OptimizeCacheIdIncrements custom property

Problem statement:
cacheid (first 4char of jsessionid) in cluster env was getting update after 2hours of session inactivity however we had 24hrs of session inactivity set in application server. Due to this some of the applications which were dependent on session was throwing unexpected exception. Users were required to clear their cookies to resolve the issue.
We wanted to know why it was getting updated and if there is a way to stop this activity from occurring?

Solution:
set custom property OptimizeCacheIdIncrements parameter to true

Set the OptimizeCacheIdIncrements custom property to true to make the session manager assess whether the in-memory session for a web module is older than the copy in persistent store. Setting this property resolves the continually increasing cache ID.
If HTTP session management is configured to use session persistence and the user's browser session is moving back and forth across multiple web applications you might see extra persistent store activity as the in-memory sessions for a web module are refreshed from the persistent store. As a result, the cache IDs are continually increasing and the in-memory session attributes are overwritten by those of the persistent copy. Set this property to true if you want to prevent the cache IDs from continually increasing.
If the configuration is a cluster, ensure that the system times of each cluster member is identical as possible.

Reference link: http://www-01.ibm.com/support/knowledgecenter/SSAW57_8.0.0/com.ibm.websphere.nd.doc/info/ae/ae/rprs_custom_properties.html%23OptimizeCacheIdIncrements?lang=en

Using Application Server>URL resources to manage J2EE property files and external service url

Use following code to retrieve url resource using jndi
InitialContext initCtx = new InitialContext();
URL url = (java.net.URL) initCtx.lookup(jndi);
URLConnection conn = url.openConnection();
InputStream is = conn.getInputStream();

With this method you can either enter web service url in resource field or properties file path.

Note: You need to restart the server to lookup the url resource from code.

Reference link: http://www.ibm.com/developerworks/websphere/library/techarticles/0502_botzum/0502_botzum.html

How to access authentication alias from WebSphere Application Server> J2C

You can use the following code to obtain credentials from J2C authentication data entry:

import com.ibm.wsspi.security.auth.callback.Constants;
import com.ibm.wsspi.security.auth.callback.WSMappingCallbackHandlerFactory;
import javax.resource.spi.security.PasswordCredential;
import javax.security.auth.Subject;
import javax.security.auth.callback.CallbackHandler;
import javax.security.auth.login.LoginContext;

Map map = new HashMap();
map.put(Constants.MAPPING_ALIAS, "YOUR_J2C_DATA_ALIAS");
CallbackHandler callbackHandler = WSMappingCallbackHandlerFactory.getInstance().getCallbackHandler(map, null);

LoginContext loginContext = new LoginContext("DefaultPrincipalMapping", callbackHandler);
loginContext.login();

Subject subject = loginContext.getSubject();
Set credentials = subject.getPrivateCredentials();

PasswordCredential passwordCredential = (PasswordCredential) credentials.iterator().next();

String user = passwordCredential.getUserName();
String password = new String(passwordCredential.getPassword());

Reference link: http://stackoverflow.com/questions/4663534/how-to-access-authentication-alias-from-ejb-deployed-to-websphere-6-1/6355992#6355992