Challenges in Achieving IaaS Cloud Interoperability across Multiple Cloud Management Frameworks

In academia, many institutes have deployed IaaS cloud services in isolation, based on cloud management frameworks of their choice, making the cloudscape quite heterogeneous. Now, with the effort to federate cloud resources well underway, the challenge is not to make everyone switch to a common solution, but rather to allow everyone to keep their setup but still provide uniform access to essential services. This seems to be best achieved by implementing common standards. This paper discusses the different areas such standardization effort must address, ranging from the choice of the actual standardization approach (i.e., Choosing a recognized open standard or possibly a non-standard solution with a strong community backing) through authentication and virtual machine life-cycle management to monitoring or accounting (billing) services. The discussion is based on the authors´ own practical experience with implementing standard compliance in multiple cloud management frameworks, producing a real-world interoperability solution -- the rOCCI Framework - which is also introduced in the paper.