GET version and version metadata; shared method for content negotiation.

doc/examples/store_layouts/graph_per_aspect.trig

@@ -8,6 +8,7 @@ PREFIX fcg: <info:fcsystem/graph/>
 PREFIX foaf: <http://xmlns.com/foaf/0.1/>
 PREFIX ldp: <http://www.w3.org/ns/ldp#>
 PREFIX ns: <http://example.edu/lakesuperior/ns#>
+PREFIX premis: <http://www.loc.gov/premis/rdf/v1#>
 PREFIX xsd: <http://www.w3.org/2001/XMLSchema#>
 
 # Admin data graphs.
@@ -30,26 +31,26 @@ PREFIX xsd: <http://www.w3.org/2001/XMLSchema#>
     fcrepo:created "2017-11-23"^^xsd:date ;
     fcrepo:lastModified "2017-11-27"^^xsd:date ;
     fcrepo:hasVersion
-      <info:fcres/a/b/c;v1> , <info:fcres/a/b/c;v2> , <info:fcres/a/b/c;v3> ;
+      <info:fcres/a/b/c/fcr:versions/v1> , <info:fcres/a/b/c;v2> , <info:fcres/a/b/c;v3> ;
     .
 }
 
-<info:fcsystem/graph/admin/a/b/c;v1> {
-  <info:fcres/a/b/c;v1> a fcrepo:Version ;
+<info:fcsystem/graph/admin/a/b/c/fcr:versions/v1> {
+  <info:fcres/a/b/c/fcr:versions/v1> a fcrepo:Version ;
     fcrepo:created "2017-11-23"^^xsd:date ;
     fcrepo:lastModified "2017-11-23"^^xsd:date ;
   .
 }
 
-<info:fcsystem/graph/admin/a/b/c;v2> {
-  <info:fcres/a/b/c;v2> a fcrepo:Version ;
+<info:fcsystem/graph/admin/a/b/c/fcr:versions/v2> {
+  <info:fcres/a/b/c/fcr:versions/v2> a fcrepo:Version ;
     fcrepo:created "2017-11-23"^^xsd:date ;
     fcrepo:lastModified "2017-11-24"^^xsd:date ;
   .
 }
 
-<info:fcsystem/graph/admin/a/b/c;v3> {
-  <info:fcres/a/b/c;v3> a fcrepo:Version ;
+<info:fcsystem/graph/admin/a/b/c/fcr:versions/v3> {
+  <info:fcres/a/b/c/fcr:versions/v3> a fcrepo:Version ;
     fcrepo:created "2017-11-23"^^xsd:date ;
     fcrepo:lastModified "2017-11-25"^^xsd:date ;
   .
@@ -107,23 +108,23 @@ PREFIX xsd: <http://www.w3.org/2001/XMLSchema#>
 }
 
 # Previous states (versions) of a resource.
-<info:fcsystem/graph/userdata/_main/a/b/c;v1> {
-  <info:fcres/a/b/c;v1> a ns:Book ;
+<info:fcsystem/graph/userdata/_main/a/b/c/fcr:versions/v1> {
+  <info:fcres/a/b/c/fcr:versions/v1> a ns:Book ;
     fcrepo:hasParent <info:fcres/> ;
     dc:title "Moby Dick" ;
     .
 }
 
-<info:fcsystem/graph/userdata/_main/a/b/c;v2> {
-  <info:fcres/a/b/c;v2> a ns:Book ;
+<info:fcsystem/graph/userdata/_main/a/b/c/fcr:versions/v2> {
+  <info:fcres/a/b/c/fcr:versions/v2> a ns:Book ;
     fcrepo:hasParent <info:fcres/> ;
     dc:title "Moby Dick" ;
     dc:creator "Herman Melvil" ;
     .
 }
 
-<info:fcsystem/graph/userdata/_main/a/b/c;v3> {
-  <info:fcres/a/b/c;v3> a ns:Book ;
+<info:fcsystem/graph/userdata/_main/a/b/c/fcr:versions/v3> {
+  <info:fcres/a/b/c/fcr:versions/v3> a ns:Book ;
     fcrepo:hasParent <info:fcres/> ;
     dc:title "Moby Dick" ;
     dc:creator "Herman Melville" ;
@@ -147,29 +148,37 @@ PREFIX xsd: <http://www.w3.org/2001/XMLSchema#>
 # Historic version metadata. This is kept separate to optimize current resource
 # lookups.
 <info:fcsystem/graph/historic>  {
-  <info:fcsystem/graph/admin/a/b/c;v1>
-    foaf:primaryTopic <info:fcres/a/b/c;v1> ;
+  <info:fcsystem/graph/admin/a/b/c/fcr:versions/v1>
+    foaf:primaryTopic <info:fcres/a/b/c/fcr:versions/v1> ;
     fcrepo:created "2017-11-24"^^xsd:date ;
+    fcrepo:hasVersionLabel "v1" ;
   .
-  <info:fcsystem/graph/admin/a/b/c;v2>
-    foaf:primaryTopic <info:fcres/a/b/c;v2> ;
+  <info:fcsystem/graph/admin/a/b/c/fcr:versions/v2>
+    foaf:primaryTopic <info:fcres/a/b/c/fcr:versions/v2> ;
     fcrepo:created "2017-11-25"^^xsd:date ;
+    fcrepo:hasVersionLabel "v2" ;
   .
-  <info:fcsystem/graph/admin/a/b/c;v3>
-    foaf:primaryTopic <info:fcres/a/b/c;v3> ;
+  <info:fcsystem/graph/admin/a/b/c/fcr:versions/v3>
+    foaf:primaryTopic <info:fcres/a/b/c/fcr:versions/v3> ;
     fcrepo:created "2017-11-26"^^xsd:date ;
+    fcrepo:hasVersionLabel "v3" ;
   .
 
-  <info:fcsystem/graph/userdata/_main/a/b/c;v1>
-    foaf:primaryTopic <info:fcres/a/b/c;v1> ;
+  <info:fcsystem/graph/userdata/_main/a/b/c/fcr:versions/v1>
+    foaf:primaryTopic <info:fcres/a/b/c/fcr:versions/v1> ;
     fcrepo:created "2017-11-24"^^xsd:date ;
+    fcrepo:hasVersionLabel "v1" ;
+    # Provenance data can also be added.
+    premis:actor <http://ex.org/user/1325> ;
   .
-  <info:fcsystem/graph/userdata/_main/a/b/c;v2>
-    foaf:primaryTopic <info:fcres/a/b/c;v2> ;
+  <info:fcsystem/graph/userdata/_main/a/b/c/fcr:versions/v2>
+    foaf:primaryTopic <info:fcres/a/b/c/fcr:versions/v2> ;
     fcrepo:created "2017-11-25"^^xsd:date ;
+    fcrepo:hasVersionLabel "v2" ;
   .
-  <info:fcsystem/graph/userdata/_main/a/b/c;v3>
-    foaf:primaryTopic <info:fcres/a/b/c;v3> ;
+  <info:fcsystem/graph/userdata/_main/a/b/c/fcr:versions/v3>
+    foaf:primaryTopic <info:fcres/a/b/c/fcr:versions/v3> ;
     fcrepo:created "2017-11-26"^^xsd:date ;
+    fcrepo:hasVersionLabel "v3" ;
   .
 }

lakesuperior/endpoints/ldp.py

@@ -131,16 +131,8 @@ def get_resource(uid, force_rdf=False):
         if isinstance(rsrc, LdpRs) \
                 or is_accept_hdr_rdf_parsable() \
                 or force_rdf:
-            resp = rsrc.get()
-            if request.accept_mimetypes.best == 'text/html':
-                rsrc = resp.resource(request.path)
-                return render_template(
-                        'resource.html', rsrc=rsrc, nsm=nsm,
-                        blacklist = vw_blacklist)
-            else:
-                for p in vw_blacklist:
-                    resp.remove((None, p, None))
-                return (resp.serialize(format='turtle'), out_headers)
+            rsp = rsrc.get()
+            return negotiate_content(rsp, out_headers)
         else:
             logger.info('Streaming out binary content.')
             rsp = make_response(send_file(rsrc.local_path, as_attachment=True,
@@ -213,7 +205,7 @@ def get_version_info(uid):
     except TombstoneError as e:
         return _tombstone_response(e, uid)
     else:
-        return rsp.serialize(format='turtle'), 200
+        return negotiate_content(rsp)
 
 
 @ldp.route('/<path:uid>/fcr:versions/<ver_uid>', methods=['GET'])
@@ -233,7 +225,7 @@ def get_version(uid, ver_uid):
     except TombstoneError as e:
         return _tombstone_response(e, uid)
     else:
-        return rsp.serialize(format='turtle'), 200
+        return negotiate_content(rsp)
 
 
 @ldp.route('/<path:uid>/fcr:versions', methods=['POST'])
@@ -427,6 +419,21 @@ def tombstone(uid):
         return '', 404
 
 
+def negotiate_content(rsp, headers=None):
+    '''
+    Return HTML or serialized RDF depending on accept headers.
+    '''
+    if request.accept_mimetypes.best == 'text/html':
+        rsrc = rsp.resource(request.path)
+        return render_template(
+                'resource.html', rsrc=rsrc, nsm=nsm,
+                blacklist = vw_blacklist)
+    else:
+        for p in vw_blacklist:
+            rsp.remove((None, p, None))
+        return (rsp.serialize(format='turtle'), headers)
+
+
 def uuid_for_post(parent_uid=None, slug=None):
     '''
     Validate conditions to perform a POST and return an LDP resource

lakesuperior/model/ldpr.py

@@ -20,6 +20,8 @@ from lakesuperior.dictionaries.srv_mgd_terms import  srv_mgd_subjects, \
         srv_mgd_predicates, srv_mgd_types
 from lakesuperior.exceptions import *
 from lakesuperior.model.ldp_factory import LdpFactory
+from lakesuperior.store_layouts.ldp_rs.rsrc_centric_layout import (
+        VERS_CONT_LABEL)
 
 
 ROOT_UID = ''
@@ -104,8 +106,6 @@ class Ldpr(metaclass=ABCMeta):
     RES_DELETED = '_delete_'
     RES_UPDATED = '_update_'
 
-    RES_VER_CONT_LABEL = 'fcr:versions'
-
     base_types = {
         nsc['fcrepo'].Resource,
         nsc['ldp'].Resource,
@@ -294,7 +294,7 @@ class Ldpr(metaclass=ABCMeta):
         '''
         if not hasattr(self, '_version_info'):
             try:
-                self._version_info = self.rdfly.get_version_info(self.urn)
+                self._version_info = self.rdfly.get_version_info(self.uid)
             except ResourceNotExistsError as e:
                 self._version_info = Graph()
 
@@ -395,10 +395,32 @@ class Ldpr(metaclass=ABCMeta):
         This gets the RDF metadata. The binary retrieval is handled directly
         by the route.
         '''
-        global_gr = g.tbox.globalize_graph(self.out_graph)
-        global_gr.namespace_manager = nsm
+        gr = g.tbox.globalize_graph(self.out_graph)
+        gr.namespace_manager = nsm
+
+        return gr
+
+
+    def get_version_info(self):
+        '''
+        Get the `fcr:versions` graph.
+        '''
+        gr = g.tbox.globalize_graph(self.version_info)
+        gr.namespace_manager = nsm
 
-        return global_gr
+        return gr
+
+
+    def get_version(self, ver_uid):
+        '''
+        Get a version by label.
+        '''
+        ver_gr = self.rdfly.get_metadata(self.uid, ver_uid).graph
+
+        gr = g.tbox.globalize_graph(ver_gr)
+        gr.namespace_manager = nsm
+
+        return gr
 
 
     @atomic
@@ -475,7 +497,7 @@ class Ldpr(metaclass=ABCMeta):
         LIMIT 1
         ''')
         ver_uid = str(ver_rsp.bindings[0]['uid'])
-        ver_trp = set(self.rdfly.get_version(self.urn, ver_uid))
+        ver_trp = set(self.rdfly.get_metadata(self.urn, ver_uid))
 
         laz_gr = Graph()
         for t in ver_trp:
@@ -509,22 +531,6 @@ class Ldpr(metaclass=ABCMeta):
         return self._purge_rsrc(inbound)
 
