https://wiki.openstack.org/w/index.php?title=XMLTemplates&feed=atom&action=historyXMLTemplates - Revision history2024-03-29T14:46:15ZRevision history for this page on the wikiMediaWiki 1.28.2https://wiki.openstack.org/w/index.php?title=XMLTemplates&diff=17653&oldid=prevRyan Lane: Text replace - "__NOTOC__" to ""2013-02-17T23:30:57Z<p>Text replace - "__NOTOC__" to ""</p>
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</table>Ryan Lanehttps://wiki.openstack.org/w/index.php?title=XMLTemplates&diff=16228&oldid=prevOlaph at 00:14, 17 February 20132013-02-17T00:14:58Z<p></p>
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<td colspan='2' style="background-color: white; color:black; text-align: center;">Revision as of 00:14, 17 February 2013</td>
</tr><tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l5" >Line 5:</td>
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<tr><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"></td><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"><div>== XMLTemplates ==</div></td><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"><div>== XMLTemplates ==</div></td></tr>
<tr><td class='diff-marker'>−</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div><del style="font-weight: bold; text-decoration: none;">'''Time: ''' <<[[DateTime]](2011-10-06T17:11:30Z)>></del></div></td><td colspan="2"> </td></tr>
<tr><td class='diff-marker'>−</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div><del style="font-weight: bold; text-decoration: none;"></del></div></td><td colspan="2"> </td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"><div>'''Drafter: '''[[Vek]]</div></td><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"><div>'''Drafter: '''[[Vek]]</div></td></tr>
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</table>Olaphhttps://wiki.openstack.org/w/index.php?title=XMLTemplates&diff=8869&oldid=prevVek at 22:21, 6 October 20112011-10-06T22:21:19Z<p></p>
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<td colspan='2' style="background-color: white; color:black; text-align: center;">Revision as of 22:21, 6 October 2011</td>
</tr><tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l39" >Line 39:</td>
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<tr><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"><div>The lazy serialization potentially adds 3 new variables to the WSGI environment.  (Note "potentially"—for JSON serialization, none of these variables are added.)  The '''nova.serializer''' variable contains a reference to the body serializer to use (typically a subclass of XMLDictSerializer or, preferably, a subclass of XMLTemplateSerializer), and the '''nova.action''' variable contains the action to pass to the serializer's serialize() method.  If the serializer has a get_template() method, the return value of that method will be assigned to the '''nova.template''' variable; extensions may attach their slave templates to this master template as necessary.</div></td><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"><div>The lazy serialization potentially adds 3 new variables to the WSGI environment.  (Note "potentially"—for JSON serialization, none of these variables are added.)  The '''nova.serializer''' variable contains a reference to the body serializer to use (typically a subclass of XMLDictSerializer or, preferably, a subclass of XMLTemplateSerializer), and the '''nova.action''' variable contains the action to pass to the serializer's serialize() method.  If the serializer has a get_template() method, the return value of that method will be assigned to the '''nova.template''' variable; extensions may attach their slave templates to this master template as necessary.</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"></td><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;">----</ins></div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;">Blueprint: https://blueprints.launchpad.net/nova/+spec/xml-templates</ins></div></td></tr>
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<tr><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"><div>[[Category:Proposal]]</div></td><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"><div>[[Category:Proposal]]</div></td></tr>
</table>Vekhttps://wiki.openstack.org/w/index.php?title=XMLTemplates&diff=8868&oldid=prevVek at 17:48, 6 October 20112011-10-06T17:48:55Z<p></p>
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<td colspan='2' style="background-color: white; color:black; text-align: center;">Revision as of 17:48, 6 October 2011</td>
</tr><tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l33" >Line 33:</td>
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<tr><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"><div>Once an element tree has been constructed, it can be wrapped up in a Template subclass.  There are two subclasses available—MasterTemplate and SlaveTemplate.  Both can serialize an object against the template directly, but MasterTemplate instances can additionally have SlaveTemplate instances attached which can further extend the serialization; the effect is as if the elements in the SlaveTemplate instances were merged with the elements in the MasterTemplate.  Additionally, MasterTemplate instances have version numbers, and automatically exclude SlaveTemplate instances which do not apply to that MasterTemplate version (SlaveTemplate instances have a minimum version and an optional maximum version for this selection criteria).  This makes it easy for extensions to modify a serializer to include their extended data.</div></td><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"><div>Once an element tree has been constructed, it can be wrapped up in a Template subclass.  There are two subclasses available—MasterTemplate and SlaveTemplate.  Both can serialize an object against the template directly, but MasterTemplate instances can additionally have SlaveTemplate instances attached which can further extend the serialization; the effect is as if the elements in the SlaveTemplate instances were merged with the elements in the MasterTemplate.  Additionally, MasterTemplate instances have version numbers, and automatically exclude SlaveTemplate instances which do not apply to that MasterTemplate version (SlaveTemplate instances have a minimum version and an optional maximum version for this selection criteria).  This makes it easy for extensions to modify a serializer to include their extended data.</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"></td><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"></td></tr>
