SIP service support environment and Application Server

The business support environment mainly includes the application server, Business Management Server, and business generation environment. They work together to quickly complete the tasks that provide users with diverse and flexible value-added services based on the next generation network. The application server is the subject of the business support environment. The Business Management Server and business generation environment can be used as part of the application server.

Figure 2 sip Application Server

Application Server and its Functions

The application server is the main body of the business support environment. It provides the resident and execution environment of the business logic of various value-added businesses or smart businesses, and also provides various open APIs, provides a creation platform for third-party business development. The Business Management Server and business generation environment can also be part of the application server, so that the application server can provide support for business management and business creation. The Application Server indirectly utilizes the underlying network resources through open protocols or API interaction with Softswitch devices, thus realizing the separation of business and call control, which is conducive to the introduction of new businesses.

The functions of the Application Server are similar to those of the SCP (Business Control Point) in the traditional intelligent network, but they are also quite different. Their main functions include:

First, provide value-added services and their resident and Running Environments. It mainly includes service performance monitoring, system resource monitoring, system logs and business logs, load control and balancing, and troubleshooting. The service performance monitoring, system resource monitoring, and log functions work together with load control, load balancing, and troubleshooting to jointly provide carrier-level operation support for the service.

Second, provide support for business lifecycle management. It mainly includes service loading, Service Activation, activation, and service uninstallation support. As a carrier-level core device in the Next Generation Network, dynamic service loading and dynamic version update are essential without affecting the running services.

Third, provide support for third-party business resident, operation and management. New services emerge in an endless stream. In addition to providing certain services, application servers must also provide operation and management support for third-party services to maintain scalability and openness. The introduction of a large number of third-party services will inevitably increase the security factors of network operations. Therefore, when introducing third-party services, you must fully consider the security issues arising therefrom.

Fourth, provide personalized services based on Web and proxy technology. A key factor in the success of the Internet is that users can easily use a large number of web-based applications through browsers, and the introduction of proxy technology brings users a way to provide personalized services. Applying these two successful experiences to the service provision of application servers can provide users with more user-friendly services and fully meet the interests of service providers. The challenge is that the application server must handle the security of service access in an Internet open environment.

Fifth, avoid, detect, and resolve business conflicts. With the proliferation of business types and quantities in the Next Generation Network, the possibility of conflicts between businesses also increases rapidly. In this context, the business conflict management function is particularly important. To separate complex service conflict management from service operation support, you can set up an application server dedicated to solving service conflicts.

Sixth, provide different levels of business development interfaces. To facilitate third-party business development, the application server can provide multiple programming interfaces, such as Parlay API, SIP servlet API, sip cgi api, CPL, and VoiceXML. From the abstract level perspective, these interfaces come from different abstract levels. The higher the abstract level of the interface, the simpler the business development.

 

Application Server category

From the perspective of business users, various businesses can be divided into general public businesses and specialized personal businesses with low utilization. Services accepted by most users in traditional intelligent networks are global public services, such as 300 and 800. This type of service features operations on a centralized database. It features a large amount of data and high versatility, and has high performance requirements for application servers running such businesses. Application servers running public services are suitable for running on core networks and maintained by network operators. They can be called "core network application servers ". Application servers that provide personalized services often need to interact with users. They are more suitable for the edge of the network. They can be called "edge application servers of the network ". Based on different business characteristics, application servers can adopt different technologies and have different structural characteristics.

Currently, the interface between the application server and SoftSwitch mainly includes the ietf sip protocol and the Parlay API specification developed by parlay. From this perspective, the Application Server can be divided into two types: the SIP application server and the Parlay Application Server. The former interacts with the softswitch using the SIP protocol, while the latter uses the Parlay API as the interface between the softswitch.

SIP Application Server

The SIP protocol is an application-layer control (signaling) protocol proposed and presided over by IETF to create, modify, and end the session Process attended by one or more participants. SIP draws on the design ideas of HTTP and SMTP protocols, follows the principles of concise, open, compatible, and scalable that the Internet has always adhered to, and fully considers various services of the traditional public telephone network, including support for in and ISDN additional services. Moreover, service development based on SIP APIs can easily take advantage of the unique business features of the Internet such as e-mail to form new business growth points.

Figure 3 Parlay Application Server

The IETF service development interface provided by the SIP Application Server provides two types of service development technologies for developers of SIP applications.

The first is for sip cgi and SIP servlets with high credibility, and the sip cgi and SIP servlet API specifications are developed. These two technologies have strong functions, but improper use may cause insecure application servers.

The other is the CPL (call processing language) language for ordinary users with low credibility. It is a script language developed by iptel Working Group of IETF Based on XML (Extensible Markup Language, it is mainly used to describe and control Personalized Internet telephone services (including call Policy Routing, call screening, call logs, and other services), with weak processing capabilities, this ensures that the CPL business logic compiled by common users will not cause damage to the application server.

Figure 2 shows a high-level architecture of the SIP application server.

The Application Server shown in Figure 2 can run services based on multiple interfaces, such as sip servlet, sip cgi, and Cpl. The underlying layer is the SIP protocol stack, which is used to provide protocol capabilities. A rule engine is introduced to handle service conflicts and event distribution. The SIP Servlet Engine provides a runtime environment based on the SIP servlet service,