database connection is broken like in the following diagram: Right-mouse click on the petcatalog connection and select Connect. as shown below: if prompted for a password, for MySQL leave it blank, for JavaDB enter user app password app. Expand the Tables node below the petcatalog database in the Services window. You should see the item table under the Tables node. You can expand the item table node to see the table columns, indexes, and any foreign keys, as shown in below : Figure 12. An Expanded Table Node You can view the contents of a table or column by right-clicking the table or column and selecting View Data as shown below: Figure 13. Viewing the Contents of a Table Follow these instructions to Create a JDBC Connection pool and JDBC resource. Name the pool mysql_petcatalog_rootPool and the jndi resource jdbc/petcatalog. Note: you do not have to create a JDBC connection pool and resource if you use the Netbeans wizard to generate JPA entities from database tables as described in this article GlassFish and MySQL, Part 2: Building a CRUD Web Application With Data Persistence. Open the catalog/setup/sun-resources.xml file and verify that the property values it specifies match those of the petcatalog database and jdbc resources you created. Edit the property values as necessary. Running the Sample solution: If you want to run the sample solution, you have to create the catalog database tables first as described above. Open the catalog project as follows: In NetBeans IDE, click Open Project in the File menu. This opens the Open Project dialog. Navigate in the Open Project dialog to the catalog directory and click the Open Project button. In response, the IDE opens the catalog project. You can view the logical structure of the project in the Projects window (Ctrl-1). Run the catalog by right-clicking on the catalog project in the Projects window and selecting Run Project. The NetBeans IDE compiles the application, deploys it on Glassfish, and brings up the default page in your browser. (at http://localhost:8080/catalog/). For more information see the following resources: A Sampling of EJB 3.1 Java EE 6 Technologies JSF 2.0 Home page Project Mojarra SDN JavaServer Faces Page JSF 2 fu, Part 1: Streamline Web application development Composite UI Components in JSF 2.0 Creating Your First Java EE 6 Application Roger Kitain's Blog (co-spec lead for JSF 2.0) Ed Burns's Blog (co-spec lead for JSF 2.0) Cay Horstmann's Blog: JSF 2.0 specifying parameters in method expressions JavaServer Faces 2.0 Ref Card Jim Driscoll's Blog Top reasons why GlassFish v3 is a lightweight server Beginning Java™ EE 6 Platform with GlassFish™ 3: From Novice to Professional Book
May 23, 2023
by Carol McDonald
· 18,410 Views · 1 Like
article thumbnail
How To Improve Performance Using AWS and Terraform
In this article, we will discuss the advantages of using AWS and Terraform and provide an example of this collaboration for better understanding.
May 22, 2023
by Vladislav Bilay
· 8,570 Views · 3 Likes
article thumbnail
Mastering Time Series Analysis: Techniques, Models, and Strategies
The article covers time series analysis, discusses unique cross-validation methods, data decomposition and transformation, and more.
May 22, 2023
by Valentine Shkulov
· 6,301 Views · 10 Likes
article thumbnail
Building a Java Payment App With Marqeta
Using Java and Marqeta, we’ll build out a fully functioning card payment system your users can use for payments anywhere that a debit or credit card is accepted.
May 22, 2023
by Michael Bogan DZone Core CORE
· 2,243 Views · 2 Likes
article thumbnail
Develop Hands-Free Weather Alerts To Ensure Safe Backpacking
Make the most of your backpacking adventure by creating customized weather alerts using Tomorrow.io weather API. Stay safe with critical alerts tailored to your needs.
May 22, 2023
by Joydeep Bhattacharya DZone Core CORE
· 1,674 Views · 2 Likes
article thumbnail
What Is Istio Ambient Mesh?
Istio has released a sidecar-less data plane called ambient mode. Explore its architecture and the benefits it can bring to enterprises.
May 22, 2023
by Debasree Panda
· 2,199 Views · 4 Likes
article thumbnail
Developers Are Scaling Faster Than Ever: Here’s How Security Can Keep Up
We know traditional security practices can’t support this scale, so how do modern practices allow us to scale security with these architectures?
