Configuring WebSphere DynaCache for Engineering Workflow Management server

Authors: Bryan Hogan, PaulEllis
Build basis: Rational Team Concert 6.x, Engineering Workflow Management 7.x

WebSphere DynaCache is an in-memory cache that is configured to store and retrieve application objects based on data matching rules. With the DynaCache service, if the application server receives an HTTP request that is the same as a previous request and the system state has not changed for the given parameters, the requested service is not run. Instead, the previously cached response is sent back to the browser. This behavior improves performance and response time and reduces the load on the web server for other requests. The use of the DynaCache service reduces performance and contention problems, even when working with many work items, custom attributes, or concurrent users.

To better understand WebSphere DynaCache, see the following IBM Redbooks publication: Mastering DynaCache in WebSphere Commerce (SG24-7393-00)

Although the publication is written for WebSphere Commerce, the behavior also applies to Engineering Workflow Management because both solutions are deployed on WebSphere Application Server.

This article provides instructions for configuring WebSphere Dynacache for Rational Team Concert 6.x and Engineering Workflow Management 7.0.1 or higher hosted on the WebSphere Liberty or the full WebSphere Application Server.

There is a list of known problems at the end of this article. This list is not exhaustive, but reflects what has been observed after enabling DynaCache with both Websphere Application Server and the new WAS Liberty server in 6.0.1, when used with IBM HTTP Server.

Configuring DynaCache in WebSphere Liberty profile

Beginning in Rational Team Concert version 6.0.1, the default application server for hosting CLM applications is IBM WebSphere Application Server Liberty Profile. Like the full WebSphere Application Server, the WebSphere Liberty profile can be configured to support DynaCache, but the DynaCache service is disabled by default. Use the following instructions to enable DynaCache with your Rational Team Concert Change and Configuration Management (CCM) system.

Activating the DynaCache service

To activate the DynaCache service on the WebSphere Liberty profile, add the webCache-1.0 feature to the list of enabled features in the server.xml file in this location: <Rational Team Concert home>/server/liberty/servers/clm/server.xml. If you intend to deploy the web cache monitor (discussed later), you can also add the webCacheMonitor-1.0 feature at this time.

<!-- Enable features -->
   <featureManager>
      <feature>monitor-1.0</feature>
      <feature>jsp-2.2</feature>
      <feature>servlet-3.0</feature>
      <feature>ssl-1.0</feature>
      <feature>appSecurity-1.0</feature>
      <feature>webCache-1.0</feature>
      <feature>webCacheMonitor-1.0</feature>
   </featureManager>

Enabling the CCM cache instance

The caching rules used by the CCM component are defined in a DynaCache cache-instance named services/cache/ccm. To properly initialize the CCM cache instance, add the following entry to the server.xml file after the featureManager element.

<distributedMap id="services/cache/ccm"  jndiName="services/cache/ccm"></distributedMap>

Installing the web cache monitor

A DynaCache monitor web application is available to help monitor and clear contents from DynaCache instances. Use the following instructions to install the webCacheMonitor application to the Liberty server. The sever should be running during the installation of the features.

1. Navigate to the server directory of the Engineering Workflow Management installation. cd <Engineering Workflow Management home>/server

2. Run the following commands

Windows systems:

set WLP_USER_DIR=%cd%\liberty
.\liberty\wlp\bin\featureManager.bat install webCacheMonitor-1.0

UNIX and Linux systems:

export WLP_USER_DIR=`pwd`/liberty
./liberty/wlp/bin/featureManager install webCacheMonitor-1.0

Read the license agreement that is displayed in the command window. If you agree to its terms, accept them. The command generates output similar to the following example:

Step 1 of 7: Starting installation...
Step 2 of 7: Checking features...
Step 3 of 7: Resolving remote features. This process might take several minutes
to complete. If the process is still running after three minutes, then restart t
he process.
Step 4 of 7: Downloading webCacheMonitor-1.0...
Step 5 of 7: Installing webCacheMonitor-1.0...
Step 6 of 7: Cleaning up temporary files...
Step 7 of 7: Installation completed
CWWKF1017I: One or more features installed successfully: [webCacheMonitor-1.0].
Validating feature: com.ibm.websphere.appserver.kernel-1.0... FAIL!
  [ERROR] Content: lib/tools-internal/isadc does not exist.
Product validation was complete, and found 1 error(s).

The error that is listed does not indicate a failed installation of the webCacheMontor application.

Activating the web cache monitor

To activate the DynaCache monitor service on the WebSphere Liberty profile, add the webCacheMonitor-1.0 feature to the list of enabled features in the server.xml file in this location: <Engineering Workflow Management home>/server/liberty/servers/clm/server.xml

<!-- Enable features -->
   <featureManager>
      <feature>monitor-1.0</feature>
      <feature>jsp-2.2</feature>
      <feature>servlet-3.0</feature>
      <feature>ssl-1.0</feature>
      <feature>appSecurity-1.0</feature>
      <feature>webCache-1.0</feature>
      <feature>webCacheMonitor-1.0</feature>
   </featureManager>

Invoking the web cache monitor

To invoke the DynaCache monitor service, enter a URL of the following format:

https://yourserver:9443/cachemonitor

See Using the web cache monitor for information about using the cache monitor.

Configuring DynaCache in full WebSphere Application Server

Activating the DynaCache service

To activate the DynaCache service by using WebSphere Application Server, you must access the application server console, which is typically in one of these locations:

https://yourserver:9443/ibm/console
https://yourserver:9060/ibm/console

where yourserver is the host name or IP address of the server, and 9043 or 9060 is the port. Depending on your configuration, you might need to specify other ports.

