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Position:IcFull.com » IC Electronic information » Category: A

IC Electronic information

A WAP browser embedded design

In Electronic Infomation Category: A | on April 13,2011

Abstract: In order to solve the traditional browser portability is poor, low efficiency problem, design a WAP-based embedded browser. Compared with the traditional browser, the browser is divided into various modules at the same time remove some useless module, and HY5DU283222Q-5 datasheet and using java language for each module. Analyzed the layout analysis module and HY5DU283222Q-5 price and the module design. Experimental results show that the browser the browser than the traditional high-portable, very good platform ported to ARM, efficiency has been greatly improved.

Complete realization of the main browser download page, analytical web scripting language, and HY5DU283222Q-5 suppliers and finally a reasonable task to the user. WAP (wireless ApplicatiON Protocol), the wireless application protocol, also known as wireless Internet protocol. WAP protocol: Users simply use a WAP-enabled mobile terminals such as mobile telephones and the wireless client, the computer will be like IE, search dogs and other PC browsers, view the various pages of information, display Intemet content. WAP formed by a series of communication protocols. WAP protocol stack used hierarchical design, application development so as to provide a scalable and extensible environment. Each stack are defined the corresponding interface. Layer of protocol can be used, but also by other services or applications directly. WAP protocol layers shown in Figure 1.


layers of Figure 1 WAP protocol

This paper analyzes the WAP browser, the main function of the embedded module, workflow, design, and layout analysis module analyzes the modules, and finally WAP browser, future development prospects.

1 embedded browser overview

General, the embedded browser includes two functions: it supports, such as HTTP, WAP transport protocol; the second is able to transport protocol running in embedded devices, and a markup language according to user features and Requirements for handling the various situations.

1.1 browser function module

Shown in Figure 2, in this design, the browser main modules are: drawing module, layout module, data processing module, DOM tree module. The aim is to determine the layered architecture, so that each layer and adjacent to communicate, and do not interact with non-adjacent, in line with software engineering "high cohesion, low coupling" thinking. Where:


Figure 2 modules

Drawing module: the use of analytical results generated XML document DOM tree and the layout of the module (RENDER) tree, while the browser window and generate the appropriate controls and displayed on the screen layout.

Layout modules: the generated DOM tree, get information about the style, such as center, font, etc., organized layout, display XML elements and so on. Data processing module: the data processing module including the handling of XML and images. Visit website for analytical processing XML documents, including tables, pictures, text and generate the corresponding DOM tree.

DOM tree module: DOM (Document Object Model) is the XML file parsed results. It includes all the current XML document elements, element sub-elements, element attributes, element of style, elements of the events. In the object tree model, each node in the file are called attributes. And it is complete, the smallest details of the documents are allowed to model it and can access. It is also the least sensitive to the modification of a model.

1.2 web workflow

Data sent from a Web page URL request, submitted to the communication module, communication module are data, data processing module to parse. Generated DOM tree, and then the layout of the module based on the layout of DOM tree nodes sorting, while the layout of the information stored in the DOM tree, and finally drawing module will draw clients. Under normal circumstances, the browser that is drawing module rendering effects. Page access process shown in Figure 3.


Figure 3, page access process

2 embedded browser system design

In the embedded browser designed to consider the C / S (Client / Server) structure, namely, the client and server architecture. It is the software system architecture, which allows full use of the advantage of both ends of the hardware environment, the rational allocation of tasks to the Client side and Server-side to implement, reducing the system communication overhead. In this design, the layout analysis processing and text processing are in the server, and ultimately displayed on the client side.

2.1 analytical processing

Access WML file, start to read WML files, access to characters, to determine whether the "<" character. If it is to begin to determine whether a tag character. If this is the start tag for element attributes, such as attribute values ??and attribute names, etc., the property defined by the WML document DTD. That is, automatically determine a text format, picture format, table format, or other formats, according to the format of different types of analysis. Finally, the current status and parameter values ??stored in cycles until the end of the cycle to produce DOM tree. Specific processes shown in Figure 4.


Figure 14 analytical process

2.2 layout handling

The layout module called, is to deal with WML syntax and DOM tree, the tree each node is an object that contains all the properties of the object settings. Final submission to the drawing module, for processing by the drawing module, display page information.

2.2.1 Image Layout

Img element is a picture element. Under normal circumstances, img element src attribute value will be through the URL points to a picture, the picture is the need to display images, and layout will be given priority img wIDTh property values ??and the height of their property value, if the two attribute values ??are present, the value of their property in accordance with the corresponding values ??in the layout, display images corresponding attribute values; if only one property value, the actual photos of the property value scale, display pictures; If the img element does not have these two attributes, the typography Photo is the actual width and height; when only one attribute value or no width and height attributes attribute of the img element of the layout will be skipped, while the corresponding image URL will go to the download queue, waiting for the image download is successful, the current re-layout the page.

2.2.2 Text Layout

Figure 2 shows the layout layer is located between the analytical and mapping, semantic analysis is used to typeset the document content processing, Web content will be discharged in an appropriate manner on the display screen.

WML less control over text layout language, only the center, left and right alignment of 3 ways; followed by the expression of WML language control is weak, only em: strengthening (italics), STrong: add (italic) , i: italics, b: bold, u: Underline, big: large fonts (font increase the One), small: small fonts (fonts decreases One) and other 7 languages ??of expression.

3 Results and Analysis

This paper, for embedded Java browser supporting the design and implementation. System for the development of J2ME platform, communication protocol HTTP protocol did not take, but as the adoption of a WAP protocol stack to WML as the markup language as a form of data pages in the embedded browser for easy, rich multimedia information visit services.

In the simulation results, shown in Figure 5, the picture outside the network to access Baidu page, but also forward, backward, refresh the signs are that this application can be implemented in embedded devices. If the user in order to save traffic, you can consider switching to the minimalist version of the resolution process is not handled in the analytical picture, just simple analytical text. The HTML page, Baidu logo image is greater than the screen size, so the display after compression. In this design, picture download a full, able to fully display.


Figure 5 Baidu page

4 Summary

Pass the test, the modules of the portability of a good browser to solve the traditional browser portability problems as well as the relatively narrow bandwidth of the screen is relatively small problem. At the same time, the browser application for the special design of embedded systems, eliminating the need for some not practical, system efficiency and impact of redundant modules, portable, running efficiency.

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