Recently I was comparing servlet specifications after 2.4 version, Here is a short matrix for reference
Liferay 6 offers feature of Site Templates , where in you can design a site template . Using the newly designed template you can create multiple communities and organization on the fly. Just apply the template while creating those communities .
Site templates is nothing but a community which will act as a template for new communities. It will have Pages , Portlets , Content just as a regular community can.
Here are the steps to create a site template and create a community using the newly created site template.
Liferay 6 comes with new functionality , Page Templates. User can define a page with certain portlets/Layouts and Save the Page as templates. Later on while creating the new page , user can select the Page Template.
Here are the Steps :
World of Liferay portlets (Friends Activity, Recent Activity) give you feed of activities about your friends and overall.Here I am explaining how Blogs portlet generates feed for these portlets.
You can follow same steps to implement it, to display your portlet in feeds.
What is web service
Web service is nothing but exposes your software as service for other application over the network. Applications can be written in any programming language and if they support the statandard they can be integrated.It removes the concern of writing custom interfaces and REST/HTTP Post based calls for each integration point.