--- a/paq/prov-aq.html Thu Feb 07 16:41:47 2013 +0000
+++ b/paq/prov-aq.html Thu Feb 07 17:29:45 2013 +0000
@@ -256,7 +256,7 @@
</p>
<ul>
<li>
- Simple mechanisms for retrieving and discovering provenance records are described in <a href="#accessing-provenance-descriptions" class="sectionRef"></a> and <a href="#locating-provenance-descriptions" class="sectionRef"></a> .
+ Simple mechanisms for retrieving and discovering provenance records are described in <a href="#accessing-provenance-records" class="sectionRef"></a> and <a href="#locating-provenance-records" class="sectionRef"></a> .
</li>
<li>
Provenance query mechanisms that may be used for more demanding deployments are described in <a href="#provenance-query-services" class="sectionRef"></a>.
@@ -285,11 +285,11 @@
<dt><a href="#dfn-provenance-uri"><dfn>Provenance-URI</dfn></a></dt>
<dd>a URI denoting some <a class="internalDFN">provenance record</a>.</dd>
<dt><a href="#dfn-provenance-query-service"><dfn>Provenance query service</dfn></a></dt>
- <dd>a query service that accesses provenance given a <a class="internalDFN">target-URI</a> or other information about the desired provenance.</dd>
+ <dd>a service that accesses provenance using a query containing a <a class="internalDFN">target-URI</a> or other information about the desired provenance.</dd>
<dt><a href="#dfn-service-uri"><dfn>Service-URI</dfn></a></dt>
<dd>the URI of a <a class="internalDFN">provenance query service</a>.</dd>
<dt><a href="#dfn-pingback-uri"><dfn>Pingback-URI</dfn></a></dt>
- <dd>the URI of a provenance pingback service that can receive forward provenance (i.e. provenance describing how a resource is used after it has been created - see <a href="#forward-provenance" class="sectionRef"></a>).</dd>
+ <dd>the URI of a provenance pingback service that can receive forward provenance (i.e. provenance describing how a resource is used after it has been created).</dd>
<dt><a href="#dfn-accessing"><dfn>Accessing</dfn></a> provenance records</dt>
<dd>given the identity of a resource, the process of discovering and retrieving some <a class="internalDFN">provenance record</a>(s) about that resource. This may involve <a class="internalDFN">locating</a> a provenance record, then performing an HTTP GET to retrieve it, or locating and using a query service for provenance about an identified resource, or some other mechanism not covered in this document.</dd>
<dt><a href="#dfn-locating"><dfn>Locating</dfn></a> provenance records</dt>
@@ -299,6 +299,9 @@
<dd>...</dd>
-->
</dl>
+ <p class="TODO">
+ Check pingback defn after considering Stian's proposal
+ </p>
</section>
@@ -314,7 +317,7 @@
Requests for provenance about a resource may return provenance records that use one or more target-URIs to refer to versions of that resource. Some provenance records may use multiple target-URIs if there are assertions referring to the same underlying resource in different contexts. For example, a provenance record for a W3C document might include information about all revisions of the document using statements that use the different target-URIs of the various revisions.
</p>
<p>
- In summary, a <a class="internalDFN">provenance record</a> may be not universally applicable to a <a class="internalDFN">resource</a>, but may be expressed with respect to that resource in a restricted context (e.g. at a particular time). This restriction is itself just another resource (e.g. the weather forecast for a give date as opposed to the current weather forecast), with its own URI for referring to it within a provenance record.
+ These ideas are represented in the provenance data model [[PROV-DM]] by the concepts <a href="http://www.w3.org/TR/prov-dm/#term-entity" class="externalRef">entity</a> and <a href="http://www.w3.org/TR/prov-dm/#term-specialization" class="externalRef">specialization</a>. In particular, an entity may be a specialization of some resource whose "fixed aspects" provide sufficient constraint for expressed provenance about the resource to be invariant with respect to that entity. This entity is itself just another resource (e.g. the weather forecast for a give date as opposed to the current weather forecast), with its own URI for referring to it within a provenance record.
