What is the basic database structure difference between Joomla! 1.5 and Joomla! 2.5 versions? From the module and component development point of view, table structure has been updated. Earlier, we had #__modules and #__components tables which have been merged to #__extensions in the new version. This new table includes all type of extensions in single table.
I was able to create and load modules easily in Joomla! 1.5 but I cant do the same in Joomla! 2.5? In Joomla 1.5, system was able to detect a new module automatically but in Joomla 2.5, you would need to discover the module post development. For this, please go to yoursite/admin and select top-menu/extensions/extension manager and click on the discover tab. On discover tab, you would be able to find new extensions by clicking the discover button on top- right toolbar.
Are too many modules a problem for the Joomla! site? Yes, it there are many modules or extensions then it put extra load on the loading of the page and website. Some of the websites have been experienced working good with up to 50 extensions but some might start delay in loading.
Does the extension be compulsory an open source code? No, but since the CMS is open source and if you want to take benefits of community then it should be an open source code.
Do I really need to switch to Joomla! 2.5 from Joomla! 1.5 and why? Yes, there are two types of releases ◦ STS: Short Term Support ◦ LTS: Long Term Support ◦ 1.5 version is LTS version and Joomla! has officially stopped support for it from April, 2012 so for any further system level issue, it won’t be supported hence it is good to move to next release for code level support. However, forums and community is always available.
How and where can I get more information on Joomla! extension development? http://docs.joomla.org