| Soft-Switch is based on the concept that network is switch as well as a distributed software platform for switching and controlling information among network nodes. And Object-Oriented software technology provides the possibility for developers that gradually designing and implementing the application systems in terms of the processes of understanding them and embodying all the detailed solutions for them step by step.Creational abstract factory pattern has something to do with creation of objects, makes the instance turning process abstract and the objective system separated from those objects it created. It provides the interfaces for a series of related objects but don't need to specify their concrete implementations. Constructional adapter pattern is responsible for the combination of the objects, involves how to combine the objects to acquire the larger structures and convert the interface of one class to the specified interface.In the software architecture of Soft-Switch, call supporting module is the key to the whole call processing software as well as deeply involves call process and supplementary service in software comprehension and development. It consists of object management package, basic FSM package, high availability FSM package, call trace FSM package and event-driven FSM package that all of each package is derived from the previous one. The design of object management package follows Object-Oriented rule to make the objects built throughout all call processing modules. Basic FSM package, of which design follows creational abstract factory pattern, defines that abstract factory manager and abstract factory to create and manage a lot of various FSMs, and declares the interface of abstract running mechanisms and message processing procedure for all call processing modules. High availability FSM package encapsulates HA state management, data synchronization and consistency check function for all call processing modules. Call trace FSM package encapsulates the trace function of messages, state and events for each FSM. Event-driven FSM package is specially designed for basic call process module and expands the capability of FSM that can manage and transact with its several sub-FSMs by abstract events. The use of abstract factory design pattern greatly enhanced reusability and maintainability of the whole call processing application software.On the other hand, the media gateway agent module implements the H.248 protocol stated functions of media gateway controller. Channel associated signaling capability software package is derived from media gateway agent module and expands the international R2 protocol capabilities defined. Its design follows open close rule for reusing the running mechanism of media gateway agent module and greatly increasing the quantity of the reusable codes. Its design follows objects composition prior to class inheritance rule for simplifying the core data structures and their relations in the module. Its design follows adapter software pattern for improving the maintainability and expandability of this module. The design of channel associated signaling capability software package is the representative application of Object-Oriented technology and adapter software pattern. |
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