Abstract: This article in the automobile network complex stratification structure and in many kinds of network protocol coexisting foundation, proposed that carries the multi-layered network take the vehicle as to apply the environment, take the browser as the central application model, and discussed one kind the network embedded browser to design based on this model Che Zai and to realize in detail.
Key word: Automobile network; XML; Browser; B/S model; News mechanism
Now, vehicles’ control to high accuracy, high secure development, automobile profession trend intellectualization, network. During this process, the automobile network is playing the vital role, the CAN main line and the LIN main line is the important automobile network main line.
But, when the automobile develops into an information terminal gradually, actually has the network architecture lag the situation, during the Internet uses B/S generally (browser/server pattern) three network architecture, the vehicle carries the network also to occupy simple C/S (client side/server pattern) two network architecture stage. In view of automobile network standard not unified, connection confusion, management difficulty, network system lag condition, may introduce in the current Internet the widespread use mark language (ML Markup Language) and the B/S network architecture. The mark language is one cross platform exchange of information way, uses the mark language in the automobile network, may solve between the different intelligent node the standard not unified, the connection different and the cross level exchange of information question. The B/S network architecture may solve the condition which well node information-handling capacity is insufficient, everywhere manages the ability formidable main equipment the majority of information processing through the network submission, even connects the large-scale main engine through the Internet, but from the equipment needs merely through the browser software analysis main engine processing result.
But the present use mark language and the B/S network architecture most major problem is lacks in view of the vehicle carries the network the embedded browser system. The general embedded browser uses the HTML language to take the information the carrier, but the HTML language has the content and the displayed information is not divided, shortcomings and so on description structure data ability difference. In addition, general embedded browser to real-time data processing and demonstration ability insufficiency and so on, is also the question which needs to solve. Therefore, designs one section face the multi-layered automobile confined network, carries the network information processing need in view of the vehicle, the use may expand mark language (XML) is the information carrier, may simultaneously demonstrate that the automobile interior real-time information and the Internet information’s special-purpose embedded browser, has the very vital significance.
Embedded browser system design
According to automobile network own characteristic, the vehicle carry the network browser’s special request, as well as in module high cohesion and module low coupling request, carries the network browser’s design the vehicle and realizes divides 5 modules, respectively be expansion mark language module, network turning on and information buffer module, mark language analysis module, layout module, user interface module.
The expansion mark language module mainly carries the network according to the vehicle the characteristic, while maintains with HTML language compatible, uses the XML technology to carry on the expansion for the HTML language, defines one kind to carry the network based on the vehicle mark language EXML, the expansion mark language module by the module way definition. The network interface and the buffer module mainly uses in simultaneously connecting the automobile confined network and the Internet, gains the automobile real-time information and the widespread Internet information; The documents analysis module is in carries the mark language which based on the vehicle the network in the embedded browser uses, two kinds, respectively are HTML and EXML, including the HTML language the basic label. Therefore, uses the identical resolver in the language analysis module, carries on the analysis to two kind of mark languages, and will analyze in result existence memory; The documents layout module mainly uses in determining that each page element the size, the page element divides into the text, the image and the graph two kinds, the image and the image size may gain directly, the text size receives the label and the attribute influence; The user interface display module’s function demonstrates the user interface, including: Work area, title block, label fence, real-time label demonstration area and so on. Between them relations as shown in Figure 1.
Carries the network based on the vehicle the embedded browser’s module design
Network interface design
The network architecture module divides into two parts, namely Internet connection and real-time network interface.
Internet connection primary cognizance Internet turning on function. First is establishes server’s connection through the network protocol, then requested to the server transmission, the server confirms requested, and is responsible for the document which requested the browser through the network protocol transmit for the browser. Concrete process as shown in Figure 2.
Figure 2 Internet connection working model
The vehicle carries the confined network interface mainly to realize the browser to the automobile real-time information gain. The browser and the automobile node correspondence’s way has two kinds: Reply type correspondence and passive form correspondence.
