import logging from abc import ABCMeta from collections import defaultdict from urllib.parse import urldefrag from uuid import uuid4 import arrow from rdflib import Graph, URIRef, Literal from rdflib.namespace import RDF from lakesuperior.env import env from lakesuperior.globals import ( RES_CREATED, RES_DELETED, RES_UPDATED, ROOT_UID) from lakesuperior.dictionaries.namespaces import ns_collection as nsc from lakesuperior.dictionaries.srv_mgd_terms import ( srv_mgd_subjects, srv_mgd_predicates, srv_mgd_types) from lakesuperior.exceptions import ( InvalidResourceError, RefIntViolationError, ResourceNotExistsError, ServerManagedTermError, TombstoneError) from lakesuperior.store.ldp_rs.rsrc_centric_layout import VERS_CONT_LABEL from lakesuperior.toolbox import Toolbox rdfly = env.app_globals.rdfly logger = logging.getLogger(__name__) class Ldpr(metaclass=ABCMeta): """ LDPR (LDP Resource). This class and related subclasses contain the implementation pieces of the `LDP Resource `__ specifications, according to their `inheritance graph `__. **Note**: Even though LdpNr (which is a subclass of Ldpr) handles binary files, it still has an RDF representation in the triplestore. Hence, some of the RDF-related methods are defined in this class rather than in :class:`~lakesuperior.model.ldp_rs.LdpRs`. **Note:** Only internal facing (``info:fcres``-prefixed) URIs are handled in this class. Public-facing URI conversion is handled in the :mod:`~lakesuperior.endpoints.ldp` module. """ EMBED_CHILD_RES_URI = nsc['fcrepo'].EmbedResources FCREPO_PTREE_TYPE = nsc['fcrepo'].Pairtree INS_CNT_REL_URI = nsc['ldp'].insertedContentRelation MBR_RSRC_URI = nsc['ldp'].membershipResource MBR_REL_URI = nsc['ldp'].hasMemberRelation RETURN_CHILD_RES_URI = nsc['fcrepo'].Children RETURN_INBOUND_REF_URI = nsc['fcrepo'].InboundReferences RETURN_SRV_MGD_RES_URI = nsc['fcrepo'].ServerManaged # Workflow type. Inbound means that the resource is being written to the # store, outbounnd is being retrieved for output. WRKF_INBOUND = '_workflow:inbound_' WRKF_OUTBOUND = '_workflow:outbound_' DEFAULT_USER = Literal('BypassAdmin') """ Default user to be used for the `createdBy` and `lastUpdatedBy` if a user is not provided. """ base_types = { nsc['fcrepo'].Resource, nsc['ldp'].Resource, nsc['ldp'].RDFSource, } """RDF Types that populate a new resource.""" protected_pred = ( nsc['fcrepo'].created, nsc['fcrepo'].createdBy, nsc['ldp'].contains, ) """Predicates that do not get removed when a resource is replaced.""" smt_allow_on_create = { nsc['ldp'].DirectContainer, nsc['ldp'].IndirectContainer, } """ Server-managed RDF types ignored in the RDF payload if the resource is being created. N.B. These still raise an error if the resource exists. """ delete_preds_on_replace = { nsc['ebucore'].hasMimeType, nsc['fcrepo'].lastModified, nsc['fcrepo'].lastModifiedBy, nsc['premis'].hasSize, nsc['premis'].hasMessageDigest, } """Predicates to remove when a resource is replaced.""" ## MAGIC METHODS ## def __init__(self, uid, repr_opts={}, provided_imr=None, **kwargs): """ Instantiate an in-memory LDP resource. :param str uid: uid of the resource. If None (must be explicitly set) it refers to the root node. It can also be the full URI or URN, in which case it will be converted. :param dict repr_opts: Options used to retrieve the IMR. See `parse_rfc7240` for format details. :param str provd_rdf: RDF data provided by the client in operations such as `PUT` or `POST`, serialized as a string. This sets the `provided_imr` property. """ self.uid = ( rdfly.uri_to_uid(uid) if isinstance(uid, URIRef) else uid) self.uri = nsc['fcres'][uid] # @FIXME Not ideal, should separate app-context dependent functions in # a different toolbox. self.tbox = Toolbox() self.provided_imr = provided_imr # Disable all internal checks e.g. for raw I/O. @property def rsrc(self): """ The RDFLib resource representing