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Subject: RE: [wsia] [wsrp] [wsrp-wsia joint interfaces] Merged interfacesdocument

Title: Message
I don't have an extremely strong feeling as to the question of whether to leverage infrastructure (HTTP/1.1) for multiplexing or put it as part of the protocol (it will work both ways). It's clearly an engineering tradeoff (has advantages/disadvantages, but I feel that the cost/benefit is of putting it explicitly in the protocol is marginal.
The advantage to it is providing out-of-the-box support for request multiplexing.
The main disadvantages I see are:
1. Simplicity - naturally a protocol based on arrays is harder to explain/use (at both ends).
2. Exception handling - with arrays, you would have to re-invent some of the built-in SOAP exception mechanism. You wouldn't necessarily want the entire call to fail even if just one portlet fails, and you'd need to return multiple result types, so you'd also have to create a custom data structure to use instead of SOAP exceptions.
3. Compatibility with SOAP network infrastructure - this is a concern I have even in having a single service serving multiple portlets, but is becoming even more so with multiplexing as part of the protocol. In general, we should expect software programs such as SOAP gateways, SOAP proxies, SOAP firewalls, etc. to gradually evolve. With multiple calls multiplexed onto a single call, such devices would not be able to add value. So, one may argue that a behavior like the one you described (distributing calls to different places) should be supplied e.g. by a SOAP gateway based on configuration rules so that if a call comes in with a specific parameter, it would be directed one way, versus another. Declaring everything as a single SOAP call essentially prevents us from pushing functionality down the technology stack.
As for performance perspective HTTP/1.1 does support multiplexing of requests, namely the ability to send one request while the first one is being processes, so this should still result in the same number of roundtrips. Obviously, there's the addition of the HTTP header in the payload, but this is negligible. For example, by using a non-SOAP protocol we will save much more in terms of overhead. (We don't get many benefits from the SOAP envelope anyway, especially if our granularity is such that a single service supports multiple portlets and even more so if we can't use exceptions). The reason why we use SOAP is to be "good citizens", which also applies to using more granular calls that can be managed using services in the lower part of the technology stack.
Such an approach would allow the Producer to handle multiple requests concurrently, with the only limitation being that the Producer would not have full visibility into all the request so it would have to use an online algorithm for distributing the requests. However, that last issue is, I believe, balanced by another consideration that was brought up earlier. If you use a single request with an array of arguments, if the Consumer uses one of the common frameworks, it would have to wait for the full result before dumping it to the output stream. If the Consumer can issue multiple calls, it can manage this in more flexible ways.
As for the overhead in marshaling and de-marshaling requests, this is indeed a consideration. However, I believe people can optimize this overhead out, either with pooling or by creating services on top of thinner libraries. My approach, in that respect, is that it would inappropriate for us to optimize - at the application level - issues that result from the temporary immaturity of specific SOAP frameworks, which especially in our case can be overcome since we only have a single interface (Proxy code). (Unlike issues inherent to the protocol, which we should optimize the hell out of).
Please also note that an approach that's based on multiplexing at the network layer also lends itself well to optimization of heterogeneous calls, such as performAction and getFragment or even setProperties and not just a collection of related calls.
Despite my long e-mail (my apologies ;-), I view this as a possible tactical optimization, only that I feel that the tradeoff here works better for simplicity. Part of it may also be the balance between optimizing for Producers which are sophisticated multi-service portals versus simpler home-grown Producers.
-----Original Message-----
From: Carsten Leue [mailto:cleue@de.ibm.com]
Sent: Wednesday, June 12, 2002 6:56 AM
To: Eilon Reshef
Cc: 'Thomas Klein6'; wsia@lists.oasis-open.org; wsrp@lists.oasis-open.org
Subject: RE: [wsia] [wsrp] [wsrp-wsia joint interfaces] Merged interfaces document


thanx for providing more details on your approach. However I still prefer
the explicit option for performance optimization for the following reasons:

- what I understood from your comment is that you want to make use of the
HTTP/1.1 feature to leave an established connection open during multiple
request. This would reduce the overhead of opening/closing a connection.
However it would not reduce the number of total roundtrips as you would
still call the method (e.g. getFragments) multiple times. Furthermore you
would still have the overhad of instantiating all the intermediate objects
your SOAP implementation used to marshal/unmarshal the SOAP request. By
passing arrays as parameters both disadvantages disappear.
- from my point of view one of the major advantages of using arrays is that
the producer can exploit parallelity when satisfying the requests. In your
approach this would not be possible as all requests come in sequentially.
- I don't agree that a consumer would be more difficult to implement. If
its does not support arrays, its just sends out one element. The producer
however would have to be able to deal with arrays. But this is trivial as
in the simplest case it would just iterate over the elements of the array
in a single loop.

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 07:37  |
|         |           PM                |
|         |           Please respond to |
|         |           "Eilon Reshef"    |
|         |                             |

  |                                                                                                                                             |

  |       To:       Carsten Leue/Germany/IBM@IBMDE                                                                                              |

  |       cc:       <wsia@lists.oasis-open.org>, <wsrp@lists.oasis-open.org>, Thomas Klein6/Germany/IBM@IBMDE                                   |

  |       Subject:  RE: [wsia] [wsrp] [wsrp-wsia joint interfaces] Merged interfaces document                                                   |

  |                                                                                                                                             |

  |                                                                                                                                             |



I apologize for the confusion.

What I meant to say is that SOAP relies on an underlying stack of

In our case, we can safely assume as much as optimization is concerned that
the underlying protocol is HTTP (unless anybody has in mind SMTP portlets).

