Wiki source code of How to setup a cluster of XWiki instance based on distributed events
Version 6.1 by Thomas Mortagne on 2010/12/17
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| author | version | line-number | content |
|---|---|---|---|
| 1 | {{warning}} | ||
| 2 | This tutorial is a simple way to setup a XWiki clustering for test purpose. | ||
| 3 | {{/warning}} | ||
| 4 | |||
| 5 | The goal of a cluster of XWiki instance is to provide several XWiki in different servers accessing the same database server to be able to do load balancing. | ||
| 6 | |||
| 7 | = Install two instances of XWiki on the same MySQL database = | ||
| 8 | |||
| 9 | Here we will use the XWiki standard distribution but instead of using the embedded hsqldb database we will use a MySql database. For this you need to: | ||
| 10 | |||
| 11 | * modify the ##hibernate.cfg.xml## file to change hsqldb configuration by a proper MySQL configuration | ||
| 12 | * copy your database driver JAR in WEB-INF/lib or in some shared lib directory | ||
| 13 | |||
| 14 | See http://www.xwiki.org/xwiki/bin/view/AdminGuide/Installation for more details on how to install XWiki. | ||
| 15 | |||
| 16 | At this point you almost have a XWiki cluster: you have two instances of XWiki which are using the same datas. But there is a remaining "detail": the problem is that for performance reason XWiki is using lots of different caches which mean that even if one instance of XWiki modify a document it's possible the other XWiki instance will not see it and keep showing the document from its cache. | ||
| 17 | |||
| 18 | = Configure event distribution = | ||
| 19 | |||
| 20 | To handle this we will use the network event distribution system. When anything happens in a XWiki instances it generate a local event which is used to update caches. Here we will make theses events send to other XWiki instances as well and emulate local events. This way all the code updating its cache each time something changed in a particular document for example will also be notified if it has been done by another instance of XWiki. | ||
| 21 | |||
| 22 | == Enable remote observation == | ||
| 23 | |||
| 24 | First you need to enable remote observation system. | ||
| 25 | |||
| 26 | For this go to xwiki.properties file and set the property ##observation.remote.enabled## to ##true##. | ||
| 27 | |||
| 28 | == Set the channels == | ||
| 29 | |||
| 30 | Then you need to indicate to remote observation manager which communications channels it should start when XWiki starts. | ||
| 31 | |||
| 32 | For this you need to list in property ##observation.remote.channels## the names of the channels. | ||
| 33 | |||
| 34 | Here we set ##tcp1## in one instance and ##tcp2## in the other XWiki installation. | ||
| 35 | |||
| 36 | == Put the JGroups channels xml configuration files == | ||
| 37 | |||
| 38 | The names of the channels are used to match the configuration files names in located in ##WEB-INF/observation/remote/jgroups/## configuration folder. For example in this case we will add a attach:tcp1.xml file in one XWiki instance and attach:tcp2.xml file in the other XWiki instance. | ||
| 39 | |||
| 40 | = Start XWiki instance on different ports = | ||
| 41 | |||
| 42 | For this tutorial we run two instance of XWiki in the same server. So we need each instance to use different ports. | ||
| 43 | |||
| 44 | To run a XWik instance if a custom port you can provide it in parameter of the script start_xwiki.sh. | ||
| 45 | |||
| 46 | Here we start the first instance with: | ||
| 47 | |||
| 48 | {{code}} | ||
| 49 | sh start_xwiki.sh 8080 8070 | ||
| 50 | {{/code}} | ||
| 51 | |||
| 52 | and the second one with: | ||
| 53 | |||
| 54 | {{code}} | ||
| 55 | sh start_xwiki.sh 8081 8071 | ||
| 56 | {{/code}} | ||
| 57 | |||
| 58 | The second port is the port used to stop jetty server, it's not mandatory to run XWiki but it's better to have differents ports if you don't want to have to kill the java process instead of using the stop_xwiki.sh script ;) | ||
| 59 | |||
| 60 | = Check = | ||
| 61 | |||
| 62 | * Load a page in both instances | ||
| 63 | * Modify a page in one instance | ||
| 64 | * Reload it in the other instance | ||
| 65 | * It should have taken into account the modification made on the other instance |