 
-    def get_version_info(self):
-        '''
-        Get the `fcr:versions` graph.
-        '''
-        return g.tbox.globalize_graph(self.version_info)
-
-
-    def get_version(self, ver_uid):
-        '''
-        Get a version by label.
-        '''
-        ver_gr = self.rdfly.get_version(self.urn, ver_uid)
-
-        return g.tbox.globalize_graph(ver_gr)
-
-
     @atomic
     def create_version(self, ver_uid):
         '''
@@ -558,7 +564,7 @@ class Ldpr(metaclass=ABCMeta):
         if backup:
             self.create_version(uuid4())
 
-        ver_gr = self.rdfly.get_version(self.urn, ver_uid)
+        ver_gr = self.rdfly.get_metadata(self.urn, ver_uid)
         revert_gr = Graph()
         for t in ver_gr:
             if t[1] not in srv_mgd_predicates and not(
@@ -682,8 +688,8 @@ class Ldpr(metaclass=ABCMeta):
         Perform version creation and return the internal URN.
         '''
         # Create version resource from copying the current state.
-        ver_add_gr = Graph()
-        vers_uid = '{}/{}'.format(self.uid, self.RES_VER_CONT_LABEL)
+        ver_add_gr = set()
+        vers_uid = '{}/{}'.format(self.uid, VERS_CONT_LABEL)
         ver_uid = '{}/{}'.format(vers_uid, ver_uid)
         ver_uri = nsc['fcres'][ver_uid]
         ver_add_gr.add((ver_uri, RDF.type, nsc['fcrepo'].Version))
@@ -707,25 +713,13 @@ class Ldpr(metaclass=ABCMeta):
                         g.tbox.replace_term_domain(t[0], self.urn, ver_uri),
                         t[1], t[2]))
 
-        self.rdfly.modify_rsrc(
-                self.uid, add_trp=ver_add_gr, types={nsc['fcrepo'].Version})
-
-        # Add version metadata.
-        add_gr = set()
-        add_gr.add((
-        elf.urn, nsc['fcrepo'].hasVersion, ver_uri))
-        add_gr.add(
-           (ver_uri, nsc['fcrepo'].created, g.timestamp_term))
-        add_gr.add(
-                (ver_uri, nsc['fcrepo'].hasVersionLabel, Literal(ver_uid)))
-
-        self.rdfly.modify_rsrc(self.uid, add_trp=add_gr)
-
-        # Update resource.
-        rsrc_add_gr = Graph()
-        rsrc_add_gr.add((
-            self.urn, nsc['fcrepo'].hasVersions, nsc['fcres'][vers_uid]))
+        self.rdfly.modify_rsrc(ver_uid, add_trp=ver_add_gr)
 
+        # Update resource admin data.
+        rsrc_add_gr = {
+            (self.urn, nsc['fcrepo'].hasVersion, ver_uri),
+            (self.urn, nsc['fcrepo'].hasVersions, nsc['fcres'][vers_uid]),
+        }
         self._modify_rsrc(self.RES_UPDATED, add_trp=rsrc_add_gr, notify=False)
 
         return nsc['fcres'][ver_uid]

lakesuperior/store_layouts/ldp_rs/rsrc_centric_layout.py

@@ -6,12 +6,12 @@ from urllib.parse import quote
 
 import requests
 
-from flask import current_app
+from flask import g
 from rdflib import Graph
 from rdflib.namespace import RDF
 from rdflib.query import ResultException
 from rdflib.resource import Resource
-from rdflib.term import URIRef
+from rdflib.term import URIRef, Literal
 
 from lakesuperior.dictionaries.namespaces import ns_collection as nsc
 from lakesuperior.dictionaries.namespaces import ns_mgr as nsm
@@ -22,6 +22,7 @@ from lakesuperior.exceptions import (InvalidResourceError, InvalidTripleError,
 
 META_GR_URI = nsc['fcsystem']['meta']
 HIST_GR_URI = nsc['fcsystem']['historic']
+VERS_CONT_LABEL = 'fcr:versions'
 
 
 class RsrcCentricLayout:
@@ -56,6 +57,7 @@ class RsrcCentricLayout:
     '''
 
     _logger = logging.getLogger(__name__)
+    _graph_uids = ('fcadmin', 'fcmain', 'fcstruct')
 
