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Archive for the ‘Java’ Category

NWT – .Net Web Toolkit

Posted by Igor Moochnick on 10/26/2011

Now, after waiting for quite some time, we finally can implement the real solution for .Net <-> javascript conversion and bridge the impedance gap in the projects that heavily rely on the powerful rich web UI.

Currently we have solutions like Script# and CofeeScript and others. The pros in cons of these systems have been discussed countless times (ex: HanselminutesJavaScript is Assembly Language for the Web: Semantic Markup is Dead! Clean vs. Machine-coded HTML).

With the recently released project Roslyn (or alternatively Mono Compiler Services) it is possible to have a clean solution to the problem:  I write my data and data model in a language and an environment that allow solid validation and refactoring.

I’m ironing out some kinks in my implementation and, as soon as it’ll be in a stable state, I’m going to release a NWT (NeWT) project that will provide a similar to GWT (Google Web Toolkit) functionality.

Posted in C#, GWT, Javascript, jQuery, Web | 1 Comment »

XML/JSON symmetric REST web services providers for Jersey

Posted by Igor Moochnick on 07/27/2009

Many times I’ve been asked to provide a set of Web Services interfaces where both JSON and XML clients can communicate with the server. Primarily it’s done for a set of reasons:

  1. XML is very convenient to use for inter-service communication.
  2. JSON is great for AJAX (web) clients. It’s perfect for GWT too.

In the recent project we’ve been using XStream for all serialization aspects and, since it can serialize both to XML and JSON, it was plugged into Jersey as a provider too. Following you can see XML and JSON providers implemented using XStream library.

XML Provider (annotated to be a default provider, it’ll be used if no Content-Type or Accept headers provided):

Read the rest of this entry »

Posted in GWT, Java, Jersey, JSON, REST, Tutorials, XML, XStream | 2 Comments »

Adding Watermark to GWT Textbox widget

Posted by Igor Moochnick on 06/30/2009

Let’s see how we can improve our UI by adding some watermarked “spice”:

clip_image001

Let’s define the primary style for the text box (textInput) and the dependent style for the watermark (textInput-watermark):

.textInput {
	border: 1px solid #C9C7BA;
	font-family:Tahoma, Verdana, Arial, Helvetica, sans-serif;
	font-size: 11px;
	padding-left: 2px;
	padding-top: 2px;
}

.textInput-watermark {
   /* background-image: url('images/overlay.gif');
   background-repeat: no-repeat;
   padding-left: 20px;
   vertical-align: middle; */
   font-style: italic;
   color: DarkGray;
}

Note that the watermark style can contain images as well (see the commented out piece).

After the styles were defined we need to add some code that will apply it to the text box. To do this I’m going to extend the default GWT TextBox. The trick is to hijack the OnBlur and OnFocus events. When the OnBlur is occurring, we’re going to show the watermark and OnFocus – hide it:

public class WatermarkedTextBox extends TextBox implements BlurHandler, FocusHandler
{
	String watermark;
	HandlerRegistration blurHandler;
	HandlerRegistration focusHandler;
	
	public WatermarkedTextBox( )
	{
		super();
		this.setStylePrimaryName("textInput");
	}
	
	public WatermarkedTextBox(String defaultValue)
	{
		this();
		setText(defaultValue);
	}
	
	public WatermarkedTextBox(String defaultValue, String watermark)
	{
		this(defaultValue);
		setWatermark(watermark);
	}
	
	/**
	 * Adds a watermark if the parameter is not NULL or EMPTY
	 * 
	 * @param watermark
	 */
	public void setWatermark(final String watermark)
	{
		this.watermark = watermark;
		
		if ((watermark != null) && (watermark != ""))
		{
			blurHandler = addBlurHandler(this);
			focusHandler = addFocusHandler(this);
			EnableWatermark();
		}
		else
		{
			// Remove handlers
			blurHandler.removeHandler();
			focusHandler.removeHandler();
		}
	}

	@Override
	public void onBlur(BlurEvent event)
	{
		EnableWatermark();
	}
	
	void EnableWatermark()
	{
		String text = getText(); 
		if ((text.length() == 0) || (text.equalsIgnoreCase(watermark)))
		{
			// Show watermark
			setText(watermark);
			addStyleDependentName("watermark");
		}
	}

	@Override
	public void onFocus(FocusEvent event)
	{
		removeStyleDependentName("watermark");
		
		if (getText().equalsIgnoreCase(watermark))
		{
			// Hide watermark
			setText("");
		}
	}
}

Posted in Design, GWT, Java, Tutorials, Web | 10 Comments »

Job trends for GWT and jQuery on a sharp rise

Posted by Igor Moochnick on 06/11/2009

Gotta love this …

jobgraph[1]

Posted in GWT, jQuery | Leave a Comment »

Building GWT web clients [Part 4] – How to connect GWT client to Azure web service?

Posted by Igor Moochnick on 06/08/2009

Stay tuned …

Posted in Azure, Cloud, GWT, Java, JSON, REST, Tutorials | Leave a Comment »

Building GWT web clients [Part 3] – How to connect GWT client to JAX-RS Jersey server?

Posted by Igor Moochnick on 06/08/2009

Stay tuned …

Posted in Cloud, GWT, Java, JAX-RS, Jersey, JSON, REST, Tutorials | 7 Comments »

Building GWT web clients [Part 2.1] – How to control JSON output format from Jersey?

