[DAIS-WG] WS-DAI Core WSDL

[Mike Jackson]

Hi Alasdair,

On Thu, 14 Jan 2010, Alasdair J G Gray wrote:

> As part of the SemSorGrid4Env project [1], I have been developing a Web 
> service to enable data access to data streams. As a project, we have 
> decided to adopt the WS-DAI standard for data access and define suitable 
> extensions for streaming data. However, I have encountered numerous 
> problems in using the WS-DAI Core WSDL specifications [2] with recent 
> Web service frameworks, specifically Axis2 [3] and CXF [4]. The root 
> cause of these problems stems from the use of multiple porttypes in the 
> WS-DAI Core specification, which is not so well supported in these Web 
> service frameworks due to the move to using a single interface for a Web 
> service in WSDL 2.0. 
>
> Here are some specific questions:

I'm an OGSA-DAI developer, so can answer this question...

> Have other developers, e.g. the OGSA-DAI team, encountered such issues 
> and how have they resolved them? Also, are there plans on moving the 
> OGSA-DAI software to use a more recent Web service framework than Axis 
> [5]?

We didn't encounter the issue as the WS-DAI WSDLs are based on WSDL 1.1 so 
we continued to use Apache Axis 1.4, which (in addition to GT4.0/4.2) we 
traditionally use for web service development.

I should clarify at this point the distinction between WS-DAI and 
OGSA-DAI. OGSA-DAI is not an implementation of WS-DAI as it currently 
stands - its service APIs are based on a version from March 2003 which 
featured workflows. The specifications diverged from OGSA-DAI after this 
point and WS-DAI no longer has the notion of workflows. However, the 
product retained them as they were of use to our users.

OGSA-DAI WS-DAIR and WS-DAIX are however reference implementations of the 
latest WS-DAIR versions. These were built using OGSA-DAI - 
WS-DAI-compliant service layers have their functionality implemented 
behind the scenes using OGSA-DAI's workflow engine. AMGA WS-DAIR provides 
another reference implementation using a different approach.

There are no plans at this time to update OGSA-DAI to use more recent web 
service frameworks.

I'll leave these questions to the specification authors...

> Are there plans to update the WS-DAI standards, specifically to use WSDL 
> 2.0 with its single interface declaration per service? 
> Why does the WS-DAI Core specification WSDL not declare the 
> GenericQueryFactory operation in the same way that it has a GenericQuery 
> operation?

Cheers,

mike

> Thanks,
>
> Alasdair
>
> [1] http://www.semsorgrid4env.eu/
> [2] http://www.ogf.org/documents/GFD.74.pdf
> [3] http://ws.apache.org/axis2/
> [4] http://cxf.apache.org/
> [5] http://ws.apache.org/axis/
>
> Dr Alasdair J G Gray
> Research Associate
> A.Gray at cs.man.ac.uk
>
> Room 2.126
> School of Computer Science
> Kilburn Building
> University of Manchester
> Oxford Road
> Manchester
> M13 9PL, UK
>
> tel: (+44) 0161 275 6132
> fax: (+44) 0161 275 6204
>
> Please consider the environment before printing this email.
>
>

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Dr. Michael (Mike) Jackson      E-mail: m.jackson at epcc.ed.ac.uk
OGSA-DAI project                EPCC
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      http://sourceforge.net/projects/ogsa-dai

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