     # @TODO Move to a config file?
     attr_map = {
@@ -66,6 +68,7 @@ class RsrcCentricLayout:
                 nsc['fcrepo'].created,
                 nsc['fcrepo'].createdBy,
                 nsc['fcrepo'].hasParent,
+                nsc['fcrepo'].hasVersion,
                 nsc['fcrepo'].lastModified,
                 nsc['fcrepo'].lastModifiedBy,
                 # The following 3 are set by the user but still in this group
@@ -168,7 +171,7 @@ class RsrcCentricLayout:
         See base_rdf_layout.extract_imr.
         '''
         if incl_children:
-            incl_child_qry = 'FROM {}'.format(self._struct_uri(uid).n3())
+            incl_child_qry = 'FROM {}'.format(nsc['fcstruct'][uid].n3())
             if embed_children:
                 pass # Not implemented. May never be.
         else:
@@ -181,8 +184,8 @@ class RsrcCentricLayout:
         {chld}
         WHERE {{ ?s ?p ?o . }}
         '''.format(
-                ag=self._admin_uri(uid).n3(),
-                sg=self._main_uri(uid).n3(),
+                ag=nsc['fcadmin'][uid].n3(),
+                sg=nsc['fcmain'][uid].n3(),
                 chld=incl_child_qry,
             )
         try:
@@ -228,7 +231,7 @@ class RsrcCentricLayout:
         '''
         See base_rdf_layout.ask_rsrc_exists.
         '''
-        meta_gr = self.ds.graph(self._admin_uri(uid))
+        meta_gr = self.ds.graph(nsc['fcadmin'][uid])
         return bool(
                 meta_gr[nsc['fcres'][uid] : RDF.type : nsc['fcrepo'].Resource])
 
@@ -238,11 +241,36 @@ class RsrcCentricLayout:
         This is an optimized query to get everything the application needs to
         insert new contents, and nothing more.
         '''
-        gr = self.ds.graph(self._admin_uri(uid, ver_uid)) | Graph()
+        if ver_uid:
+            uid = self.snapshot_uid(uid, ver_uid)
+        gr = self.ds.graph(nsc['fcadmin'][uid]) | Graph()
 
         return Resource(gr, nsc['fcres'][uid])
 
 
+    def get_version_info(self, uid):
+        '''
+        Get all metadata about a resource's versions.
+        '''
+        # @NOTE This pretty much bends the ontology—it replaces the graph URI
+        # with the subject URI. But the concepts of data and metadata in Fedora
+        # are quite fluid anyways...
+        qry = '''
+        CONSTRUCT {?v ?p ?o .} {
+          GRAPH ?ag {
+            ?s fcrepo:hasVersion ?v .
+          }
+          GRAPH fcsystem:historic {
+            ?vm foaf:primaryTopic ?v .
+            ?vm  ?p ?o .
+            FILTER (?o != ?v)
+          }
+        }'''
+
+        return self.ds.query(qry, initBindings={'ag': nsc['fcadmin'][uid],
+            's': nsc['fcres'][uid]}).graph
+
+
     def get_inbound_rel(self, uri):
         '''
         Query inbound relationships for a subject.
@@ -270,27 +298,6 @@ class RsrcCentricLayout:
             return qres.graph
 
 
-    def create_snapshot(self, uid, ver_uid):
-        '''
-        Create a version snapshot.
-        '''
-        state_gr = self.ds.graph(self._main_uri(uid))
-        state_ver_gr = self.ds.graph(self._main_uri(uid, ver_uid))
-        meta_gr = self.ds.graph(self._admin_uri(uid))
-        meta_ver_gr = self.ds.graph(self._admin_uri(uid, ver_uid))
-
-
-
-
-    def get_version(self, uid, ver_uid):
-        '''
-        See base_rdf_layout.get_version.
-        '''
-        # @TODO
-        gr = self.ds.graph(self._main_uri(uid, ver_uid))
-        return Resource(gr | Graph(), nsc['fcres'][uid])
-
-
     def purge_rsrc(self, uid, inbound=True, backup_uid=None):
         '''
         Completely delete a resource and (optionally) its references.
@@ -331,7 +338,6 @@ class RsrcCentricLayout:
             mg=META_GR_URI.n3(),
             hg=HIST_GR_URI.n3())
 
-        import pdb; pdb.set_trace()
         if inbound:
             # Gather ALL subjects in the user graph. There may be fragments.
             #subj_gen = self.ds.graph(self._main_uri(uid)).subjects()
@@ -352,21 +358,26 @@ class RsrcCentricLayout:
         self.ds.update(qry)
 
