 security. Scalability and robustness, flexibility, and a decreased cost of ownership are other improvement goals when comparing service solutions in vertical networks versus hori- zontal networks. The service network is also affected by what is called the processing dimensioning in this book. OMA has established a workgroup for mobile web services. The group creates a specification suite to aid developers in applying web service technology and standard development tools to discover, access and leverage service enablers within the OMA framework. This results in much richer application services. The specification suite provides developers with bearer-independent service components such as location, content downloading, device management and presence. Understanding Changing Telecommunications - Building a Successful Telecom Business Other new workgroups include requirements, architecture and interoperability. The requirements group identifies and specifies technical requirements for the development of mobile services. The architecture group defines the overall OMA system architec- ture including evolution, integration and maintenance. The interoperability group ensures end-to-end interoperability. See http://www.openmobilealliance.org/docs. The sections on XML for business documents and web services and the section on MExE (mobile execution environment = WAP and Java) in this chapter are also part of this dynamic subject area. Regarding XML see also Chapter 3, Section 3.11.2 A number of support services exist in the service network to aid the proper operation of the IP network that connects all the servers. Service networks are initially deployed together with mobile systems. 9.5 TERMINOLOGY For the purposes of this book, the definitions and abbreviations given below apply: Home environment: actor responsible for overall provision of services to users. HE-VASP: home environment value-added service provider. This is a VASP that has an agreement with the home environment to provide services. Personal service environm