Abstract: Push technology in mobile network - WAP PUSH has both information to send active, timely features, and has the advantage of receiving information in any time, thereby having good application prospects. Introduced the WAP PUSH system framework, push agreement and push mode;
The application instance of the WAP Push in the Message Notification System illustrates the information push process, which gives the system model, workflow, and message format.
Keywords: wireless application agreement, promotion technology, push agent gateway, service instruction
I. Introduction to WAP Push Technology
1. WAP Push concept
The so-called push technology is a technique based on the customer server mechanism, which is actively transmitted to the client to the client, which is usually subscribed in advance. The most important difference is that the former is transmitted by the server by the server.
Information, while the latter is actively requested by the client. The advantage of PUSH technology is the initiative and timeliness of information, and the weakness is poor accuracy.
Push technology has not been achieved in the Internet because of many aspects. Fixed devices such as fixed networks provide users with sufficient resources and capabilities to find information , so users usually use the window of browsing information, not passive information recipients.
. The requirements for fixed network users for information accuracy are far more than their timely requirements.
In the mobile network, the user cannot find information as soon as the fixed network is as convenient, if there is a network bandwidth, mobile device capabilities, and high tariff standards, users can easily find information as in fixed nets, if important information is active in time to user movement The equipment is undoubtedly greatly convenient. Mobile communication
The advantage is that the mobile device can receive information anytime, so the PUSH technology can be largely displayed in the mobile network, and WAP PUSH is the product of PUSH technology and mobile communications that binds to avoid shortcomings.
WAP Push is a PUSH technology applied in a mobile network It has the characteristics of the characteristics of general PUSH technology and a mobile network. Its system framework, the use of protocols and services is very different from PUSH technology on fixed network.
2. WAP Push System Framework
The WAP PUSH framework mainly includes push initiators (PI: Push Initiator), pushing proxy gateway ppg: push proxy Gateway PPG: Push Proxy Gateway 和PPG: Push CLIENT PC: Push Client three functional parts. PI is located in the Internet, and the protocol used by the PC in the WAP field, the PI and WAP clients is different, and a protocol conversion gateway is required in the middle is PPG. PPG By Push Access Protocol (PAP: Push Access Protocol)
Communication with PI, the data transfer task that pushes information to the customer by pushing the spatial transport protocol (Push OTA: Push Over-air).
PPG completes most of the work in the push architecture, including access access from the Internet to mobile network, and all works such as certification, security, client control. In summary, the main services provided by PPG include:
· The logo, authentication and access control of PI;
· Some analysis of the push content, and error correction is detected according to the data type definition (DTD);
· Customer addressing and information transmission;
· Protocol conversion between PAP and Push OTA;
· In order to improve the transmission efficiency in the wireless channel, compress, compile information, etc.
In addition, PPG can also achieve multicast and broadcast through alignment mechanism, which is to map certain address alias to multicast or broadcast operations, and specific schemes can be determined by the system implementation. Different clients, their ability is different, and PPG is responsible for responding to the Customer capacity query request for PI to facilitate the constructive content format of different clients.
3. Push agreement
PAP is a communication protocol between PI and PPG, which uses the Scalable Markup Language (XML) as a description language of the message, completes data transmission by simple request response mechanism. PAP can be in a variety of communication protocols (including Hypertext Transfer Protocol (HTTP), Simple Mail Transfer Protocol
(SMTP), etc.).
Push OTA is a simpler protocol layer running on the Wireless Session Protocol (WSP), responsible for data transfer from PPG to customer agents. Push OTA can use two WSP layer services for connection-oriented sessions, pushing
Delivery, you need to have an activated session context during the PPG and the client; for the connectionless push, the communication is completed by the reserved port.
4. Push service method
A Service Indication (Si: Service Indication) and service loading SL: Service Load ics is defined in the WAP push agreement to give users and network operators more choices. Service indication is the instructions and related information of new information
The Universal Resource Identifier (URI) is pushed to the user, and the user selection is to process information immediately or later. The service load is to push the URI of a service to the user, and the client automatically uses the PULL technology to start the service according to the URI. The difference between the two services is whether the user is involved in push
Send information processing. SL is transparent to the user's processing of the push information, while Si is indicating the user, please select the subsequent processing.
Second, WAP PUSH Application Example
Push technology is most commonly used in the message notification system, and the notification system can be applied to a variety of industries, such as securities, banks, and business websites. This article is based on the notification system model as an example to describe the working principle of WAP PUSH technology. 1. WAP Push Notification System Model
The WAP Push Notification System model is mainly composed of a database, and the WAP server (also PI), PPG, and mobile browsers. The database is mainly composed of address information tables, and the WAP server stores the notification content in the form of a wireless tag language (WML) web page, and the WAP server
Also act as a PI. PPG receives, encodes, and protocol conversions after receiving the push message. The mobile browser is used to receive push messages and browse notification pages.