</p>
</section>
@@ -352,7 +355,7 @@
</tr>
<tr style="vertical-align: top;">
<td><a class="internalDFN">Service-URI</a></td>
- <td>A provenance query service (i.e. a resource of type <code>prov:ProvenanceQueryService</code>). This is the initial URI used when accessing a provenance query service; following REST API style [[REST-APIs]], actual URIs for accessing provenance are determined via the query service description.</td>
+ <td>A provenance query service (i.e. a resource of type <code>prov:ProvenanceQueryService</code>). This is the initial URI used when accessing a provenance query service; following REST API style [[REST-APIs]], URIs for accessing provenance are determined via the query service description.</td>
<td>A provenance query service description per <a href="#provenance-query-service-description" class="sectionRef"></a>. Alternative formats may be offered via HTTP content negotiation.</td>
</tr>
<tr style="vertical-align: top;">
@@ -380,20 +383,19 @@
</ol>
<p>
Web applications may access a provenance record in the same way as any resource on the Web, by dereferencing its URI (commonly using an HTTP GET operation). Thus, any provenance record may be associated with a <a class="internalDFN">provenance-URI</a>, and may be accessed by dereferencing that URI using web mechanisms.
+ How much or how little provenance is returned in a provenance record is a matter for the provider; a provenance trace may extend as linked data across multiple provenance records.
</p>
<p>
- When there is no easy way to associate a provenance-URI with individual resources (e.g. for resources not directly web-accessible, or whose publication mechanism is controlled by someone else), one may provide provenance about multiple resources through a provenance query service. A REST protocol for provenance querying is defined in Section <a href="#provenance-query-services" class="sectionRef"></a>; also described there is a mechanism for locating a SPARQL query service.
+ When there is no easy way to associate a <a class="internalDFN">provenance-URI</a> with a resource (e.g. for resources not directly web-accessible, or whose publication mechanism is controlled by someone else), a provenance description may be obtained using a provenance query service at an indicated <a class="internalDFN">service-uri</a>.
+ A REST protocol for provenance queries is defined in Section <a href="#provenance-query-services" class="sectionRef"></a>; also described there is a mechanism for locating a SPARQL query service.
</p>
<p>
- How much or how little provenance is returned in response to a retrieval request is a matter for the provenance provider application.
+ When publishing provenance, corresponding <a class="internalDFN">provenance-URI</a>s or <a class="internalDFN">service-URI</a>s should be discoverable using one or more of the mechanisms described in <a href="#locating-provenance-records" class="sectionRef"></a>.
</p>
<p>
Retrieved provenance is not guaranteed to be authoritative. Trust in provenance records must be determined separately from trust in the original resource that they may describe. Just as in the web at large, it is a user's responsibility to determine an appropriate level of trust in any resource; e.g. based on the domain that serves it, or an associated digital signature. (See also <a href="#security-considerations" class="sectionRef"></a>.)
</p>
<p>
- When publishing provenance records, corresponding <a class="internalDFN">provenance-URI</a>s or <a class="internalDFN">service-URI</a>s should be discoverable using one or more of the mechanisms described in <a href="#locating-provenance-descriptions" class="sectionRef"></a>.
- </p>
- <p>
Provenance may be presented as a <a href="/TR/prov-dm/#component4" class="externalRef">bundle</a>, which is "<cite>a named set of provenance descriptions, and is itself an entity, so allowing provenance of provenance to be expressed</cite>" [[PROV-DM]]. There is no requirement that a bundle identifier can be dereferenced to access the corresponding provenance, but where practical it is RECOMMENDED that matters be arranged so this is possible. One possible realization of a bundle is that it is published as part of an RDF Dataset [[RDF-CONCEPTS11]] or similar composite structure containing multiple RDF graphs in a single document. To access such a bundle would require accessing the RDF Dataset and then extracting the identified component; this in turn would require knowing a URI or some other way to retrieve the dataset. This specification does not describe a specific mechanism for extracting components from a document containing multiple graphs.
