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 (~APP_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.

Limitation

Cross-context access is not always allowed in a container, e.g. Tomcat, you need to enable crossContext first before including another context resources.

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. Please read Include_a_Page#Classpath_Web_Resource_Path.