The basic operation of WebAppProvider is to scan a directory at startup for WAR files or webapp directories and to deploy the web applications found. Typically this is done from a jetty.xml style file; in the jetty distribution the name of this file is jetty-webapps.xml:
<Configure id="Server" class="org.eclipse.jetty.server.Server"> <Ref id="DeploymentManager"> <Call id="webappprovider" name="addAppProvider"> <Arg> <New class="org.eclipse.jetty.deploy.providers.WebAppProvider"> <Set name="monitoredDirName"><Property name="jetty.home" default="." />/webapps</Set> <Set name="defaultsDescriptor"><Property name="jetty.home" default="."/>/etc/webdefault.xml</Set> <Set name="scanInterval">1</Set> <Set name="contextXmlDir"><Property name="jetty.home" default="." />/contexts</Set> <Set name="extractWars">true</Set> </New> </Arg> </Call> </Ref> </Configure>
The WebAppProvider is added to the server as a LifeCycle. This simply means that the deployer starts and stops with the server, that is, when server.start() is called, then start is also called on the deployer.
The context passed in is a reference to a HandlerContainer in which the discovered webapps are deployed. This is normally an instance of ContextHandlerCollection.
The contextXmlDir points to a directory like that the ContextProvider uses. When you use this option the WebappProvider checks any webapp or WAR files in the monitored directory for an associated context file. If it finds one, it defers to the ContextProvider to deploy the webapp. If it does not find a context file, the WebAppProvider deploys the webapp.
The monitoredDirName is a file path or URL to the directory to scan for web applications. Zip files ending with .war or .zip are deployed. Directories not called CVS are also deployed. The basename of the WAR (for example, foo from foo.war) or the directory name are used as the context path of the discovered webapps, unless the name is "root", in which case the context path of / is used.
The parentLoaderPriority parameter is a boolean that selects whether the standard Java parent first delegation classloading will be used or the servlet specification webapp Jetty/Reference/Jetty_Classloading priority.
If the extract parameter is true, any packed WAR or zip files are first extracted to a temporary directory before being deployed. This is advisable if there are uncompiled JSPs in the web apps.
If the allowDuplicates parameter is false, the discovered webapps are checked against existing deployed webapps and are not deployed if the same context path or WAR file is already deployed (perhaps by another deployer).
The defaultsDescriptor parameter allows an alternative webdefault.xml config file to be set on the discovered web applications. The webdefault.xml file controls the configuration of the JSP and Default servlets.