Module mod_jk

The JkAsfTomcat directive allows the ASF Tomcat plugin to be turned off without deleting particular plugin directives from the HTTP Server (powered by Apache) configuration file. When this directive is set to Off, it appears to the user as if the servlet engine is not enabled.

Parameter: On | Off

• When set to On, the ASF Tomcat module is enabled.
• When set to Off, the module loads, but URL requests are not redirected to the ASF Tomcat servlet engine.

The JkLogFile directive is used to specify the full path and file name of the log file for the ASF Tomcat module. For example:

JkLogFile /QIBM/UserData/HTTPA/tomcat/logs/tomcat.log

The log file describes the flows of header and data between the HTTP Server (powered by Apache) and the ASF Tomcat servlet engine. It does not contain information relative to what happens while the servlet engine is processing a request. See the ASF Tomcat servlet engine log for this information. The plugin log file is never purged or wrapped. The file may need to be periodically purged by the administrator.

Parameter: directory-filename

• The directory-filename parameter specifies the fully-qualified directory path and filename for the ASF Tomcat module log file.

The directive supports both the Root and QOpenSys file systems.

The JkLogLevel directive is used to describe what level of detail is written to the log file defined by JkLogFile.

Parameter: log-level

• Possible log level values are:
  • debug
  • info
  • error
  • emerg

  These values correspond to the HTTP Server (powered by Apache) logging level descriptions. For more information, see LogLevel

The JkMount directive specifies a mapping between a URI context (or URI pattern) and an ASF Tomcat module worker. The URI context is used to identify which requests are to be handled by the module, and the worker name identifies which worker is used to forward matching requests to the servlet engine.

ASF Tomcat workers are defined in a file specified by the JkWorkersFile directive. This file is used to map a worker name to a worker type and various other settings. The worker type determines whether requests are forwarded by the module to an in-process ASF Tomcat server or an out-of-process ASF Tomcat server.

Parameter One: URI-path

• The URI-path parameter used by this directive is compared to the incoming URL from the client browser to determine if the request must be forwarded to the ASF Tomcat servlet engine.

Parameter Two: workername

• The workername can include the following characters: alpha, numeric, dash (-), underscore (_), percent (%), and question mark (?).

The URI-path parameter can assume three different forms: exact match, context match and suffix match. All URL path forms must be preceded by a forward slash (/) character (for instance, /Example, /Example/* or /Example/*.jsp).

• Exact match is used when JkMount must match exactly to a URL path in the client URL. For example, for an incoming client URL of http://systemname:port/example/SampleServlet , JkMount identifies the URL path then the HTTP Server (powered by Apache) forwards the URL request to the ASF Tomcat worker jniworker. The directive displays in the form:

  JkMount /example/SampleServlet jniworker 
  JkMount /SampleServlet jniworker

• Context match forwards client URL requests that have URL paths matching the directive URL path. This form supports the use of the wildcard character (*). For example, with an incoming client URL of http://systemname:port/server1/example/samples/ExampleServlet, JkMount identifies the URL path then the HTTP Server (powered by Apache) forwards all URL requests with a /example subcontext to the ASF Tomcat worker System1worker. The directive displays in the form:

  JkMount /example/* System1worker

• Suffix match forwards client URL requests that have a particular suffix. The form is used to support JSPs that are given in the client URL with a suffix of .jsp. For example:

  JkMount /*.jsp System1worker

  All client URL requests that have a .jsp suffix are forwarded to worker System1worker for processing.

The JkMountCopy directive indicates whether the base server mount points should be copied to the virtual server. Any mount points defined outside <VirtualHost> </VirtualHost> are inherited by the virtual host.

Parameter: On | Off

• When set to On, the base server mount points are copied to the virtual server.
• When set to Off, the base server mount points are not copied to the virtual server.

The JkWorkersFile directive is used to define the name of a file that contains configuration information that describes how the ASF Tomcat module forwards requests to the servlet engine. The two interfaces, used to support the connection between HTTP Server (powered by Apache) and ASF Tomcat, are JNI (Java™ Native Interface) and sockets connections. The JNI interface is used for an in-process ASF Tomcat server. An in-process ASF Tomcat server runs within the HTTP Server process, or job, and starts up and ends at the same times as the HTTP server. The socket interface is for use with an out-of-process ASF Tomcat server that runs within its own process, or job. With an out-of-process ASF Tomcat server, the server could be on the same system or on a different system. Either the AJP12 or AJP13 protocol may be used by a worker to communicate with an out-of-process ASF Tomcat server.

Parameter: directory-filename

• The directory-filename parameter defines the directory path and filename for the file that contains configuration information that describes how the ASF Tomcat module forwards requests to the servlet engine.

There is no default; this directive must be specified or ASF Tomcat will not function. The typical file name is workers.properties.

This directive supports both the Root and QOpenSys file systems.