perfSONAR is, finally, an example set of code (implementation of services) that attempts to implement an interoperable peformance middleware framework. Those sets of code are developed by different partners. Some pieces of code are "more important" than others because their goal is to ensure interoperability between domains (e.g. the Lookup Service and the Authentication Service). Different subsets of code are important to each partner, with a great deal of overlap. The services developed acts as an intermediate layer, between the performance measurement tools and the diagnostic or visualization applications.