PB-based C / S two-layer structure to smooth excessive web distributed applications, current status and development trend of enterprise application systems 1. Application status currently most application software systems are two-layer structure in the form of Client / Server, application installation In the client's computer, connect to the background database server through a LAN or WAN connection and sharing data, and store the original data or the processed data in the background database. 2. Development trend The current software application system is developing to distributed web applications; internal and external users can access new and existing applications, Web and Client / Server applications can perform the same business processing; Different application modules share logical components; new application systems can be extended through logic in existing application systems. This is the development direction of the current application system. (1) The advantage of the web application compares the basic elements of the traditional client / server application system and web applications, it will find that the web application has many advantages compared to traditional client / server applications (Table 1). Table 1 Client / Server Application and Web Application Comparison Content Customer / Server Application Web Application Network Protocol IPX / SPXTCP / IPNETBEUITCP / IP Run Environment Windows'95NT, MacunixBrowser client configuration Database driverrun-rime application (fat client) ZERO (thin Client) Therefore, based on web technology-based construction applications, you can significantly reduce system maintenance and submission, users can also benefit from unified interfaces and simplified operations. (2) Web Application Development Due to the traditional WEB application's HTTP protocol is an impermanent connection protocol, it is unable to get real-time data on the browser, which cannot process data and accurate transactions in real time, and cannot Construct OLTP (online processing) app on the web. Therefore, a new communication protocol must be provided between the browser to the application server. In response to this market demand, major mainstream database vendors, such as Sybase, Oracle, and browser and web server providers, such as Microsoft, Netscape, etc., have been launched by Web Server and browser extension technology, and database manufacturers provide implementation. Database Access Application Server. In this way, the web application extends from the traditional client / server two-layer architecture, the three-layer or multi-layer architecture of the browser / web server application server / database server. The extension of the Web platform can be divided into two categories of web server-side extensions and browser-side extensions. The main web server extension technology is generally implemented by providing a application server that supports CGI, ISAPI or NSAPI extension criteria. Among them, CGI (Common Gateway Interface) is a universal web server extension standard, while ISAPI and NSAPI belong to the extension specification independently defined by vendors, only for their respective specific web servers. The application servers provided by database vendors generally support these extension standards to ensure openness. At this point, Sybase's products are particularly highlighted (later in detail later). The basic principles of extension technology based on the application server are as follows: Application Server By extending the web server, enabling the browser to call the function provided by the application server via HTML or other similar scripting language, thereby expanding the application area of the browser and web services. . When the browser introduces a URL with the application server function, the web server calls the function of the application server through standard extension technology, completes the application of the script, passing the parameters, and results formation, and finally the execution result of the application server HTML's format is passed to the browser.
Using objects on the application server or web server, access to the background database is implemented through these objects, so that each transaction can be better controlled to get a faster access speed, and you can implement the OLTP application on the web. Second, SYBASE Web Solution With the rapid development of web technology, the demand for web applications based on Web technology is also growing rapidly. Sybase as the industry-leading database product provider, keeping up with the development trend of Internet technology, and continuously introducing new application products. Sybase proposed E-MAP strategy, "Sybase E-MAPTO E-Business" is a complete web solution. It depicts how to build an e-commerce (web application) using the easiest way, you can guide you quickly, efficiently and easily convert existing services into e-commerce models, and do not need to do way to operate existing business. Too big change. Sybase E-MAP for PowerBuilder is a component of the Sybase E-MAP policy. It is a shortcut that developers rapidly port existing PowerBuilder to web, which can not only support current business needs, but also adapt to new E-commerce application. Sybase can meet the security, scalability, and reliability of important application servers. Many companies use Sybase's application server Enterprise Application Server, referred to as Easerver. It is in a leading position in similar products. 