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RE: [wsia] The search for per-entity-per-user Consumer state

  • 1.  RE: [wsia] The search for per-entity-per-user Consumer state

    Posted 06-18-2002 14:56
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    Subject: RE: [wsia] The search for per-entity-per-user Consumer state


    
    Gil - I think I missed your point.
    
    May new attempt to answer the question: the client needs to store one
    handle per entity per user (or to be more precise: a handle for each entity
    users display on their pages).
    
    
    Best regards
    Carsten Leue
    
    -------
    Dr. Carsten Leue
    Dept.8288, IBM Laboratory B�blingen , Germany
    Tel.: +49-7031-16-4603, Fax: +49-7031-16-4401
    
    
    
    |---------+---------------------------->
    |         |           Gil Tayar        |
    |         |           <Gil.Tayar@webcol|
    |         |           lage.com>        |
    |         |                            |
    |         |           06/18/2002 05:40 |
    |         |           AM               |
    |         |           Please respond to|
    |         |           Gil Tayar        |
    |         |                            |
    |---------+---------------------------->
      >---------------------------------------------------------------------------------------------------------------------------------------------|
      |                                                                                                                                             |
      |       To:       Carsten Leue/Germany/IBM@IBMDE                                                                                              |
      |       cc:       wsia@lists.oasis-open.org, wsrp@lists.oasis-open.org, "'Michael.Freedman@oracle.com'" <Michael.Freedman@oracle.com>         |
      |       Subject:  RE: [wsia] The search for per-entity-per-user Consumer state                                                                |
      |                                                                                                                                             |
      |                                                                                                                                             |
      >---------------------------------------------------------------------------------------------------------------------------------------------|
    
    
    
    Carsten,
    
    Either I misunderstood your answer, or you may have missed the fact that I
    was searching for _Consumer_ (not Producer) information that must be stored
    per-entity-per-user.
    
    Mike's concern about the OO-way of thinking - in which the basis is a
    per-entity-per-user references - is that the Consumer will have too many of
    these references.
    
    What I was trying to say in this email is that the Consumer _must_ have
    information that is per-entity-per-user _anyway_: because of the way
    actions
    work, and for stateless producer services, the Consumer must at least store
    the last action of the producer service.
    
    Gil
    
    -----Original Message-----
    From: Carsten Leue [mailto:CLEUE@de.ibm.com]
    Sent: Mon, June 17, 2002 19:33
    To: Gil Tayar
    Cc: wsia@lists.oasis-open.org; wsrp@lists.oasis-open.org
    Subject: Re: [wsia] The search for per-entity-per-user Consumer state
    
    
    
    Gil - wouldn't a portlet that displays the user's prefered stock price be
    an example. There you have per-entity (stock portlet) per user (stock
    symbol) state.
    
    
    Best regards
    Carsten Leue
    
    -------
    Dr. Carsten Leue
    Dept.8288, IBM Laboratory B�blingen , Germany
    Tel.: +49-7031-16-4603, Fax: +49-7031-16-4401
    
    
    
    |---------+---------------------------->
    |         |           Gil Tayar        |
    |         |           <Gil.Tayar@webcol|
    |         |           lage.com>        |
    |         |                            |
    |         |           06/12/2002 12:16 |
    |         |           PM               |
    |         |           Please respond to|
    |         |           Gil Tayar        |
    |         |                            |
    |---------+---------------------------->
    
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      |       Subject:  [wsia] The search for per-entity-per-user Consumer
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    Michael,
    Your inclination towards the "web approach" is largely based on scalability
    reasons - i.e. try to reduce the amount of information the Consumer has to
    store per all entities per all users. To that effect, let me try and
    continue to search for reasons why a Consumer will _have_ to have
    information per-entity-per-user.
    
    In the discussion in the joint interfaces meeting yesterday, I suggested
    that the Consumer would have to store (per-entity-per-user) whether to call
    performAction or getFragment. You, rightly so, told me that you never liked
    the distinction so that this is (not yet) a valid argument.
    
    To tell you the truth, I'm not sure *I* like the distinction between
    performAction and getFragment. It may be that we will have *only*
    performAction, where the action should be _exactly_ the "URL state" you
    mentioned in your point (a) below.
    
    Well, in this case, if the consumer has multiple portlets on the page, it
    _must_ store the "last" action of all of them, and this _must_ be per-user.
    To contrast with the web approach, in the simple Web application, the
    browser stores the application's state in the address bar per-user. In the
    WSRP/WSIA scenario, the Consumer must also store that information,
    per-portlet! This is the only way to allow stateless portlets.
    
    Am I missing something?
    Gil
    
    
    -----Original Message-----
    From: Michael Freedman [mailto:
    Sent: Wednesday, June 12, 2002 00:19
    To: wsia@lists.oasis-open.org; wsrp@lists.oasis-open.org
    Subject: Re: [wsia] Follow-on Example
    
    
    Eilon,
       Oracle's approach/point of view (on the web approach) is as follows:
        a) we strongly discourage portlets from maintaining any kind of
    transient state.  We have found that even with moderate sized user
    communities, stateless portlets lead to significantly improved portal
    response times.  So our preferred solution for your reservation scenario is
    (0):  there is neither a session nor a transient entity.  The reservation
    state is maintained by encoding the information in URLs inserted into the
    generate response content.  I.e. only use sessions when state must be
    shared
    between entities.
        b) recognizing that sessions will be used however, the base scenario
    should be one in which the two reservation portlets cooperatively run in
    the
    same session.  In this scenario the two portlets would be responsible for
    namespacing encoding their session data to avoid collisions.  This is
    analogous to the (servlet) web model though obviously a more insidious
    situation as servlets often (safely) assume only one "instance" runs in a
    session.  All we would need to do to support this would be ensure that a
    portlet is able to determine and use a "key" that distinguishes one use (on
    a page) from another.  If this key/id were generated by the consumer, the
    consumer could easily choose an algorithm for generating such an id that is
    repeatable without maintaining any dynamic (state) information.  Hence the
    ID would have little/no cost.
    
       For us/me the above completely covers Approach 1: the web approach.  It
    allows multiple entities of the same type to run in a session with entity
    private session data while still allowing these same entities to share
    session data between themselves of entities of other types.
    
    The outstanding question is whether we consider the situation where a
    portlet only has entity private data so common that we should allow for
    them
    to be so declared and mandate the consumer honor such a declaration?
    Personally, I think this is reasonable.  Not having to partition
    (namespace)
    the session would be useful to such developers.  And I think this occurs
    commonly enough for us to represent formally.
    
    Another scenario to consider is one where a set of entities want to share a
    session distinguished from another set running in the same consumer.  This
    is a situation where a service provides 2 portlets designed to work
    together.  For example a news feed display portlet and a topic portlet.  If
    2 sets of these run is the same page how is one set's session data isolated
    from the other?  My answer is that the consumer merely chooses to establish
    2 sessions (vs. one) and passes the correct session ID to each set.  I
    further believe we shouldn't define how a consumer chooses/learns to do
    this.  I.e. I don't think we should define producer meta data that
    describes
    potential groupings for its sessions.  Rather, portlets must expect that
    the
    consumer will potentially run all of these entities in the same session and
    behave accordingly.  In many circumstances this may mean that the sets
    trounce each others shared data.  However, well coded portlets could choose
    to represent this demarcation in its own settable configuration data for
    the
    portlets.  I.e. the config screen could have a setting for group id
    allowing
    the page developer to set a common group id for the 2 portlets in each set.
          -Mike-
    
    
    
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