RFC 9: SOAP Binding of WCS GetCoverage Response

Author:Milan Novacek
Last Edit:2011-05-30


The current/draft OGC specifications for the SOAP binding for a WCS GetCoverage Response are inconsistent with the SOAP spec if the GetCoverage response includes a binary file. This RFC proposes an update to OGC 09-149r1 to resolve the inconsistencies: Requirements 5 and 6 should be changed to use SOAP MTOM where the entire coverage response comprises the attachment. This coverage attachment is referred to from within a new element ‘Coverage’ which is also defined as part of this RFC.

Problem Description

In OGC 09-149r1, Requirement 5 mandates that a GetCoverage SOAP response shall be encoded as “SOAP with Attachments” as defined in [W3C Note 11], but using SOAP 1.2 rather than SOAP 1.1. Requirement 6 says, rather imprecisely, that in a GetCoverage response, the SOAP Envelope shall contain one Body element which contains the Coverage as its single element.

For binary attachments to SOAP 1.2 messages, W3C recommends the usage of MTOM instead of SwA (see [1] and [2]). According to the guidance in [1], the SOAP 1.2 MTOM standard requires the use of the xop:Include element to refer to binary attachments. The difficulty arises because the “gml:rangeSet” element, which according to OGC 09-110r is mandated for a GetCoverage response, does not have a provision for using the xop:Include element to refer to an attached file. For this reason one cannot include a reference to an MTOM SOAP attachment in the GetCoverage response.

Proposed Changes to OGC 09-149r1

To resolve the problem, we propose to update two requirements of OGC 09-149r1 as follows:

Requirement 5: A GetCoverage SOAP response shall be encoded according to the W3C SOAP 1.2 standard [http://www.w3.org/TR/soap12-part1/] using MTOM [http://www.w3.org/TR/soap12-mtom/].

Requirement 6: In a GetCoverage response, the SOAP Body shall contain one element, “Coverage” of type “SoapCoverageType”, defined in the namespace http://www.opengis.net/wcs/2.0, according to the schema definition in http://www.opengis.net/wcs/2.0/wcsSoapCoverage.xsd.

Schema Location

For discussion purposes of this RFC, the proposed schema wcsSoapCoverage.xsd is available in the sandbox [3]. For convenience, wcsCommon.xsd in the same directory has been modified to include wcsSoapCoverage.xsd.



Voting History

Motion:Adopted on 2011-05-30 with +1 from Martin Paces, Stephan Meißl, Milan Novacek, Stephan Krause, and +0 from Arndt Bonitz