You also must have the right permissions to log in and use the administrative console where Rational Team Concert is deployed.

To enable the DynaCache service, open the WebSphere administrative console and go the Web container configuration page for the server where Rational Team Concert is deployed (usually server1). Select the Enable servlet and command caching check box:

Figure 1. Enabling the DynaCache service in WebSphere Application Server

Important: After you select the Enable servlet and command caching check box, you must restart the web server. When that check box is selected, the WebSphere DynaCache service is enabled. Depending on your configuration, you may also need to uncheck the Enable Edge Side Include check box for IBM HTTP Server. For instructions, see the section, "Configuring IBM HTTP Server".

Enabling the CCM cache instance

The caching rules used by the CCM component are defined in a DynaCache cache-instance with JNDI name services/cache/ccm. Use the following instructions to configure WebSphere to allow access of the services/cache/ccm cache-instance by Rational Team Concert.

1. In the administrative console, click Resources > Cache instances > Servlet cache instances.
2. Specify services/cache/ccm for both the Name and Java Naming and Directory interface (JNDI) name fields. The JNDI name is the name attribute that is used by Rational Team Concert to resolve the cache instance.

Figure 2. Configuring the services/cache/ccm cache instance

For additional information on servlet cache instances, see Using servlet cache instances

Configuring IBM HTTP Server

During the activation of the DynaCache service, you might also need to configure the IBM HTTP Server. To avoid compatibility problems, open the IBM HTTP Server console and uncheck the Enable Edge Side Include check box:

Figure 3. Configuring the IBM HTTP Server

Activating the web cache monitor

WebSphere Application Server includes a monitor that allows control of the status and contents of the cache in real time. To use it, you locate the CacheMonitor.ear file in the WAS_installdir/installableApps directory and then use the WebSphere configuration screens to install it as a common J2EE application.

The process to install the monitor is easy. The following screen captures show the WebSphere Application Server version 7 administrative console. Other versions of the application server are similar.

1. Open the Enterprise Applications page.
2. Click Install.
   
   
   Figure 4. Enterprise Applications
   
   
3. Browse to select the .ear file to install.
   
   
   Figure 5. Path to the new application
   
   
   Figure 6. Select the .ear file
   
   
4. Click OK to return to the path screen.
   
   
5. Click Next to open and specify the installation options.
   
   
   Figure 7. Path to the new application
   
   
6. Click Fast Path and then click Next to configure the additional installation options.
   
   
   Figure 8. Installation options
   
   
   Figure 9. Additional installation options
   
   
7. Click Next to map modules to servers.
   
   
   Figure 10. Map modules to servers
   
   
8. Click Next to review your selections.
9. Click Finish to complete the installation. The install log shows your installation results.
   
   
   Figure 11. Review installation selections
   
   
10. When the installation finishes, click Save directly to the Master configuration.
    
    
    Figure 11. Install log
    
    

Map security roles to a user

In WebSphere Integrated Solutions Console click Applications > Application Types > WebSphere enterprise applications. Click the Dynamic Cache Monitor application to open it for editing.

In the Detail Properties section, click Security role to user/group mapping. Select the administrator role and then the Map Users... button above.

Enter a search string to return your users or group names. Click Search to run the query. From the list of available users or groups that is returned, select the particular user or group and move it to the Selected column. Click OK to map the users Save the changes.

Start the Dynamic Cache Monitor.


Figure 12. Start the monitor from the main page


Figure 13. The main page shows the status of the applications

The Dynamic Cache service is now started.

Invoking the web cache monitor

After the cache monitor application is installed and started, view and manage the cache information by using a URL that is in this format:

https://yourserver:9443/cachemonitor

where yourserver is the host name or IP address of your server, and 9443 or 9060 is the port. Depending on your configuration, other ports might need to be specified. For example, https://ipServer:portApplication/cachemonitor.

Using the web cache monitor

Using the cache monitor, you can explore information and clear the cache contents. After invoking the cache monitor URL from a web browser, the monitor console opens. By default, the monitor opens with the baseCache cache instance selected. To view contents from the services/cache/ccm instance, select it from the drop-down, and click OK.



Figure 14. Cache Statistics

The following screen shows the Cache Contents of the services/cache/ccm cache instance after opening a work item for the first time.

Figure 15. Cache Contents for services/cache/ccm

For detailed information about the cache monitor, see IBM Knowledge Center at http://www-01.ibm.com/support/knowledgecenter/SSEQTP_8.5.5/com.ibm.websphere.base.doc/ae/tdyn_servletmonitor.html.

Considerations for clustered environments

Beginning in version 6.0.5, you can configure DynaCache for use in a clustered Engineering Workflow Management environment. In this configuration, an independent DynaCache instance is retained for each node in the cluster. Cache entries are not replicated across the different nodes; however, cache invalidation is synchronized across nodes to prevent expired entries from being retained in any of the caches.

To configure DynaCache for clustered environments, you must repeat the instructions from Configuring DynaCache in WebSphere Liberty profile for each cluster node.

Known problems:

There are no known issues or defects after enabling DynaCache with Websphere Application Server or WebSphere Liberty. Prior to Engineering Workflow Management 6.0.5 issues were observed when used with IBM HTTP Server; for details see previous versions of this article.

Related topics: Deployment web home

External links:

• IBM
• MustGather: Dynamic cache problems in WebSphere Application Server

Additional contributors: RosaNaranjo