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
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
|
DICOM web services
==================
.. highlight:: c++
.. note::
Even though Odil implements the DICOM web services, it does not contain an HTTP server; the library however contains everything required to create and parse the content of HTTP requests and responses.
The web services implementation in Odil revolves around two classes: `odil::webservices::HTTPRequest`_ and `odil::webservices::HTTPResponse`_ which create and parse HTTP requests and responses. Each web service is implemented by a pair of classes which generate and parse the specific service requests and responses, as show in the table below.
.. table:: DICOM wen services and Odil classes
+------------+--------------------------------------+
| Service | Odil classes |
+============+======================================+
| `QIDO-RS`_ | `odil::webservices::QIDORSRequest`_, |
| | `odil::webservices::QIDORSResponse`_ |
+------------+--------------------------------------+
| `WADO-RS`_ | `odil::webservices::WADORSRequest`_, |
| | `odil::webservices::WADORSResponse`_ |
+------------+--------------------------------------+
| `STOW-RS`_ | `odil::webservices::STOWRSRequest`_, |
| | `odil::webservices::STOWRSResponse`_ |
+------------+--------------------------------------+
Common data structures
----------------------
URLs are represented by `odil::webservices::URL`_ and contain fields as defined in `RFC 3986`_ (scheme, authority, path, query and fragment). The ``URL`` class can parse a string to the URL components and be converted to a string:
::
#include <iostream>
#include <odil/webservices/URL.h>
int main()
{
auto url = odil::webservices::URL::parse("foo://info.example.com?fred");
url.path = "/people";
std::cout << url << "\n";
}
HTTP messages, i.e. requests and responses, are handled by `odil::webservices::HTTPRequest`_ and `odil::webservices::HTTPResponse`_, both having serialization (i.e. ``operator<<``) and de-serialization (i.e. ``operator>>``). Both contains headers and a body; the HTTP request contains the method (e.g. *GET* or *POST*), the target URL, the HTTP version, the headers and the body; the HTTP response contains the HTTP version, the status and its text representation (i.e. the reason), the headers and the body.
::
#include <iostream>
#include <sstream>
#include <odil/webservices/HTTPRequest.h>
#include <odil/webservices/HTTPResponse.h>
int main()
{
odil::webservices::HTTPRequest request{
"POST", odil::webservices::URL::parse("https://www.example.com:80/")};
request.set_header("Content-Type", "application/json");
request.set_body("{\"foo\": \"bar\" }");
std::cout << request << "\n";
std::istringstream stream(
"HTTP/1.0 200 OK\n"
"Content-Type: application/json\n");
odil::webservices::HTTPResponse response;
stream >> response;
std::cout << response.has_header("Content-Type") << "\n";
}
Querying a database
-------------------
The following example show how to use `Boost.Asio`_ in order to create a very simple HTTP client. The ``http_client`` function is assume to be defined in subsequent examples.
::
#include <boost/asio.hpp>
#include <odil/webservices/HTTPRequest.h>
#include <odil/webservices/HTTPResponse.h>
#include <odil/webservices/URL.h>
odil::webservices::HTTPResponse
http_client(
std::string const & host, std::string const & port,
odil::webservices::HTTPRequest const & request)
{
boost::asio::ip::tcp::iostream stream;
stream.connect(host, port);
stream << request;
odil::webservices::HTTPResponse response;
stream >> response;
return response;
}
QIDO-RS queries are similar to C-FIND queries: both have a query root and a data set. The query root is specified by ``set_affected_sop_class`` in C-services, while in web services it is specified by `odil::webservices::Selector`_. The data set is specified the same way in C-services and web services: non-empty elements are used as filters while empty terms are used to specified extra fields to be returned. The following example shows how to retrieve all the studies of a given patient through QIDO:
::
#include <iostream>
#include <odil/DataSet.h>
#include <odil/webservices/QIDORSRequest.h>
#include <odil/webservices/QIDORSResponse.h>
#include <odil/webservices/Selector.h>
#include <odil/webservices/URL.h>
int main()
{
auto const root = odil::webservices::URL::parse(
"http://dicomserver.co.uk:81/qido");
odil::webservices::QIDORSRequest qido_request(root);
odil::webservices::Selector selector;
selector.set_study("");
odil::DataSet query;
query.add("PatientName", {"Doe"});
query.add("StudyDescription");
qido_request.request_datasets(
odil::webservices::Representation::DICOM_JSON, selector, query,
false, -1, 0, true);
auto http_request = qido_request.get_http_request();
auto const http_response = http_client(
"dicomserver.co.uk", "81", http_request);
odil::webservices::QIDORSResponse qido_response(http_response);