1. Easerver supports all major component type Easerver has integrated business logic submission capabilities, this feature is a key factor that extends the Client / Server application to the Web. It can handle all major setup types, including PowerBuilder, Java, COM, CORBA, and C . Therefore, only Easerver can allow you to use the NVO components in the COM component in the Visual Basic app, and only Easerver can support existing components and other interactions between C , CORBA, and Java components. 2, Easerver can connect all major customer type Sybase Easerver managed logical components that can be called by many types of clients, including PowerBuilder, Java, COM, CORBA, and C , and even HTML. 3. Continue PowerBuilder investment If you develop the current system using Powerbuilder, then Sybase's E-Map for PowerBuilder is very important. First, the technology of using PowerBuilder can still be used to develop e-commerce applications. Second, E-MAP can keep the value of PowerBuilder developers in the company. In summary, Sybase E-MAPFOR POWERBUILDER pointed out a road to e-commerce, but there is still a lot of way to go to e-commerce, which is also the E-MAP policy contains training, consultant services and technical support. s reason. The following will be specified in a detailed description of the PB programmer's web application. Third, the traditional PB's two-layer structure web road here mainly introduces the traditional PowerBuilder programmers how smoothly is smooth to the web-based three-layer architecture, which is to establish a company solution using Easerver and other relevant Sybase tools. You can use PowerJ to establish a distributed application, but this article will focus on how to use PowerBuilder7.0 to establish a distributed application. With the launch of PowerBuilder 7.0, this work is very simple, Sybase is quite successful in PowerBuilder and Easerver integration issues.
It is a very easy thing to transfer the PowerBuilder components and the techniques accumulated by Powerbuilder to the web or other distributed environment. The following will focus on this problem. Before discussing, first talk about the difference between Easerver and Jaguar CTS. Easerver (Enterprise Application Server - Enterprise Application Server) is a new name after Jaguar CTS and PowerDynamo integration. These two products complement each other, JAGUAR CTS provides component transaction support, and PowerDynamo uses it to provide scaled dynamic HTML support for extension capabilities of various major web servers on the market. In this article, Easerver refers to the JAGUAR CTS and PowerDynamo-integrated products, but it will focus on the JAGUAR CTS, ie, component. The following will be discussed in detail how to access data in a third-party database in a third-party database (Oracle 8 in this article), and the discussion component is completed by using the JAGUAR CTS JDBC / ODBC Bridge Establish several main links in Java applications, including connecting to the server Easerver, instantiation, method calls, etc. of Java components. First configure Easerver, which is very important, only the correct configuration of Easerver can provide component services to the application, otherwise even if successful PB components cannot be called in the web. 1, the setting of environment variables For environment variables ClassPath, add two ClassPaths (identity system):% jaguar% / html / classes;% jaguar% / java / classes environment variable PATH: Add the following directory: C: / Program Files / sybase / shared / suy / jdk118 / bin. Suppose Sybase is installed in a C: / Program Files / Sybase directory. 2. Configuring the Listener Configure the purpose of the listener is to enable the other machines outside the machine to access Easerver, which is very important for the team development. Of course, if you don't want other machines to access Easerver, you can cross this step. The default setting of the listener is "Localhost". To change this default setting, you should start from Jaguar CTS, enable Jaguar Manager, which is selected from the menu, and select "Tools│Connect│Jaguar Manager". After Jaguar Manager starts, you can log in with the default user, ie User name is jagadmin, Password is empty, Host Name is Localhost. After the login is successful, find the listener address "Sybase Central / Jaguar Manager / Servers / Jaguar / Listener" by following the path. At this time, a listener address table can be seen on the right side of the screen. Although we actually use only two addresses, it is still a corresponding change for all addresses: Right-click each listener address and select "Listener Properties", and then send it to your machine's IP address in the "Host" domain. TCP / IP name; if you use WinNT, Win98 or Win95, you should fill in the computer name you use in the network settings in this domain. The JAGUAR CTS then looks for the corresponding IP address when the server is started. After all of these work, close the Jaguar Manager, then restart the JAGUAR CTS server.
