It is the service-oriented architecture of Microsoft. You can start with this tutorial if you want to learn now.
WCF can work, in theory, with any data model, such as XML (default), JSON, Odata, or an unusual format, such as YAML.
This architecture is simpler than WCF in terms of configurations and tends to be more granularized. While WCF works best on atomic requests (one call to perform the entire task), the Web API works best due to the task in multiple requests (more resource-oriented).
The standard data transfer format is JSON, but the Web API also works with XML, Odata and YAML.
Outside the scope of the question, but also interesting: SSIS
This is mostly out of curiosity because it’s outside the scope . NET, but it might be interesting for you to know. SQL Server Integration Services (SSIS) integrates databases into SQL Server transparently. It may be an option if desire is good timing and performance.
Rest ?
– DontVoteMeDown