What is aPaaS?
Application platform as a service (aPaaS) or PaaS (Platform as a Service) is a more advanced IaaS (Infrastructure as a Service). It consists of outsourcing not only the hardware infrastructure but also your middleware applications:
operating systems;
database;
web servers;
etc.
This allows you to have an entire platform as a service. You are free to add your own applications and tools. Examples of PaaS include Windows Azur or IBM Bluemix.
Complementary solutions of aPaaS
Application Monitoring & Performance
Integration Platform as a Service (iPaaS)
Application Lifecycle Management
Managed Service Providers (MSP)
Electronic Data Interchange (EDI)