Configuring Seam applications for Seam Remoting

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Configuring Seam applications for Seam Remoting
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To configure a web application to use Seam Remoting, declare the Seam Resource servlet within our application's WEB-INF/web.xml file as follows. 

 <servlet>
  <servlet-name>Seam Resource Servlet</servlet-name>
  <servlet-class>
  org.jboss.seam.servlet.SeamResourceServlet
  </servlet-class>
 </servlet>
  <servlet-mapping>
  <servlet-name>Seam Resource Servlet</servlet-name>
  <url-pattern>/seam/resource/*</url-pattern>
 </servlet-mapping>

That's all a Seam web application will work with Seam Remoting. To make things even easier, this configuration is automatically done when applications are created with SeamGen, so you would have to worry about this configuration only if you are using non-SeamGen created projects.


Contents

[edit] Configuring Seam Remoting server side

To declare that a Seam component can be used via Seam Remoting, the methods that are to be exposed need to be annotated with the @WebRemote annotation. For simple POJO components, this annotation is applied directly on the POJO itself, as shown in the following code snippet. 

 
 @Name("helloWorld")
 public class HelloWorld implements HelloWorldAction {
 @WebRemote
 public String sayHello() {
 return "Hello world !!";
 }

For Session Beans, the annotation must be applied on the Session Beans business interface rather than on the implementation class itself. A Session Bean interface would be declared as follows. 

 import javax.ejb.Local;
 import org.jboss.seam.annotations.remoting.WebRemote;
  @Local
  public interface HelloWorldAction {
  @WebRemote
  public String sayHello();
  @WebRemote
  public String sayHelloWithArgs(String name);
 }

The implementation class is defined as follows: 

 import javax.ejb.Stateless;
 import org.jboss.seam.annotations.Name;
 @Stateless
 @Name("helloWorld")
 public class HelloWorld implements HelloWorldAction {
  public String sayHello() {
  return "Hello world !!";
  }
  public String sayHelloWithArgs(String name) {
  return "Hello "+name;
  }
  }

Note that, to make a method available to Seam Remoting, all we need to do is to annotate the method with @WebRemote and then import the relevant class. As we can see in the preceding code, it doesn't matter how many parameters our methods take.

[edit] Configuring Seam Remoting client side

In the previous sections, we've seen that minimal configuration is required to enable Seam Remoting and to declare Seam components as Remoting-aware. Similarly in this section, we'll see that minimal work is required within a Facelets file to enable Remoting.


The Seam Framework provides built-in JavaScript to enable Seam Remoting. To use this JavaScript, we first need to define it within a Facelets file in the following way: 

 <script type="text/javascript" 
 src="/HelloWorld/seam/resource/ remoting/resource/remote.js">
 </script>
 <script type="text/javascript" 
 src="/HelloWorld/seam/resource/ remoting/interface.js?helloWorld">

To include the relevant JavaScript into a Facelets page, we need to import the /seam/resource/remoting/resource/remote.js and /seam/resource/remoting/interface.js JavaScript files.

You can see that the interface.js file takes an argument defining the name of the Seam component that we will be accessing (this is the name of the component for which we have defined methods with the @WebRemote annotation).

If we wish to use two or more different Seam components from a Remoting interface, we would specify their names as parameters to the interface.js file separated by using an "&", for example: 

<script type="text/javascript" src="/HelloWorld/seam/resource/ remoting/interface.js?helloWorld&mySecondComponent& myThirdComponent">

To specify that we will use Seam components from the web tier is straight-forward, however, the Seam tag library makes this even easier.

Instead of specifying the JavaScript shown in the preceding examples, we can simply insert the <s:remote /> tag into Facelets, passing the name of the Seam component to use within the include parameter. 

 <ui:composition
 xmlns="http://www.w3.org/1999/xhtml"
 xmlns:s="http://jboss.com/products/seam/taglib"
 xmlns:ui="http://java.sun.com/jsf/facelets"
 xmlns:f="http://java.sun.com/jsf/core"
 xmlns:h="http://java.sun.com/jsf/html"
 xmlns:rich="http://richfaces.org/rich"
 template="layout/template.xhtml">
   <ui:define name="body">
   <h1>Hello World</h1>
<s:remote include="helloWorld"/>

To use the <s:remote /> tag, we need to import the Seam tag library, as shown in this example. When the web page is rendered, Seam will automatically generate the relevant JavaScript.