In the reply type course of communications, the vehicle carries the network embedded browser to gain some parameter request to the node transmission, the node basis request by the EXML news form transmission real-time information. After the browser receives the information, through analysis module analysis, refresh data and refurbishing demonstration.
Under the passive way, the node contains the real-time information according to certain time period transmission the EXML news, the information which the browser interception link firing in bursts sends. Once has the recent news to transmit, browser on notice analysis module refresh data, and refurbishing demonstration. The EXML news’s form is as follows:
<msg>< information category > parameter value < \ information category >< \ msg>
Analysis module design
The documents analysis module is overall system’s base module. In carries the network based on the vehicle in the embedded browser, we act according to the vehicle to carry the network the application practice to carry on the HTML language the expansion, has formed the EXML language. The EXML language is the XML language, in the vehicle carries in a network system’s application, therefore may use the standard to the EXML language’s analysis the XML language to analyze the technology. The XML analysis way also has two kinds: Based on event driven analysis way (SAX way) and based on tree’s analysis way (DOM way). The SAX technology carries on processing during response event’s to the mark text, does not preserve the middle construction of data. What the DOM analysis way uses is based on tree’s analysis way, and uses XML Schema to confirm. This way after analyzing the XML documents produces a documents tree, the application procedure may traversal, the search, edit this documents tree.
In actual Che in Zai the network, the embedded browser not only needs to carry on the browsing to the static hypertext information, but also needs to send in the lower node the data carries on the real-time processing, the demonstration and the preservation. This needs to preserve a complete analysis construction of data in the memory, by facilitates the data the real-time renewal and the demonstration. Therefore uses the DOM analysis technology to conform to the vehicle to carry the network the application request.
In the documents analysis, after following first outside, the label, the attribute, arrives at the order which first analyzes first. First processes is in the nesting outer layer the label, then processes label’s attribute; Front regarding the identical level’s label, analyzes first. Obtains the nesting information through a label storehouse, to label’s father label indicator evaluation. Concrete analysis algorithm as shown in Figure 3.
Figure 3 analysis module algorithm flow chart
Layout module design
HTML language to mark in definition including two kind of information: The data message and the displayed information, but are indicated in the XML language definition’s mark language documents to the information structurization, not including displayed information. In processes to the XML language demonstration, may use CSS (Cascading Style Sheets) the style to increase the extra displayed information only, or transforms through xCBL the XML documents the HTML form the document, then pays to give the browser again, by the browser demonstrated transforms result.
The EXML language including the displayed information, cannot decide the page element the demonstration position. Will illuminate through CSS and the XML definition demonstration’s way becomes browser’s high resources to take. Therefore, uses the subject file definition each page element in the embedded browser the demonstration position.
The page element’s layout divides into the dynamic layout and the static layout two kinds, because the HTML mark contains the demonstration data, when analyzes the HTML compatible mark uses the dynamic placement algorithm, and the mark itself decides the layout through the mark attribute. When to other label layout, carries on according to the demonstration resolution and the use custom to the element layout defines and stores up in the subject document. The browser when processes these label’s layout, first reads the subject document to obtain the layout information, then carries on the layout according to the label content.
The documents layout module will be responsible after in the resolver processing mark language documents the element in the browser work area the appropriate position demonstration. Page’s layout divides into the following 3 steps:
(1) gain page element. The page element the form memory which marks by the EXML documents, the browser analysis module through to marks the language the analysis, will mark the modulation information storage which contains in the label construction of data. The layout module first in order reads the label information.
(2) transfers label’s layout function. The layout module realizes through the binding layout function to the layout function transfer. The binding element’s layout function is realizes through the search layout function tabulation. The layout function tabulation is a storage label name and the corresponding label layout function address two-dimensional table. Layout module transfer layout function, element basis placement algorithm layout to hypothesized demonstration construction of data. If label’s name in the label layout function tabulation, the care label does not belong to the expansion mark, through expansion mark function demonstration.