 
-    def create_or_replace_rsrc(self, uid, trp, backup_uid=None):
+    def create_or_replace_rsrc(self, uid, trp):
         '''
         Create a new resource or replace an existing one.
         '''
-        self.delete_rsrc_data(uid, backup_uid)
+        self.delete_rsrc_data(uid)
 
         return self.modify_rsrc(uid, add_trp=trp)
 
 
     def modify_rsrc(self, uid, remove_trp=set(), add_trp=set()):
         '''
-        See base_rdf_layout.update_rsrc.
+        Modify triples about a subject.
+
+        This method adds and removes triple sets from specific graphs,
+        indicated by the term rotuer. It also adds metadata about the changed
+        graphs.
         '''
         remove_routes = defaultdict(set)
         add_routes = defaultdict(set)
+        historic = VERS_CONT_LABEL in uid
 
         # Create add and remove sets for each graph.
         for t in remove_trp:
@@ -376,6 +387,8 @@ class RsrcCentricLayout:
             target_gr_uri = self._map_graph_uri(t, uid)
             add_routes[target_gr_uri].add(t)
 
+        # Decide if metadata go into historic or current graph.
+        meta_uri = HIST_GR_URI if historic else META_GR_URI
         # Remove and add triple sets from each graph.
         for gr_uri, trp in remove_routes.items():
             gr = self.ds.graph(gr_uri)
@@ -383,50 +396,35 @@ class RsrcCentricLayout:
         for gr_uri, trp in add_routes.items():
             gr = self.ds.graph(gr_uri)
             gr += trp
-            self.ds.graph(META_GR_URI).add((
+            # Add metadata.
+            self.ds.graph(meta_uri).set((
                 gr_uri, nsc['foaf'].primaryTopic, nsc['fcres'][uid]))
+            self.ds.graph(meta_uri).set((
+                gr_uri, nsc['fcrepo'].created, g.timestamp_term))
+            if historic:
+                # @FIXME Ugly reverse engineering.
+                ver_uid = uid.split(VERS_CONT_LABEL)[1].lstrip('/')
+                self.ds.graph(meta_uri).set((
+                    gr_uri, nsc['fcrepo'].hasVersionLabel, Literal(ver_uid)))
+            # @TODO More provenance metadata can be added here.
 
 
-    def delete_rsrc_data(self, uid, backup_uid=None):
-        if backup_uid:
-            self.create_snapshot(uid, backup_uid)
-        ag_uri.n3(), mg=mg_uri.n3(), sg=sg_uri.n3())
-
-        for guid in ('fcadmin', 'fcmain', 'fcstruct'):
-            self.ds.remove_graph(self.ds.graph(nsc[guid][uid])
-
-
-    ## PROTECTED MEMBERS ##
-
-    def _main_uri(self, uid, ver_uid=None):
-        '''
-        Convert a UID into a request URL to the graph store.
-        '''
-        if ver_uid:
-            uid += ';' + ver_uid
-
-        return nsc['fcmain'][uid]
+    def delete_rsrc_data(self, uid):
+        for guid in self._graph_uids:
+            self.ds.remove_graph(self.ds.graph(nsc[guid][uid]))
 
 
-    def _admin_uri(self, uid, ver_uid=None):
+    def snapshot_uid(self, uid, ver_uid):
         '''
-        Convert a UID into a request URL to the graph store.
+        Create a versioned UID string from a main UID and a versio n UID.
         '''
-        if ver_uid:
-            uid += ';' + ver_uid
+        if VERS_CONT_LABEL in uid:
+            raise ValueError('Resource \'{}\' is already a version.')
 
-        return nsc['fcadmin'][uid]
+        return '{}/{}/{}'.format(uid, VERS_CONT_LABEL, ver_uid)
 
 
-    def _struct_uri(self, uid, ver_uid=None):
-        '''
-        Convert a UID into a request URL to the graph store.
-        '''
-        if ver_uid:
-            uid += ';' + ver_uid
-
-        return nsc['fcstruct'][uid]
-
+    ## PROTECTED MEMBERS ##
 
     def _map_graph_uri(self, t, uid):
         '''