I however has guide- lines on using JMS, though its usage is not mandatory for implementing MTOSI compliant APIs. OSS/J also supports XML, but the XML API is wrapped with Java API. The MTOSI back end implementation is not based on a specific technology as compared to OSS/J where the back end implementation is in Java. As MTOSI evolved from MTNM most of the issues in interface APIs were fixed and the defini- tions were to offer a service oriented interface on a heterogeneous platform environ- ment. So when multitechnology, multinetwork support is required MTOSI would be a good choice, while in open source based environment OSS/J would be the popular choice. Support to both these interface standards can be implemented in the same OSS solution. 25.6 Conclusion An application programming interface (API) is an interface that defines the ways by which an application program may request services from another application. APIs provide the format and calling conventions the application developer should Standard Interfaces use to work on the services. It may include specifications for routines, data struc- tures, object classes, and protocols used to communicate between the applications. The APIs are mostly abstract interface specifications and controls the behavior of the objects specified in that interface. The application that provides the function- ality described by the interface specification is the implementation of the API. This chapter gives the reader an overview of the management interface standards used in OSS/BSS development. It considers MTOSI and OSS/J for developing applications in the customer, service, and network layers of OSS/BSS. The basic concepts of these two popular interface standards are discussed without diving into the details of a specific topic. Additional Reading 1. www.tmforum.org (Latest version of the documents can be downloaded from the Web site) TMF608: MTOSI Information Agreement TMF517: MTOSI Business Agreement TMF854: MTOSI Systems Interface: XML Solution Set TMF608: MTNM Information 