The core Teiid code is same as one in JBoss EAP environment, so as far as the stability question on "Teiid Query Engine" goes, it is as good as server version. JBoss EAP deployment version of makes use of several other services, like classloading, JCA, transactions, deployment framework. JCA and Transaction modules being essential. So as long as you have viable alternatives you can plugin for these services then you can use the embedded mode. As per scalability goes, that depends on how your architecture with embedded looks like
BTW, JBoss EAP 6.x is very light weight server, you can reconfigure it to remove unnecessary services you think are not required my removing their subsystems from the standalone.xml file.
Ramesh, thanks for advising on that. Our ultimate aim is to have Teiid running in a slim server with smaller footprint and quick to start and stop. If that can be achieved by removing certain subsystems not required by our application and Teiid, that would be our preferred choice over plugging in JCA and transaction modules for Embedded Teiid.
Separately, another objective is to make a REST API available from Teiid VDB. I know Teiid has this facility available (REST Service Through VDB - Teiid 8.11 (draft) - Project Documentation Editor) . Is there an example around it which we can refer and do a POC around it?
The link you showed above has an example already in it. Basically, you define REST:URI, REST:METHOD, REST:PATH etc kind of extension properties on a virtual procedure, that can return either JSON or XML payload. Then when you deploy the VDB a REST service is automatically generated. Let me know if you have questions or anything not clear from document, I will update it.
The other option is to use OData. Currently OData V2 is supported, I am working on V4 support hopefully in 8.11.