What are necessary steps?- You need to start with Database upgrade first . Once you are done with database upgrade you can you need to upgrade Document Library or Image gallery (If there is any change in hook).
- Upgrade your code plugins - Ext , Portlet , Theme and Layout.
What should be taken care of?- For Database upgrade make sure there are no obvious issue with your current database. I mean to say if you are upgrading from LR 6.1 to LR 6.2 but LR 6.1 already has some issue then you need to first fix issue in your old database and then start upgrade.
-Backed up your database.
-Once database upgrade is failed you can use the same database again . You need to again restore old database then perform upgrade on restored database.
How to Move modified code (API) to upper version?- API Changes can be either in Ext , Hook and Portlet . You can not directly copy your old plugin into latest version . There is different strategy to upgrade code plugins.
To upgrade plugin portlet you can create a blank portlet in new Liferay version and you can copy content of old plugin one by one. (For configuration files there might be change with DTD so don't copy entire file instead copy its content)
You can check my blog entry
Plugin Portlet Migration Tips.
- For Ext also you can not use old files into latest version. There might be possibility of change in source code . Let say if you have modified LoginAction in old version don't use the same file in latest version copy LoginACtion from new versions portal source and identify your changes.
Avoid new portlet and service creation inside ext. That is not recommended if you old version had services and portlet in ext then move it to either portlet or hook.
How to take care of Hooks in Upper version?For Hook you need to repeat above exercise. Copy new hooked JSP or class from latest version's portal source and identify your changes.
How to upgrade properties?It might be possible that some of the properties might have changed from one version to another. i.e in Liferay 5.x for document library hook property is dl.impl.hook but in LR 6.x document library hook property is changed to dl.store.impl. You need to identify changes of property in new version . Use new property in latest version.
You can also refer to below links for more details about database upgrade.
http://itsliferay.blogspot.in/2012/06/upgrade-database-from-liferay-52-sp-3.htmlhttp://itsliferay.blogspot.in/2012/06/upgrade-database-from-liferay-60-to.htmlHope this will help you .
Thank you
Jitendra Rajput
http://itsliferay.blogspot.in/
