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Spring Web Flow OptForRepl

What is it about?

It is a set of classes aiming to improve Spring Web Flow's behavior for Optimized Session Replication.

Features

  • Supports Spring Web Flow 2.4.x
  • An implementation of Conversation Manager for Spring Web Flow (SWF) with the purpose of improving session replication that use fine granularity.
  • Id generation utility, designed to generate ids for uniquely identifying. It includes a couple of generator strategies.

Conversation Manager

Conversation Manager manages conversations and effectively controls how state is stored physically when a flow execution is paused. SWF provides a default ConversationManager implementation: the SessionBindingConversationManager, which simply manages conversational state in the HttpSession storing all of the webflow conversations in the same attribute. For application servers who do session replication on changes in and per attribute of the session map, like Jboss AS, this cause that all of the conversations's data get replicated even though just one conversation is altered.

This solution provides an option for Conversation Manager to stores each conversation in it's own slot in the session map, thereby limiting replication to the conversation that are executed: ReplicationOptimizedSessionBindingConversationManager. It supports the same configuration facilities that SessionBindingConversationManager,

  • max-conversations. The maximum number of active conversations allowed in a session
  • lock-timeout. Time period that can elapse before a timeout occurs on an attempt to acquire a conversation lock
  • session-key. The key this conversation manager uses to store common conversations's data in the session and as prefix of the session-key for each individual conversation.

And it also allows to set a custom id generator strategy for generating ids for uniquely identifying the conversations managed through property conversationIdGenerator (see Extended usages).

Building from source

Clone the Git repository first and switch to the created directory:

$ git clone https://github.com/gfernandez598/springwebflow-optforrepl.git

You can install binaries only or includes sources and javadoc too:

$ mvn install
$ mvn install -Pgenerate-sources-and-javadocs

Basic Usage

Add dependency to the project

<dependency>
  <groupId>com.github.gfernandez598</groupId>
  <artifactId>springwebflow-optforrepl</artifactId>
  <version>1.1-SNAPSHOT</version>
</dependency>

Configure SWF: define custom conversation manager and set it to the Flow Execution Repository.

<bean id="replicationConversationManager" class="com.github.gfernandez598.swf.conversation.optforrepl.ReplicationOptimizedSessionBindingConversationManager" />

<flow-executor id="flowExecutor">
  <flow-execution-repository	conversation-manager="replicationConversationManager" />
</flow-executor>

Extended Usage

The solution provides conversation Id generators RandomUUIDUidGenerator (default) and SequenceUidGenerator, but can choose any other. Custom generators must implements the UidGenerator interface. Continuing the example, can be set it:

<bean id="prettyConversationIdGenerator" class="com.github.gfernandez598.swf.util.SequenceUidGenerator" />

<bean id="replicationConversationManager" class="com.github.gfernandez598.swf.conversation.optforrepl.ReplicationOptimizedSessionBindingConversationManager">
  <property name="conversationIdGenerator" ref="prettyConversationIdGenerator" />
</bean>

So far tested on:

  • Spring Web Flow 2.4.x
  • Jboss AS 7.1.1.Final (will not appreciate improvement because of this AS7-4743)
  • Jboss AS 7.1.3.Final

Extra info

Samples

Take a look at springwebflow-optforrepl-samples.

Take care about

Doesn't support Spring Web Flow 2.x below 2.4.x version.

The implementation of ReplicationOptimizedSessionBindingConversationManager use org.springframework.webflow.conversation.impl.JdkConcurrentConversationLock class which is not public for previous versions.

Credits

This implementation is based on the workaround created by Jon Osborn (see SWF-1030)

License

The project is licensed under the Apache License, Version 2.0.