May 22, 2023
by Aakash Shah
· 2,982 Views · 1 Like
article thumbnail
Multi-Stream Joins With SQL
Learn how to combine two or more streams of data together in real-time with a streaming database, run SQL queries and create a materialized view.
May 22, 2023
by Bobur Umurzokov
· 2,196 Views · 2 Likes
article thumbnail
Avoiding Pitfalls With Java Optional: Common Mistakes and How To Fix Them [Video]
Learn how to avoid traps with Java Optional and how to use it efficiently by taking the best of this API to make a readable code.
May 22, 2023
by Otavio Santana DZone Core CORE
· 9,809 Views · 11 Likes
article thumbnail
HTML5's IndexedDB: Transactions Tutorial
Last week I wrote a brief introduction to Kristof Degrave's ongoing, multi-stage IndexedDB tutorial. Judging by the number of reads, it looks like quite a few of you are interested in learning more about HTML5's IndexedDB. I'm following Kristof's tutorial anyway, so I might as well keep posting about it here. Today Kristof has posted his next IndexedDB tutorial -- Transactions -- and here's where IndexedDB begins to get exciting, where the work of creation and definition begins to pay off. We're preparing for actual data retrieval and manipulation, so we'll be creating a READ_WRITE transaction. At this point, if you're trying to understand IndexedDB formally as well as use it pragmatically, you might want to get more comfortable with W3C's conceptual treatment of transactions along with the formal object description, and maybe the IDBTransaction interface too. (For me, it especially helps to understand emerging tech like HTML5 a little more abstractly, just in case the standard takes a different turn than previously expected.) If you prefer learning by doing, here's how Kristof explains transactions: Today, I’ll handle the transaction subject. As said in previous posts, every request made to the database needs to be done in a transaction. So for every read or write request we need to create a new transaction. There for we need a database connection and 2 argument that we will pass to the transaction method. The post is, like his previous tutorials, quite straightforward -- painlessly showing you how to use what is potentially one of the most powerful features of HTML5. Take a look, create an IndexedDB transaction, and get ready to retrieve and manipulate data.
May 22, 2023
by John Esposito
· 9,527 Views · 1 Like
article thumbnail
HowTo: Store and Retrieve Images in a SQL CE Database on Windows Phone Mango
Serious local database support is probably one of the coolest new features of Windows Phone 7.1(5). For the Windows Phone developer, it's not hard to create a local database, or add some columns, indexes or tables. But if you're using a SQL CE database then you are, after all, developing for a phone. And one of phones' most exciting powers isn't their hard drives -- it's their cameras. And it turns out that Mango makes storing camera photos -- or any image data for that matter -- pretty easy. To see how easy, look at this HowTo from Anton Swanevelder, posted a few days ago on his blog. Anton breaks SQL CE image-storage into three steps (the CRU in CRUD), and every step takes less than 20 lines. For example, you can create a column to store image data like this: [Column] public byte[] ItemImage { get { return _ItemImage; } set { if (_ItemImage != value) { _ItemImage = value; NotifyPropertyChanging("ItemImage"); NotifyPropertyChanged("ItemImage"); } } } The other two steps are more interesting (converting a camera stream to a storable byte array, then converting the byte array to a bitmap markup-able in XAML), but no more difficult. Read the full post for the full implementation.
May 22, 2023
by John Esposito
· 11,689 Views · 2 Likes
  • Previous
  • ...
  • 147
  • 148
  • 149
  • 150
  • 151
  • 152
  • 153
  • 154
  • 155
  • 156
  • ...
  • Next
  • RSS
  • X
  • Facebook

ABOUT US

  • About DZone
  • Support and feedback
  • Community research

ADVERTISE

  • Advertise with DZone

CONTRIBUTE ON DZONE

  • Article Submission Guidelines
  • Become a Contributor
  • Core Program
  • Visit the Writers' Zone

LEGAL

  • Terms of Service
  • Privacy Policy

CONTACT US

  • 3343 Perimeter Hill Drive
  • Suite 215
  • Nashville, TN 37211
  • [email protected]

Let's be friends:

  • RSS
  • X
  • Facebook
×