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<a class="user-hover" rel="ian@iay.org.uk" id="email_ian@iay.org.uk" href="https://issues.shibboleth.net/jira/secure/ViewProfile.jspa?name=ian%40iay.org.uk" style="color:#326ca6;">Ian Young</a>
created <img src="https://issues.shibboleth.net/jira/images/icons/issuetypes/newfeature.png" height="16" width="16" border="0" align="absmiddle" alt="New Feature"> <a style='color:#326ca6;text-decoration:none;' href='https://issues.shibboleth.net/jira/browse/MDA-135'>MDA-135</a>
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<a style='color:#326ca6;text-decoration:none;' href='https://issues.shibboleth.net/jira/browse/MDA-135'><strong>add subtractive merge strategy</strong></a>
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<strong style="font-weight:normal;color:#505050;">Issue Type:</strong>
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<img src="https://issues.shibboleth.net/jira/images/icons/issuetypes/newfeature.png" height="16" width="16" border="0" align="absmiddle" alt="New Feature"> New Feature
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<strong style="font-weight:normal;color:#505050;">Affects Versions:</strong>
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0.8.0 </td>
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<strong style="font-weight:normal;color:#505050;">Assignee:</strong>
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<a class="user-hover" rel="ian@iay.org.uk" id="email_ian@iay.org.uk" href="https://issues.shibboleth.net/jira/secure/ViewProfile.jspa?name=ian%40iay.org.uk" style="color:#326ca6;">Ian Young</a>
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<strong style="font-weight:normal;color:#505050;">Components:</strong>
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Pipeline </td>
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<strong style="font-weight:normal;color:#505050;">Created:</strong>
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20/Mar/14 6:55 AM
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<strong style="font-weight:normal;color:#505050;">Description:</strong>
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<p style='margin-top:0;margin-bottom:10px;'>We have a couple of merge strategy implementations today. The first just includes all entities from all collections, and it's probably doesn't have a lot of application when processing SAML metadata, where there is a constraint that each <tt>entityID</tt> only appears once. For that case, we have the deduplicating strategy, and that works very well for the case in federations like the UKf where imported metadata is added to an existing collection and published as a single aggregate.</p>
<p style='margin-top:0;margin-bottom:10px;'>Some other federations publish imported metadata in a separate aggregate, but would still like to exclude those entities present in their main aggregate. This could be achieved using a "subtractive" merge strategy. I can think of two definitions for this.</p>
<p style='margin-top:0;margin-bottom:10px;'>Option 1 would be like the deduplicating strategy except that the entities from the base collection are not included in the output. They would still act to remove "duplicates" from the collections being merged "in", however. This would allow multiple aggregates to be deduplicated with a single source of, essentially, a dynamic blacklist.</p>
<p style='margin-top:0;margin-bottom:10px;'>Option 2 would be to use the collections being merged as blacklist sources. This seems a little more natural for the simple case, but means that people merging multiple metadata sources against a single blacklist source would need to perform a two-stage merge.</p>
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<strong style="font-weight:normal;color:#505050;">Project:</strong>
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<a style="color:#326ca6;" href="https://issues.shibboleth.net/jira/browse/MDA">Metadata Aggregator</a>
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<strong style="font-weight:normal;color:#505050;">Priority:</strong>
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<img src="https://issues.shibboleth.net/jira/images/icons/priorities/minor.png" height="16" width="16" border="0" align="absmiddle" alt="Minor"> Minor
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<strong style="font-weight:normal;color:#505050;">Reporter:</strong>
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<a class="user-hover" rel="ian@iay.org.uk" id="email_ian@iay.org.uk" href="https://issues.shibboleth.net/jira/secure/ViewProfile.jspa?name=ian%40iay.org.uk" style="color:#326ca6;">Ian Young</a>
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