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8	<title>12.4. Debugging SOAP Web Services</title>
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55	<div class="section" lang="en">
56	<div class="titlepage">
57	<div>
58	<div>
59	<h2 class="title"><a name="soap.debug"></a>12.4. Debugging <span class="acronym">SOAP</span> Web Services
60	</h2>
61	</div>
62	</div>
63	<div></div>
64	</div>
65	<div class="abstract">
66	<p>The <span class="acronym">SOAP</span> libraries provide an easy way to see what's going on behind the scenes.
67	</p>
68	</div>
69	<p>Turning on debugging is a simple matter of setting two flags in the <tt class="classname">SOAPProxy</tt>'s configuration.
70	</p>
71	<div class="example"><a name="d0e30423"></a><h3 class="title">Example 12.7. Debugging <span class="acronym">SOAP</span> Web Services
72	</h3><pre class="screen">
73	<tt class="prompt">>>> </tt><span class="userinput"><span class='pykeyword'>from</span> SOAPpy <span class='pykeyword'>import</span> SOAPProxy</span>
74	<tt class="prompt">>>> </tt><span class="userinput">url = <span class='pystring'>'http://services.xmethods.net:80/soap/servlet/rpcrouter'</span></span>
75	<tt class="prompt">>>> </tt><span class="userinput">n = <span class='pystring'>'urn:xmethods-Temperature'</span></span>
76	<tt class="prompt">>>> </tt><span class="userinput">server = SOAPProxy(url, namespace=n)</span> <a name="soap.debug.1.1"></a><img src="../images/callouts/1.png" alt="1" border="0" width="12" height="12">
77	<tt class="prompt">>>> </tt><span class="userinput">server.config.dumpSOAPOut = 1</span> <a name="soap.debug.1.2"></a><img src="../images/callouts/2.png" alt="2" border="0" width="12" height="12">
78	<tt class="prompt">>>> </tt><span class="userinput">server.config.dumpSOAPIn = 1</span>
79	<tt class="prompt">>>> </tt><span class="userinput">temperature = server.getTemp(<span class='pystring'>'27502'</span>)</span> <a name="soap.debug.1.3"></a><img src="../images/callouts/3.png" alt="3" border="0" width="12" height="12">
80	<span class="computeroutput">* Outgoing SOAP ****************************************************
81	<?xml version="1.0" encoding="UTF-8"?>
82	<SOAP-ENV:Envelope SOAP-ENV:encodingStyle="http://schemas.xmlsoap.org/soap/encoding/"
83	xmlns:SOAP-ENC="http://schemas.xmlsoap.org/soap/encoding/"
84	xmlns:xsi="http://www.w3.org/1999/XMLSchema-instance"
85	xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/"
86	xmlns:xsd="http://www.w3.org/1999/XMLSchema">
87	<SOAP-ENV:Body>
88	<ns1:getTemp xmlns:ns1="urn:xmethods-Temperature" SOAP-ENC:root="1">
89	<v1 xsi:type="xsd:string">27502</v1>
90	</ns1:getTemp>
91	</SOAP-ENV:Body>
92	</SOAP-ENV:Envelope>
93	************************************************************************
94	* Incoming SOAP ****************************************************
95	<?xml version='1.0' encoding='UTF-8'?>
96	<SOAP-ENV:Envelope xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/"
97	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
98	xmlns:xsd="http://www.w3.org/2001/XMLSchema">
99	<SOAP-ENV:Body>
100	<ns1:getTempResponse xmlns:ns1="urn:xmethods-Temperature"
101	SOAP-ENV:encodingStyle="http://schemas.xmlsoap.org/soap/encoding/">
102	<return xsi:type="xsd:float">80.0</return>
103	</ns1:getTempResponse>
104
105	</SOAP-ENV:Body>
106	</SOAP-ENV:Envelope>
107	************************************************************************
108	</span>
109	<tt class="prompt">>>> </tt><span class="userinput">temperature</span>
110	<span class="computeroutput">80.0</span>
111	</pre><div class="calloutlist">
112	<table border="0" summary="Callout list">
113	<tr>
114	<td width="12" valign="top" align="left"><a href="#soap.debug.1.1"><img src="../images/callouts/1.png" alt="1" border="0" width="12" height="12"></a>
115	</td>
116	<td valign="top" align="left">First, create the <tt class="classname">SOAPProxy</tt> like normal, with the service <span class="acronym">URL</span> and the namespace.
117	</td>
118	</tr>
119	<tr>
120	<td width="12" valign="top" align="left"><a href="#soap.debug.1.2"><img src="../images/callouts/2.png" alt="2" border="0" width="12" height="12"></a>
121	</td>
122	<td valign="top" align="left">Second, turn on debugging by setting <tt class="varname">server.config.dumpSOAPIn</tt> and <tt class="varname">server.config.dumpSOAPOut</tt>.
123	</td>
124	</tr>
125	<tr>
126	<td width="12" valign="top" align="left"><a href="#soap.debug.1.3"><img src="../images/callouts/3.png" alt="3" border="0" width="12" height="12"></a>
127	</td>
128	<td valign="top" align="left">Third, call the remote <span class="acronym">SOAP</span> method as usual. The <span class="acronym">SOAP</span> library will print out both the outgoing XML request document, and the incoming XML response document. This is all the hard
129	work that <tt class="classname">SOAPProxy</tt> is doing for you. Intimidating, isn't it? Let's break it down.
