Analysis of application form of Gateway server for WAP Web site

Server

1. Introduction

At present, WAP has become a hot topic in the field of information technology (IT), and there are many articles about it, including all aspects of WAP, such as the protocol stack itself, WAP application and so on. Indeed, WAP is the 21st century's dream of ' surfing the internet ' anytime, and it's one of the best ways to combine wireless with the Internet. WAP application domain is quite rich, its biggest characteristic is the flexibility of system structure and the openness of protocol, WAP Gateway server is a key part of it, and the connection mode of the mobile network directly determines its application mode's performance. This article will discuss the further enhancement WAP gateway server function aspect to talk about the preliminary view.

　　

2. The classic WAP application structure model

WAP protocol developed by WAP Forum (WAP FORUM) 廾 basic structure for bottom load (bearer) + Wireless Datagram Protocol (WDP) + Transport Layer Security Protocol (WTLS) + Transaction layer Protocol (WTP) + Session Layer Protocol (WSP) + Wireless Application Environment (WAE), Many new application patterns have been sik in the latest WAP1.2 release, such as push, a protocol that sends Internet content to mobile users, and so on. The WAP protocol stack is applied to the structure model as shown in Figure 1. The WAP gateway server, which is the core component, accomplishes two functions: the Protocol conversion between WAP protocol stack (WSP/WTP/WTLS/WDP) and Internet Protocol stack (HTTP/TLS/TCP/IP), and the encoding and decoding of information content. WAP data compression coding to reduce network data traffic, maximize the use of wireless resources.

WAP realizes mobile Internet, which is coordinated between mobile terminal, mobile network (composed of base station and switch), WAP gateway server and network content supplier (ICP), Network service provider (ISP). This typical mobile phone access process can be summarized as follows:

(1) Mobile phone issue request;

(2) The mobile network (GSM, CDMA or other mobile network) connected to the local ISP;

(3) Local ISP connection WAP gateway server;

(4) The WAP Gateway server makes a request to the target content server;

(5) The target content server passes the information to the WAP gateway server;

(6) The WAP gateway server sends the processed information to the local ISP;

(7) The local ISP will return the residence to the mobile network;

(8) The mobile phone receives the Internet information;

It can be seen that there are more network entities involved in this process, and the coordination between them is more complicated. At the same time, WAP gateway server is only used as a gateway to assume the function is relatively insufficient. Therefore, it may be possible to use the openness of WAP protocol to change this single form of connection, so as to make full use of the power of WAP gateway server, so that it becomes a real ' server '.

3. WAP Server and mobile network (MN) connection of several forms and the change of protocol stack

3.1 Connection Forms

WAP as a gateway server (connecting MN to the Internet gateway), and mobile network connectivity is to determine its structure and function of the main factors, namely, the so-called ' WAP Gateway server solution '. For mobile networks with packet switching, such as GPRS and third-generation networks, WAP gateway servers can be directly connected with IP, which is not discussed here. However, for non-IP networks, such as GSM circuit Exchange data (CSD) network, it is possible to adopt a number of different forms of connection. These changes are illustrated below with the more common CSD and SMS hosting entities, as well as the advantages and disadvantages of this and the changes in the effectiveness of WAP gateway servers.

(1) used in the circuit Exchange data bearer entity

On a circuit-switched data bearer entity, a WAP gateway server can have three connections with MN, as shown in Figure 2.

The first form is the classical method, CSD through a series of intermediate conversion (in turn, through the IWF, PSTN, MODEM), and finally by the ISP to provide the IP connection with the WAP gateway server;

The second way is to provide a digital relay directly to the ISP by the mobile network switch, the ISP provides the IP connection with the WAP gateway server, and the ISP plays the role of the protocol conversion between the CSD and the IP.

The third way is to provide digital relaying directly to the WAP gateway server by the mobile network switch.

The first way to make full use of the current infrastructure, that is, a large number of user lines can be connected to the WAP gateway server, the direct benefit is that WAP service providers will be increased, can fully introduce competition and improve services.

In the second way, ISPs need to rent relatively expensive trunk, but also assume the role of protocol conversion between CSD and IP, which may affect ISP's enthusiasm to participate in WAP service.

The third Way is the most concise and reliable connection, but it needs the WAP Gateway server to undertake the protocol conversion of CSD to IP, in which WAP gateway server also plays the role of ISP. From the perspective of fully utilizing WAP gateway server function, the third scheme will be a better solution.

