JNDI Resources HOW-TO

Table of Contents

Introduction

Tomcat provides a JNDI InitialContext implementation instance for each web application running under it, in a manner that is compatible with those provided by a Java Enterprise Edition application server. The Java EE standard provides a standard set of elements in the /WEB-INF/web.xml file to reference/define resources.

See the following Specifications for more information about programming APIs for JNDI, and for the features supported by Java Enterprise Edition (Java EE) servers, which Tomcat emulates for the services that it provides:

web.xml configuration

The following elements may be used in the web application deployment descriptor (/WEB-INF/web.xml) of your web application to define resources:

  • <env-entry> - Environment entry, a single-value parameter that can be used to configure how the application will operate.
  • <resource-ref> - Resource reference, which is typically to an object factory for resources such as a JDBC DataSource, a JavaMail Session, or custom object factories configured into Tomcat.
  • <resource-env-ref> - Resource environment reference, a new variation of resource-ref added in Servlet 2.4 that is simpler to configure for resources that do not require authentication information.

Providing that Tomcat is able to identify an appropriate resource factory to use to create the resource and that no further configuration information is required, Tomcat will use the information in /WEB-INF/web.xml to create the resource.

Tomcat provides a number of Tomcat specific options for JNDI resources that cannot be specified in web.xml. These include closeMethod that enables faster cleaning-up of JNDI resources when a web application stops and singleton that controls whether or not a new instance of the resource is created for every JNDI lookup. To use these configuration options the resource must be specified in a web application's <Context> element or in the <GlobalNamingResources> element of $CATALINA_BASE/conf/server.xml.

context.xml configuration

If Tomcat is unable to identify the appropriate resource factory and/or additional configuration information is required, additional Tomcat specific configuration must be specified before Tomcat can create the resource. Tomcat specific resource configuration is entered in the <Context> elements that can be specified in either $CATALINA_BASE/con