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    <p>You could use the session-per-conversation pattern a.k.a. "long conversations". Try the grails webflow plugin, which works this way or if you think webflow is inappropriate for your needs implement session-per-conversation yourself.</p> <p>The basic premise is at the start of a conversation you open a new hibernate session (with flush mode = manual) and store it in the users' http session. At the start of each subsequent http request you need to ensure sessionFactory.getCurrentSession returns the conversation's hibernate session, and remember to disconnect this session at the end of each request to close the jdbc connection between requests. When you reach the end of the conversation you flush the session to persist all changes, or close without flushing to cancel them.</p> <p>The hibernate web site / Java Persistence with Hibernate book has some really good info on how to do this, but other than webflow there's no out of the box support in grails. I'm in the process of writing a SessionPerConversation plugin, but it's very early days. My approach was to look at the grails 1.2.0 source code and copy how they implemented .withNewSession, then decorate my controllers with methods for .withConversation, .endConversation and .discardConversation. When I've got a bit further I'll probably post some code on <a href="http://stateyourbizness.blogspot.com/" rel="nofollow noreferrer">State Your Bizness</a></p> <p>The gotchas I've come across so far are...</p> <ol> <li><p>If the user never ends their conversation the hibernate session will be kept open (although not the jdbc connection) until their http session times out. If you support multiple conversations, then each user may have multiple hiberate sessions and for a high usage site you could get memory problems</p></li> <li><p>You have to watch out for automatic session flushing. This can happen when you new up entities depending on which strategy you use for id generation, <strike>or if your calling transactional services</strike>.</p></li> </ol>
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    1. POmanaging associations over multiple requests in grails application
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    1. COad 1.) wouldn't it be possible to serialize the hibernate session (i guess the domain classes must be serializable than) and throw the data into a hidden field? http session's memory consumption would be reduced though... ad 2.) i thought using an appropriate flush-mode would disable automatic session flushing even when using transactional services etc.?
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      1. USAndre Steingress
    2. CO1. Hibernate's session is serializable so you could probably do this, however you would need to submit the serialized session for any request occuring within your conversation - including navigation and redirects. For this scenario it's more convenient to associate the hibernate session with a conversationId, and pass the conversationId around as a request parameter. Interesting idea though 2. Looks like you're right. I misread the grails webflow docs (which say you have to mark services as non-transactional if you want to store them in flow/conversation scope).
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    3. COi like that approach - i am going to implement it (not sure about the hidden field, but file serialization could suffice) and post my results afterwards...
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      1. USAndre Steingress
 

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