Using DWR with Springframework (I)

Recently, I have integrated DWR (direct web remoting) in a spring application. There are some ways to do that, I'm going to explain only one, that uses spring support for namespaces introduced since Spring 2.0.

The first step is adding a new servlet in web.xml and map it to /dwr/*:
<br /> <servlet><br /> <servlet-name>dwr</servlet-name><br /> <servlet-class>org.directwebremoting.spring.DwrSpringServlet</servlet-class><br /> <init-param><br /> <param-name>debug</param-name> <param-value>true</param-value> </init-param><br /> <init-param><br /> <param-name>allowScriptTagRemoting</param-name> <param-value>true</param-value> </init-param><br /> <init-param><br /> <param-name>crossDomainSessionSecurity</param-name> <param-value>false</param-value> </init-param><br /> </servlet><br /> <br /> <servlet-mapping><br /> <servlet-name>dwr</servlet-name><br /> <url-pattern>/dwr/*</url-pattern><br /> </servlet-mapping><br />

Second step is adding the namespace to our applicationContext:

<br /> <beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:context="http://www.springframework.org/schema/context" xmlns:p="http://www.springframework.org/schema/p" xmlns:dwr="http://www.directwebremoting.org/schema/spring-dwr" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.5.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-2.5.xsd http://www.directwebremoting.org/schema/spring-dwr http://www.directwebremoting.org/schema/spring-dwr-2.0.xsd"><br /> </beans><br />

This allows us to use DWR namespace for spring. Now, we are able to add the DWR controller to manage DWR requests:

<dwr:controller id="dwrController" debug="true" /><dwr:configuration />

We have setup dwr with spring, it's as easy as it seems. Supposing we have a service that returns a java.util.List of Article class. Article could be a simple bean like this:

<br /> public class Article implements java.io.Serializable{<br /> private String id;<br /> private String title;<br /> private String bodytext;<br /> //accesor methods....<br /> }<br /> public class ArticleService{<br /> public List<article> getLastArticles(){}<br /> }<br />

To setup getLastArticles() as a remote ajax method with Spring we only have to annotate the related ArticleService spring bean:

<br /> <bean id="articleService" class="com.mycompany.myservicepackage.ArticleService"><br /> <property name="articleDao" ref="articleDao" /><br /> <dwr:remote javascript="ArticleService"><br /> <dwr:include method="getLastArticles"/><br /> <dwr:convert type="bean"class="com.mycompany.mymodelpackage.Article" /><br /> </dwr:remote><br /> </bean><br />

That's all. We are telling DWR to convert our bean Article to JSON. And, only the method specified in dwr:include tag, is callable by ajax. We can call this method from any view in our web application. In the next episode, I will explain how.

Using DWR with Springframework (II)