Re: [wsrp] unclear behavior for dynamic nav params and transient properties

[Richard Jacob <richard.jacob@de.ibm.com>]

I think the nature of events is different to public nav state and transient
properties.
Events are payload/data/signasl that others may consume without the need of
the source to receive the event itself.
The portlet description defines IN&OUTevents. The OUT events are mainly
declared for wiring purposes.
The IN events declaration can be considered something like a subscription
to a cetrain set of events.
So a portlet may raise A,B,C events while intested in receiving event D.
If the portlet raises event E (dynamic, non-declared event) it doesn't
receive it but only portlet which declared interest in E (or the ones the
Consumer admin wired them to).

In contrast public nav params and transient properties are shared state.
So I view the declaration of public nav params and transient properties as
both: IN & OUT (enabling wiring and distribution).
I'm not sure if there are use cases of dynamically add new state params and
wanting to receive them. However one could easily think there are :-)
On the other hand would it make sense for a portlet to set a state param
without the need to receive it back again? I don't think so. Therefor I
would keep the property/public param declaration as an IN&OUT declaration.

BUT: I think this could really impose a burden on the Consumer to process
this.
Enabling such a dynamic adding of properties would require the consumer to
update the set of IN properties for each portlet on a per request basis.
This would mean that the Consumer would have to compare the set of
properties set in UpdateResponse (or even URL in case of nav params) to the
portlets metadata and update it if necessary.
Example:
portlet exposes A, B as the IN&OUT public nav state
now portlet suddenly sets C in its response/URL.
Now the Consumer has to go of and compare the set of IN&OUT params for the
portlet and add it dynamically.
This potentially has to be done on every URL invocation, right? I think
this might kill performance.

Another issue arises when the Consumer would like to update the portlet
description, would it drop the set it stored till then, would it merge?

This is the difference to events. Portlets can't declare dynamically that
they want to RECEIVE a changed set of events (only via service/portlet
description).
And I think this is what you are basically asking for: change the set of IN
params, be it events, public nav state, transient properties.

I guess the best way to do it would be our famously discussed "portlet
description changed" event. Here portlets could signal that the Consumer
has to update the portlets metadata and potentially change the set of
IN/OUT events, public params, transient properties.

Mit freundlichen Gruessen / best regards,

        Richard Jacob
______________________________________________________
IBM Lab Boeblingen, Germany
Dept.8288, WebSphere Portal Server Development
WSRP Team Lead & Technical Lead
WSRP Standardization
Phone: ++49 7031 16-3469  -  Fax: ++49 7031 16-4888
Email: mailto:richard.jacob@de.ibm.com


                                                                           
             Stefan Hepper                                                 
             <sthepper@hursley                                             
             .ibm.com>                                                  To 
                                       WSRP TC <wsrp@lists.oasis-open.org> 
             02/24/06 02:35 PM                                          cc 
                                                                           
                                                                   Subject 
                                       [wsrp] unclear behavior for dynamic 
                                       nav params and transient properties 
                                                                           
                                                                           
                                                                           
                                                                           
                                                                           
                                                                           




Hi,
for events you can declare at runtime new events that you publish by
just returning them in pbia or he.
For nav params and transient properties it is not required that the
updates you send in the UpdateResponse must be declared in the portlet
description. However, it is stated that the updates must be executed.
As input it is stated that the portlet only receives the nav params or
transient properties it has declared in its portlet definition.

Questions I have:

1. If we allow to dynamically create new events, why not new nav params
or transient properties and provide these new nav params or transient
properties with subsequent requests?

2. If we don't allow to dynamically add new nav params or transient
properties, why don't we state that updates only apply to properties
defined in the portlet description?

Stefan


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