this LDPR. This is a live representation of the stored data if present. :rtype: rdflib.Resource """ if not hasattr(self, '_rsrc'): self._rsrc = rdfly.ds.resource(self.uri) return self._rsrc @property def imr(self): """ In-Memory Resource. This is a copy of the resource extracted from the graph store. It is a graph resource whose identifier is the URI of the resource. >>> rsrc = rsrc_api.get('/') >>> rsrc.imr.identifier rdflib.term.URIRef('info:fcres/') >>> rsrc.imr.value(rsrc.imr.identifier, nsc['fcrepo'].lastModified) rdflib.term.Literal( '2018-04-03T05:20:33.774746+00:00', datatype=rdflib.term.URIRef( 'http://www.w3.org/2001/XMLSchema#dateTime')) The IMR can be read and manipulated, as well as used to update the stored resource. :rtype: rdflib.Graph :raise lakesuperior.exceptions.ResourceNotExistsError: If the resource is not stored (yet). """ if not hasattr(self, '_imr'): if hasattr(self, '_imr_options'): logger.debug( 'Getting RDF representation for resource {}' .format(self.uid)) #logger.debug('IMR options:{}'.format(self._imr_options)) imr_options = self._imr_options else: imr_options = {} options = dict(imr_options, strict=True) self._imr = rdfly.get_imr(self.uid, **options) return self._imr @imr.setter def imr(self, v): """ Replace in-memory buffered resource. :param v: New set of triples to populate the IMR with. :type v: set or rdflib.Graph """ self._imr = Graph(identifier=self.uri) self._imr += v @imr.deleter def imr(self): """ Delete in-memory buffered resource. """ delattr(self, '_imr') @property def metadata(self): """ Get resource metadata. """ if not hasattr(self, '_metadata'): if hasattr(self, '_imr'): logger.info('Metadata is IMR.') self._metadata = self._imr else: logger.info( 'Getting metadata for resource {}'.format(self.uid)) self._metadata = rdfly.get_metadata(self.uid) return self._metadata @metadata.setter def metadata(self, rsrc): """ Set resource metadata. """ if not isinstance(rsrc, Resource): raise TypeError('Provided metadata is not a Resource object.') self._metadata = rsrc @property def out_graph(self): """ Retun a graph of the resource's IMR formatted for output. """ out_gr = Graph(identifier=self.uri) for t in self.imr: if ( # Exclude digest hash and version information. t[1] not in { #nsc['premis'].hasMessageDigest, nsc['fcrepo'].hasVersion, } ) and ( # Only include server managed triples if requested. self._imr_options.get('incl_srv_mgd', True) or not self._is_trp_managed(t) ): out_gr.add(t) return out_gr @property def version_info(self): """ Return version metadata (`fcr:versions`). """ if not hasattr(self, '_version_info'): try: self._version_info = rdfly.get_version_info(self.uid) except ResourceNotExistsError as e: self._version_info = Graph(identifier=self.uri) return self._version_info @property def version_uids(self): """ Return a generator of version UIDs (relative to their parent resource). """ gen = self.version_info[ self.uri: nsc['fcrepo'].hasVersion / nsc['fcrepo'].hasVersionLabel:] return {str(uid) for uid in gen} @property def is_stored(self): if not hasattr(self, '_is_stored'): if hasattr(self, '_imr'): self._is_stored = len(self.imr) > 0 else: self._is_stored = rdfly.ask_rsrc_exists(self.uid) return self._is_stored @property def types(self): """All RDF types. :rtype: set(rdflib.term.URIRef) """ if not hasattr(self, '_types'): if len(self.metadata): metadata = self.metadata elif getattr(self, 'provided_imr', None) and \ len(self.provided_imr): metadata = self.provided_imr else: return set() self._types = set(metadata[self.uri: RDF.type]) return self._types @property def ldp_types(self): """The LDP types. :rtype: set(rdflib.term.URIRef) """ if not hasattr(self, '_ldp_types'): self._ldp_types = {t for t in self.types if nsc['ldp'] in t} return self._ldp_types ## LDP METHODS ## def head(self): """ Return values for the headers. """ out_headers = defaultdict(list) digest = self.metadata.value(self.uri, nsc['premis'].hasMessageDigest) if digest: etag = digest.identifier.split(':')[-1] out_headers['ETag'] = 'W/"{}"'.format(etag), last_updated_term = self.metadata.value( self.uri, nsc['fcrepo'].lastModified) if last_updated_term: out_headers['Last-Modified'] = arrow.get(last_updated_term)\ .format('ddd, D MMM YYYY HH:mm:ss Z') for t in self.ldp_types: out_headers['Link'].append( '{};rel="type"'.format(t.n3())) return out_headers def get_version(self, ver_uid, **kwargs): """ Get a version by label. """ return rdfly.get_imr(self.uid, ver_uid, **kwargs) def create_or_replace(self, create_only=False): """ Create or update a resource. PUT and POST methods, which are almost identical, are wrappers for this method. :param boolean create_only: Whether this is a create-only operation. """ create = create_only or not self.is_stored ev_type = RES_CREATED if create else RES_UPDATED self._add_srv_mgd_triples(create) ref_int = rdfly.config['referential_integrity'] if ref_int: self._check_ref_int(ref_int) # Delete existing triples if replacing. if not create: rdfly.truncate_rsrc(self.uid) remove_trp = { (self.uri, pred, None) for pred in self.delete_preds_on_replace} add_trp = ( set(self.provided_imr) | self._containment_rel(create)) self.modify(ev_type, remove_trp, add_trp) new_gr = Graph(identifier=self.uri) for trp in add_trp: new_gr.add(trp) self.imr = new_gr return ev_type def bury_rsrc(self, inbound, tstone_pointer=None): """ Delete a single resource and create a tombstone. :param boolean inbound: Whether to delete the inbound relationships. :param rdflib.URIRef tstone_pointer: If set to a URN, this creates a pointer to the tombstone of the resource that used to contain the deleted resource. Otherwise the deleted resource becomes a tombstone. """ logger.info('Burying resource {}'.format(self.uid)) # Create a backup snapshot for resurrection purposes. self.create_rsrc_snapshot(uuid4()) remove_trp = { trp for trp in self.imr if trp[1] != nsc['fcrepo'].hasVersion} if tstone_pointer: add_trp = { (self.uri, nsc['fcsystem'].tombstone, tstone_pointer)} else: add_trp = { (self.uri, RDF.type, nsc['fcsystem'].Tombstone), (self.uri, nsc['fcrepo'].created, env.timestamp_term), } self.modify(RES_DELETED, remove_trp, add_trp) if inbound: for ib_rsrc_uri in self.imr.subjects(None, self.uri): remove_trp = {(ib_rsrc_uri, None, self.uri)} ib_rsrc = Ldpr(ib_rsrc_uri) # To preserve inbound links in history, create a snapshot ib_rsrc.create_rsrc_snapshot(uuid4()) ib_rsrc.modify(RES_UPDATED, remove_trp) return RES_DELETED def forget_rsrc(self, inbound=True): """ Remove all traces of a resource and versions. """ logger.info('Purging resource {}'.format(self.uid)) refint = env.config['store']['ldp_rs']['referential_integrity'] inbound = True if refint else inbound rdfly.forget_rsrc(self.uid, inbound) # @TODO This could be a different event type. return RES_DELETED def create_rsrc_snapshot(self, ver_uid): """ Perform version creation and return the version UID. """ # Create version resource from copying the current state. logger.info( 'Creating version snapshot {} for resource {}.'.format( ver_uid, self.uid)) 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)) for t in self.imr: if ( t[1] == RDF.type and t[2] in { nsc['fcrepo'].Binary, nsc['fcrepo'].Container, nsc['fcrepo'].Resource, } ) or ( t[1] in { nsc['fcrepo'].hasParent, nsc['fcrepo'].hasVersions, nsc['fcrepo'].hasVersion, nsc['premis'].hasMessageDigest, } ): pass else: ver_add_gr.add(( self.tbox.replace_term_domain(t[0], self.uri, ver_uri), t[1], t[2])) rdfly.modify_rsrc(ver_uid, add_trp=ver_add_gr) # Update resource admin data. rsrc_add_gr = { (self.uri, nsc['fcrepo'].hasVersion, ver_uri), (self.uri, nsc['fcrepo'].hasVersions, nsc['fcres'][vers_uid]), } self.modify(RES_UPDATED, add_trp=rsrc_add_gr) return ver_uid def resurrect_rsrc(self): """ Resurrect a resource from a tombstone. @EXPERIMENTAL """ tstone_trp = set(rdfly.get_imr(self.uid, strict=False)) ver_rsp = self.version_info.query(''' SELECT ?uid { ?latest fcrepo:hasVersionLabel ?uid ; fcrepo:created ?ts . } ORDER BY DESC(?ts) LIMIT 1 ''') ver_uid = str(ver_rsp.bindings[0]['uid']) ver_trp = set(rdfly.get_metadata(self.uid, ver_uid)) laz_gr = Graph() for t in ver_trp: if t[1] != RDF.type or t[2] not in { nsc['fcrepo'].Version, }: laz_gr.add((self.uri, t[1], t[2])) laz_gr.add((self.uri, RDF.type, nsc['fcrepo'].Resource)) if nsc['ldp'].NonRdfSource in laz_gr[:RDF.type:]: laz_gr.add((self.uri, RDF.type, nsc['fcrepo'].Binary)) elif nsc['ldp'].Container in laz_gr[:RDF.type:]: laz_gr.add((self.uri, RDF.type, nsc['fcrepo'].Container)) laz_set = set(laz_gr) | self._containment_rel() self.modify(RES_CREATED, tstone_trp, laz_set) return self.uri def create_version(self, ver_uid=None): """ Create a new version of the resource. **Note:** This creates an event only for the resource being updated (due to the added `hasVersion` triple and possibly to the ``hasVersions`` one) but not for the version being created. :param str ver_uid: Version UID. If already existing, a new version UID is minted. """ if not ver_uid or ver_uid in self.version_uids: ver_uid = str(uuid4()) return self.create_rsrc_snapshot(ver_uid) def revert_to_version(self, ver_uid, backup=True): """ Revert to a previous version. :param str ver_uid: Version UID. :param boolean backup: Whether to create a backup snapshot. Default is True. """ # Create a backup snapshot. if backup: self.create_version() ver_gr = rdfly.get_imr( self.uid, ver_uid=ver_uid, incl_children=False) self.provided_imr = Graph(identifier=self.uri) for t in ver_gr: if not self._is_trp_managed(t): self.provided_imr.add((self.uri, t[1], t[2])) # @TODO Check individual objects: if they are repo-managed URIs # and not existing or tombstones, they are not added. return self.create_or_replace(create_only=False) def check_mgd_terms(self, trp): """ Check whether server-managed terms are in a RDF payload. :param rdflib.Graph trp: The graph to validate. """ subjects = {t[0] for t in trp} offending_subjects = subjects & srv_mgd_subjects if offending_subjects: if self.handling == 'strict': raise ServerManagedTermError(offending_subjects, 's') else: for s in offending_subjects: logger.info('Removing offending subj: {}'.format(s)) for t in trp: if t[0] == s: trp.remove(t) predicates = {t[1] for t in trp} offending_predicates = predicates & srv_mgd_predicates # Allow some predicates if the resource is being created. if offending_predicates: if self.handling == 'strict': raise ServerManagedTermError(offending_predicates, 'p') else: for p in offending_predicates: logger.info('Removing offending pred: {}'.format(p)) for t in trp: if t[1] == p: trp.remove(t) types = {t[2] for t in trp if t[1] == RDF.type} offending_types = types & srv_mgd_types if not self.is_stored: offending_types -= self.smt_allow_on_create if offending_types: if self.handling == 'strict': raise ServerManagedTermError(offending_types, 't') else: for to in offending_types: logger.info('Removing offending type: {}'.format(to)) for t in trp: if t[1] == RDF.type and t[2] == to: trp.remove(t) #logger.debug('Sanitized graph: {}'.format(trp.serialize( # format='turtle').decode('utf-8'))) return trp def sparql_delta(self, q): """ Calculate the delta obtained by a SPARQL Update operation. This is a critical component of the SPARQL update prcess and does a couple of things: 1. It ensures that no resources outside of the subject of the request are modified (e.g. by variable subjects) 2. It verifies that none of the terms being modified is server managed. This method extracts an in-memory copy of the resource and performs the query on that once it has checked if any of the server managed terms is in the delta. If it is, it raises an exception. NOTE: This only checks if a server-managed term is effectively being modified. If a server-managed term is present in the query but does not cause any change in the updated resource, no error is raised. :rtype: tuple(rdflib.Graph) :return: Remove and add graphs. These can be used with ``BaseStoreLayout.update_resource`` and/or recorded as separate events in a provenance tracking system. """ logger.debug('Provided SPARQL query: {}'.format(q)) pre_gr = self.imr post_gr = pre_gr | Graph() post_gr.update(q) remove_gr, add_gr = self._dedup_deltas(pre_gr, post_gr) #logger.debug('Removing: {}'.format( # remove_gr.serialize(format='turtle').decode('utf8'))) #logger.debug('Adding: {}'.format( # add_gr.serialize(format='turtle').decode('utf8'))) remove_trp = self.check_mgd_terms(set(remove_gr)) add_trp = self.check_mgd_terms(set(add_gr)) return remove_trp, add_trp ## PROTECTED METHODS ## def _is_trp_managed(self, t): """ Whether a triple is server-managed. :param tuple t: Triple as a 3-tuple of terms. :rtype: boolean """ return t[1] in srv_mgd_predicates or ( t[1] == RDF.type and t[2] in srv_mgd_types) def modify( self, ev_type, remove_trp=set(), add_trp=set()): """ Low-level method to modify a graph for a single resource. This is a crucial point for messaging. Any write operation on the RDF store that needs to be notified should be performed by invoking this method. :param ev_type: The type of event (create, update, delete) or None. In the latter case, no notification is sent. :type ev_type: str or None :param set remove_trp: Triples to be removed. :param set add_trp: Triples to be added. """ rdfly.modify_rsrc(self.uid, remove_trp, add_trp) if ( ev_type is not None and env.config['application'].get('messaging')): logger.debug('Enqueuing message for {}'.format(self.uid)) self._enqueue_msg(ev_type, remove_trp, add_trp) def _enqueue_msg(self, ev_type, remove_trp=None, add_trp=None): """ Compose a message about a resource change. The message is enqueued for asynchronous processing. :param str ev_type: The event type. See global constants. :param set remove_trp: Triples removed. Only used if the """ try: rsrc_type = tuple(str(t) for t in self.types) actor = self.metadata.value(self.uri, nsc['fcrepo'].createdBy) except (ResourceNotExistsError, TombstoneError): rsrc_type = () actor = None for t in add_trp: if t[1] == RDF.type: rsrc_type.add(t[2]) elif actor is None and t[1] == nsc['fcrepo'].createdBy: actor = t[2] env.app_globals.changelog.append((set(remove_trp), set(add_trp), { 'ev_type': ev_type, 'timestamp': env.timestamp.format(), 'rsrc_type': rsrc_type, 'actor': actor, })) def _check_ref_int(self, config): """ Check referential integrity of a resource. :param str config: If set to ``strict``, a :class:`lakesuperior.exceptions.RefIntViolationError` is raised. Otherwise, the violation is simply logged. """ for o in self.provided_imr.objects(): if( isinstance(o, URIRef) and str(o).startswith(nsc['fcres']) and urldefrag(o).url.rstrip('/') != str(self.uri)): obj_uid = rdfly.uri_to_uid(o) if not rdfly.ask_rsrc_exists(obj_uid): if config == 'strict': raise RefIntViolationError(obj_uid) else: logger.info( 'Removing link to non-existent repo resource: {}' .format(obj_uid)) self.provided_imr.remove((None, None, o)) def _add_srv_mgd_triples(self, create=False): """ Add server-managed triples to a provided IMR. :param create: Whether the resource is being created. """ # Base LDP types. for t in self.base_types: self.provided_imr.add((self.uri, RDF.type, t)) # Message digest. cksum = self.tbox.rdf_cksum(self.provided_imr) self.provided_imr.set(( self.uri, nsc['premis'].hasMessageDigest, URIRef('urn:sha1:{}'.format(cksum)))) # Create and modify timestamp. if create: self.provided_imr.set(( self.uri, nsc['fcrepo'].created, env.timestamp_term)) self.provided_imr.set(( self.uri, nsc['fcrepo'].createdBy, self.DEFAULT_USER)) else: