Jim,
I can set that up early this afternoon but it requires at least a couple of days doesn't it? I'll have to review the rules first since this is the first time
to use the process.
Regards,
Martin Sarabura
R&D Fellow, PTC
From: [mailto:]
On Behalf Of Jim Amsden
Sent: July-28-15 9:46 AM
To: OASIS
Subject: Re: [oslc-core] Resource Preview issues
Martin,
Nice analysis. Agreed, and unless there are any further objections, let's proceed to vote on this proposal. Martin, want to try an electronic vote on this so we don't have to wait until the next
meeting to resolve it? I'm ready to do the editing today.
Jim Amsden, Senior Technical Staff Member
OSLC and Linked Lifecycle Data
919-525-6575
From: Martin P Pain <>
To: Jim Amsden/Raleigh/IBM@IBMUS
Cc: OASIS () <>
Date: 07/28/2015 05:32 AM
Subject: Re: [oslc-core] Resource Preview issues
Sent by: <>
My counter-proposal would be to go with:
application/x-oslc-compact+xml - OSLC 2.0 specific XML format
application/x-oslc-compact-turtle - Turtle
application/x-oslc-compact-rdf+xml - RDF/XML
application/x-oslc-compact+json - JSON
application/x-oslc-compact-ld+json - JSON-LD
(note the "-" in place of "+" to keep us to just using the registered suffixes).
RFC6838 §4.2.8 doesn't say anything about the meaning of removing a suffix from a media type, and I see no meaning in doing so. So the difference between your proposal and this approach would be whether to be consistent with the registered suffixes, or to be
consistent in what is before the suffix. I see slightly more value in the former.
I think this is ready for a TC vote to decide on which approach to take.
Perhaps we could first vote on moving away from Prefer back to just media types, taking your ones as the draft ones to use. Then vote on whether to change to my ones.
Kind regards,
Martin Pain
Software Developer - Green Hat
Rational Test Virtualization Server, Rational Test Control Panel
Phone:+44 (0)1962 815317
| Tie-Line:37245317
E-mail:
Find me on:
and
within IBM on:
IBM United Kingdom Limited Registered in England and Wales with number 741598 Registered office: PO Box 41, North Harbour, Portsmouth, Hants. PO6 3AU
From: "Jim Amsden" <>
To: OASIS () <>
Date: 27/07/2015 19:00
Subject: Re: [oslc-core] Resource Preview issues
Sent by: <>
Martin,
1. https://tools.ietf.org/html/rfc6838#page-12:probably doesn't
apply to x- unregistered or experimental MIME types. Of the underlying structural syntaxes of the application/x-oslc-compact MIME type and subtype, XML and JSON suffixes are registered, but RDF/XML, JSON-LD and Turtle are not.
The registered Media Types (http://www.iana.org/assignments/media-types/media-types.xhtml)
seem a bit inconsistent in this regard. application/rdf+xml and application/ld+json are defined, but this does not recognize the fact that an RDF or Linked-Date resource can have many other standard formats including Turtle and JSON. For example, LDP uses
text/turtle and application/ld+json to reference different representations of the same resource. It would seem that application/ld+turtle would be more consistent. And what's the semantic difference between application/rdf and application/ld (ignoring their
suffixes)? These MIME types aren't actually even defined.
I suggest we don't worry too much about this given that the OSLC MIME types aren't registered and are likely never going to be registered since they are already used in existing standards.
2. So I suggest we include the following Compact resource representations in the Accept header:
application/x-oslc-compact+xml - OSLC 2.0 specific XML format
application/x-oslc-compact+turtle - Turtle
application/x-oslc-compact+rdf+xml - RDF/XML
application/x-oslc-compact+json - JSON
application/x-oslc-compact+ld+json - JSON-LD
Jim Amsden, Senior Technical Staff Member
OSLC and Linked Lifecycle Data
919-525-6575
From: Martin P Pain <>
To: Jim Amsden/Raleigh/IBM@IBMUS
Cc: OASIS () <>
Date: 07/24/2015 06:02 AM
Subject: Re: [oslc-core] Resource Preview issues
Sent by: <>
https://tools.ietf.org/html/rfc6838#page-12:
"+suffix" constructs for as-yet unregistered
structured syntaxes SHOULD NOT be used, given the possibility of
conflicts with future suffix definitions.