</p>
<p class="note">The W3C Linked Data Platform group (<a href="http://www.w3.org/2012/ldp/" class="externalRef">www.w3.org/2012/ldp/</a>) is chartered to produce a W3C Recommendation for HTTP-based (RESTful) application integration patterns using read/write Linked Data; we anticipate that they may address access to RDF Datasets in due course.
@@ -450,7 +452,7 @@
A <code>hasProvenance</code> link relation type for referencing a provenance record may be used thus:
</p>
<pre class="pattern">Link: <<cite>provenance-URI</cite>>; rel="http://www.w3.org/ns/prov#hasProvenance"; anchor="<cite>target-URI</cite>"</pre>
- <p>When used in conjunction with an HTTP success response code (<code>2xx</code>), this HTTP header field indicates that <code><cite>provenance-URI</cite></code> is the URI of a provenance record about the originally requested resource, and that the requested resource is identified within the provenance record as <code><cite>target-URI</cite></code>. (See also <a href="#interpreting-provenance-descriptions" class="sectionRef"></a>.)</p>
+ <p>When used in conjunction with an HTTP success response code (<code>2xx</code>), this HTTP header field indicates that <code><cite>provenance-URI</cite></code> is the URI of a provenance record about the originally requested resource, and that the requested resource is identified within the provenance record as <code><cite>target-URI</cite></code>. (See also <a href="#interpreting-provenance-records" class="sectionRef"></a>.)</p>
<p>
If no <code>anchor</code> parameter is provided then the <code><cite>target-URI</cite></code> is assumed to be the URI of the requested resource used in the corresponding HTTP request.
</p>
@@ -578,7 +580,7 @@
<section>
<h2>Resource represented as RDF</h2>
<p>
- If a resource is represented as RDF (in any of its recognized syntaxes, including RDFa), it may contain references to its own provenance using additional RDF statements. For this purpose the link relations introduced above (<a href="#locating-provenance-descriptions" class="sectionRef"></a>) may be used as RDF properties: <code>prov:hasProvenance</code>, <code>prov:hasAnchor</code>, and <code>prov:hasQueryService</code>, where the <code>prov:</code> prefix here indicates the PROV namespace URI <code>http://www.w3.org/ns/prov#</code>.
+ If a resource is represented as RDF (in any of its recognized syntaxes, including RDFa), it may contain references to its own provenance using additional RDF statements. For this purpose the link relations introduced above (<a href="#locating-provenance-records" class="sectionRef"></a>) may be used as RDF properties: <code>prov:hasProvenance</code>, <code>prov:hasAnchor</code>, and <code>prov:hasQueryService</code>, where the <code>prov:</code> prefix here indicates the PROV namespace URI <code>http://www.w3.org/ns/prov#</code>.
(These terms may be used to indicate provenance of arbitrary other resources too, but discussion of such usage is beyond the scope of this section.)
</p>
<p>
@@ -762,7 +764,7 @@
<section>
<h2>Provenance query service discovery</h2>
<p>
- Previously, <a href="#locating-provenance-descriptions" class="sectionRef"></a> has described use of HTTP <code>Link:</code> header fields and HTML <code><link></code> elements to indicate provenance query services. Beyond that, this specification does not define any specific mechanism for discovering query services. Applications may use any appropriate mechanism, including but not limited to: prior configuration, search engines, service registries, etc.
+ Previously, <a href="#locating-provenance-records" class="sectionRef"></a> has described use of HTTP <code>Link:</code> header fields and HTML <code><link></code> elements to indicate provenance query services. Beyond that, this specification does not define any specific mechanism for discovering query services. Applications may use any appropriate mechanism, including but not limited to: prior configuration, search engines, service registries, etc.
</p>
<p>
To facilitate service discovery, we recommend that RDF publication of dataset and service descriptions use the property <code>prov:hasQueryService</code> and the provenance service type <code>prov:ProvenanceQueryService</code> as appropriate (see the appendix <a href="#prov-namespace" class="sectionRef"></a>).