If we are using the <s:remote /> tag and we want to invoke methods on multiple Seam components, we need to place the component names as comma-separated values within the include parameter of the tag instead, for example:</blockquote>
<s:remote include="helloWorld, mySecondComponent, myThirdComponent" />
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[edit] Hello World

<s:remote include="helloWorld"/> </pre> To use the <s:remote /> tag, we need to import the Seam tag library, as shown in this example. When the web page is rendered, Seam will automatically generate the relevant JavaScript.


If we are using the <s:remote /> tag and we want to invoke methods on multiple Seam components, we need to place the component names as comma-separated values within the include parameter of the tag instead, for example:</blockquote>
<s:remote include="helloWorld, mySecondComponent, myThirdComponent" />

[edit] Hello World

<s:remote include="helloWorld"/> </pre> To use the <s:remote /> tag, we need to import the Seam tag library, as shown in this example. When the web page is rendered, Seam will automatically generate the relevant JavaScript.


If we are using the <s:remote /> tag and we want to invoke methods on multiple Seam components, we need to place the component names as comma-separated values within the include parameter of the tag instead, for example:</blockquote>
<s:remote include="helloWorld, mySecondComponent, myThirdComponent" />

[edit] Debugging Seam Remoting

When writing Seam Remoting applications, it can be useful to see the AJAX conversations that are being carried out between the browser and the server.

Seam enables a debug window that shows all of the Remoting communications to be turned on. Debugging is turned off by default, but can be enabled by editing the WEB-INF/components.xml file.

Debugging can be enabled within this file in two ways:

  • Setting the debug property of the org.jboss.seam.remoting.remoting component to true.
  • Setting the debug property of the remoting:remoting component to true.

[edit] The org.jboss.seam.remoting.remoting component

The simplest way to enable Seam Remoting debugging is to set the debug property to true on the org.jboss.seam.remoting.remoting component. This is achieved by specifying the following code within the WEB-INF/components.xml file. 

 <component name="org.jboss.seam.remoting.remoting">
 <property name="debug">true</property>
 </component>

However, if this mechanism is used for enabling debugging, the XML within the components.xml cannot be validated fully against the XML schema, because the component name cannot be validated. The following technique allows better control, and helps to ensure that the components.xml file can be validated against its schema.

[edit] The org.jboss.seam.remoting.remoting component

The simplest way to enable Seam Remoting debugging is to set the debug property to true on the org.jboss.seam.remoting.remoting component. This is achieved by specifying the following code within the WEB-INF/components.xml file. 

 <component name="org.jboss.seam.remoting.remoting">
 <property name="debug">true</property>
 </component>

However, if this mechanism is used for enabling debugging, the XML within the components.xml cannot be validated fully against the XML schema, because the component name cannot be validated. The following technique allows better control, and helps to ensure that the components.xml file can be validated against its schema.

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[edit] Debugging Seam Remoting

When writing Seam Remoting applications, it can be useful to see the AJAX conversations that are being carried out between the browser and the server.

Seam enables a debug window that shows all of the Remoting communications to be turned on. Debugging is turned off by default, but can be enabled by editing the WEB-INF/components.xml file.

Debugging can be enabled within this file in two ways:

  • Setting the debug property of the org.jboss.seam.remoting.remoting component to true.
  • Setting the debug property of the remoting:remoting component to true.

[edit] The <remoting:remoting> component

Seam Remoting debugging can also be enabled by using the <remoting:remoting> component. To enable debugging, insert the following code into the WEB-INF/components.xml file. 

<remoting:remoting debug="true" />

It's evident from this code that the component name can be fully validated against the XML schema, which will help to reduce errors within the configuration.

To use this type of configuration, we must first specify the namespace and schema location for the Seam Remoting component. This is achieved within the <components /> element of the WEB-INF/components.xml file, as shown in the following code snippet. 

  <components xmlns="http://jboss.com/products/seam/components"
  xmlns:core="http://jboss.com/products/seam/core"
  xmlns:persistence="http://jboss.com/products/seam/persistence"
  xmlns:drools="http://jboss.com/products/seam/drools"
  xmlns:bpm="http://jboss.com/products/seam/bpm"
  xmlns:security="http://jboss.com/products/seam/security"
  xmlns:mail="http://jboss.com/products/seam/mail"
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xmlns:remoting="http://jboss.com/products/seam/remoting"
  xsi:schemaLocation=
  "http://jboss.com/products/seam/core
  http://jboss.com/products/seam/core-2.1.xsd
  http://jboss.com/products/seam/persistence
  http://jboss.com/products/seam/persistence-2.1.xsd
  http://jboss.com/products/seam/drools
  http://jboss.com/products/seam/drools-2.1.xsd
  http://jboss.com/products/seam/bpm
  http://jboss.com/products/seam/bpm-2.1.xsd
  http://jboss.com/products/seam/security
  http://jboss.com/products/seam/security-2.1.xsd
  http://jboss.com/products/seam/mail
  http://jboss.com/products/seam/mail-2.1.xsd
  http://jboss.com/products/seam/remoting
  http://jboss.com/products/seam/remoting-2.1.xsd
  http://jboss.com/products/seam/components
  http://jboss.com/products/seam/components-2.1.xsd">

From this XML fragment, we can see that we define the XML namespace remoting as http://jboss.com/products/seam/remoting. We then define the schema location as http://jboss.com/products/seam/remoting-2.1.xsd.

Once debugging is enabled via either of the two methods described earlier, whenever a Remoting method is executed, all of the data that is passed between the server and the web browser is displayed within a popup browser window, as shown in the following screenshot.

For our simple HelloWorld method, let's see what the HTML exchanges between client and server are.

In the request packet, we can see that the sayHelloWithArgs method on the helloWorld component is being invoked, passing the parameter value "David". This is being invoked with a conversation handle of "5".

In the response packet, we can see that the value "Hello David" is returned as the response.

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[edit] The <remoting:remoting> component

Seam Remoting debugging can also be enabled by using the <remoting:remoting> component. To enable debugging, insert the following code into the WEB-INF/components.xml file. 

<remoting:remoting debug="true" />

It's evident from this code that the component name can be fully validated against the XML schema, which will help to reduce errors within the configuration.

To use this type of configuration, we must first specify the namespace and schema location for the Seam Remoting component. This is achieved within the <components /> element of the WEB-INF/components.xml file, as shown in the following code snippet. 

  <components xmlns="http://jboss.com/products/seam/components"
  xmlns:core="http://jboss.com/products/seam/core"
  xmlns:persistence="http://jboss.com/products/seam/persistence"
  xmlns:drools="http://jboss.com/products/seam/drools"
  xmlns:bpm="http://jboss.com/products/seam/bpm"
  xmlns:security="http://jboss.com/products/seam/security"
  xmlns:mail="http://jboss.com/products/seam/mail"
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xmlns:remoting="http://jboss.com/products/seam/remoting"
  xsi:schemaLocation=
  "http://jboss.com/products/seam/core
  http://jboss.com/products/seam/core-2.1.xsd
  http://jboss.com/products/seam/persistence
  http://jboss.com/products/seam/persistence-2.1.xsd
  http://jboss.com/products/seam/drools
  http://jboss.com/products/seam/drools-2.1.xsd
  http://jboss.com/products/seam/bpm
  http://jboss.com/products/seam/bpm-2.1.xsd
  http://jboss.com/products/seam/security
  http://jboss.com/products/seam/security-2.1.xsd
  http://jboss.com/products/seam/mail
  http://jboss.com/products/seam/mail-2.1.xsd
  http://jboss.com/products/seam/remoting
  http://jboss.com/products/seam/remoting-2.1.xsd
  http://jboss.com/products/seam/components
  http://jboss.com/products/seam/components-2.1.xsd">

From this XML fragment, we can see that we define the XML namespace remoting as http://jboss.com/products/seam/remoting. We then define the schema location as http://jboss.com/products/seam/remoting-2.1.xsd.

Once debugging is enabled via either of the two methods described earlier, whenever a Remoting method is executed, all of the data that is passed between the server and the web browser is displayed within a popup browser window, as shown in the following screenshot.

For our simple HelloWorld method, let's see what the HTML exchanges between client and server are.

In the request packet, we can see that the sayHelloWithArgs method on the helloWorld component is being invoked, passing the parameter value "David". This is being invoked with a conversation handle of "5".

In the response packet, we can see that the value "Hello David" is returned as the response.

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And Like Costumes and Halloween Costumes

And Like The Global Information Network and Global Information Network

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