RE: [wsrp][pfbm] -- Getting started

[Jeff Broberg <jbroberg@silverstream.com>]

Title: Message

My comments added to doco as well.

-----Original Message-----
From: Eilon Reshef [mailto:eilon.reshef@webcollage.com]
Sent: Wednesday, April 03, 2002 12:12 PM
To: 'Cassidy, Mark'; 'Michael Freedman'; tim.granshaw@sapportals.com
Cc: 'WSRP'
Subject: RE: [wsrp][pfbm] -- Getting started

I think the main topics are covered. Added a couple more thoughts and questions.

-----Original Message-----
From: Cassidy, Mark [mailto:mcassidy@Netegrity.com]
Sent: Wednesday, April 03, 2002 12:32 AM
To: 'Michael Freedman'; WSRP; 'tim.granshaw@sapportals.com'
Subject: RE: [wsrp][pfbm] -- Getting started

I think your approach is fine.  Let me throw out a couple thoughts for
starters:

- From interactions with customers and others involved with web services
currently, I've found few that really are pushing on the 'Find' part of
PFBM.  Most folks are dealing with services they explicitly know about.   So
I would propose that WSRP really doesn't need to invent anything new in the
'Find' arena, unless of course the requirements we converge on for 'PBM'
have some implications on what can be supported with the current UDDI
specs(which I'm not a SME on).

- On a similar note, I would argue that 'Publish' is simply a formal method
of making known Bind/Metadata information about a WSRP service, and that we
don't need to invent anything new in this arena either.  Another arguement
deferring much of a focus on publish/find, at least initially, is that it
seems these could be affected by what the bind/metadata part ends up looking
like. 

So, I'd suggest we focus on bind/metadata for starters.

Some initial questions(should be answered in order):
a) What actions should a portal application be able to take based on the
published metadata about a WSRP service?
Metadata requirements should directly fall out of this.
b) Which metadata is required?  Which is optional?
c) Will we support an extension mechanism to allow vendors to include custom
metadata?  Example scenario?

As far as work product, it seems that we need to document requirements and
then a spec for the metadata schema(perhaps dtd & any companion semantic
information?).  Not sure we need to do anything more...

Note:  Tim Granshaw sent me a note following the F2F expressing an interest
in contributing to this group.  We should include Tim in any
correspondance(if we have any outside of the standard wsrp mail alias).

-----Original Message-----
From: Michael Freedman [mailto:Michael.Freedman@oracle.com]
Sent: Tuesday, April 02, 2002 5:41 PM
To: WSRP
Subject: [wsrp][pfbm] -- Getting started

Note: [PFBM] is short for [Publish, Find, Bind, and Meta-data]

Folks,  in particular Mark Cassidy, Jeff Broberg, Petr Palas, its time
to get ourselves organized and going.  At the face-to-face we decided
not to schedule regular conference calls -- but didn't really discuss
how we would begin.  Any suggestions?  Did you like the approach I took
with [interfaces and protocols]? Namely, attempt to categorize the
problem space and pose the questions we need to begin discussing?  If so
would someone like to make a stab at this to get us started?  Other
ideas?

I also am interested in what work product(s) you think we should
produce.  Is our first task (once we understand what questions we are
answering) to write a requirements doc? If so do we stop there?  Do we
also try and move from requirements to spec?

  -Mike-

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Title: InterfacesProtocols

Comments by Eilon Reshef in red

Comments by Carsten Leue in blue

Comments by Jeff Broberg in green.

Discussion Areas

• SOAP encoding

How do we return marked up content in a soap response?  efficiently?
Should we support an escape hatch so the getContent request can be made via HTTP post?
Are there any performance numbers we would like the implementation team to generate for us to better understand how to most efficiently use SOAP?

Make sure that the SOAP flavour used is compatible to implementations other that J2EE (e.g. .NET)

The 2001 spec seems to be better for compatability between java & .net

 

• WSIA

I am assuming for the moment that the areas where WSIA/WSRP overlap will NOT be discussed in this subcommittee -- the pupose of this ietm is to define explicitly what is exlcuded.  From my notes taken at last week's meeting this would seem to be:

• activation/deactivation
• version detection/expression
• look and feel customization?
• WSRP interfaces
• Instance lifecycle
• create -- What are the things we want a producer to be able to do when a portlet instance is created?  What information is needed from the consumer to do this?  Who controls/creates the instance handle (portlet id)? Is the handle persistent? Is the handle cloneable? Can one (server side) handle be used by multiple clients concurrently?
• destroy -- What are the things we want a producer to be able to do when a portlet instance is deleted? Can a (persistent) handle expire?
• other operations -- Are there other operations we should consider?  Do we need to define a copy method?  How about a publish method (when a portal is being moved from a dev to a stage to a production environment)?  Others?

A couple of quick thoughts:

- There seem to be different notions of lifecycle and state: one is design-time (when setting up new portals or portal pages) and one is run-time (when new users come to a portal page and create specific instances of porlets). It could be nice to form a terminology around that (e.g., design-time versus run-time and portlet template versus portlet instance??) .

