This chapter describes how to cache session information for Web application instances that are deployed across WebLogic Server instances.
This chapter has the following sections:
WebLogic Server includes features that enable deployed applications to use Coherence data caches and seamlessly incorporate Coherence*Web for session management and TopLink Grid as an object-to-relational persistence framework. Collectively, these features are referred to as ActiveCache.
ActiveCache is employed by applications running on WebLogic Server and provides replicated and distributed caching services that make an application's data available to all servers in a Coherence data cluster. Applications can obtain direct access to data caches either through resource injection or component-based JNDI lookup. You can display, monitor, create, and configure Coherence clusters using the WebLogic Server Administration Console and WLST.
Using ActiveCache with WebLogic Server instances enables you to create a data tier dedicated to caching application data and storing replicated session state. This is separate from the application tier, where the WebLogic Server instances are dedicated to running the application.
Using Coherence*Web with ActiveCache enables you to provide Coherence-based HTTP session state persistence to applications running on WebLogic Server. Coherence*Web enables HTTP session sharing and management across different Web applications, domains, and heterogeneous application servers. Session data can be stored in data caches outside of the application server, thus freeing application server heap space and enabling server restarts without losing session data.
Coherence and Coherence*Web are included in the default installation of WebLogic Server 11g Release 1 (10.3.4). If you do not already have WebLogic Server 11g Release 1 (10.3.4) on your system, you can get it at the following URL:
http://www.oracle.com/technology/software/products/middleware/index.html
For more information on the integration of Oracle WebLogic Server, Coherence, and Coherence*Web, see Using ActiveCache and User's Guide for Oracle Coherence*Web.
The following example demonstrates how to use ActiveCache to cache session information for Web application instances that are deployed across WebLogic Server instances. To do this, you will create a Web application and deploy it to two server instances. The application is a simple counter that stores the current count as a session attribute. Coherence*Web automatically serializes and replicates the attribute across both server instances. A browser is used to access each application instance to demonstrate that the same session attribute is used among the instances.
By default, the installation of WebLogic Server 11g release 1 (10.3.4) installs Coherence 3.6 in the coherence_3.6
folder. To complete this example, ensure that your server start-up files and class paths continue to point to the Coherence 3.7 files you have already installed. Also, ensure that when you are deploying files (such as coherence.jar
and coherence-web-spi.war
) later in this example, that you are deploying release 3.7 versions.
Start a Coherence cache server. Example 11-1 illustrates a sample script to start the cache server. In this example, tangosol.coherence.clusterport=7777
is the default multicast listen port of a Coherence cluster and tangosol.coherence.clusteraddress=231.1.1.1
is the default multicast listener address.
Example 11-1 Script to Start the Cache Server
setlocal set COHERENCE_HOME=c:\oracle\product\coherence set COH_OPTS=%COH_OPTS% -server -cp %COHERENCE_HOME%\lib\coherence.jar;%COHERENCE_HOME%\lib\coherence-web-spi.war; set COH_OPTS=%COH_OPTS% -Dtangosol.coherence.management.remote=true -Dtangosol.coherence.cacheconfig=/WEB-INF/classes/session-cache-config.xml -Dtangosol.coherence.distributed.localstorage=true -Dtangosol.coherence.clusterport=7777 -Dtangosol.coherence.clusteraddress=231.1.1.1 -Dtangosol.coherence.session.localstorage=true java %COH_OPTS% -Xms512m -Xmx512m -XX:MaxPermSize=256m com.tangosol.net.DefaultCacheServer :exit
Note:
If you define and start the Coherence cache server using the WebLogic Administration Console, you must indicate the location of the cache configuration file, and set distributed local storage and session local storage to true in the Arguments field of the Server Start tab. For example:-Dtangosol.coherence.cacheconfig=/WEB-INF/classes/session-cache-config.xml -Dtangosol.coherence.distributed.localstorage=true -Dtangosol.coherence.session.localstorage=true
To configure and start a Coherence cluster:
Run the Oracle WebLogic Configuration Wizard (Start then All Programs then Oracle WebLogic then WebLogic Server 11gR1 then Tools then Configuration Wizard) to create a new WebLogic Server domain called test_domain
.
Before exiting the wizard, select the Start Admin Server check box and click Done. The Configuration Wizard automatically starts the Administration Server.
Start the WebLogic Server Administration Console.
From the browser, log in to the Oracle WebLogic Server Administration Console using the following URL:http://
hostname
:7001/console
. The Console starts and the domain home page displays.
