Hi Vasanth,
I think a good starting point for information on developing SAP HANA apps is here:
What is HANA Application development?
SAP HANA application development is mainly javascript development / HTML5 GUI.
It is based on the MVC (Model-View-Controller) paradigm.
I would compare it to Sybase Powerbuilder or MS .NET, where you can address data structures directly in code.
What is the use of build and deploy the next-generation real-time applications on top of HANA and Why it's so needed today?
What is the use: like any application development is there to satisfy a customer need "See a need fill a need", the main areas where it has real business benefits at the moment is as an accelerator, where certain business processes take a whole day or hours to complete, can now be done in seconds.
Why is it so needed today? Everything is going towards mobile app development and devices. How long do you wait on a mobile phone for an app to respond? 1-3 seconds, then you give up. SAP has (from Sybase) a well established mobile platform (SMP) and coupled with SAP HANA a database and development platform to deliver the whole package.
What HANA application development road map says for now and future?
I keep track of the latest developments from here: Product Road Map Updates
Latest SAP HANA related here:
https://websmp201.sap-ag.de/~sapidb/011000358700000462232012D.pdf
Where i can find out HANA development architecture?
See first link at the top "SAP HANA".
What makes it different than existing?
Existing compared to what, I would need more details? I think the topic is to broad to list all differences here. Maybe the key differentiator is that SAP tries to push all the processing down to the database away from the application server (like Tomcat).
What are the language does it support?
It has an ODBC/JDBC interface/driver, so any development tool can connect to it.
Natively you will need to know SQL (or CEscript) and javascript.
Does it support only web based application?
Natively it supports only web based applications (or client apps which can pull from web services), but as mentioned above, any development language can connect to it via ODBC/JDBC.
What are the basic skill required to build an Application?
If you know how to program MVC applications, you know how to build a native SAP HANA application.
FAQ - What skills are needed to develop applic... - SAP Application Development Partner Center
Denis