Reconciling 2.0 domain specification base requirements with OSLC Core 3.0

["Jim Amsden" <jamsden@us.ibm.com>]

I went through the AM 2.0 specification
comparing the base requirements with CM 3.0. I found the following potential
incompatibilities with Core 3.0:

1. RDF serialization format - AM specifies
MUST for RDF/XML which is OK, but doesn’t mention turtle or json-ld. -
Recommendation: change to follow Core 3.0 RDF serialization formats, including
proposal to change core RDF serialization formats clauses.

2. Discovery - AM says ServiceProvider
resource is MUST, Core MAY - Recommendation: ok to strengthen compliance
level in a domain spec, so no problem. However this should just say MUST
support OSLC discovery, and need not say exactly how. Servers just follow
core which already covers OSLC 2.0 discovery compatibility.

So not much there. Other domain specs
should retain the base capabilities and supporting text from the OSLC 2.0
specifications unless there's some compelling reason they can't. In particular,
the RM spec should not have copied the CM base requirements, but instead
stick with the ones in the RM 2.0 spec.

Here's the details:


Architecture
Management

Thu Jan 11 09:39:53
EST 2018

Analyzing the differences
between CM
3.0 and AM
2.0 Base
Requirements. 
The result of this
analysis applies to the subsections of the document as well. Ideally these
would be cloned and be quite similar for each domain specification.

CM 3.0 Requirement	Level	Meaning	AM 2.0 Differences
Unknown properties and content	may/ must	OSLC servers mayignore unknown content and OSLC clients mustpreserve unknown content	Client MUST is in a separate entry.
Resource Operations	must	OSLC service mustsupport resource operations via standard HTTP operations
Resource Paging	may	OSLC servers mayprovide paging for resources but only when specifically requested by client	Paging is SHOULD for query results, MAY on large resource entity response bodies.
Partial Resource Representations	must	OSLC servers mustsupport request for a subset of a resource’s properties via the oslc.properties URL parameter retrieval via HTTP GET	AM is MAY support selective properties
Partial Update	may	OSLC servers maysupport partial update of resources using [LDPPatch], or via HTTP PUT.
Discovery	may/ should	OSLC servers shouldprovide a ServiceProvider resource for Core v2 compatibility, mayprovide a ServiceProviderCatalog, and mayprovide other forms of discovery described in Core 3.0 Discovery.	Specifically states MUST provide ServiceProvider resource. Servers MAY support ServiceProviderCatalog
Creation Factories	must	OSLC servers mustprovide LDPC creation factories to enable resource creation of Change Management resources via HTTP POST	Creation factory capability is MAY, and also servers MAY support creation factories in other resource serialization formats indicated with oslc:usage.
Query Capabilities	should	OSLC servers shouldprovide query capabilities to enable clients to query for resources	query capability is a MUST
Query Syntax	should/ may	OSLC query capabilities shouldsupport the OSLC Core Query Syntax and mayuse other query syntax
Delegated UI Dialogs	must/ should	OSLC Services mustoffer delegated UI dialogs (creation and selections) specified via OSLC Core 3.0 Delegated Dialogs and shouldinclude discovery through a ServiceProvider resource for OSLC v2 compatibility	Delegated selection UI is SHOULD, delegated creation dialog is separate entry and MAY.
UI Preview	should	OSLC Services shouldoffer UI previews for resources that may be referenced by other resources specified via OSLC Core 3.0 Preview and shouldinclude discovery through a server resource for OSLC v2 compatibility
Authentication	may	OSLC Services shouldfollow the recommendations for Authentication specified in [OSLCCore3]	SHOULD support one of the OSLC Core recommendations, Has separate MAY for each one (HTTP Basic, OAuth, Form)
Error Responses	should	OSLC Services shouldprovide error responses using OSLC Core 3.0 defined error formats
Turtle Representations	must	OSLC servers mustprovide a Turtle representation for HTTP GET requests and shouldsupport Turtle representations on POST and PUT requests.
RDF/XML Representations	should	OSLC servers shouldprovide an RDF/XML representation for HTTP GET requests and shouldsupport RDF/XML representations on POST and PUT requests for compatibility with Change Management 2.0.	RDF/XML is MUST
XML Representations	should	OSLC servers shouldprovide a XML representation for HTTP GET, POST and PUT requests that conform to the Core 2.0 Guidelines for XML.
JSON Representations	must	OSLC servers mustprovide JSON-LD representations for HTTP GET, POST and PUT requests that conform to the Core Guidelines for JSON-LD
HTML Representations	should	OSLC servers shouldprovide HTML representations for HTTP GET requests

Other Differences:

1. Servers MUST use absolute URIs - not sure this is a good idea, but its there, so ok to keep it.
2. Servers MUST support If-Match header on PUT and DELETE - note mentioned in CM, but may be in Core 3.0
3. Unique AM Link Type Query Capability
4. CM does not specify which HTTP resource operations may, must, or should be provided - AM say PUT & DELETE are SHOULD, may be covered in Core.
5. Specifically states servers SHOULD support paging for queries

Potential conflicts
with OSLC Core 3.0:

1. RDF serialization format - AM specifies MUST for RDF/XML which is OK, but doesn’t mention turtle or json-ld. - Recommendation: change to follow Core 3.0 RDF serialization formats
2. Discovery - AM says ServiceProvider resource is MUST, Core MAY - Recommendation: ok to strengthen compliance level, so no problem, should just say MUST support OSLC discovery, and need not say exactly how. Servers just follow core.

Jim Amsden, Senior Technical Staff Member
OSLC and Linked Lifecycle Data
919-525-6575