<tr><td class='diff-marker'>−</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>The existing code also includes a TemplateBuilder class, which can be used to ensure that a given template only ever needs to be built once; and an <del class="diffchange diffchange-inline">!</del>XMLTemplateSerializer, which is similar to the existing <del class="diffchange diffchange-inline">!</del>XMLDictSerializer.</div></td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>The existing code also includes a TemplateBuilder class, which can be used to ensure that a given template only ever needs to be built once; and an XMLTemplateSerializer, which is similar to the existing XMLDictSerializer.</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"></td><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"><div>=== WSGI Environment ===</div></td><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"><div>=== WSGI Environment ===</div></td></tr>
</table>Vekhttps://wiki.openstack.org/w/index.php?title=XMLTemplates&diff=8867&oldid=prevVek at 17:47, 6 October 20112011-10-06T17:47:18Z<p></p>
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<td colspan='2' style="background-color: white; color:black; text-align: center;">Revision as of 17:47, 6 October 2011</td>
</tr><tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l37" >Line 37:</td>
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<tr><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"><div>=== WSGI Environment ===</div></td><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"><div>=== WSGI Environment ===</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"></td><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"></td></tr>
<tr><td class='diff-marker'>−</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>The lazy serialization potentially adds 3 new variables to the WSGI environment.  (Note "potentially"—for JSON serialization, none of these variables are added.)  The '''nova.serializer''' variable contains a reference to the body serializer to use (typically a subclass of <del class="diffchange diffchange-inline">!</del>XMLDictSerializer or, preferably, a subclass of <del class="diffchange diffchange-inline">!</del>XMLTemplateSerializer), and the '''nova.action''' variable contains the action to pass to the serializer's serialize() method.  If the serializer has a get_template() method, the return value of that method will be assigned to the '''nova.template''' variable; extensions may attach their slave templates to this master template as necessary.</div></td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>The lazy serialization potentially adds 3 new variables to the WSGI environment.  (Note "potentially"—for JSON serialization, none of these variables are added.)  The '''nova.serializer''' variable contains a reference to the body serializer to use (typically a subclass of XMLDictSerializer or, preferably, a subclass of XMLTemplateSerializer), and the '''nova.action''' variable contains the action to pass to the serializer's serialize() method.  If the serializer has a get_template() method, the return value of that method will be assigned to the '''nova.template''' variable; extensions may attach their slave templates to this master template as necessary.</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"></td><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"><div>----</div></td><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"><div>----</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"><div>[[Category:Proposal]]</div></td><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"><div>[[Category:Proposal]]</div></td></tr>
</table>Vekhttps://wiki.openstack.org/w/index.php?title=XMLTemplates&diff=8866&oldid=prevVek at 17:46, 6 October 20112011-10-06T17:46:43Z<p></p>
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<td colspan='2' style="background-color: white; color:black; text-align: center;">Revision as of 17:46, 6 October 2011</td>
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<td colspan="2" class="diff-lineno">Line 21:</td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"><div>=== Lazy Serialization ===</div></td><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"><div>=== Lazy Serialization ===</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"></td><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"></td></tr>
<tr><td class='diff-marker'>−</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>The first and simplest part of the specification is lazy serialization.  Basically, this involves the creation of a <del class="diffchange diffchange-inline">[[</del>LazySerializationMiddleware<del class="diffchange diffchange-inline">]] </del>which is added to the openstackapi pipelines, and some modifications to nova.api.openstack.wsgi—specifically, Response is modified to track a lazy_serialization attribute (defaulting to True), and <del class="diffchange diffchange-inline">[[</del>ResponseSerializer<del class="diffchange diffchange-inline">]]</del>'s serialize_body() method is modified to store the actual serializer and action (and template, if available) into the request if lazy_serialization is True.  The data itself is serialized as a JSON object in order to be passed through the webob pipeline (webob is designed to pass text response bodies, and extending it to allow raw objects to be passed between components would be difficult).</div></td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>The first and simplest part of the specification is lazy serialization.  Basically, this involves the creation of a LazySerializationMiddleware which is added to the openstackapi pipelines, and some modifications to nova.api.openstack.wsgi—specifically, Response is modified to track a lazy_serialization attribute (defaulting to True), and ResponseSerializer's serialize_body() method is modified to store the actual serializer and action (and template, if available) into the request if lazy_serialization is True.  The data itself is serialized as a JSON object in order to be passed through the webob pipeline (webob is designed to pass text response bodies, and extending it to allow raw objects to be passed between components would be difficult).</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"></td><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"><div>=== Extensions ===</div></td><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"><div>=== Extensions ===</div></td></tr>
<tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l29" >Line 29:</td>
<td colspan="2" class="diff-lineno">Line 29:</td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"><div>=== XML Templates ===</div></td><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"><div>=== XML Templates ===</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"></td><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"></td></tr>
<tr><td class='diff-marker'>−</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>The most complicated part of the proposal is the introduction of an XML template.  XML templates can be constructed the same way an XML tree is constructed using the <del class="diffchange diffchange-inline">[[</del>ElementTree<del class="diffchange diffchange-inline">]] </del>interface of lxml; there exists a <del class="diffchange diffchange-inline">[[</del>TemplateElement<del class="diffchange diffchange-inline">]] </del>class and a <del class="diffchange diffchange-inline">[[</del>SubTemplateElement<del class="diffchange diffchange-inline">]]</del>() helper function that operate in a similar manner to <del class="diffchange diffchange-inline">[[</del>ElementTree<del class="diffchange diffchange-inline">]]</del>.  The critical difference is the use of selectors; when an object is serialized against an XML template, the object is passed in, and a selector (basically, a simple callable) is used to select the data to operate on.  There is a selector associated with each element, and selectors can also be attached as attribute values and as the text contents of the element; these selectors further refine the element's selector.  Subelements will also be passed the object selected by their parent, and have the chance to further refine selection for their own purposes.</div></td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>The most complicated part of the proposal is the introduction of an XML template.  XML templates can be constructed the same way an XML tree is constructed using the ElementTree interface of lxml; there exists a TemplateElement class and a SubTemplateElement() helper function that operate in a similar manner to ElementTree.  The critical difference is the use of selectors; when an object is serialized against an XML template, the object is passed in, and a selector (basically, a simple callable) is used to select the data to operate on.  There is a selector associated with each element, and selectors can also be attached as attribute values and as the text contents of the element; these selectors further refine the element's selector.  Subelements will also be passed the object selected by their parent, and have the chance to further refine selection for their own purposes.</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"></td><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"></td></tr>
<tr><td class='diff-marker'>−</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>Once an element tree has been constructed, it can be wrapped up in a Template subclass.  There are two subclasses <del class="diffchange diffchange-inline">available—[[MasterTemplate]] </del>and <del class="diffchange diffchange-inline">[[</del>SlaveTemplate<del class="diffchange diffchange-inline">]]</del>.  Both can serialize an object against the template directly, but <del class="diffchange diffchange-inline">[[</del>MasterTemplate<del class="diffchange diffchange-inline">]] </del>instances can additionally have <del class="diffchange diffchange-inline">[[</del>SlaveTemplate<del class="diffchange diffchange-inline">]] </del>instances attached which can further extend the serialization; the effect is as if the elements in the <del class="diffchange diffchange-inline">[[</del>SlaveTemplate<del class="diffchange diffchange-inline">]] </del>instances were merged with the elements in the <del class="diffchange diffchange-inline">[[</del>MasterTemplate<del class="diffchange diffchange-inline">]]</del>.  Additionally, <del class="diffchange diffchange-inline">[[</del>MasterTemplate<del class="diffchange diffchange-inline">]] </del>instances have version numbers, and automatically exclude <del class="diffchange diffchange-inline">[[</del>SlaveTemplate<del class="diffchange diffchange-inline">]] </del>instances which do not apply to that <del class="diffchange diffchange-inline">[[</del>MasterTemplate<del class="diffchange diffchange-inline">]] </del>version (<del class="diffchange diffchange-inline">[[</del>SlaveTemplate<del class="diffchange diffchange-inline">]] </del>instances have a minimum version and an optional maximum version for this selection criteria).  This makes it easy for extensions to modify a serializer to include their extended data.</div></td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>Once an element tree has been constructed, it can be wrapped up in a Template subclass.  There are two subclasses <ins class="diffchange diffchange-inline">available—MasterTemplate </ins>and SlaveTemplate.  Both can serialize an object against the template directly, but MasterTemplate instances can additionally have SlaveTemplate instances attached which can further extend the serialization; the effect is as if the elements in the SlaveTemplate instances were merged with the elements in the MasterTemplate.  Additionally, MasterTemplate instances have version numbers, and automatically exclude SlaveTemplate instances which do not apply to that MasterTemplate version (SlaveTemplate instances have a minimum version and an optional maximum version for this selection criteria).  This makes it easy for extensions to modify a serializer to include their extended data.</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"></td><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"></td></tr>
