WfXML and OGC Services

[cappelaere]

Philippe,

In our case, WfXML provides a unified interface to various OGC
services that can be implemented as a workflow (SPS, WPS...).

It is true that the client will have to get the descriptions of inputs/
outputs relevant to that workflow. But this is at least a more
consistent interface. The current alternative is to be familiar with
the individual OGC specifications and various methods and input/output
parameters. Not easy nor scalable.

The advantage of going back to the process definition stored in the
registry allows for versioning and improvement of interfaces/
profiles. The SpotImage SPS and the EO-1 SPS have different input/
output parameters that have been evolving over time. With this
approach, older definitions can get deprecated quickly (upload new
definition... disable old one... and eventually delete it)

This is simple and interoperable and avoid the re-invention of
specifications as services evolve or new services come online.

If this can be simplified further, now would be a good time to bring
this up and test it during OWS-5.

Let us know what you have in mind. I know that SpotImage was
exploring similar avenues. We will be presenting this approach to the
TC in St Louis as a unified interface to a Virtual SensorWeb Enabled
Data Node.

Regards,

Pat.



> From: "Merigot, Philippe" <Philippe...@spotimage.fr>
> Date: Fri, 18 Jan 2008 10:16:41 +0100
> To: <p...@cappelaere.com>
> Cc: <ows-...@opengeospatial.org>
> Conversation: You've been invited to WfXML
> Subject: RE: You've been invited to WfXML
>
> Hi Pat,
>
> I had a look on WfXML and this is very interesting. I personally think that
> instead of thinking in terms of Web Service, thinking in terms of workflow (in
> the sense of WS chaining) may be a better approach for developers and
> companies, because it's easier to add new functionalities to a workflow with
> no impact for the client, just by adding a new WS - or workflow - into (seen
> as a black box by the client).
>
> But there are two ways for considering workflows:
> 1. the client sees an OGC WS (SPS, WCS, WPS, etc.), but in fact the service is
> implemented as a workflow (like what we called the "Virtual SPS" provided by
> Spot Image for OWS4)
> 2. all workflows share the same interface (same set of operation
> start/stop/..., etc.)
>
> If I well understood, WfXML is only compatible with the second approach, in
> which WS are involved via the Interface 3 in the Workflow Reference Model
> Diagram. But in this case, the client has to get the description of input and
> outputs of each involved WS, and provide values. Can this be achieved in a
> simple and interoperable way, without reinventing a new spec that would
> deprecate all the current ones (SPS...) ?
>
> Regards,
> Philippe
>
> ---------------------------
> Philippe Merigot
> Spot Image, Web and E-Business
> Tel: 33 (0) 5 62 19 42 52