Posted by Igor Moochnick on 05/21/2009

As you know that in XML you can represent the same data in variety of ways by using fields, names, attributes, etc..

The same is true to JSON. In many cases different serializers produce different JSON representation of the same objects.

JAX-RS (as well as Jersey) provide you control over what and how you want to serialize. This is accomplished via providers.

Here is an example of such provider (Note that the class should be marked with @Provider annotation):

@Provider
public class JAXBContextResolver implements ContextResolver<JAXBContext> { 
    private JAXBContext context;
    private Class<?>[] types = { ListDescription.class }; 

    public JAXBContextResolver() throws Exception {
        JSONConfiguration config = JSONConfiguration.natural().build();
        context = new JSONJAXBContext(config, types);
    } 

    public JAXBContext getContext(Class<?> objectType) {
        for (Class<?> type : types) {
            if (type == objectType) {
                return context;
            }
        }
        return null;
    }
}

Note that by creating an appropriate JSONConfiguration (JSONConfiguration.natural().build()) you, in fact, control the output JSON format. The JSONConfiguration class provide 4 different JSON formatters:

  1. natural (Jackson)
  2. mapped
  3. mappedJettison
  4. Badgerfish

Here is how the output will vary, depending on the choice of the configuration. Don’t forget that the class should be annotated with A simple class (with fields (int)ID and (String)Name) added to an ArrayList and then returned back as a @GET return value:

@XmlRootElement
public class ListDescription
{
	public int ID;
	public String Name;
}

@GET
@Produces({MediaType.APPLICATION_JSON })
public List<DataListInfo> getAllLists()
{
	List<ListDescription> lists = new ArrayList<ListDescription>();
	ListDescription ls = new ListDescription();
	ls.ID = 1;
	ls.Name = "Test";
	lists.add(ls);
	return lists;
}

This is what you’ll get from each configuration (respectively):

mappedJettison:

{"listDescriptions":{"listDescription":{"ID":1,"Name":"Test"}}}

mapped:

{"listDescription":{"ID":"1","Name":"Test"}}

natural (jackson):

[{"ID":1,"Name":"Test"}]

Badgerfish:

{"listDescriptions":{"listDescription":{"ID":{"$":"1"},"Name":{"$":"Test"}}}}

Posted in Java, JAX-RS, JAXB, Jersey, JSON, REST | 1 Comment »

Building GWT web clients [Part 2] – How to expose REST-full JAX-RS service with Jersey on Tomcat server?

Posted by Igor Moochnick on 05/20/2009

In the previous article (Part 1) we’ve seen how to create a web-based REST-full client (and an appropriate server) by using GWT. GWT is not providing any “standard” REST (if you can use this word in REST context at all) interface, but, merely, exposes the server-side logic via a proprietary GWT RPC interface.

Today, the most common REST standard is the JAX-RS specification. By implementing your code along the JAX-RS guidelines you can be rest assured that you can easily switch one REST-RX library with another.

As of today there are a couple of JAX-RS libraries used by the Java community:

  1. Jersey
  2. Restlet
  3. Portlet
  4. etc…

On the other hand, being a big fan of Spring, I was hoping that Spring will provide the JAX-RS support in it’s Spring v3 release, but, looking at the M3 drop, I have realized that it’s nowhere near that promise (check my discussion on the StackOverflow).

For this post I’m going to use Jersey JAX-RS implementation. Let’s start with creating

Read the rest of this entry »

Posted in Java, JAX-RS, JAXB, Jersey, JSON, REST, Tomcat, XML | 6 Comments »

Building fat GWT web clients [Intro] – How to create a GWT RPC client?

Posted by Igor Moochnick on 05/18/2009

After months of working (mainly fighting with quirks of Java) with GWT I’ve accumulated so much knowledge on the topic so, I feel, it starts spilling over. I’m planning to convert this spill into a series of articles on how to build fat REST-full GWT web fat clients both on Java and .NET.

Here is the list of topics I’ll cover:

  1. Building GWT fat client
  2. Java REST-full Web services
  3. .NET REST-full Web services
  4. Internationalization and localization
  5. IOC/DI
  6. Unit testing and integration testing of all the components of the system
  7. Build automation
  8. and much, much more …

Here is a draft list of technologies I’ll be using:

  1. GWT
  2. Eclipse
  3. Spring
  4. Jersey
  5. Tomcat
  6. XStream
  7. AJAX
  8. JSON/XML
  9. WCF
  10. JUnit/TestND/NUnit
  11. Selenium
  12. Ant
  13. TeamCity
  14. and much, much more …

For starters, let’s see how to create a simple GWT fat client that talks to the REST-full Web services. As an example,

Read the rest of this entry »

Posted in Cloud, GWT, Java, REST, Tutorials, Web | 3 Comments »

Tree event handler in GWT 1.6

Posted by Igor Moochnick on 04/28/2009

The documentation was a little sparse so, if you’d like to subscribe to the click events on the tree nodes you need to add a selection handler.

This is how you add a selection handler to the whole tree:

Tree optionsTree = new Tree();
optionsTree.addSelectionHandler(new SelectionHandler()
{
    @Override
    public void onSelection(SelectionEvent event)
    {
        Window.alert(event.getSelectedItem().getText());
    }
});

Posted in GWT, Java | 4 Comments »

 
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