Microsoft Azure BizTalk Services (MABS) was Microsoft's first attempt at providing an integration PaaS in Azure. While the platform was somewhat limited in functionality, it did help to illustrate the promise of implementing integration solutions in the cloud, even when some of the targets were on-premise. This was made possible through hybrid connections which requires an agent service to run on-premise that aids with inbound connectivity from Azure, much like a Service Bus Relay, and of course through having BizTalk Server on-premise to provide further connectivity with on-premise components.

Rather than build upon MABS, which was a platform that was very isolated from the other Azure PaaS offerings, Microsoft has taken the best of what MABS had to offer and built a brand new platform called Azure App Services. Azure App Services stitches together what used to be Azure Websites, Mobile Services, and MABS into a single integrated offering with great potential for synergies...