<tr><td class='diff-marker'>−</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>The existing code also includes a <del class="diffchange diffchange-inline">[[</del>TemplateBuilder<del class="diffchange diffchange-inline">]] </del>class, which can be used to ensure that a given template only ever needs to be built once; and an XMLTemplateSerializer, which is similar to the existing XMLDictSerializer.</div></td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>The existing code also includes a TemplateBuilder class, which can be used to ensure that a given template only ever needs to be built once; and an <ins class="diffchange diffchange-inline">!</ins>XMLTemplateSerializer, which is similar to the existing <ins class="diffchange diffchange-inline">!</ins>XMLDictSerializer.</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"></td><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"><div>=== WSGI Environment ===</div></td><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"><div>=== WSGI Environment ===</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"></td><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"></td></tr>
<tr><td class='diff-marker'>−</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>The lazy serialization potentially adds 3 new variables to the WSGI environment.  (Note "potentially"—for JSON serialization, none of these variables are added.)  The '''nova.serializer''' variable contains a reference to the body serializer to use (typically a subclass of XMLDictSerializer or, preferably, a subclass of XMLTemplateSerializer), and the '''nova.action''' variable contains the action to pass to the serializer's serialize() method.  If the serializer has a get_template() method, the return value of that method will be assigned to the '''nova.template''' variable; extensions may attach their slave templates to this master template as necessary.</div></td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>The lazy serialization potentially adds 3 new variables to the WSGI environment.  (Note "potentially"—for JSON serialization, none of these variables are added.)  The '''nova.serializer''' variable contains a reference to the body serializer to use (typically a subclass of <ins class="diffchange diffchange-inline">!</ins>XMLDictSerializer or, preferably, a subclass of <ins class="diffchange diffchange-inline">!</ins>XMLTemplateSerializer), and the '''nova.action''' variable contains the action to pass to the serializer's serialize() method.  If the serializer has a get_template() method, the return value of that method will be assigned to the '''nova.template''' variable; extensions may attach their slave templates to this master template as necessary.</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"></td><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"><div>----</div></td><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"><div>----</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"><div>[[Category:Proposal]]</div></td><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"><div>[[Category:Proposal]]</div></td></tr>
</table>Vekhttps://wiki.openstack.org/w/index.php?title=XMLTemplates&diff=8865&oldid=prevVek: Add description for the blueprint2011-10-06T17:44:19Z<p>Add description for the blueprint</p>
<table class="diff diff-contentalign-left" data-mw="interface">
<col class='diff-marker' />
<col class='diff-content' />
<col class='diff-marker' />
<col class='diff-content' />
<tr style='vertical-align: top;' lang='en'>
<td colspan='2' style="background-color: white; color:black; text-align: center;">← Older revision</td>
<td colspan='2' style="background-color: white; color:black; text-align: center;">Revision as of 17:44, 6 October 2011</td>
</tr><tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l18" >Line 18:</td>
<td colspan="2" class="diff-lineno">Line 18:</td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"></td><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"><div>Much of the code for this is already written, and many elements of nova-api converted over to use template-based serializers in preference to the hand-coded serializers currently utilized.  This page is to document what has been done.</div></td><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"><div>Much of the code for this is already written, and many elements of nova-api converted over to use template-based serializers in preference to the hand-coded serializers currently utilized.  This page is to document what has been done.</div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;"></ins></div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;">=== Lazy Serialization ===</ins></div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;"></ins></div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;">The first and simplest part of the specification is lazy serialization.  Basically, this involves the creation of a [[LazySerializationMiddleware]] which is added to the openstackapi pipelines, and some modifications to nova.api.openstack.wsgi—specifically, Response is modified to track a lazy_serialization attribute (defaulting to True), and [[ResponseSerializer]]'s serialize_body() method is modified to store the actual serializer and action (and template, if available) into the request if lazy_serialization is True.  The data itself is serialized as a JSON object in order to be passed through the webob pipeline (webob is designed to pass text response bodies, and extending it to allow raw objects to be passed between components would be difficult).