- From: Andy Seaborne <andy.seaborne@epimorphics.com>
- Date: Thu, 20 Sep 2012 09:02:52 +0100
- To: public-ldp-wg@w3.org
On 19/09/12 23:56, Ashok Malhotra wrote: > Thanks, Andy, that very useful but your example > http://server/graphstore?graph=http://example/snapshot556 > did not work for me. In what way do you mean "did not work"? It's just an example, of named graph <http://example/snapshot556> at graph store <http://server/graphstore>, not an operational system. It is simply not possible to manage a typical graph store without some way to name a graph by full IRI so indirect naming is a MUST for GSP. The fact that this unfriendly format has to used is "unfortunate" (worse - it has to be %-encoded to be used). Andy > All the best, Ashok > > On 9/19/2012 2:48 PM, Andy Seaborne wrote: >> tl;dr: >> >> GSP is a description of how to use HTTP for data management. It >> defines very little; it is a direct use of HTTP. >> >> LDBP provides a higher level notion of resource - it places >> restrictions on data to enhance app interoperability but making it >> unsuitable for general data management. >> >> They are addressing different use cases. >> >> ---------------------------------- >> >> See [1] - I see the two protocols (LBDP and GSP) as siblings both >> built on RFC 2616. They have different use cases. >> >> LBDP adds machinery and restrictions to the use of HTTP in order to >> provide a lifecycle. >> >> GSP is a data management protocol for SPARQL graph stores. It defines >> only: >> >> GSP-1: Indirect naming. >> GSP-2: POST means add triples. >> >> it is arguable that GSP-2 is "defining" anything because in RFC2616 >> section 9.5 already says: >> """ >> - Extending a database through an append operation. >> """ >> >> So GSP defines indirect naming, nothing else. This has been shown to >> be a useful and effective means of managing a graph store 9a >> collection of graphs). GSP is deployed and in use today with multiple >> implementations. >> >> Indirect naming is the ability to have a graph name in a store that is >> not related to the local server name. It is a common usage for graph >> store management. >> >> http://server/graphstore?graph=http://example/snapshot556 >> >> Other than that, GSP is a description of how HTTP (RFC 2616) applies >> to a graph store. GET means GET, PUT means create/replace, POST means >> add data, DELETE means delete. A valid implementation of direct >> naming GSP is a file-system backed HTTP server. >> >> GSP has no concept of a container with an RDF presentation or >> containers-in-containers or of paging or ordering. >> >> LDBP does not consider indirect naming. >> >> LDBP is unsuitable for data management - it forbids general RDF data, >> for example. (4.1.9 - "BPR representations MUST use only the following >> standard datatypes"; 4.4.5 is also problematic where it hints at >> changing the predicates it does understand; 4.1.4 is at odds with IRI >> resolution; other requirements are problematic in intent and approach). >> >> If LDBP for BPRs removes the restrictions on simple "upload-download" >> to result in the same data then it might be able to use GSP(direct), >> and in fact it would just be RFC2616. >> >> LDBP for BPCs is not relevant for graph stores. Graph stores do not >> have such a container model. >> >> Alternative: >> >> Why not make LDBP for BPRs be simply a link to RFC 2616? + discussion >> that text/turtle be provided. Then a plain HTTP server can be used to >> provide LDBP for BPRs (not BPCs). >> >> > The reality is that many implementations of LDBP will be >> > based on graph stores, >> >> The key here is "will be based on graph stores" rather than "will be >> graph stores" -- the graph store is not directly implementing LDBP >> but being used to implement it. There will need an additional layer >> to implement the requirements specific to LDBP like containers. >> >> One final comment - I see nowhere in the submission that precludes a >> single graph, which has all the resources and containers in it. A >> graph store - multiple graphs, flat structure - is not necessary. Do >> you want to constraint >> >> Andy >> >> [1] http://lists.w3.org/Archives/Public/public-ldp-wg/2012Jul/0004.html >> >
Received on Thursday, 20 September 2012 08:03:21 UTC