Design and implementation of IP multimedia subsystem applications: An enabler-oriented approach

Multiparty networked applications, which are gaining interest in areas as diverse as online games, e-learning, e-health, and collaborative work, tend to depend on a set of common functions. In conventional IP networks, these shared functions require application-specific servers, leading to scale diseconomies and complicating interoperability. The IP Multimedia Subsystem addresses this by incorporating basic services called service enablers, which can be used as building blocks to facilitate application development. This article discusses our experience creating innovative enablers for IMS networks, and combining them into new multimedia applications. An enabler-centric process is described, and the configuration of a development IMS network is explained, with suggestions on how to replicate this architecture with freely available components. Following these principles, we designed and implemented a series of novel group-centric enablers exploiting the advantages of group management, which we describe in detail. A use case made possible by these enablers is shown, consisting of an e-health scenario for remote medical visits. We reflect on the advantages and challenges introduced by this development methodology, and provide insight on how a project of this nature should be approached.