- We need to get these terms into the glossary.  Has anyone seen the doc from the f2f that had the proposed items ??

-         A couple of additional questions related to the design-time model. What workflow is supported for creating a portlet template? Does the portal need to be “registered” with the portlet? Any extensibility around the process for creating and approving creation of a design-time portlet? (E.g., if the portlet owner needs to know about it or approve it?) Any design-time information the portlet needs to get? Is the persistent data always stored at the portlet? Also on the portal?

-         I don’t think we should be talking about workflow and portlets, in my opinion they are separate, expcept that we may want to describe the potential ( not mandatory ) interaction that a portal administrator may have in regards to the discovery of available portlets, and the inclusion of them into their environment.  But how this is done, I believe is probably where the portal vendors can have their value add.

-         Are we all under the assumption that the portlet producer will provide an opaque handle to a portlet template, which can be instantiated in run-time?

• Content generation

What information does the producer need to generate content?  How does the producer know what content to produce?  How does the producer return content?  How does it indicate content type and encoding?  Should we start with an assumption that most renderers adhere to the HTTP get/post response model and try and map from that to SOAP?

• Actions

What are actions?  How are they different from events? Why are they needed?  Do actions produce content?  Can action handlers cause other actions or events to be triggered? If so how does a portlet instance discover and identify targets? How can actions be efficiently implemented? How are actions encoded in the markup?

I have heard others refer to the notion of an “action” as an “option”.

• Events/messaging

What are events?  How are they different from actions?  Why are they needed?  Do events produce content? Can event handlers cause other actions or events to be triggered?  If so how does a portlet instance discover and identify targets?  Are events a general purpose concept that should utilize a general purpose messaging system or is the messaging system defined and managed by the consumer/Portal? How can events be efficiently implemented? Do we need events in WSRP or can we live with actions for the sake of ease-of-use and ease-of-implementation?

I think we need both to truly handle both the embedded and customized use cases.

• Session Management/Portlet Grouping

What are session for; maintaining state within a single portlet and/or maintaining between a set of (cooperating) portlets?  If the later, do we need a notion of a Portal application/group/provider int he API?  If we do, what is its role (from an API/abstraction perspective)?  How are sessions established?  By the consumer? By the consumer requesting a session? Or willy-nilly in responses by the producer (this is the http/servlet model)?  Is the portlet always stateful? (probably not) Who can invalidate a session?  How does each side get notified? How does a consumer react when told a session has become invalid?  How does the portlet/producer? Can user-specific run-time data be persistent as well? (e.g., a “Remember Me” box in a login page) If so, is this part of this topic or the lifecycle topic? (Might be a good idea to combine the two under “State Management”)

How should the portlet react when running in a cluster, what effect does this have on the session information ?

• Request data

What information should the portal pass to the portlets when requesting markup? Will all data need to be published with each request or will it be possible to initialize the service once and send only differential data in the subsequent calls? 

I think that this type of information could potentially be passed in the first bind operation, and removed from the subsequent traffic.

• Order of method invocation, client, & server contracts

I don't have any specific questions to throw out here -- to a certain extent this probably falls out of answering the questions in the other topic areas.  Anyone have any ideas?

• URL Rewriting

Does the consumer or a producer do URL rewriting?  (Note: If the producer then URL rewriting is used loosely here as no rewriting might take place if URLs are written correctly in the first place)  What are the factors we need to consider to make a decision?  Performance? Ease of use?  Correctness?  Decoupling between producer and consumer?  Robustness? Is there a way to support both styles transparently to the producer? How do we support hardcoded/(absolute?) URLs? URLs created dynamically with scripting (i.e., JavaScript)? URLs encapsulated in some binary content (e.g., links from a Flash file or an applet)? Is there an explicit/implicit notion of URLs that shouldn’t be rewritten?

I think that we should scope the url rewriting into the two categories, stream based and property based rewriting.

• namespace encoding

How does the portal/portlets distinguish portlet instance form/request parameters such that each instance can (safely) locate its parameters in the request?  If namespace/prefixing is used, what is a name composed of? Does the portal expose only a portlet instance's parameters to the instance or does the instance "see" other request parameters?  If parameters are isolated how is this implemented? Can the URL rewriting principle be used to rewrite namespace prefixes? Performance and ease of use need to be considered. It would be nice if WSRP would allow for services with static content (so namespace rewriting would be done on the client). Are there any namespace restrictions around content elements (HTML IDs, JavaScript function names, etc.)? Across different portlets? Across different instances of the same portlet?

There are probably situations where the parameters can either be considered private to the originating portlet, or public for inspection by others.

• Remote portlet vs remote portlet container
  Does the API we are designing generally require a producer side runtime (portlet container) to make it convenient for content developers?  If so, should WSRP define a least one more API, a simple API, that removes/hides the extra complexity of the full version?
• I don’t think we should go here, once again, the value-add for the portal vendors.