Dear all,

Here is my issue proposal. This is just formalizing the phone presentation I did in December.

Title: A need for a "GetUI" or "StartTask" request/message for a Task Web Service

Raised By: Yoichi Takayama

Target:

WS-BPEL Extension for People (BPEL4People) Specification V 1.1, CD 02 (proposal), 6 Jan 2009, Section 6 (and related sections)

Also:

Web-Services Human Task (WS-HumanTask) Specification Version 1.1, CD 02 (proposal), 6 Jan 2009, Section 7 (and related sections)

http://www.oasis-open.org/apps/org/workgroup/bpel4people/document.php? document_id=30552

Description:

In WS-HumanTask Section 7, Figure 1, the requestMessage presumably corresponds to createTask message of the Task Life Cycle management. Although this causes to "Register" the WS-C protocol handler EPRs between the Task Parent and the Task (implemented as a Web Service) as the (2) and (3) indicate, the "requestMessage is an asynchronous request and nothing follows after that. The (4a) is the asynchronous return for the (1) requestMessage, as I understand it.

Presumably, following this step, there is the "start" message handled by the Task Life Cycle management (BPEL4People 4.8 or WS-HumanTask 4.7), which presumably would get UI from the Task Implementation to the Task Parent (and then to a Task Client and to its user agent that the end human user uses to do the Task) and let the end user do the human task. However, how this would be dealt with in an interoperable manner is not shown by the specification.

Obviously, the (4a) or (4b) would not occur until the Task UI is presented to the end user and some outcome has been produced. So, the "start" step is a Task Service step that should be documented and defined before the termination of the Task such as (4a) or (4b). This is lacking in the specification.

We cannot presume that the Task Parent or the Task Coordinator knows what operation or EPR to ask for to call it, since the specification does not have any place that states such an operation or how to specify such additional EPR for that operation, i.e. "StartTask".

Proposal:

1. Add a "StartTask" request message to Section 6.1 of the WS- HumanTask and to the table of WS-C WS-HT messages (page 31). This corresponds to the "start" Task Life Cycle management command, but is distinct from it because it is one of the Task Web Service massages.

This may return either a single page UI (such as HTML Form or XML) or an application UI (that could be a form of an EPR or URL or e.g. XUL- application XML launch point). The Task may be an multiple-page Web application or Desktop UI of an comprehensive application, for example.

2. For this reason, the interoperable format for the response message of the "StartTask" must be defined so that it can be interpreted by the Task Coordinator, Task Parent, and Task Client properly (so that they will know what the response contains and what to do with the information/data).

Alternative

We could provide an ability or a place to state the additional EPR for StartTask, but that is tedious. If a fixed WS-C WS-HT message can handle it, it is more consistent with the current CD and it may be simpler.

Potential Problem

If a Web Service implements multiple Tasks with different EPRs, each Task must implement different WS-C protocol handler and the "StartTask" message handler with it. In this case, there may be more efficient way to organize the whole WS-C WS-HT better.

Yoichi

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-- Yoichi Takayama, PhD Senior Research Fellow RAMP Project MELCOE (Macquarie E-Learning Centre of Excellence) MACQUARIE UNIVERSITY

Phone: +61 (0)2 9850 9073 Fax: +61 (0)2 9850 6527 www.mq.edu.au www.melcoe.mq.edu.au/projects/RAMP/

On 16/01/2009, at 10:05 AM, Dave Ings wrote: