DTDs are used to specify XML document structure. In par- ticular, a DTD defines the names and contents of elements that are permitted in an XML document. The XML-based, multi-protocol configuration server is at the bottom of the pro- visioning framework. The configuration server supports TL1, SNMP and CLI/Telnet to the network element. The provisioning framework builds its templates on the XML configuration capability of the configuration server. The design of the configuration engine is given in Figure 6.6. It supports user- specific tasks or configuration XML files that contain the detailed parameters that are needed for configuring network elements using one or more protocols. These tasks can be loaded, added or modified by users and applied to the network element using the configuration client. The flow of configuration XML to be applied to a device begins with the client requesting the server to configure one or more network elements using the supplied XML. Before applying the configuration, the XML can be pre-processed using cus- tom filters. Security and audit processing are completed and the configuration is applied. Once configuration is complete, the topology database is updated accord- ing to the XML configuration. Custom filters can be applied to directly update the database. The provisioning framework builds upon this capability to provide template- based provisioning. It makes it possible to parameterise the templates so that many different service-provisioning requirements can be met. For example, service tem- plates can be set up that require some specified user input. The template captures the detailed configuration requirements while specifying the rules governing the necessary inputs from the user and other sources of information. OSS for Telecom Networks Client Topology Module Database Update Configuration API Managed Object Update Config Update Secutiry & Rules Rules Audit User Config Configuration Module Policies Tasks Multi-protocol Management Server Telnet Figure 6.6 Configuration engine d