(2) on the bearer entity of the short message service

On a short Message service (SMS) hosting entity, there are also two connections between the WAP gateway server and MN, as shown in Figure 3. The first scenario is the classic scenario. The second option is to move the wireless data gateway functionality to the WAP gateway server in the case of retaining a short message center, which allows the WAP gateway server to assume as many functions as possible. The current mobile network is supported by a short message service with limited traffic (up to only 140Bytes of content), it does not make much sense to host the Internet. Further consideration is the application of WAP gateway server as a short Message Service center, which is of great practical value. From the point of view of telecommunications equipment manufacturers, two hosting entities (which can actually be extended to all hosting entities) tend to choose a more powerful solution to the WAP gateway server. Technically speaking, WAP Gateway is a large amount of storage, processing capacity of the computer to bear, if only to complete the role of the gateway, a ' overqualified ' suspicion. Therefore, in order to make full use of existing capabilities, it is entirely feasible to move some functions to WAP gateway servers. And for operators, such a network connection is simple, relatively low cost, reliable operation, easy maintenance. Theoretically speaking, the openness of WAP protocol can guarantee the flexibility of these kinds of connections.

3.2 Protocol Stack Design

The change of connection form above brings about the corresponding change of protocol stack. As an open technology, WAP protocols are designed to support these changes. The following is still taking GSM and CDMA bearer entity as an example to illustrate the change of protocol stack.

WAP protocol stack on bearer entity of 3.2.1 CSD

As shown in Figure 4-6. The first scenario is a typical protocol stack structure without any change. In the second scenario, subnets from the ISP to the WAP gateway server can be any kind of transmission network, such as Ethernet LAN, WAN, etc., which eliminates PSTN connections and related protocol conversions, and establishes a PPP direct connection between the ISP and the mobile network. The third scenario must establish a direct connection similar to dial-up between the mobile network and the WAP gateway server, which can be done by the PPP protocol.

　　

　　

　　

3.2.2 WAP protocol stacks on SMS hosted entities

As shown in Figure 7-8. In the first scenario, wireless data gateways (Wireless data Gateway) encapsulate short messages in IP tunnels (tunnel over IP) to WAP gateway servers, WAP gateway servers take SMS out of tunnels, and the downlink process is typical. In the second scheme, tunnel transmission is omitted, but it must be implemented by a short message real interface (sme-if for GSM and MC i/f for CDMA) to transform the short message to the WDP protocol, and the wireless data gateway will be integrated into the WAP gateway server.

It is not only feasible but relatively simple to complete the changes as described above in the Open WAP protocol structure, and the resulting efficiency gains are worth paying attention to.

　　

　　

4. The deep application of WAP gateway server

At present, the WAP gateway server that has been put into use can only realize the basic application defined by the protocol, that is, to transmit Internet content and only to play the role of Gateway. In fact, the WAP protocol defined by the application is far more than these, WAP can provide more business should be all-inclusive. In addition to the above mentioned the use of change and mobile network connection to give the WAP gateway server more powerful features, but also the use of WAP gateway server to provide users with a variety of value-added services and so-called ' personalized service '.

E-mail is a typical value-added service, the current application in the WAP business is also more popular. To provide users with such as address directory management, personal information services (such as geographical positioning, etc.) reflects the WAP gateway server can truly achieve ' personalized service ' characteristics. Because of the limitation of mobile terminal memory and processing power, it is difficult to implement these functions, WAP gateway server can process and store the information and content, and can be transmitted to them whenever the user needs it. Using the WAP Transport Layer Security protocol, the important encryption in the mobile e-commerce domain and who work on the WAP gateway server are also performed, eliminating the heavy processing tasks of mobile networks and terminals. The WAP protocol stack also retains a portion of the definition of future WAP applications and businesses, which can be done on a WAP gateway server in the right conditions. Using a short message hosting entity to deliver Internet content is of little practical value, but using a WAP gateway server to accomplish the functions of a short message center is a good idea, and telecom operators should welcome this option. It can be expected that a WAP gateway server may be assigned a greater purpose in the future and become a comprehensive gateway server.

5. Concluding remarks

The openness of WAP protocol makes the connection form of WAP Gateway server and mobile network can be varied, which lays a foundation for improving the traffic of WAP gateway server, and also ensures the flexibility and diversity of design, development, installation and operation. At the same time, the WAP gateway server can be given a variety of functions under the appropriate conditions, and its application mode changes with the development of technology and market.