To create a Machine on which to host WebLogic Server instances:
From the Domain Structure window, select Environment and then Machines. Click New. The Create a New Machine page displays. Enter a name for the Machine (in this case, Test) and click Next. Click Finish on the following page. Figure 11-1 illustrates the Create a New Machine page.
The Summary of Machines page should look similar to Figure 11-2.
Create two server instances associated with the Machine. The application will be deployed to these servers in a later step.
To create server instances:
Click the name of the Machine in the Summary of Machines page to open the Settings for machine page. Click the Servers tab and then click Add to create a server.
Select Create a new server and associate it with this machine in the Add a Server to Machine page, and click Next.
Provide details about the server in the Create a New Server page.
Enter ServerA
as the Server Name and 8081
as the Server Listen Port. Enter the appropriate value for the Server Listen Address. This is illustrated in Figure 11-3. Click Finish.
When you are returned to the Settings for machine page, click Add, and repeat the previous three steps to create a second server.
Enter ServerB
as the Server Name and 8082
as the Server Listen Port. Enter the appropriate value for the Server Listen Address. Click Finish.
Expand Environment in the Domain Structure menu and click Servers.
The Summary of Servers page displays and is similar to Figure 11-4.
A Coherence cluster is a group of Coherence nodes that share a group address which allows them to communicate. Coherence clusters consist of nodes formed by applications, modules, or application servers (WebLogic Server instances or cache servers).
To create a Coherence Cluster:
Click Environment in the domain Structure Window and then click Coherence Clusters. In the Summary of Coherence Clusters page, click New. In the Coherence Cluster Properties page of the Create Coherence Cluster Configuration wizard, enter CoherenceCluster
in the Name field, then click Next.
Figure 11-5 illustrates the Create Coherence Cluster Configuration page.
Enter a value such as 8085
, in the Unicast Listen Port field. Do not change any of the other values and click Next.
Figure 11-6 Specifying a Unicast Listen Port for a Coherence Cluster
In the Coherence Cluster Targets page of the Create Coherence Cluster Configuration wizard, select ServerA and ServerB as the targets. Click Finish.
Figure 11-7 Choosing Coherence Cluster Targets
The Summary of Coherence Clusters page looks similar to Figure 11-8.
Figure 11-8 Summary of Coherence Clusters
In addition to the coherence.jar
file, Coherence provides a deployable shared library, coherence-web-spi.war
, that contains a native plug-in to WebLogic Server's HTTP Session Management interface. Coherence also provides the active-cache-1.0.jar
file that contains the classes that enable WebLogic Server to interact with Coherence.
You do not have to deploy coherence.jar
for this example. It will be bundled with the application in a later step.
To deploy the coherence-web-spi.war
and active-cache-1.0.jar
files:
From the Domain Structure menu, click Deployments. The Summary of Deployments page displays.
Click Install. The Install Application Assistant window displays.
Use the Install Application Assistant to deploy coherence-web-spi.war
as a library to ServerA
and ServerB
.
Locate and select the coherence-web-spi.war
file as illustrated in Figure 11-9. The WAR file can be found in the coherence\lib
folder of the Coherence installation. Click Next.
Figure 11-9 Selecting the coherence-web-spi.war File for Deployment
In the Choose targeting style page, ensure that Install this deployment as a library is selected, as illustrated in Figure 11-10. Click Next.
Figure 11-10 Installing the Deployment as a Library
Select ServerA and ServerB as the deployment targets (do not deploy coherence-web-spi.war
to AdminServer) as illustrated in Figure 11-11. Click Next.
Figure 11-11 Selecting Deployment Targets
In the Optional Settings page, select the Copy this application onto every target for me option in the Source accessibility section.
You can click Finish to skip the rest of the steps in the Install Application Assistant. The Summary of Deployments page displays after the application is deployed.
Repeat Steps 1 through 3 to deploy active-cache-1.0.jar
to ServerA
and ServerB
(do not deploy active-cache-1.0.jar
to the AdminServer
).
When you reach the Optional Settings page, select the I will make the deployment accessible from the following location option. This will mimic the nostage
WLST option.
Enter the path to the active-cache-1.0.jar
file. The file is included in the WebLogic Server installation. Assuming that you installed the WebLogic Server at C:\oracle\product
, you will find the file in the C:\oracle\product\wls1033\wlserver_10.3\common\deployable-libraries
folder.
