For my 2 pence, I have implemented the statement in EPrints in the Google Docs API way which has solved a lot of problems with one solution in my view and is also compliant with the GDocs clients.
If an object has contents (e.g. a resource has many documents) then the following tags are included in the atom: <xmlns:docs="http://schemas.google.com/docs/2007"; xmlns:batch="http://schemas.google.com/gdata/batch"; xmlns:gd="http://schemas.google.com/g/2005";> <entry> .... .... <category scheme="http://schemas.google.com/g/2005#kind"; term="http://schemas.google.com/docs/2007#folder"; label="folder"/> [Required to state that this item has contents] <link rel="edit-media" href="http://www.myrepository.com/id/eprint/154/contents"/> [The abstract URI for the contents of the folder/resource] <link rel="contents" href="http://www.myrepository.com/id/eprint/154/contents"/> [Direct link to contents of resource - not from GDocs API] </entry> According to GDocs if you want to put an item in a folder, you create the folder then post to the contents URI (the EM-URI) which can then return an entry corresponding to the document where the Edit-Media URI is then the URI of the item, not the abstract one (solving that problem) So for backward compatibility, if a SWORD 1.3 client posts a file, I think we should create the container (folder) put the file in the contents URI and return the EM-URI as the contents link, not the document URI (unless the folder only contains one file at which point it might just be easier to return the URI of that as the edit-media URI). Further if you wanted you could content negotiate on the contents URI to return a single file/document of that type. A kinda bodge of all previous thoughts! SWORD 2 clients should first create the container, obtaining the contents URI and then POST files into this. A statement about any of the URIs can then be obtained by simply querying the URI of each element (container and contents). Further you can create really complex objects (if the server lets you) by creating lots of sub-folders for HTML documents for example. Really quiet nice, plus all the implementation docs are already written. Dave T On 10 Feb 2011, at 07:51, Richard Jones wrote: > Hi Alistair, > >> I'm new to sword and this thread, so apologies if this has already been >> covered, but one thought... >> >> On Fri, Feb 04, 2011 at 08:54:49AM +0000, Richard Jones wrote: >>> Dear All, >>> >>> Thanks for your extensive feedback on the various issues that we have >>> been discussing on this list, it has been really valuable for the >>> project team to get this input. We have, we think, identified 3 >>> particular issues of contention: >>> >>> 1/ Whether the Statement should be embedded in the Deposit Receipt or be >>> a separate document referenced in an atom:link element >> >> ...why don't you allow servers to optionally inline the content within the >> link? There are two separate IETF I-Ds covering an atom link inline >> extension, >> one older [1] and one newer [2] which I believe is active. >> >> I.e., allow something like... >> >> <atom:entry> >> <atom:link rel="http://purl.org/net/sword/terms/statement"; >> type="application/rdf+xml" href="http://.....";> >> <atom:inline> >> <rdf:RDF> >> <!-- ORE statement goes here --> >> </rdf:RDF> >> </atom:inline> >> </atom:link> >> <atom:link rel="http://purl.org/net/sword/terms/statement"; >> type="application/atom+xml;type=feed" href="http://.....";> >> <atom:inline> >> <atom:feed> >> <!-- statement goes here --> >> </atom:feed> >> </atom:inline> >> </atom:link> >> </atom:entry> >> >> Seems to be a fairly commonly used pattern (we use it heavily for a malaria >> data repository project). > > This is quite intriguing, I definitely want to consider using this > approach. There is only one thing that I'm not sure about: > > It is possible (at the moment) that servers may only supply the embedded > Statement, and not any atom:link elements which resolve to it. In this > case there would be no atom:link to embed the atom:inline inside. > > The question then, is should we /require/ that a server be able to > provide at least one separate Statement URI? If so, then I think we > should adopt the atom:inline approach here, but if not we'll have to > continue with the rdf embedded as foreign markup. > > Looking at the examples in the references, I see that they actually > embed atom:feed elements; this would level the playing field nicely with > ORE as the embedded format. > > Thoughts? > > Cheers, > > Richard > > >> >> Cheers, >> >> Alistair >> >> [1] http://tools.ietf.org/html/draft-mehta-atom-inline-01 >> [2] http://tools.ietf.org/html/draft-snell-atompub-inline-01 >> >>> >>> 2/ Whether to use OAI-ORE for the Statement format or an Atom Feed (as >>> per CMIS and GData) >>> >>> 3/ How the client and server should negotiate over the format of the >>> content returned by the edit-media link (EM-URI) >>> >>> The project team has gone through each of these issues carefully, and >>> attempted to extract the simplest solutions but with a view to keeping >>> the SWORD 2.0 specification quite open at this stage, so that community >>> best practices can actually inform the standard itself in the long run. >>> Therefore, we're proposing the following approaches to these issues: >>> >>> 1/ Whether