Among the different developer technologies to connect to the PI and AF servers, I would encourage you to check out the following two:
- PI AF SDK: PI AF SDK is a .NET library that allows applications to read from and write to the PI System. Since you are developing a .NET web application, you can easily use this library for accessing AF data. You can check out the programming references here.
- PI Web API: PI Web API provides a RESTful interaction model to data contained within the PI System. It is targeted at providing cross-platform, multi-user programmatic access to PI System data. If your application will be deployed on a web server outside of the PI/AF servers domain environment, it might be easier to use PI Web API than PI AF SDK.
Both products are undergoing active development (see product roadmap here).
You may also want to check out the SQL access technologies, OLE DB Enterprise and ODBC Provider.
I don't think there is a "best way" to connected, it depends on your needs. The SDK will give you the most capabilities, while PI Web API is good for basic stuff, but can get a little complex depending on what you are trying to do. The SQL access if good if you need to do more complex queries. My preference is to use the SDK because it is the most developed. But If I had a lot of users accessing data in a simple way, I would look to the PI Web API, because it can use indexing, does caching, and works well for situations where you have a lot of concurrent connections.
Thanks a lot Daphne and Lonnie