(3) completes through the demonstration window by the layout mark demonstration. Sometimes because in the embedded application display monitor’s resolution limit, cannot a demonstration all element. The layout module according to the display monitor resolution and page’s size decision demonstration element quantity.
Interactive contact surface design
The interactive contact surface is also the browser contact surface module, the primary cognizance browser’s main frame demonstrated that provides the label browsing, the subject to demonstrate, as well as processing with user’s interaction.
In view of the different hardware platform even same hardware platform different size’s liquid crystal box, the interactive contact surface must have the change. The probability and configurable are also the embedded browser must.
In order to adapt to the different hardware circumstances is the different resolution screen specially, in carries the network based on the vehicle in the embedded browser design process to use the multi-subjects, realizes may transplant and may dispose. The thematic approach is refers to the use configuration files to realize the user interactive contact surface to the visualization system to carry on the graph effect disposition one way. Carries the network based on the vehicle the embedded browser’s subject is to may dispose the thematic approach the expansion, not only may dispose the contact surface using the subject document the color style, the display mode, but may also act according to the different screen’s resolution, adjusts the contact surface element conveniently the size and the layout.
Considered system’s probability, configurable and system’s time spatial behavior, carries the network based on the vehicle the embedded browser’s graphics system to use the microwindows embedded graphics system. This is an open sound code embedded GUI software, the goal is introduces the modern graph Windows environment in the bantam platform.
Double-decked news mechanism design
Because the vehicle carries the network the complexity, the browser must process the information not only originates from the Internet, but may also come from the first floor network the real-time news which transmits through the gateway. From Internet’s information often is the static state, carries on the renewal according to user’s request, but from the first floor network’s real-time news is dynamic, is very high to the timely request. The use monolayer’s news circulation mechanism will cause the real-time information not to be able to demonstrate promptly that or the interactive news will take the massive system resources, therefore, will use the double-decked news mechanism in the browser.
Is realizes in the double-decked news mechanism through the news grouping. First divides into the news the real-time news and the interactive news two groups, the real-time news expressed that the news needs the real-time processing, the interactive news expresses the non-real-time interactive news. And, the real-time news arranges into a group according to the different priority, the system automatic reduction priority high news, retards the priority low news. The interactive news group’s news is not divided the priority, the system first inspects the real-time priority group news syntagma array in one time whether to have the news which takes, if has, then chooses the highest priority news to carry on the response, the response finished the elimination real-time news to take the symbol. If for spatial, then changes over to the interactive news circulation. The concrete news round-robin algorithm schematic code as follows shows:
Msgloop()
{
while (1) {
if (msg_select_hmsg()==-1)
// does not have the real-time news arrival
{
GrSelectNextMSG();
// gains in an interactive news formation’s under news
switch()
// acts according to the interactive message type choice message handling function
…….}
else
{
* (Rtmsg_msgarr [msg_select_ hmsg()] .func) ();
// chooses the highest priority real-time news to carry on the response.
}
}
The double-decked news recurrent structure’s essence is processes the interactive news group as the priority lowest news. The logical organization and concrete news response as shown in Figure 4.
Figure 4 real-time news priority judgment flow chart
Embedded browser’s in different embedded hardware platform application
Other may transplant the software likely to be the same, the embedded browser’s development uses the stratification structure, has reserved the standard interface according to the different network environment, and uses the standard C language to compile. Therefore, glances over the appliance to be possible to adapt day by day complex Che well Zai the network environment.
So long as provides the correspondence operating system’s hardware actuation, may use in the different hardware platform.
Table 1 is the operating system which and the compiler tabulation supports through the test embedded browser.
Conclusion
Carried the network based on the vehicle the embedded browser research and development main achievement is designs and has realized one section face the multi-layered automobile confined network, in view of Yu Chezai the network information processing need, used XML is the information carrier, might simultaneously demonstrate the automobile interior real-time information and the Internet information special-purpose embedded browser. This browser may simultaneously demonstrate that the automobile interior real-time information and the Internet information, the versatility is good, can move in the different hardware platform. ■
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