OASIS Web Services Interactive Applications TC

Re: [wsia] Follow-on Example

  • 1.  Re: [wsia] Follow-on Example

    Posted 06-17-2002 20:04
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    Subject: Re: [wsia] Follow-on Example


    
    Eilon - comments are in [CL]
    
    
    Best regards
    Carsten Leue
    
    -------
    Dr. Carsten Leue
    Dept.8288, IBM Laboratory B�blingen , Germany
    Tel.: +49-7031-16-4603, Fax: +49-7031-16-4401
    
    
    
    |---------+----------------------------->
    |         |           Eilon Reshef      |
    |         |           <eilon.reshef@webc|
    |         |           ollage.com>       |
    |         |                             |
    |         |           06/11/2002 09:44  |
    |         |           PM                |
    |         |           Please respond to |
    |         |           Eilon Reshef      |
    |         |                             |
    |---------+----------------------------->
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      |       To:       wsia@lists.oasis-open.org, wsrp@lists.oasis-open.org                                                                        |
      |       cc:                                                                                                                                   |
      |       Subject:  [wsia] Follow-on Example                                                                                                    |
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    The example below demonstrates the differences in view regarding
    transient handles.
    
    Example:
    --------
    Many applications use the session object to store transient data, which
    includes data entered by the user. For example, when you buy a plane
    ticket, the application stores the departure airport, the arrival
    airport, etc. in the session object.
    
    For argument's sake, assume a third party creates a reservation portlet
    for tickets, and has no data-sharing-across-portlets issue. And, assume
    that the portal wants to put two of those services side-by-side and
    allow two reservation to be placed in parallel (without one affecting
    the other).
    
    Assessment:
    -----------
    
    There are two views (again, I am hoping that I am doing the right
    association with names, please correct me otherwise):
    
    Approach 1 - Web Architecture (Mike, Carsten):
    
    The Producer and the Consumer collaborate to create two separate
    "sessions". This can be achieved with Producer meta-data that hints that
    the Consumer should do so (suggested e.g. by Carsten) or by the Producer
    receiving some sort of context information that allows it to know it
    needs to use a separate session (suggested e.g., by Alejandro).
    
    [CL] My view on this scenario would be the following:
    - there exist two different persistent entities the user has put on his
    page (one for each portlet). This allows the user to configure the
    reservation portlets differently (which something the belongs to the
    portlet's persistent state). The portlet service indicates that it does not
    want to share session data with other portlets of its kind. The consumer
    then creates a separate session for each of the portlets if the user logs
    on. The combination of session state and persistent entity handle uniquely
    identifies the interaction and persistent state for each portlet on the
    user's page (e.g. lets him enter different data in each of the portlets).
    No transient entity is involved in this step.
    
    [CL]
    
    Approach 2 - Object Oriented (Gil, Charlie):
    
    The Producer does not use user sessions at all. (Well, there's nothing
    to share)
    
    (Side comment: conceptually, there's nothing user-ish about this
    transient information. In fact, this creates the well-known usability
    thing, that when a user opens two Web windows today, she can't make two
    reservations in parallel).
    
    Instead, the Producer requires the portal to (ALWAYS!) create a
    transient entity each time it wants to use the service. Each such
    transient entity, presumably creates a dedicated session object at the
    Producer end. Subsequent requests are segregated because they are
    associated with two separate sessions.
    
    --> I would like to know that approach (2) implies an object-oriented
    thinking. It may simplify development on the portlet end (no need for
    manual segregation of sibling portlets), but as Mike noted requires a
    bit more data on the portal's end. Approach (1) would be very natural in
    a stateless line of thinking.
    
    
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