HTTP GET vs. HTTP POST for DEV-25 - need clear guidance

Section Number

Relates to section GetMetaData (DEV-25) transaction

Priority

Medium

Issue

According to the W3C standard (https://www.w3.org/TR/2011/REC-ws-metadata-exchange-20111213/), section 5 mentions that HTTP GET should be used for SOAP messages like in GetMetaData(DEV25).

However, the current implementation uses HTTP POST, and it has been tested and worked during the plugathons with our partners.

Further investigation leads to the conclusion that the wrong version of WS Metadata Exchange is referenced – DPWS and MDPWS reference an older version. In DPWS 1.1 it is referenced:

[WS-MetadataExchange]

K. Ballinger, et al, Web Services Metadata Exchange 1.1 (WS-MetadataExchange), http://www.w3.org/Submission/2008/SUBM-WS-MetadataExchange-20080813/, 13 August 2008.

Reading this submission, you will notice that HTTP GETs are only for querying the mex:Location, but all metadata exchange is over WS-Transfer, and WS-Transfer has to happen over SOAP und POSTs.

The latter – WS-Transfer over SOAP and Post – is again defined by SOAP standard. There, depending on the messaging pattern, POST or GET is used. For Request Response message exchange patterns, post has to be used: https://www.w3.org/TR/soap12-part2/#http-suptfeatures

Proposed Change

Clearly descibe in the corresponding section if HTTP GET or HTTP POST must be used.