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---+Example of Linked Data Usage of PubSubHubbub Implementation

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The following example demonstrates how to use Virtuoso's implementation of the [[http://pubsubhubbub.googlecode.com/svn/trunk/pubsubhubbub-core-0.3.html][draft PubSubHubBub Protocol]] to handle Linked Data. 

We extend the idea of tracking a feed to track Linked Data resource URIs. 

To reveal the hub to subscribers, we propose Linked Data resources return the following HTTP header --
<verbatim>
Link: <http://cname/psh/subscribe.vsp>; rel="hub"
</verbatim>
-- or include the following in an HTML &lt;head&/lt; (or similar) element --
<verbatim>
<link rel="hub" uri="http://cname/psh/subscribe.vsp">
</verbatim>


---++ Endpoints

The <nop>PubSubHubBub package installed on a system would define the following endpoints :

| <code><nowiki>http://cname/psh/subscribe.vsp</nowiki></code>  | subscription endpoint  |
| <code><nowiki>http://cname/psh/publish.vsp</nowiki></code>  | publishing endpoint  |
| <code><nowiki>http://cname/psh/</nowiki></code>  | index to UI of the simple test clients  |
| <code><nowiki>http://cname/psh/callback.vsp</nowiki></code>  | default built-in client callback endpoint  |

---++ Example of use of the built-in demo client

   1 As a very first step we use a simple client to subscribe to a SIOC document containing data for an ODS-Weblog.  In our tests we subscribe to the Linked Data document <code>&lt;[[http://ec2-174-129-156-25.compute-1.amazonaws.com/dataspace/demo/weblog/demo%27s%20Weblog/sioc.rdf][http://ec2-174-129-156-25.compute-1.amazonaws.com/dataspace/demo/weblog/demo%27s%20Weblog/sioc.rdf]]&gt;</code>.
%BR%%BR%<img src="%ATTACHURLPATH%/step1.png" style="wikiautogen"/>%BR%%BR%
   1 The Weblog post is as follows:
%BR%%BR%<img src="%ATTACHURLPATH%/step2.png" style="wikiautogen"/>%BR%%BR%
   1 During the subscription process, the client will get the initial state of the SIOC feed, so we can execute the following query to see all post titles:
%BR%%BR%<img src="%ATTACHURLPATH%/step3.png" style="wikiautogen"/>%BR%%BR%
   1 In the query result is the title of the existing Weblog post:
%BR%%BR%<img src="%ATTACHURLPATH%/step4.png" style="wikiautogen"/>%BR%%BR%
   1 Next we add a new blog post to force a change to the SIOC data:
%BR%%BR%<img src="%ATTACHURLPATH%/step5.png" style="wikiautogen"/>%BR%%BR%
   1 Using a simple publishing UI, we notify the Hub the data has changed:
%BR%%BR%<img src="%ATTACHURLPATH%/step6.png" style="wikiautogen"/>%BR%%BR%
   1 The Hub takes the delta and notifies the subscribers: 
%BR%%BR%<img src="%ATTACHURLPATH%/step7.png" style="wikiautogen"/>%BR%%BR%
   1 Again we execute the same SPARQL query as in the earlier step, and now we can see the data contains the new blog post title:
%BR%%BR%<img src="%ATTACHURLPATH%/step8.png" style="wikiautogen"/>%BR%%BR%

---++Related 

   * [[VirtODSPubSubHub][Setting up PubSubHub in ODS]]
   * [[VirtFeedPubSubHub][Feed subscription via PubSubHub protocol Example ]]
   * [[VirtPubSubHubACL][Setting Up PubSubHub to use WebID Protocol or IP based control lists]]
   * [[http://virtuoso.openlinksw.com/dataspace/dav/wiki/Main/VirtGraphReplication][Virtuoso Graph Replication Guide]]
   * [[http://virtuoso.openlinksw.com/dataspace/dav/wiki/Main/VirtSPARQLSSL][Creating and Using a SPARQL-SSL based Endpoint]]
   * [[http://virtuoso.openlinksw.com/dataspace/dav/wiki/Main/VirtAuthServerUI][Set WebID Protocol ACLs using the Virtuoso Authentication Server UI]]
   * [[http://virtuoso.openlinksw.com/dataspace/dav/wiki/Main/VirtAuthFOAFSSLACL][WebID Protocol ACLs Tutorial]]
   * [[http://virtuoso.openlinksw.com/dataspace/dav/wiki/Main/VirtOAuthSPARQL][SPARQL OAuth Tutorial]]
   * [[VirtODSFOAFSSL][WebID Protocol Support in OpenLink Data Spaces]]
   * [[ODSPkiSetup][Guide to Setting up a X.509 certificate issuer and HTTPS listener and Generating ODS user certificates]]
   * [[OdsKeyImport][CA Keys Import using Conductor]]
   * [[ODSGenerateX509Certificate][Generate an X.509 Certificate hosted WebID Guide]]
   * [[ODSBriefcaseFOAFSSLShareFile][ODS Briefcase WebID Protocol Share File Guide]]
   * [[http://esw.w3.org/topic/foaf+ssl][WebID Protocol Specification]]
   * [[https://foaf.me/simpleLogin.php][Test WebID Protocol Certificate page]]
   * [[http://test.foafssl.org/cert/][WebID Protocol Certificate Generation page]]
   * [[https://demo.openlinksw.com/sparql-ssl][Virtuoso Demo SPARQL-SSL Endpoint]]