These are the registered suffixes:
http://www.iana.org/assignments/media-type-structured-suffix/media-type-structured-suffix.xhtml
I think the only ones we are interested in are "+xml" and "+json". That doesn't give us the full range that we might want to support.
Options:
1. Only specify the existing plain XML (RDF/XML subset) and a new plain JSON (JSON-LD subset), as "+xml" and "+json" respectively.
Or:
2. In addition to "application/x-oslc-compact+xml" and "+json" for the plain formats, use something like "application/x-oslc-compact-rdf+xml" and "+json" for the full syntax of RDF/XML and JSON-LD. Not sure about tutrle, maybe "application/x-oslc-compact-turtle"
or just "application/x-oslc-compact-rdf".
I suggest option 1. Lower burden on servers (as IIRC they MUST support the XML subset anyway), and fewer media types. Unfortunately it doesn't allow clients to get the compact resource in Turtle.
(An unofficial workaround [hack] if a server wanted to make a Turlte representation available could be for a HEAD or OPTIONS response to an "Accept: application/x-oslc-compact+xml" or "+json" request could return a Content-Location header, and a request on
the URI provided by that header with an Accept:text/turtle header could return a turtle representation of the compact resource, but I won't suggest for a second that we standardize that.)
Kind regards,
Martin Pain
Software Developer - Green Hat
Rational Test Virtualization Server, Rational Test Control Panel
Phone:+44 (0)1962 815317
| Tie-Line:37245317
E-mail:
Find me on:
and
within IBM on:
IBM United Kingdom Limited Registered in England and Wales with number 741598 Registered office: PO Box 41, North Harbour, Portsmouth, Hants. PO6 3AU
From: "Jim Amsden" <>
To: OASIS () <>
Date: 23/07/2015 22:24
Subject: Re: [oslc-core] Resource Preview issues
Sent by: <>
Hummm...
OSLC Core 2.0 uses an unregistered, experimental media type to access the Compat resource: application/x-oslc-compact+xml. RFC 4288 discourages this, but indicates they are ok for use only with the active agreement of the parties exchanging them - that certainly
applies to an OASIS Standard.
Given that these are unregistered, we could easily create other variants for application/x-oslc-compact+turtle, application/x-oslc-compact+xml+rdf, application/x-oslc-compact+ld-json, etc. As Martin suggests, that feels like contributing to a bad practice.
But even if we decided to retain the OSLC3 Link and Prefer header approach to Preview discovery, we'd stll need to support Accept: application/x-oslc-compact+xml for backward compatibility. Given that, it seem like the simplest and most straight forward solution
is to hold our noses and start cluttering the media type space as needed.
Jim Amsden, Senior Technical Staff Member
OSLC and Linked Lifecycle Data
919-525-6575
From: Martin P Pain <>
To: Jim Amsden/Raleigh/IBM@IBMUS
Cc:
Date: 07/23/2015 12:20 PM
Subject: Re: [oslc-core] Resource Preview issues
Sent by: <>
See response inline below
Kind regards,
Martin Pain
Software Developer - Green Hat
Rational Test Virtualization Server, Rational Test Control Panel
Phone:+44 (0)1962 815317
| Tie-Line:37245317
E-mail:
Find me on:
and
within IBM on:
IBM United Kingdom Limited Registered in England and Wales with number 741598 Registered office: PO Box 41, North Harbour, Portsmouth, Hants. PO6 3AU
From: "Jim Amsden" <>
To: OASIS () <>
Date: 22/07/2015 20:37
Subject: [oslc-core] Resource Preview issues
Sent by: <>
Resource Preview 2.0 compatibility raises a few issues, hopefully a small enough number to be able to address in a single email.
1. Preview Discovery
OSLC2 does Preview Discovery via GET on a resource that supports Preview using an Accept: application/x-oslc-compact+xml header to request the Compact resource representation of the resource.
