Servicepack patches applying procedure

Recently I was involved in implementing Servicepack feature on Carbon kernel. Up to this implementation WSO2 products only supported to apply patches as needed. But when time goes this number of patches get increased(sometimes patche0001 to patch0100 so on....) and it will be difficult to maintain and sometimes some of these patches can get missed and will be difficult to check. Servicepack implementation was taken into account to address this scenario.

Let me first tell you the structure of a Servicepack. Servicepack is a collection of patches combined to one such that it will be easy to distribute to a customer. (ex: patch0001 to patch0080). It mainly contain two elemets,

• lib directory : which contain all the jar files corresponding to the patches that will be applied by Servicepack
• servicepack_patches.txt file : contain the list of patch numbers included on the servicepack

With this approach during server start up with ./wso2server.sh -DapplyPatches the code will first check on available service packs on $CARBON_HOME/repository/components/servicepack directory and apply the latest Servicepack available in the directory. Then with the help of servicepack_patches.txt file of the Servicepack patch applying process will apply the remaining patches that was not applied by Servicepack to the server.

The order the patches and Servicepacks get installed will be shown in the below diagram. It will first apply patch0000 which is the plugins backup directory if exist. Then it apply the latest Servicepack available. Finally the process apply the remaining patches which was not applied by Servicepack.

Then we will verify the components inside applied latest Servicepack and patch list with the $CARBON_HOME/repository/components/plugins directory. If plugins directory contain the latest patch list we assume the process is successfully completed :)