2. System workflow
When adding new notifications, managers add notifications to the WAP server through the human-machine interface, and input the condition to the information address table to search for the notification objects and their mobile numbers. The address information table contains information booking. WAP server get
When the object address table is notified, the SI message is sent to the PPG. The SI message includes address tables that inform WML links and push objects. The specific sending steps of Si are as follows:
(1) PI Sends a Si to the mobile client through the PAP protocol command PPG, and the PI provides an appropriate message to the SI and the URI pointing to the notification service;
(2) After the PPG is authenticated and formatted, it is compressed into a binary message suitable for wireless links, and sends to the specified user using the PUSH OTA protocol;
(3) After the mobile client receives this push information containing Si, the message in Si is displayed to the user client to provide two options to the user: Access or postpone access. This process takes immediate access as an example;
(4) Mobile Client According to the URI carried by the SI, the mobile client issues a request to the PI, the traditional PULL method; (5) PPG is protocol conversion, and use hypertext transmission The protocol request method (HTTP GET) issues a text request to the WAP server;
(6) The WAP server sends a WML file to the PPG in response to the HTTP GET request;
(7) PPG compiles the WML text file into binary code to pass to the client;
(8) The client receives the WML file and browses the conference notification.
3. Push message format
Push mess generally includes three parts: control entity, content entity and ability entity 6 . In multipart messages, control entities include all related control information, content entities including content transmitted to wireless devices, capability entities include user agent structure (USP)
ROF) Customerial Capacity. The control entity contains the XML document of the PAP unit, and each PAP request and response must have a control entity. The type of content entity can be any type as long as it is described by the Multi-Use Internet Save Extension Protocol (MIME). The content entity is only included in the push
In the message. The capability entity contains the power of the wireless device or user agent, if there is no existence, determine the ability to wireless devices or user agents by default. The following is a SI message sent to PI to PPG. If the content entity is changed to the content of SL, the message becomes the SL message.
Content-type Multipart / Related Type = "Application / XML"
Content-Type Application / XML
<DOCTYPE PAP PUBLIC "- // WAPFORUM / / DTD PAP 1.0 // en"
"Http // www.wapforum.org / dTD / pap_1.0.dtd">
Content-Type Application / XML
<DOCTYPE SI PUBLIC "- // WAPFORUM / / DTD Si 1.0 // En" "http // www.wapforum.org / dtd / si.dtd">
Created = "2002-09-01T15.23.15Z"
Si-expires = "2002-09-05t00.00.00Z"
YOU HAVE A New Meeting Notice.
Content-Type Application / XML
XMLnsprf = "http // www.wapforum.org / uaprof / ccppschema1.0 #"> < - WAP Browser Vendor Site Default Description of Wap Properties -> 4. PPG processes the flow of Si messages PPG is the key to the entire push process. PPG first to identify the legality of PI, identifying the PI method mainly: using the session layer certification (such as Transport Layer Security (TLS) and Security Sliding (SSL) protocol) and object layer authentication (signature and encryption), then According to Si The DTD format checks the syntax of the SI, and finally sends a compact binary code format Si message according to the client address provided by Si. If it is not possible, the reason for the send failed will be sent back to PI. PI To be able to send the same message to multiple recipients, and should not submit multiple identical push messages to each recipient. After the PI submits a message with multiple addresses, the PPG must contain each recipient in the result notification. Client address is an important task for PPG. PI uses a specific text address format to identify the client, the PPG must convert these addresses into the form that can be transmitted in the wireless network; in contrast, the PPG must convert the address specified in the wireless network into text address form, used to the same PI communication. The client address consists of a client identifier and a PPG identifier. The client identifier mainly has two types of user-defined identifiers and device addresses, which are all composed of two parts of the identifier itself and address types. The system uses the device address method, ie the mobile phone number identifier, its format: WAPPUSH = 13818115588 / TYPE = PLMN @ppg. Carrier. COM Among them, the client identifier is mobile phone number 13818115588, the type is a public land mobile network (PLMN); the PPG identifier is PPG. Carrier. COM. PPG is looking for a PUSH client based on the address. Three, junction WAP PUSH technology combines the advantages of PUSH technology and the characteristics of mobile communication services, and has good application prospects. Applying PUSH technology in the field of mobile communications can produce many telecom value-added services This includes mobile to send emails, at any time, weather forecast , News and location related services, etc. The common feature of all of these services is that the user's timely requirement is relatively high, and the user wants to be able to obtain the service anytime, anywhere, such as mobile devices such as mobile phones, PDA. The notification system in this article is an application example of WAP Push, which can Enough to send a notification to the user, with great practical value. However, WAP Push technology still has some problems to be solved. If the information is authenticated and certified, the accuracy of information is accurate, how to avoid spam, etc. How to solve these problems will be the key to the success of WAP PUSH technology. In addition, with the development of GPRS technology and 3G wireless communication technology, the bandwidth of the wireless channel will gradually increase, and WAP PUSH will also further push multimedia information.
