Right for the ConversationManager.beginConversation, there is already Conversation.begin. I've been mistaken by the ConversationManager.endConversation of Niklas' proposal.

I can maybe explain how we use the currently existing API, and in fact we are relatively happy with what exists today, except for one thing :

start() {

    ConversatonManager manager = { get from BeanManager };

    manager.beginOrRestoreConversation(cid);

    Conversation conversation = { get from BeanManager };

    // Beginning of the ugly part !!

    String cid = ((ConversationImpl)conversation).getUnderlyingId();

    ConversationContext ctx = Container.instance().deploymentServices().get(ContextLifecycle.class).getConversationContext();

    ctx.setBeanStore(new ConversationBeanStore(httpSession, cid));

    ctx.setActive(true);

    // End of the ugly part

    if (cid != null && conversation.isTransient())  // Don't remember why I need this, beginOrRestore should be enough

        conversation.begin(cid);

}

end() {

    ConversationManager manager = { get from BeanManager };

    manager.cleanupConversation();

}

The main thing is that I would prefer not having to mess with bean stores and contexts, so the manager.activateContext() looks fine. Ideally here what I would like to do (I know, I'm too lazy :-)) : 

start() {

    ConversatonManager manager = { get from BeanManager };

    manager.startupConversation();

    if (cid != null && conversation.isTransient())

        conversation.beginOrRestoreConversation(cid);

}

end() {

    ConversationManager manager = { get from BeanManager };

    manager.cleanupConversation();

}

From Flex, there is no need to switch the conversation in a particular request, but getting the list of the currently existing conversations with ConversationManager.getCurrentConversationIds() can be useful.

Finally I really think it's necessary to be able to share a conversation instance between different UIs and use the same ConversationContext implementation for all. We could obviously ship a FlexConversationContext with GraniteDS/CDI but we want to make possible to build applications where a part of the UI uses JSF, another part uses Flex and why not another uses ZK or the iPhone SDK.