Re: Call a service, but still with one DataContext

From: Chris Murphy (chri..trandz.org)
Date: Mon Aug 11 2008 - 21:16:24 EDT

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    Hi Kevin,

    I'm coming from JDO which has PersistenceManager instead of a
    DataContext - but they should be conceptually the same thing. I am
    interested in using Cayenne over a client/server connection from a Swing
    front end. Hence there's a proxy-DataContext that the Swing client will
    be communicating with? I imagine the part that runs on the server that
    handles the client requests normally runs as a servlet? My issue is that
    as Spring also runs as a servlet, how can both servlets use the same
    DataContext?

    It has been a long time since I've done any servlet or Spring
    configuration - so do let me know if any of the assumptions I've just
    made are wrong.

     From what you say: "bind your DataContext to the user session" - is the
    answer to lazily load the DataContext from the Session enabling both the
    servlets to have access to the same DataContext - by always finding it
    through the Session object?

    thanks - Chris

    PS./ What's a WS server? Is that a 'web service'?

    Kevin Menard wrote:
    > Hi Chris,
    > I'm not really sure I understand your question. I think you're slightly
    > confused by our nomenclature. Cayenne server really is just a plain Java
    > package. The server part comes from a three-tier role, where we have a
    > separate client package. In this case, you'd run some sort of WS server to
    > handle the client requests. Otherwise, you can use the "server" package in
    > any app.
    >
    > Viewed that way, you're best bet is probably to use the servlet filter and
    > bind your DataContext to the user session. This should ensure that you only
    > have one DC per user. From there, you just need to apply basic principles
    > for using a single DC. In particular, don't get messy with uncommitted
    > state.
    >
    >

    -- 
    Seaweed Software Pty Ltd,
    http://www.strandz.org
    



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