WebSphere Application Server V8.5 Administration and Configuration Guide for the Full Profile

972 WebSphere Application Server V8.5 Administration and Configuration Guide for the Full Profile

 Cookie maximum age

Specifies the amount of time that the cookie lives in the client browser. This option

includes the following choices:

– Expire at the end of the

Current browser session which is the default option.

– Expire by configuring

Set maximum age

If you choose the maximum age option, specify the age in seconds. This value

corresponds to the

Time to Live (TTL) value described in the Cookie specification.

 Cookie path

Sets the paths on the server that define where the browser sends the session tracking

cookie. Specify any string that represents a path on the server:

– Use the context root

– Set cookie path, which is also the default option (use the forward slash (/) to indicate

the root directory).

Specifying a value restricts the paths to which the cookie is sent. By restricting paths, you

can keep the cookie from being sent to certain URLs on the server. If you specify the root

directory, the cookie is sent no matter which path on the given server is accessed.

28.3 Storing session information

By default, WebSphere places session objects in memory as local session cache. However,

the administrator can enable persistent session management to place session objects in a

persistent store.

Administrators must enable persistent session management in the following situations:

 In a distributed environment, when the user’s session data must be recovered by another

cluster member after a cluster member in a cluster fails or is shut down.

 The user’s session data is too valuable to lose through unexpected failure at the

application server.

 The administrator desires better control of the session cache memory footprint by sending

cache overflow to a persistent session store.

28.3.1 Local sessions

Many web applications use the simplest form of session management, which is the

in-memory, local session cache. The local session cache keeps session information in

memory and local to the WebSphere Application Server where the session information was

first created.

Local session management does not share user session information with other clustered

servers. The local session management lacks a persistent store for the sessions it manages.

A server failure eliminates the WebSphere Application Server instances and also destroys

any sessions that are managed by those instances.

The administrator can define a limit on the number of sessions that are held in the in-memory

cache by specifying the

Maximum in-memory session count setting, as shown in 28.2.1,

“Session management properties” on page 966. The session manager also permits an

unlimited number of sessions in memory by enabling the

Allow overflow setting. If you

choose to enable session overflow, monitor the state of the session cache closely for

performance purpose.

Chapter 28. Session management 973

28.3.2 Persistent sessions management

WebSphere Application Server provides the following options for persistent session

management:

 Database session persistence, where sessions are stored in the database specified.

 Memory-to-memory session replication using the data replication service available in

distributed server environments.

In a distributed environment, you can have both these two session mechanism options, as

shown in Figure 28-5. In a stand-alone environment, you can only set the database session

persistence.

Figure 28-5 Persistent session options

All information that is stored in a persistent session store must be serialized. As a result, all of

the objects that are held by a persistent session store must implement java.io.Serializable. In

general, consider making all objects that are held by a session serialized, even if immediate

plans do not call for the use of persistent session management. Enabling this feature makes

the transition between local and persistent management occur transparently.

The session manager maintains a cache of the most recently used sessions in memory. If it

cannot find the session information from the cache, session manager queries the persistent

storage. Retrieving a user session from the cache eliminates a more expensive retrieval from

the persistent store. Session data is stored to the persistent store based on your selections

for write frequency and write content option.

WAS

Web

container

WAS

Web

container

Database

Database

persistent

sessions

WAS

Web

container

WAS

Web

container

Data

replication

service

WAS

(Store)