OSLC3 uses HEAD or OPTIONS on the resource and gets the URI for the Preview from a Link header. This takes two HTTP requests. Clients can get the Compact resource in one step by using the Prefer: return=representation; include="http://open-services.net/ns/core#PreferCompact"
header on the GET to get the Compact resource in a single request.
Discussion: The OSLC2 application/x-oslc-compact+xml header would be a third way to get the Compact resource. Should all three be supported, or is the OSLC2 approach actually the simplest and most HTTP consistent?
Resolution: I think OSLC2 got this right and OSLC3 preview discovery is unnecessarily complex. Accept headers are used to negotiate resource representations, and a Compact resource is an indirect representation of a resource for display purposes. So I recommend
continuing to use the Accept: application/x-oslc-compact+xml to get the Compact resource, and eliminate the OSLC3 Link and Prefer headers.
MP: Covered in the meeting.
2. Compact Resource Representation
Compact resource is an XML document in OSLC2, although it may be RDF/XML it should be processed as XML. This format will also need to be supported and return when the media-type requested through the Accept header is application/x-oslc-compact+xml.
OSLC3 Compact resource representation MUST be application/json and text/turtle, SHOULD be application/ld+json.
Resolution: add OSLC3 Compact resource MUST support media-type application/x-oslc-compact+xml in addition to the JSON and RDF representations. Clients use Accept header to get the representation they want.
MP: OSLC 3 servers need to return the same subset of RDF/XML as defined by v2 unless the client explicitly asks otherwise. For v2 cients to be abe to work with v3 servers. SI that what you're saying?
MP: They can't use the request header to request JSON or Turtle, as the content-type is already being used to select that we want the compact representation(/resource) rather than the regular representation(/resource). We could have a "+json" equivalent, which
would probably be a json-ld-compatible specific subset of JSON (which I think we might have already been talking about in the Prefer: and Link: header ideas for preview discovery?). But I don't expect "+turtle" would be valid or a good idea.
MP: It looks like neither "application/json"
nor "text/turtle" officially
support a "profile" parameter. If they did, we could have used the existing content type for XML, and then used the "profile" parameter on those two for JSON & Turtle. But we can't...
MP: My suggestion is to leave the existing one as is (as we agree ni the meeting today) and also define a "+json" equivalent. Feels like doing more of a bad thing, but it seems the best approach to me given where we are right now.
3. Preview Resize message
OSLC2 resize message is "oslc-preview-height: <newHeight>"
OSLC3 resize message is oslc-resize: {"oslc:hintHeight": <newHeight>, "oslc:hintWidth": <newWidth>}
Resolution: OSLC3 supports 2 resize messages, one for just height that would work with 2.0 clients, and one that includes height and width in the oslc-resize message. OSLC 3.0 clients would look for both. OSLC3 servers should send just the height message or
both if there is a reason to send height and width information.
MP: Agreed. I think it's important to say that servers should send both "oslc-preview-height" and "oslc-resize" messages if setting the width. Just saying "both" might be intepreted as "send just oslc-resize, containing 'both' width and height". It's an unfortunate
burden on servers, and one that I expect a number will not follow, but it seems that the only alternative is not allowing changing of width, which we want to do. (Or, saying that for previews you can only specify oslc:hintWidth in an oslc-resize message, and
the height always has to go through an oslc-preview-height message. That would avoid duplication.)
Jim Amsden, Senior Technical Staff Member
OSLC and Linked Lifecycle Data
919-525-6575
Unless stated otherwise above:
IBM United Kingdom Limited - Registered in England and Wales with number 741598.
Registered office: PO Box 41, North Harbour, Portsmouth, Hampshire PO6 3AU
Unless stated otherwise above:
IBM United Kingdom Limited - Registered in England and Wales with number 741598.
Registered office: PO Box 41, North Harbour, Portsmouth, Hampshire PO6 3AU
Unless stated otherwise above:
IBM United Kingdom Limited - Registered in England and Wales with number 741598.
Registered office: PO Box 41, North Harbour, Portsmouth, Hampshire PO6 3AU
