[wsrp] Re: [wsia] Follow-on Example

[Carsten Leue <CLEUE@de.ibm.com>]

Eilon - comments are in [CL]


Best regards
Carsten Leue

-------
Dr. Carsten Leue
Dept.8288, IBM Laboratory Böblingen , Germany
Tel.: +49-7031-16-4603, Fax: +49-7031-16-4401



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|         |           Eilon Reshef      |
|         |           <eilon.reshef@webc|
|         |           ollage.com>       |
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|         |           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                                                                        |
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  |       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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