The Counter Web application is a simple counter implemented as a JSP. The counter is stored as an HTTP session attribute and increments each time the page is accessed.
To create the Counter Web application:
Create a standard Web application folder as follows:
/ /WEB-INF
Copy the following code to a text file and save it as a file named web.xml
in the /WEB-INF
folder.
<?xml version = '1.0' encoding = 'windows-1252'?> <web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd" xmlns="http://java.sun.com/xml/ns/j2ee" version="2.5"> <description>Empty web.xml file for Web Application</description> </web-app>
Create a weblogic.xml
file in the /WEB-INF
folder.
Add a library reference for the coherence-web-spi.war
file.
Reference the Coherence Cluster in a coherence-cluster-ref
stanza.
Example 11-2 illustrates a sample weblogic.xml
file.
Example 11-2 Sample weblogic.xml File
<weblogic-web-app xmlns="http://xmlns.oracle.com/weblogic/weblogic-web-app" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://xmlns.oracle.com/weblogic/weblogic-web-app http://www.oracle.com/technology/weblogic/weblogic-web-app/1.1/weblogic-web-app.xsd"> <library-ref> <library-name>coherence-web-spi</library-name> </library-ref> <coherence-cluster-ref> <coherence-cluster-name>CoherenceCluster</coherence-cluster-name> </coherence-cluster-ref> </weblogic-web-app>
Bundle the coherence.jar
file with the application: copy coherence.jar
from the coherence\lib
folder of the Coherence 3.7 installation to the WEB-INF/lib
folder.
Copy the following code for the counter
JSP to a text file and save the file as counter.jsp
in the root of the Web application folder.
<html> <body> <h3> Counter : <% Integer counter = new Integer(1); HttpSession httpsession = request.getSession(true); if (httpsession.isNew()) { httpsession.setAttribute("count", counter); out.println(counter); } else { int count = ((Integer) httpsession.getAttribute("count")).intValue(); httpsession.setAttribute("count", new Integer(++count)); out.println(count); } %> </h3> </body> </html>
Create a manifest.mf
file in the META-INF
folder. Add references to the active-cache
JAR file. Example 11-3 illustrates a sample manifest.mf
file.
The structure of the Web application folder should appears as follows:
/ /counter.jsp /META-INF/manifest.mf /WEB-INF/web.xml /WEB-INF/weblogic.xml /WEB-INF/lib/coherence.jar
ZIP or JAR the Web application folder and save the file as counter.war
.
To deploy the counter.war
application:
Open the Summary of Deployments page by clicking Deployments in the Domain Structure menu in the Oracle WebLogic Server Administration Console.
Click Install. The Install Application Assistant wizard opens.
Use the Install Application Assistant to deploy the counter.war
file to ServerA
and ServerB
. In the Optional Settings page, select the Copy this application onto every target for me option in the Source accessibility section.
The Summary of Deployments page displays after the application is deployed. Figure 11-14 illustrates the page with the deployed active-cache.jar
, coherence-web-spi.war
, and counter.war
files.
Figure 11-14 Summary of Deployments Page with Deployed Files
Start the Node Manager then start the WebLogic Server instances from the WebLogic Server Administration Console. The Node Manager is a Java utility that runs as a separate process from Oracle WebLogic Server, and enables you to perform common operations for a Managed Server, regardless of its location with respect to its Administration Server.
To start the Node Manager, go to Start, then All Programs, then Oracle WebLogic, then WebLogic Server 11gR1, then Tools, and then Node Manager.
Click Environment then Servers in the domain Structure Window. From the Summary of Servers page in the WebLogic Server Administration Console, click the Control tab and start both server instances.
Figure 11-15 illustrates the deployments table after the servers have been started.
Figure 11-15 Deployments Window Showing the Deployed Application and Libraries
To verify the example:
Open a browser and access the ServerA
counter instance using the following URL:
http://
host
:8081/counter/counter.jsp
The counter page displays and the counter is set to 1 as illustrated in Figure 11-16.
Figure 11-16 Counter Page with Counter Set to 1
In a new browser (or new browser tab), access the ServerB
counter instance using the following URL:
http://
host
:8082/counter/counter.jsp
The counter page displays and the counter increments to 2 based on the session data as illustrated in Figure 11-17.
Figure 11-17 Counter Page with Counter Set to 2
If you refresh the page, the counter increments to 3. Return to the original browser (or browser tab), refresh the instance, and the counter displays 4.