</ins></div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;"></ins></div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;">=== Extensions ===</ins></div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;"></ins></div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;">Request extensions are also slightly modified; the loop that calls all the handlers for a particular request deserializes the body and passes that as a third parameter to all the handlers.  The handlers can modify the body in place, and additionally modify the template in the wsgi environment (if present; for data requested to be encoded in JSON format, no template will be present in the wsgi environment).</ins></div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;"></ins></div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;">=== XML Templates ===</ins></div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;"></ins></div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;">The most complicated part of the proposal is the introduction of an XML template.  XML templates can be constructed the same way an XML tree is constructed using the [[ElementTree]] interface of lxml; there exists a [[TemplateElement]] class and a [[SubTemplateElement]]() helper function that operate in a similar manner to [[ElementTree]].  The critical difference is the use of selectors; when an object is serialized against an XML template, the object is passed in, and a selector (basically, a simple callable) is used to select the data to operate on.  There is a selector associated with each element, and selectors can also be attached as attribute values and as the text contents of the element; these selectors further refine the element's selector.  Subelements will also be passed the object selected by their parent, and have the chance to further refine selection for their own purposes.</ins></div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;"></ins></div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;">Once an element tree has been constructed, it can be wrapped up in a Template subclass.  There are two subclasses available—[[MasterTemplate]] and [[SlaveTemplate]].  Both can serialize an object against the template directly, but [[MasterTemplate]] instances can additionally have [[SlaveTemplate]] instances attached which can further extend the serialization; the effect is as if the elements in the [[SlaveTemplate]] instances were merged with the elements in the [[MasterTemplate]].  Additionally, [[MasterTemplate]] instances have version numbers, and automatically exclude [[SlaveTemplate]] instances which do not apply to that [[MasterTemplate]] version ([[SlaveTemplate]] instances have a minimum version and an optional maximum version for this selection criteria).  This makes it easy for extensions to modify a serializer to include their extended data.</ins></div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;"></ins></div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;">The existing code also includes a [[TemplateBuilder]] class, which can be used to ensure that a given template only ever needs to be built once; and an XMLTemplateSerializer, which is similar to the existing XMLDictSerializer.</ins></div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;"></ins></div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;">=== WSGI Environment ===</ins></div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;"></ins></div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;">The lazy serialization potentially adds 3 new variables to the WSGI environment.  (Note "potentially"—for JSON serialization, none of these variables are added.)  The '''nova.serializer''' variable contains a reference to the body serializer to use (typically a subclass of XMLDictSerializer or, preferably, a subclass of XMLTemplateSerializer), and the '''nova.action''' variable contains the action to pass to the serializer's serialize() method.  If the serializer has a get_template() method, the return value of that method will be assigned to the '''nova.template''' variable; extensions may attach their slave templates to this master template as necessary.</ins></div></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"></td><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"><div>----</div></td><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"><div>----</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"><div>[[Category:Proposal]]</div></td><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"><div>[[Category:Proposal]]</div></td></tr>
</table>Vekhttps://wiki.openstack.org/w/index.php?title=XMLTemplates&diff=8864&oldid=prevVek: Starting spec...2011-10-06T17:11:32Z<p>Starting spec...</p>
<p><b>New page</b></p><div>__NOTOC__<br />
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<br />
== XMLTemplates ==<br />
'''Time: ''' <<[[DateTime]](2011-10-06T17:11:30Z)>><br />
<br />
'''Drafter: '''[[Vek]]<br />
<br />
'''Drafters Email: ''' <<[[MailTo]](kevin DOT mitchell AT rackspace DOT com)>><br />
<br />
'''Status: ''' To be completed by POC<br />
<br />
Currently, request extensions have to deserialize data, manipulate it, and reserialize it. This happens for each extension. This is generally not much of a problem for JSON data, but XML is expensive to deserialize and reserialize, and it is currently impossible to extend the XML without directly editing the serializer or writing an independent serializer.<br />
<br />
This proposal is to establish new middleware which performs the XML serialization, and to also establish a means of creating XML templates, which can be extended by attaching slave templates to describe the extra data that an extension may wish to include.<br />
<br />
Much of the code for this is already written, and many elements of nova-api converted over to use template-based serializers in preference to the hand-coded serializers currently utilized. This page is to document what has been done.<br />
<br />
----<br />
[[Category:Proposal]]</div>Vek