the Statement should be embedded in the Deposit Receipt or be >>> a separate document referenced in an atom:link element >>> >>> If the Statement is to be embedded in the Deposit Receipt, then it needs >>> really to be in OAI-ORE form, for the purposes of being clear foreign >>> markup. Nonetheless, bearing in mind that there is a question as to >>> whether the Statement should be an Atom Feed, it is clear that this >>> solution will not be adequate by itself. We therefore propose that the >>> standard provided to the project's funded developers to code against >>> says that an OAI-ORE serialisation MAY be embedded in the Deposit >>> Receipt (the Deposit Receipt will not be required to meet the OAI-ORE >>> spec for being a resource map itself). >>> >>> Alongside - or instead - of this, there MAY be one or more atom:link >>> elements in the Deposit Receipt which link to an external Statement. >>> These atom:link elements can specify their type attribute to say whether >>> they are an application/rdf+xml or application/atom+xml;type=feed. It >>> will be a requirement of the spec that there MUST be an embedded >>> Statement or at least one separate Statement. >>> >>> Therefore, you may see a Deposit Receipt like: >>> >>> <atom:entry> >>> <atom:link rel="http://purl.org/net/sword/terms/statement"; >>> type="application/rdf+xml" href="http://....."/> >>> >>> <rdf:RDF> >>> <!-- ORE statement goes here --> >>> </rdf:RDF> >>> </atom:entry> >>> >>> 2/ Whether to use OAI-ORE for the Statement format or an Atom Feed (as >>> per CMIS and GData) >>> >>> Another good reason for the approach in (1) is that this means we can >>> provide different Statement URIs with different type attributes. We >>> plan to ask developers to produce an ORE and an Atom Feed Statement >>> format under the project funding. So you may see a Deposit Receipt like: >>> >>> <atom:entry> >>> <atom:link rel="http://purl.org/net/sword/terms/statement"; >>> type="application/rdf+xml" href="http://....."/> >>> >>> <atom:link rel="http://purl.org/net/sword/terms/statement"; >>> type="application/atom+xml;type=feed" >>> href="http://....."/> >>> >>> <rdf:RDF> >>> <!-- ORE statement goes here --> >>> </rdf:RDF> >>> </atom:entry> >>> >>> The combination of approaches in (1) and (2) may seem woolly or >>> indecisive, but we believe that we can't determine in advance which of >>> these approaches is better, and that it should be up to the community of >>> users and implementers to decide which approach works best based on >>> actual usage of the developed software. Therefore, while the burden of >>> implementation is placed on the funded portion of the project, we expect >>> community driven implementations/usages to favour one approach over >>> another (possibly taking into account things like compatibility with >>> GData and CMIS, or preferring the more semantic web approach of ORE). >>> We can then use this information later in deriving a SWORD spec which is >>> based on best practices. >>> >>> 3/ How the client and server should negotiate over the format of the >>> content returned by the edit-media link (EM-URI) >>> >>> The Content Negotiation issue arises from the fact that AtomPub requires >>> at most one edit-media URI with a given type to be available in the Atom >>> Entry (Deposit Receipt). Since the SWORD server may contain multiple >>> files rather than the one file that AtomPub assumes, what this EM-URI >>> returns under GET is unclear. We initially considered 2 approaches: >>> >>> a/ A separate HTTP header like Accept-Packaging to allow content >>> negotiation on a package format >>> b/ A separate HTTP header like Accept-Media-Features to allow general >>> content negotaiton on feature sets >>> >>> As we discussed, both of these have pros and cons, and none of the >>> approaches to doing this are marked by any best practices, which makes >>> the project team unwilling to commit to anything too complex or >>> substantial, at a risk to the simplicity and overall success of SWORD. >>> Instead we are suggesting adopting a much simpler approach: >>> >>> The Deposit Receipt can contain already contain a sword:package element >>> (as per SWORD 1.3), and SWORD 2 plans to allow an arbitrary number of >>> such elements. These elements will describe the packaging formats >>> supported by the server, so the client will know in advance what the >>> capabilities of the server are. Therefore, instead of engaging in a >>> content negotiation process, the client will just specify a separate >>> HTTP header indicating what package format should be returned. Whether >>> this header re-uses the Packaging header used during deposit or >>> specifies a new header has yet to be decided. >>> >>> >>> Hopefully these approaches make sense to the group. We are interested >>> in how you think these will go down both during the project and beyond >>> in the community, and if there are any obvious problems with what we're >>> proposing here as the way forward for SWORD. >>> >>> All the best, >>> >>> Richard >>> (On-Behalf-Of the SWORD project team) >>> >>> >>> >>> ------------------------------------------------------------------------------ >>> The modern datacenter depends on network connectivity to access resources >>> and provide services. 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