In this case, one can use HTTP/1.1 as a transport mechanism for the SOAP
requests. This does not require new opening new connections for every

However, as you noted, this is not part of the common frameworks for SOAP.
However, let's not forget that we must support the standard stack
(SOAP/HTTP) but leveraging the existing frameworks is extremely important,
but if there is a certain optimization that people can do outside those
frameworks this is not something that should discouraged.

More specifically, on the client (Consumer) side, I don't see this as a
concern since we only need to have one proxy and we can manually construct
it if necessary for the extra performance (it wouldn't be the first time
that performance requires extra work, and I prefer that to a solution that
the interface inherently implies extra work).

On the server (Producer) side, I am more concerned: I am completely unaware
of what the coupling between the Web server and the underlying frameworks
is. If someone has an idea whether HTTP/1.1 can be forced to be used there,
that would be beneficial.

I disagree with you that is "tweaking" the transport: this may be tweaking
the existing SOAP frameworks, but hey: they are just piece of auxiliary
code, and I would rather look at is as moving beyond the infancy of the
those frameworks.

      -----Original Message-----
      From: Carsten Leue [mailto:CLEUE@de.ibm.com]
      Sent: Tuesday, June 11, 2002 2:47 AM
      To: Eilon Reshef
      Cc: wsia@lists.oasis-open.org; wsrp@lists.oasis-open.org; Thomas
      Subject: RE: [wsia] [wsrp] [wsrp-wsia joint interfaces] Merged
      interfaces document

      Eilon - i was not aware of this SOAP functionality. Can you detail a
      bit on
      this topic? How would I setup a batch call programatically? Is this
      processing part of the standard stacks (SOAP4J, AXIS, .NET)?

      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>       |
      |         |                             |
      |         |           06/10/2002 08:33  |
      |         |           PM                |
      |         |           Please respond to |
      |         |           Eilon Reshef      |
      |         |                             |


        |       To:       wsia@lists.oasis-open.org,

        |       cc:

        |       Subject:  RE: [wsia] [wsrp] [wsrp-wsia joint interfaces]
      Merged interfaces document




      Rich, isn't call batching available today at part of the relevant
      stack via HTTP/1.1, unless you use a code library that doesn't
      support it?
            -----Original Message-----
            From: Rich Thompson [mailto:richt2@us.ibm.com]
            Sent: Monday, June 10, 2002 1:21 PM
            To: wsia@lists.oasis-open.org; wsrp@lists.oasis-open.org
            Subject: RE: [wsia] [wsrp] [wsrp-wsia joint interfaces] Merged
            interfaces document

            We have to work through the array idea as it as big performance

            implications and I don't see any indications that call batching
            the SOAP
            stack level will be available in a relatively short timeframe.

            My understanding from the WSRP interfaces discussions is that a

            template is
            a portal concept. It is effectively a configured portlet that
      is used
            a toolbox to design pages. The concept of an instance is a

            portlet that is linked to the layout of a portal page. This
            MAY have come from cloning a template. From the perspective of
            Producer needs to support, both of these are particular
            configurations of
            an entity the service exposes with the Consumer choosing to use
            different ways. I have been searching for reasons why there
      would be
            difference for the entity, but haven't found one yet.

            If I understand your question about transient entities
      correctly, you
            why sessions should be separated from entities so that they can
            but question whether services will ever expose entities that
            persistent. I can certainly imagine entities with no
      persistence (the

            service that hosts them likely has some persistence of who may
            along with some use log for audit & billing purposes). A simple

            entity that
            puts a UI on a stock ticker feed may be a good example. It
      chooses to

            delegate all the billing issues to the service where it is
            and all
            the configuration persistence to its Consumers. In this case,
            createPersistentEntities() would always fail as only transient
            entities are

                                  Andre Kramer

                                  <andre.kramer@eu.        To:       Rich
            Thompson/Watson/IBM@IBMUS, wsia@lists.oasis-open.org,

                                  06/10/2002 10:37         Subject:  RE:
            [wsrp] [wsrp-wsia joint interfaces] Merged
                                  AM                        interfaces

            Supporting a batch operation mode through arrays does not seem
            In the "getFragment"
            case (getFragments?), the portal will most likely then have to
            the whole array is
            returned (i.e. all remote portlets have rendered) before it can

            display the
            resulting mark-up.
            How many consumer to producer parallel calls do we expect
            rather leave
            call batching up to the (future) SOAP stack.

            Always using "Entity" as the thing to create remotely seem to
            "class" versus "object"
            semantics that the WSRP "template" and "instance" operation
            used to
            imply. Do we now see no
            no difference between remote data storage - 'templates'
            inheritance) and
            computational entities - 'instances', that WSRP seems to
            Or are these the
            persistent v.s. transient entities of the document (for me,
            instances persist too)?

            In trying to follow the discussion, I'm confused as to why we
            sessions and transient
            entities, both being under the control of the consumer. I do
      see a
            need for
            common sessions
            (same user/group or consumer portal) but do not see the need
            transient entities,
            expecting a consumer to have to pay for all entities, in some
      way, in
            real world. I know
            the next call will discuss these but could someone give a brief

            before then?


            Andre Kramer, Citrix Systems, Inc.

            -----Original Message-----
            From: Rich Thompson [mailto:richt2@us.ibm.com]
            Sent: 07 June 2002 20:38
            To: wsia@lists.oasis-open.org; wsrp@lists.oasis-open.org
            Subject: [wsia] [wsrp] [wsrp-wsia joint interfaces] Merged


            Here is a draft of the merged interfaces document that Carsten
      and I
            been working on this week. The largest conceptual change from
            0.44 Joint Spec Draft is the appearance of arrays in most of
            operations. This allows Consumers on the scale of portals to
            interact with Producer services.

            (See attached file: WSIA - WSRP Interface Specification.doc)

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