No subject

(Accomodation of stateful connection information)

> This issue has two distinct, but often confused parts.

> 1) is it adequate to rely on an external convention (URL) to provide
> the standardization needed to unambiguously describe online access
> to data?

No, not if your goal is to achieve a web service.

> points on both sides of the debate are extensibility of EML
> and rendundancy with established standards, the extent to which
> those external bodies do in fact provide expressons of all online
> access protocols in common use by the community, and are we all
> conversant enough with that standard to use it efficiently.

A premise of Web Services is that information will be passed via XML
messaages over common protocols [HTTP, SMTP, FTP etc].

The dilemma that web services purports to solve is defining and
locating the logic required to retrieve information.  So:

> 2) should EML support descriptions of online connections that do not
> return a data object but instead enable opening of a stateful
> connection over which a proprietary communication protocol operates.

A web-service should be 'self-describing'.  Does that description
belong in EML, or should EML just provide a pointer to get the
description?  If it belongs in EML then we better prepare for WSDL.  I
don't know for sure if it belongs in EML, but if it does, that makes
the job more difficult.  One approach would be to provide only URL's
in 2.0 and make some provision for WSDL style connection definitions
in a future version?

 <references>matts.soapbox.1</references>

Here, here.  As I've tried to argue before, a URL can return *just* a
distinct data object or something else: ie. the definition for a
stateful connection (or even multiple connections on multiple servers)
in a SOAP message, say.  This is what WSDL is designed to achieve:

> EML beta 9 supports online access in two forms: a download url
> which, when passed to a url processor that recognized the mode, will
> result in a data object, and an information url that is expected to
> point to a document of unknown format with further instructions on
> how to get the data.

ie. WSDL?

Peter McCartney <peter.mccartney at asu.edu> writes:

> Thinking beyond this, im not sure what would be the best way to extend this
> solution so that it also works to point to WSDL descriptions documented in a
> UDDI type registry, but we should probably ensure that it is so we dont have
> to revise it in 2.1.

So if the web-services stack looks like this:

Discovery                   UDDI                      
Description                 WSDL                   
XML Messaging               XML-RPC,SOAP,XML          
Transport                   HTTP,SMTP,FTP,BEEP        

What parts, if any, do we want EML to solve?  If we want EML to
provide description ala WSDL, then we need to have an eye on that
horizon.


-- 
Scott E. Chapal_________________________________________________
Database & Network Manager             scott.chapal at jonesctr.org
J.W. Jones Ecological Research Center          229.734.4706 x227
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