std::cout
<< "Got " << qido_response.get_data_sets().size() << " data sets"
<< "\n";
}
Retrieving data sets
--------------------
The data sets to be received through WADO-RS works are specified by the selector. Using WADO-RS is otherwise very similar to using QIDO-RS:
::
#include <iostream>
#include <odil/DataSet.h>
#include <odil/webservices/QIDORSRequest.h>
#include <odil/webservices/QIDORSResponse.h>
#include <odil/webservices/WADORSRequest.h>
#include <odil/webservices/WADORSResponse.h>
#include <odil/webservices/Selector.h>
#include <odil/webservices/URL.h>
int main()
{
odil::webservices::QIDORSRequest qido_request(
odil::webservices::URL::parse("http://dicomserver.co.uk:81/qido"));
odil::DataSet query;
query.add("PatientName", {"Doe"});
qido_request.request_datasets(
odil::webservices::Representation::DICOM_JSON,
std::map<std::string, std::string>({{"studies", ""}}),
query, false, 1, 0, true);
auto http_request = qido_request.get_http_request();
auto http_response = http_client("dicomserver.co.uk", "81", http_request);
odil::webservices::QIDORSResponse const qido_response(http_response);
auto const study = qido_response.get_data_sets()[0];
odil::webservices::WADORSRequest wado_request(
odil::webservices::URL::parse("http://dicomserver.co.uk:81/wado"));
wado_request.request_dicom(
odil::webservices::Representation::DICOM_JSON,
std::map<std::string, std::string>({
{"studies", study.as_string("StudyInstanceUID")[0]}})
);
http_request = wado_request.get_http_request();
http_response = http_client("dicomserver.co.uk", "81", http_request);
odil::webservices::WADORSResponse const wado_response(http_response);
auto const data_sets = wado_response.get_data_sets();
std::cout
<< "Got " << wado_response.get_data_sets().size() << " data sets"
<< "\n";
}
Storing data sets
-----------------
STOW-RS requires both a selector and a vector of data sets. The selector must contain the *studies* term, and may specify the Study Instance UID:
::
#include <iostream>
#include <odil/DataSet.h>
#include <odil/uid.h>
#include <odil/webservices/STOWRSRequest.h>
#include <odil/webservices/STOWRSResponse.h>
#include <odil/webservices/Selector.h>
#include <odil/webservices/URL.h>
int main()
{
odil::webservices::STOWRSRequest stow_request(
odil::webservices::URL::parse("http://dicomserver.co.uk:81/stow"));
odil::DataSet data_set;
data_set.add("PatientName", {"Doe^John"});
data_set.add("PatientID", {odil::generate_uid()});
data_set.add("StudyInstanceUID", {odil::generate_uid()});
data_set.add("Modality", {"OT"});
data_set.add("SeriesInstanceUID", {odil::generate_uid()});
data_set.add("SOPClassUID", {odil::registry::RawDataStorage});
data_set.add("SOPInstanceUID", {odil::generate_uid()});
stow_request.request_dicom(
{data_set}, std::map<std::string,std::string>({{"studies", ""}}),
odil::webservices::Representation::DICOM_XML);
auto http_request = stow_request.get_http_request();
http_request.set_http_version("HTTP/1.1");
http_request.set_header("Host", stow_request.get_base_url().authority);
http_request.set_header("Content-Length", std::to_string(http_request.get_body().size()));
http_request.set_header("Accept", "application/dicom+xml");
http_request.set_header("Connection", "close");
auto const http_response = http_client(
"dicomserver.co.uk", "81", http_request);
odil::webservices::STOWRSResponse const stow_response(http_response);
auto const responses = stow_response.get_store_instance_responses();
}
.. _Boost.Asio: http://www.boost.org/doc/libs/release/libs/asio/
.. _odil::webservices::HTTPRequest:
../../_static/doxygen/classodil_1_1webservices_1_1HTTPRequest.html
.. _odil::webservices::HTTPResponse:
../../_static/doxygen/classodil_1_1webservices_1_1HTTPResponse.html
.. _odil::webservices::QIDORSRequest:
../../_static/doxygen/classodil_1_1webservices_1_1QIDORSRequest.html
.. _odil::webservices::QIDORSResponse:
../../_static/doxygen/classodil_1_1webservices_1_1QIDORSResponse.html
.. _odil::webservices::Selector:
../../_static/doxygen/classodil_1_1webservices_1_1Selector.html
.. _odil::webservices::STOWRSRequest:
../../_static/doxygen/classodil_1_1webservices_1_1STOWRSRequest.html
.. _odil::webservices::STOWRSResponse:
../../_static/doxygen/classodil_1_1webservices_1_1STOWRSResponse.html
.. _odil::webservices::URL:
../../_static/doxygen/structodil_1_1webservices_1_1URL.html
.. _odil::webservices::WADORSRequest:
../../_static/doxygen/classodil_1_1webservices_1_1WADORSRequest.html
.. _odil::webservices::WADORSResponse:
../../_static/doxygen/classodil_1_1webservices_1_1WADORSResponse.html
.. _QIDO-RS:
http://dicom.nema.org/medical/dicom/current/output/chtml/part18/sect_6.7.html
.. _RFC 3986: https://tools.ietf.org/html/rfc3986
.. _STOW-RS:
http://dicom.nema.org/medical/dicom/current/output/chtml/part18/sect_6.6.html
.. _WADO-RS:
http://dicom.nema.org/medical/dicom/current/output/chtml/part18/sect_6.5.html
|
