I am considering building a Java EE based set of services and licensing these services to my clients. While we will aim to make these services generic for any client, reality is that customizations and new services will be needed on a client specific basis.
Likely the stack will be a Java application deployed to the EC2 cloud, possibly leveraging a framework such as Spring.
What architecture would one prescribe to have a hosted application for my clients, but also enable them to build their own custom extensions. Does anyone have technical or business example of a company that has built a hosted SaaS service that is extensible on the platform side?
I haven't done this yet, but AFAIK you could use module systems such as OSGi also on the server side to write modular, extensible server side applications.