130	</td>
131	</tr>
132	</table>
133	</div>
134	</div>
135	<p>Most of the XML request document that gets sent to the server is just boilerplate. Ignore all the namespace declarations;
136	they're going to be the same (or similar) for all <span class="acronym">SOAP</span> calls. The heart of the “<span class="quote">function call</span>” is this fragment within the <tt class="sgmltag-element"><Body></tt> element:
137	</p>
138	<div class="informalexample"><pre class="programlisting">
139	<ns1:getTemp <a name="soap.debug.2.1"></a><img src="../images/callouts/1.png" alt="1" border="0" width="12" height="12">
140	xmlns:ns1=<span class='pystring'>"urn:xmethods-Temperature"</span> <a name="soap.debug.2.2"></a><img src="../images/callouts/2.png" alt="2" border="0" width="12" height="12">
141	SOAP-ENC:root=<span class='pystring'>"1"</span>>
142	<v1 xsi:type=<span class='pystring'>"xsd:string"</span>>27502</v1> <a name="soap.debug.2.3"></a><img src="../images/callouts/3.png" alt="3" border="0" width="12" height="12">
143	</ns1:getTemp>
144	</pre><div class="calloutlist">
145	<table border="0" summary="Callout list">
146	<tr>
147	<td width="12" valign="top" align="left"><a href="#soap.debug.2.1"><img src="../images/callouts/1.png" alt="1" border="0" width="12" height="12"></a>
148	</td>
149	<td valign="top" align="left">The element name is the function name, <tt class="function">getTemp</tt>. <tt class="classname">SOAPProxy</tt> uses <a href="../scripts_and_streams/handlers_by_node_type.html" title="10.5. Creating separate handlers by node type"><tt class="function">getattr</tt> as a dispatcher</a>. Instead of calling separate local methods based on the method name, it actually uses the method name to construct the XML
150	request document.
151	</td>
152	</tr>
153	<tr>
154	<td width="12" valign="top" align="left"><a href="#soap.debug.2.2"><img src="../images/callouts/2.png" alt="2" border="0" width="12" height="12"></a>
155	</td>
156	<td valign="top" align="left">The function's XML element is contained in a specific namespace, which is the namespace you specified when you created the
157	<tt class="classname">SOAPProxy</tt> object. Don't worry about the <tt class="literal">SOAP-ENC:root</tt>; that's boilerplate too.
158	</td>
159	</tr>
160	<tr>
161	<td width="12" valign="top" align="left"><a href="#soap.debug.2.3"><img src="../images/callouts/3.png" alt="3" border="0" width="12" height="12"></a>
162	</td>
163	<td valign="top" align="left">The arguments of the function also got translated into XML. <tt class="classname">SOAPProxy</tt> introspects each argument to determine its datatype (in this case it's a string). The argument datatype goes into the <tt class="literal">xsi:type</tt> attribute, followed by the actual string value.
164	</td>
165	</tr>
166	</table>
167	</div>
168	</div>
169	<p>The XML return document is equally easy to understand, once you know what to ignore. Focus on this fragment within the <tt class="sgmltag-element"><Body></tt>:
170	</p>
171	<div class="informalexample"><pre class="programlisting">
172	<ns1:getTempResponse <a name="soap.debug.3.1"></a><img src="../images/callouts/1.png" alt="1" border="0" width="12" height="12">
173	xmlns:ns1=<span class='pystring'>"urn:xmethods-Temperature"</span> <a name="soap.debug.3.2"></a><img src="../images/callouts/2.png" alt="2" border="0" width="12" height="12">
174	SOAP-ENV:encodingStyle=<span class='pystring'>"http://schemas.xmlsoap.org/soap/encoding/"</span>>
175	<<span class='pykeyword'>return</span> xsi:type=<span class='pystring'>"xsd:float"</span>>80.0</<span class='pykeyword'>return</span>> <a name="soap.debug.3.3"></a><img src="../images/callouts/3.png" alt="3" border="0" width="12" height="12">
176	</ns1:getTempResponse>
177	</pre><div class="calloutlist">
178	<table border="0" summary="Callout list">
179	<tr>
180	<td width="12" valign="top" align="left"><a href="#soap.debug.3.1"><img src="../images/callouts/1.png" alt="1" border="0" width="12" height="12"></a>
181	</td>
182	<td valign="top" align="left">The server wraps the function return value within a <tt class="sgmltag-element"><getTempResponse></tt> element. By convention, this wrapper element is the name of the function, plus <tt class="literal">Response</tt>. But it could really be almost anything; the important thing that <tt class="classname">SOAPProxy</tt> notices is not the element name, but the namespace.
183	</td>
184	</tr>
185	<tr>
186	<td width="12" valign="top" align="left"><a href="#soap.debug.3.2"><img src="../images/callouts/2.png" alt="2" border="0" width="12" height="12"></a>
187	</td>
188	<td valign="top" align="left">The server returns the response in the same namespace we used in the request, the same namespace we specified when we first
189	create the <tt class="classname">SOAPProxy</tt>. Later in this chapter we'll see what happens if you forget to specify the namespace when creating the <tt class="classname">SOAPProxy</tt>.
190	</td>
191	</tr>
192	<tr>
193	<td width="12" valign="top" align="left"><a href="#soap.debug.3.3"><img src="../images/callouts/3.png" alt="3" border="0" width="12" height="12"></a>
194	</td>
195	<td valign="top" align="left">The return value is specified, along with its datatype (it's a float). <tt class="classname">SOAPProxy</tt> uses this explicit datatype to create a <span class="application">Python</span> object of the correct native datatype and return it.
196	</td>
197	</tr>
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199	</div>
200	</div>
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