Develop a Real time Sync Consumer Web Service from SAP ECC

Hello Experts,

We have a requirement to build a Real time Syncronous Consumer Proxy in SAP ECC to be used in Order Capture in Real time. The Web Service will be provided by the Rule Engine.

The requirements are,

1. It should have very good performance. - Since this will be invoked for price calculations, real time at pricing procedure level

2. Good to have monitoring

3. Error handling mechanisms.

We are looking at the following options,

1. Direct Web Service from ECC.

2. RESTFul service

3. SAP PI as a broker (What options are available and its value)

The Rule Engine is expected to return the price at ~ 50 ms. So please let me know the best options that we can implement to cover the above requirements.

Thanks & Regards,

Paul.