1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
|
import logging
from urllib.request import urlopen, Request
from urllib.parse import urlencode
from urllib.error import HTTPError, URLError
import base64
from io import BytesIO
from rdflib.query import Result
from rdflib import BNode
log = logging.getLogger(__name__)
class SPARQLConnectorException(Exception):
pass
# TODO: Pull in these from the result implementation plugins?
_response_mime_types = {
"xml": "application/sparql-results+xml, application/rdf+xml",
"json": "application/sparql-results+json",
"csv": "text/csv",
"tsv": "text/tab-separated-values",
"application/rdf+xml": "application/rdf+xml",
}
class SPARQLConnector(object):
"""
this class deals with nitty gritty details of talking to a SPARQL server
"""
def __init__(
self,
query_endpoint=None,
update_endpoint=None,
returnFormat="xml",
method="GET",
auth=None,
**kwargs
):
"""
auth, if present, must be a tuple of (username, password) used for Basic Authentication
Any additional keyword arguments will be passed to to the request, and can be used to setup timesouts etc.
"""
self.returnFormat = returnFormat
self.query_endpoint = query_endpoint
self.update_endpoint = update_endpoint
self.kwargs = kwargs
self.method = method
if auth is not None:
if type(auth) != tuple:
raise SPARQLConnectorException("auth must be a tuple")
if len(auth) != 2:
raise SPARQLConnectorException("auth must be a tuple (user, password)")
base64string = base64.b64encode(bytes('%s:%s' % auth, 'ascii'))
self.kwargs.setdefault("headers", {})
self.kwargs["headers"].update({"Authorization": "Basic %s" % base64string.decode('utf-8')})
@property
def method(self):
return self._method
@method.setter
def method(self, method):
if method not in ("GET", "POST", "POST_FORM"):
raise SPARQLConnectorException('Method must be "GET", "POST", or "POST_FORM"')
self._method = method
def query(self, query, default_graph: str = None, named_graph: str = None):
if not self.query_endpoint:
raise SPARQLConnectorException("Query endpoint not set!")
params = {}
# this test ensures we don't have a useless (BNode) default graph URI, which calls to Graph().query() will add
if default_graph is not None and type(default_graph) != BNode:
params["default-graph-uri"] = default_graph
headers = {"Accept": _response_mime_types[self.returnFormat]}
args = dict(self.kwargs)
# merge params/headers dicts
args.setdefault("params", {})
args.setdefault("headers", {})
args["headers"].update(headers)
if self.method == "GET":
params["query"] = query
args["params"].update(params)
qsa = "?" + urlencode(args["params"])
try:
res = urlopen(Request(self.query_endpoint + qsa, headers=args["headers"]))
except Exception as e:
raise ValueError("You did something wrong formulating either the URI or your SPARQL query")
elif self.method == "POST":
args["headers"].update({"Content-Type": "application/sparql-query"})
qsa = "?" + urlencode(params)
try:
res = urlopen(Request(self.query_endpoint + qsa, data=query.encode(), headers=args["headers"]))
except HTTPError as e:
return e.code, str(e), None
elif self.method == "POST_FORM":
params["query"] = query
args["params"].update(params)
try:
res = urlopen(Request(self.query_endpoint, data=urlencode(args["params"]).encode(), headers=args["headers"]))
except HTTPError as e:
return e.code, str(e), None
else:
raise SPARQLConnectorException("Unknown method %s" % self.method)
return Result.parse(
BytesIO(res.read()), content_type=res.headers["Content-Type"].split(";")[0]
)
def update(self, query, default_graph: str = None, named_graph: str = None):
if not self.update_endpoint:
raise SPARQLConnectorException("Query endpoint not set!")
params = {}
if default_graph is not None:
params["using-graph-uri"] = default_graph
if named_graph is not None:
params["using-named-graph-uri"] = named_graph
headers = {
"Accept": _response_mime_types[self.returnFormat],
"Content-Type": "application/sparql-update",
}
args = dict(self.kwargs) # other QSAs
args.setdefault("params", {})
args["params"].update(params)
args.setdefault("headers", {})
args["headers"].update(headers)
qsa = "?" + urlencode(args["params"])
res = urlopen(Request(self.update_endpoint + qsa, data=query.encode(), headers=args["headers"]))
|
