RE: [wsrp-coord] Comments on Events Semantics Doc

["Goldstein, Scott" <Scott.Goldstein@vignette.com>]

Thanks for the comments, Rich.

 

1. Sounds good.
2. Sorry.  My misunderstanding.

3. I’m not sure I’m following what you mean by, “if we make it an EventDescription[], it would mean that the schemas defining such interesting events would need to be reachable so that they could be dealt with via an include”.  Could you elaborate?  Also, how is having this field be of type, EventDescription[], different from having the publishedEvents field of type EventDescription[]?
4. I understand the advantage of flexibility.  However, it’s not clear to me when it would be used.  This is why I was curious if anyone had any specific use cases.  The concern I have with it is that it opens up the possibility of performance problems and even infinite recursion.  Therefore, you would want to implement a Consumer to limit the number of chained events it would handle before calling getMarkup().  On the nth event, then, you could call the handleEvents() operation with a flag stating that the Consumer will no longer send events.  A portlet may then be able to react to this, thereby putting itself in a proper state in order to serve the subsequent getMarkup() call.  Though an infinite loop is unlikely, it’s definitely possible, especially in the case where the Consumer allows event mapping within a configuration screen and the administrator maps the events in a feedback fashion.  Anyone else have thoughts on this?     
5. Why would it be beneficial for a Consumer to only handle events that were simple?  I don’t see it as being easier to implement, since the Consumer can pass data of type any from one message to the next without actually reading it.  Was there another purpose behind it?

 

Thanks.

 

Scott

 

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From: Rich Thompson [mailto:richt2@us.ibm.com]
Sent: Tuesday, September 14, 2004 2:14 PM
To: wsrp-coord@lists.oasis-open.org
Subject: Re: [wsrp-coord] Comments on Events Semantics Doc

 

My take:

1. I would like to turn the open questions into an issues list that we systematically work our way through. I think this will need people to step up to fleshing out the pros and cons of the various issues so that a decision can be reached. This will likely be a list that grows a bit as people now see the changes we have discussed in the broader context of the spec.
2. The discussion about '/' or '.' was left open the last time it was discussed.
3. I think the reason we had set the handled events as QName[] was that portlets could easily be handled events defined in other namespaces. I see the issue you raise ... if we make it an EventDescription[], it would mean that the schemas defining such interesting events would need to be reachable so that they could be dealt with via an include.
4. The semantics are that an interaction is an event that has been serialized to markup. I can't remember an eventing system where single generations of events ever dominated, though the number of generations is often small.
5. This question deals with how a Consumer advertises its capabilities. The axis discussed included doing event distribution, only distributing events whose payloads are of type string and full support for distributing generated events.

Rich

"Goldstein, Scott" <Scott.Goldstein@vignette.com>

09/14/2004 02:55 PM

To	<wsrp-coord@lists.oasis-open.org>
cc
Subject	[wsrp-coord] Comments on Events Semantics Doc

 

Rich mentioned in the last conference call that now was a good time to bring up questions/issues with the current eventing semantics doc, given that it’s being put into the 2.0 spec.  Here are our comments:
 
1.        There are still a significant number of open questions listed in the doc which appear not to have made it into the WSRP 2.0 spec draft.  Will we continue working with the semantics doc and then push the changes into the WSRP 2.0 spec?  Or, does it make sense to add the open questions to the WSRP 2.0?  It doesn’t seem to make sense at this point to apply changes to both docs.
2.        Minor - In the suggested hierarchy of event names, we had discussed changing the “/”’s to “.”’s.  I see that the open question about confusion with Xpath is still there.  I don’t recall, however, anyone having a problem changing to “.”’s.  Any thoughts on this?
3.        In the PortletDescription, why is the type of the handleEvents element a QName[] instead of a an EventDescription[]?  Imagine the following scenario:  I consume a portlet which states that it can receive events of name, “ns1:zipCodeEvent”.  Imagine that I consume another portlet which states that it published an event with name, “n55:myZipCodeEvent”, data type, “xsd:string”, and description, “The current zip code selected.”  As a portal administrator, I may want to map the published, “n55:myZipCodeEvent” to be received by the first portlet as, “ns1:zipCodeEvent”.  Unfortunately, without a data type and description, I don’t know what the first portlet is expected.  However, if handleEvents was an EventDescription[], all of this information would be provided, facilitating this mapping.
4.        Can someone provide a specific use case around event chaining (returning events from a handleEvents() calls)?  I’m having trouble seeing the need for this.  The only possibility that I can some up with, is for sending an ACK, which might be useful based on the way we’re defining the Consumer as an intelligent entity capable of making the decision not to send events.  Is this the case that has come up or are there others?  Also, would the sending of ACKs be our best practice suggestion of verifying event propagation?  
5.        Open Question #3 – What is the difference between a simpleEvent and a complexEvent?
 
Thanks.
 
Scott