Inter-Application Communication

An EAR file or the installation of Web server could have multiple WAR files. Each of them is a Web application. There are no standard way to communicate between two Web applications. However, there are a few ways to work around it.

Include Another Application's Resource with ZK URL Prefix ~APPLICATION_CONTEXT/

ZK supports a way to reference the resource from another web application on the same application server. For example, assume you want to include a resource, say /foreign.zul, from another Web application, say app2. Then, you could do as follows.

<include src="~app2/foreign.zul"/>

Similarly, you could reference resources from another Web application.

<style src="~app2/foo.css"/> <!-- assume foo.css is in the context called app2 --> 
<image src="~/foo.png"/> <!-- assume foo.png is in the root context -->

Note: Whether you can access a resource located in another Web application depends on the configuration of the Web server. For example, you have to specify crossContext="true" in conf/context.xml, if you are using Tomcat.

Use Cookie

Cookie is another way to communicate among Web applications. It can be done by setting the path to "/", such that every Web application in the same host will see it.

HttpServletResponse response = (HttpServletResponse)Executions.getCurrent().getNativeResponse();
Cookie userCookie = new Cookie("user", "foo");
userCookie.setPath("/");
response.addCookie(userCookie);

Web Resources from Classpath

Though it is not necessary for inter-application communication, you could, with ZK, reference a resource that is locatable by the classpath. The advantage is that you could embed Web resources in a JAR file, which simplifies the deployment.

<image src="~./my/jar.gif"/>

Then, it tries to locate the resource, /my/jar.gif, at the /web directory by searching resources from the classpath. Notice that WEB-INF/classes is also part of the classpath, so you could put it under WEB-INF/classes/web/my/jar.gif too.

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