Extract data from BW ODS to external application

Hello,

We have the following interface challenge:

We need to interface data from an ODS to an external application. The request for this data comes from the external application and contains selection parameters.

The datasets are small and the responses need to be fast.

How to do this?

We do not want to use Query_data_view, it is not performing and contains too much meta data

Preferably we define a webservice either in BW or XI/PI that receives the request and send back the answer.

What are the possibilities/best practices?

Brokered or non-Brokered?(using XI or PI or just using an BW webservice)

Do we need to publish the webservice to an UDDI?

How do we extract the data from the ODS, via a Function module? If so i guess that FM can be made externally available and callable from XI/PI.

Does ehp1 provide more fucntionalities in this area than 7.00?

Does PI provide more functionalities than XI in this area?

Do we need proxies for this?

Thanks for any insights