RE: Microsoft Dynamics GP API specification
As David Musgrave mentioned in this forum (community.dynamics.com/.../dynamics-gp-api ) >>
"There are many APIs for Microsoft Dynamics GP.
eConnect, REST Web Services, SOAP Web Services, Dexterity APIs
However, if you just want to read data you can use SQL directly.
If you need to access data from outside the network, you can use Service Based Architecture with the SOAP based web services to read data. If there isn't a node for the data you want, GP Power Tools can create custom Web Services to perform any task, so you can use it to create additional nodes for any table in any product."
Specific to Visual Studio, we have our Visual Studio Tools, which this document will give you information on:
VSTDGPProgrammersGuide.pdf
Let us know if you have any questions.
Thank you