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Subject: RE: [wsrp-coord] Comments on Events Semantics Doc
- From: Rich Thompson <richt2@us.ibm.com>
- To: wsrp-coord@lists.oasis-open.org
- Date: Fri, 17 Sep 2004 14:59:32 -0400
The following has been added:
Issue # 26
Spec section:
SubCommittee: Coordination
Owner:
Description:
Is it useful to have a Consumer flag provided
during a pbia() or handleEvents() call which specifies that it will not
send any events?
Note that on Wednesday we will be looking
to have people volunteer to take the lead in driving/summarizing email
discussion so that issues are driven to a resolution.
Rich
"Goldstein, Scott"
<Scott.Goldstein@vignette.com>
09/17/2004 01:59 PM
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<wsrp-coord@lists.oasis-open.org>
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Subject
| RE: [wsrp-coord] Comments
on Events Semantics Doc |
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After looking through the current
issues document, I think I would like to see one added - Is it useful to
have a Consumer flag provided during a pbia() or handleEvents() call which
specifies that it will not send any events?
Thanks.
Scott
From: Rich Thompson [mailto:richt2@us.ibm.com]
Sent: Thursday, September 16, 2004 5:34 AM
To: wsrp-coord@lists.oasis-open.org
Subject: RE: [wsrp-coord] Comments on Events Semantics Doc
It is good to work through how we got to the current state ...
3. The publishedEvents are expected to be defined by the portlet in some
manner, though this could be via an include of someone else's definitions.
I believe the thought behind handledEvents being different was a greater
likelihood that these would be from another namespace. It would be more
reliable if they were of type EventDescription as well.
4. A portlet handling a SetCustomerID event could easily be expected to
generate other events related to the side effects of doing that update.
In general, handling an event should be expected to generate the same events
that processing the equivalent from a user's interaction with the portlet's
markup, with the exception of generating the event which is being processed.
5. The use case for Consumers that only handle simple payloads is Consumers
who have already have an event distribution engine and that engine only
handles simple payloads.
Do you think we need to open additional issues related to any of these
areas or just discuss them within the current set?
Rich
"Goldstein, Scott"
<Scott.Goldstein@vignette.com>
09/15/2004 08:35 PM
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<wsrp-coord@lists.oasis-open.org>
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Subject
| RE: [wsrp-coord] Comments on Events
Semantics Doc |
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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
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
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Subject
| [wsrp-coord] Comments on Events
Semantics Doc |
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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
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