self.provided_imr.set(( self.uri, nsc['fcrepo'].created, self.metadata.value( self.uri, nsc['fcrepo'].created))) self.provided_imr.set(( self.uri, nsc['fcrepo'].createdBy, self.metadata.value( self.uri, nsc['fcrepo'].createdBy))) self.provided_imr.set(( self.uri, nsc['fcrepo'].lastModified, env.timestamp_term)) self.provided_imr.set(( self.uri, nsc['fcrepo'].lastModifiedBy, self.DEFAULT_USER)) def _containment_rel(self, create): """Find the closest parent in the path indicated by the uid and establish a containment triple. Check the path-wise parent of the new resource. If it exists, add the containment relationship with this UID. Otherwise, create a container resource as the parent. This function may recurse up the path tree until an existing container is found. E.g. if only fcres:/a exists: - If ``fcres:/a/b/c/d`` is being created, a becomes container of ``fcres:/a/b/c/d``. Also, containers are created for fcres:a/b and ``fcres:/a/b/c``. - If ``fcres:/e`` is being created, the root node becomes container of ``fcres:/e``. :param bool create: Whether the resource is being created. If false, the parent container is not updated. """ from lakesuperior.model.ldp_factory import LdpFactory if '/' in self.uid.lstrip('/'): # Traverse up the hierarchy to find the parent. path_components = self.uid.lstrip('/').split('/') cnd_parent_uid = '/' + '/'.join(path_components[:-1]) if rdfly.ask_rsrc_exists(cnd_parent_uid): parent_rsrc = LdpFactory.from_stored(cnd_parent_uid) if nsc['ldp'].Container not in parent_rsrc.types: raise InvalidResourceError( cnd_parent_uid, 'Parent {} is not a container.') parent_uid = cnd_parent_uid else: parent_rsrc = LdpFactory.new_container(cnd_parent_uid) # This will trigger this method again and recurse until an # existing container or the root node is reached. parent_rsrc.create_or_replace() parent_uid = parent_rsrc.uid else: parent_uid = ROOT_UID parent_rsrc = LdpFactory.from_stored( parent_uid, repr_opts={'incl_children': False}, handling='none') # Only update parent if the resource is new. if create: add_gr = Graph() add_gr.add( (nsc['fcres'][parent_uid], nsc['ldp'].contains, self.uri)) parent_rsrc.modify(RES_UPDATED, add_trp=add_gr) # Direct or indirect container relationship. return self._add_ldp_dc_ic_rel(parent_rsrc) def _dedup_deltas(self, remove_gr, add_gr): """ Remove duplicate triples from add and remove delta graphs, which would otherwise contain unnecessary statements that annul each other. :rtype: tuple :return: 2 "clean" sets of respectively remove statements and add statements. """ return ( remove_gr - add_gr, add_gr - remove_gr ) def _add_ldp_dc_ic_rel(self, cont_rsrc): """ Add relationship triples from a parent direct or indirect container. :param rdflib.resource.Resouce cont_rsrc: The container resource. """ cont_p = set(cont_rsrc.metadata.predicates()) logger.info('Checking direct or indirect containment.') logger.debug('Parent predicates: {}'.format(cont_p)) add_trp = {(self.uri, nsc['fcrepo'].hasParent, cont_rsrc.uri)} if self.MBR_RSRC_URI in cont_p and self.MBR_REL_URI in cont_p: from lakesuperior.model.ldp_factory import LdpFactory s = cont_rsrc.metadata.value(cont_rsrc.uri, self.MBR_RSRC_URI) p = cont_rsrc.metadata.value(cont_rsrc_uri, self.MBR_REL_URI) if cont_rsrc.metadata[RDF.type: nsc['ldp'].DirectContainer]: logger.info('Parent is a direct container.') logger.debug('Creating DC triples.') o = self.uri elif ( cont_rsrc.metadata[ RDF.type: nsc['ldp'].IndirectContainer] and self.INS_CNT_REL_URI in cont_p): logger.info('Parent is an indirect container.') cont_rel_uri = cont_rsrc.metadata.value( cont_rsrc.uri, self.INS_CNT_REL_URI) o = self.provided_imr.value(self.uri, cont_rel_uri) logger.debug('Target URI: {}'.format(o)) logger.debug('Creating IC triples.') target_rsrc = LdpFactory.from_stored(rdfly.uri_to_uid(s)) target_rsrc.modify(RES_UPDATED, add_trp={(s, p, o)}) return add_trp