--- /dev/null
+from xml.dom.minidom import getDOMImplementation
+from datetime import datetime
+import libxml2
+
+class IDataSource(object):
+ """Interface for OAI datasource adapters"""
+
+ def get_earliest_time(self):
+ """Must return the change time of the oldest record(s) as a datetime object"""
+ pass
+
+ def get_record(self, id):
+ """Must return a tuple with :
+ - record as (dict,timestamp) of Dublin Core elements
+ - last changetime as a datetime object
+ or None if the record doesn't exist"""
+ pass
+
+class DataProvider(object):
+ """OAI-PMH Data Provider"""
+
+ def __init__(self, repository_name, base_url, admin_email):
+ self.identity = {
+ 'repositoryName': repository_name,
+ 'baseURL': base_url,
+ 'adminEmail': admin_email,
+ 'protocolVersion': '2.0',
+ 'deletedRecord': 'no',
+ 'granularity': 'YYYY-MM-DDThh:mm:ssZ'
+ }
+
+ def require_argument(self, response, args, required):
+ if not args.has_key(required):
+ response.error("badArgument", msg="Missing required argument '%s'" % required)
+ return False
+ return True
+
+ def validate_format(self, response, args):
+ arg = args.get('metadataPrefix')
+ if not self.require_argument(response, args, 'metadataPrefix'):
+ return False
+ if arg != 'oai_dc':
+ response.error('cannotDisseminateFormat')
+ return False
+
+ return True
+
+ def handle(self, args, datasource):
+ """Handle a request and return the response as a DOM document"""
+ response = Response(self.identity, datasource)
+ if self.require_argument(response, args, 'verb'):
+ verb = args.get('verb')
+ response.set_verb(verb)
+ if verb == 'Identify':
+ response.identify()
+ elif verb == 'GetRecord':
+ if self.require_argument(response, args, 'identifier') and self.validate_format(response, args):
+ response.get_record(args['identifier'])
+ else:
+ response.error('badVerb')
+
+ doc = libxml2.parseDoc(response.doc.toxml(encoding="utf-8"))
+ response.free()
+ xml = unicode(doc.serialize(encoding="utf-8", format=1), "utf-8")
+ doc.free()
+ return xml
+
+class Response(object):
+ """OAI-PMH response generation"""
+
+ def __init__(self, identity, datasource):
+ self.identity = identity
+ self.datasource = datasource
+
+ impl = getDOMImplementation()
+ self.doc = impl.createDocument(None, 'OAI-PMH', None)
+ self.root = self.doc.firstChild
+ self.root.setAttribute('xmlns', 'http://www.openarchives.org/OAI/2.0/')
+ self.root.setAttribute('xmlns:xsi', 'http://www.w3.org/2001/XMLSchema-instance')
+ self.root.setAttribute('xsi:schemaLocation', 'http://www.openarchives.org/OAI/2.0/ '
+ 'http://www.openarchives.org/OAI/2.0/OAI-PMH.xsd')
+ self.append_elements(self.root, {'responseDate': self.make_time()})
+ self.request = self.root.appendChild(self.doc.createElement('request'))
+ self.request.appendChild(self.doc.createTextNode(self.identity['baseURL']))
+
+ def append_elements(self, parent, dict, prefix=None):
+ """Append several elements to parent use dict key as tag names and values as text nodes.
+ Return the parent."""
+ for k in dict:
+ if prefix:
+ tag = prefix + ':' + k
+ else:
+ tag = k
+ e = parent.appendChild(self.doc.createElement(tag))
+ e.appendChild(self.doc.createTextNode(dict[k]))
+ return parent
+
+ def set_attributes(self, element, dict):
+ """Set several attributes on element, from dict. If element is a string, then create
+ an element with than name. Return (possibly created) element."""
+ if isinstance(element, basestring):
+ element = self.doc.createElement(element)
+ for k in dict:
+ element.setAttribute(k, dict[k])
+ return element
+
+ def set_verb(self, verb):
+ self.verb = verb
+ self.request.setAttribute('verb', self.verb)
+
+ def identify(self):
+ """Append Identify tag and child nodes"""
+
+ identity = self.identity.copy()
+ earliest = self.datasource.get_earliest_time()
+ identity['earliestDatestamp'] = self.make_time(earliest)
+
+ group = self.root.appendChild(self.doc.createElement('Identify'))
+ self.append_elements(group, identity)
+
+ def make_time(self, date_time = None):
+ """Encode a datetime object using ISO8601 format"""
+ if not date_time:
+ date_time = datetime.now()
+ return date_time.strftime('%Y-%m-%dT%H-%M-%SZ')
+
+
+ def error(self, code, msg = None):
+ """Add error tag"""
+
+ msgs = {
+ 'badArgument': 'Incorrect arguments',
+ 'badVerb': 'Illegal OAI verb',
+ 'noSetHierarchy': 'This repository does not support sets.',
+ 'idDoesNotExist': 'No such record',
+ 'cannotDisseminateFormat': 'Unsupported metadata format',
+ }
+
+ if not msg:
+ msg = msgs[code]
+ if not msg:
+ raise Exception("No such error code: %s" % code)
+
+ err = self.root.appendChild(self.set_attributes('error', {'code': code}))
+ err.appendChild(self.doc.createTextNode(msg))
+
+ def make_record_header(self, id, ctime):
+ header = self.doc.createElement('header')
+ self.append_elements(header, {'identifier': id, 'dateStamp': self.make_time(ctime)})
+ return header
+
+ def make_record(self, id, dc, ctime):
+ record = self.doc.createElement('record')
+ header = record.appendChild(self.make_record_header(id, ctime))
+ metadata = record.appendChild(self.doc.createElement('metadata'))
+ container = metadata.appendChild(self.doc.createElement('oai_dc'))
+ self.set_attributes(container, {
+ 'xmlns:oai_dc': "http://www.openarchives.org/OAI/2.0/oai_dc/",
+ 'xmlns:dc': "http://purl.org/dc/elements/1.1/",
+ 'xmlns:xsi': "http://www.w3.org/2001/XMLSchema-instance",
+ 'xsi:schemaLocation': "http://www.openarchives.org/OAI/2.0/oai_dc/ "
+ "http://www.openarchives.org/OAI/2.0/oai_dc.xsd"
+ })
+ self.append_elements(container, dc, prefix='dc')
+ return record
+
+ def get_record(self, id):
+
+ record = self.datasource.get_record(id)
+ if not record:
+ self.error('idDoesNotExist')
+ else:
+ dc, ctime = record
+ self.set_attributes(self.request, {'identifier': id, 'metadataPrefix': 'oai_dc'})
+ container = self.root.appendChild(self.doc.createElement(self.verb))
+ container.appendChild(self.make_record(id, dc, ctime))
+
+
+ def free(self):
+ self.doc.unlink()
+
+
+
+
+
+
projects / telemeta.git / commitdiff