zk.xml

WEB-INF/zk.xml is the configuration descriptor of ZK. This file is optional. If you want to configure ZK differently from the default, you need to provide a file called zk.xml under the WEB-INF directory.

The root element must be <zk>. Then, you could specify any combination of the following elements under the root element.

File Location

You can place zk.xml in either a WAR file or a JAR file.

DOCTYPE restriction

Since 10.0.0

Starting from ZK 10, the xml parser used by ZK declares disallow-doctype-decl to true. This prevents the use of DOCTYPE declaration in xml files, such as zk.xml, lang-addon.xml, config. xml, etc. This is a security measure to prevent XXE attacks using <!DOCTYPE ...> as vector.

WEB-INF/zk.xml

zk.xml is usually packed with a Web application and it should be located under WEB-INF.

metainfo/zk/zk.xml

Since 3.6.0

For library providers, zk.xml is better to pack with a JAR file. This can be done by placing zk.xml in the metainfo/zk directory identifiable by the classpath (i.e., in a JAR file).

Additional Configuration File

Since 5.0.7

In addition, you could specify an additional configuration file in a library or system property called org.zkoss.zk.config.path. It is useful if some of the configuration can not be part of the WAR file (such as depending on the deployment environment). For more information, please refer to this section.

Notice that zk.xml found in the classpath is parsed first, then WEB-INF/zk.xml, and finally the additional configuration file. It means the additional configuration file, if any, has the highest priority, and WEB-INF/zk.xml (since the later will overrides the previous one if conflicts).

XML Schema Definition

Since 8.6.1

You could specify the XML schema in the zk.xml as shown below. Many XML editors works better, such as when with auto-complete, if XML schema is specified correctly.

<zk xmlns="http://www.zkoss.org/2005/zk/config"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.zkoss.org/2005/zk/config http://www.zkoss.org/2005/zk/config/zk.xsd">

The ZK schema can be downloaded from http://www.zkoss.org/2005/zk/config/zk.xsd. In addition, you can find zk.xsd under the dist/xsd directory in the ZK binary distribution.