CometD 2 Java Server Configuration

CometD 2 Java Server Configuration

BayeuxServer and server transport parameters can be specified in web.xml as init parameters of the org.cometd.server.CometdServlet.
If the CometD servlet creates the BayeuxServer instance, the servlet init parameters will be passed to the BayeuxServer instance, which will in turn configure the server transports.

If you followed the primer, then Maven has configured the web.xml file for you, but here we will detail its configuration.
This is a sample web.xml:

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://java.sun.com/xml/ns/javaee"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
         version="2.5">

    <servlet>
        <servlet-name>cometd</servlet-name>
        <servlet-class>org.cometd.server.CometdServlet</servlet-class>
        <init-param>
            <param-name>timeout</param-name>
            <param-value>60000</param-value>
        </init-param>
        <init-param>
            <param-name>logLevel</param-name>
            <param-value>3</param-value>
        </init-param>
    </servlet>
    <servlet-mapping>
        <servlet-name>cometd</servlet-name>
        <url-pattern>/cometd/*</url-pattern>
    </servlet-mapping>

</web-app>

The org.cometd.server.CometdServlet must be defined and mapped in web.xml, or otherwise the server will not be able to interpret the Bayeux protocol.
It is normally mapped on /cometd/*, but you can change the mapping url-pattern at your wish.

BayeuxServer Configuration

Here is the list of configuration init parameters accepted by the BayeuxServer implementation:

Server Transport Configuration

In CometD 2 the server transports are pluggable and can be configured using parameters that may have a prefix that specifies the transport that the parameter refers to.
For example, the parameter timeout has no prefix, and hence it is valid for all transports; the parameter long-polling.jsonp.timeout overrides the timeout parameter for the callback polling transport only, while ws.timeout overrides it for the websocket transport (see org.cometd.bayeux.Transport javadocs for details).

Here is the list of configuration init parameters accepted by server transports:

Advanced Configuration

If you are using Jetty 7, you may want to configure also the CrossOriginFilter.
This filter implements the Cross-Origin Resource Sharing specification, and allows recent browsers that implements it (as of November 2009, Firefox 3.5.x, Chrome 3.x and Safari 4.x) to perform cross-domain JavaScript requests (see also the transport section).
Here is an example of web.xml configuration for the CrossOriginFilter:

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://java.sun.com/xml/ns/javaee"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
         version="2.5">

    <servlet>
        <servlet-name>cometd</servlet-name>
        <servlet-class>org.cometd.server.continuation.ContinuationCometdServlet</servlet-class>
        <init-param>
            <param-name>timeout</param-name>
            <param-value>60000</param-value>
        </init-param>
    </servlet>
    <servlet-mapping>
        <servlet-name>cometd</servlet-name>
        <url-pattern>/cometd/*</url-pattern>
    </servlet-mapping>

    <filter>
        <filter-name>cross-origin</filter-name>
        <filter-class>org.eclipse.jetty.servlets.CrossOriginFilter</filter-class>
    </filter>
    <filter-mapping>
        <filter-name>cross-origin</filter-name>
        <url-pattern>/cometd/*</url-pattern>
    </filter-mapping>

</web-app>

Refer to this document for the filter configuration.

Servlet 3 configuration

Refer to this FAQ.