The automatic provisioning of applications is an importent task for the success of Software as a Service (SaaS) providers. Different provisioning engines from different vendors and open source projects with different interfaces have been emerging lately. Additionally, infrastructure providers that provide infrastructure on demand now provide computing resources that can be integrated in a SaaS provider’s computing environment. In order to allow SaaS application providers to specify generic installation and maintenance flows independent from the underlying provisioning engines we propose an architecture for a generic provisioning infrastructure based on Web services and workflow technology.