The Common Gateway Interface (CGI) is a programming interface that enables a Web
server to communicate with an external program.
CGI programs generally are small and are written in a script or high-level language.
They reside on a server to act as the
interface between the Web browser and the content server.
When a Web browser accesses the
Uniform Resource Locator (URL) of a CGI program, the Web server executes the CGI
program. Typically, the CGI program starts a session with a database or application
server, which in turn processes the request from the client and returns the result
to the browser by way of the Web server.
CGI is a set standard and is easy to use. It is supported by almost all
major Web servers and supports many different
programming languages such as Perl, C, C++, Visual Basic, Java, and Shell.
Purely CGI-based applications need repeated
interaction with servers in order to provide interactivity with the user.
SAS/IntrNet software provides two programming tools that are based on CGI
technology. Neither requires any CGI programming skills--our tools
handle all the details relating to CGI,
the communication of parameter values from the HTML page,
and the returning of results to the users' browsers.
Application Dispatcher. The Application Dispatcher is a set of components
that enables you to use
the Web browser to run any SAS program that can be executed in batch mode.
The components of the Application Dispatcher are
- the Application Broker (the CGI program)
- the Load Manager
- the Application Server (the SAS compute server).
A new copy of the Application Broker is started each time that a client
sends a request. The request is routed by the Load Manager to an available
Application Server (you can have a pool of Application Servers).
The Application Server runs
a program that is associated with the request and then returns results back to
the client.
htmSQL. htmSQL is a CGI program that enables you to perform SQL processing from
a Web page. You provide an input file containing SQL statements that are embedded in
HTML and htmSQL directives; htmSQL performs updates and queries on your data source and then formats any
results using the HTML in the input file.
A copy of htmSQL is run on the Web server for each request that a Web
client sends. The only software that htmSQL requires for the Web client is a
Web browser. htmSQL does all of its processing on the Web server.
SAS Design-Time Controls. SAS Design-Time Controls are add-in components for your HTML editor that help you to easily add SAS content to your Web pages. With SAS Design-Time Controls, you use the user interface of your HTML editor to insert a control into your Web page. The control presents a dialog of choices and settings. When you invoke the properties dialog for the control, the control makes connections to the SAS server. After you make selections and close the dialog, the control writes the appropriate SAS content onto your Web page.
If the control is set to generate static content, then SAS processing is performed when the control is saved and not when the Web page is browsed. If the control is set to generate dynamic content, then properties are set when the control is saved and SAS processing is performed every time the Web page is browsed.
SAS Design-Time Controls use the HTTP protocol to connect to your Web server, which runs the SAS/IntrNet Application Broker (the CGI program). The Application Broker contacts the Application Server, runs the requested program, and returns the HTML.
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Java is an object-oriented programming language that you can use to create
Web-enabled programs known as Java applets. A Java applet consists of two parts:
- an HTML page that specifies which Java applet to invoke
- a set of Java classes that contain the programming logic.
When a Web server returns the HTML page to a Web browser, the browser
reads the applet information and requests the applet classes from the Web
server. After these classes are downloaded, the applet is executed based on any
user input.
SAS/IntrNet software provides the following Java programming tools, which are available from the SAS Drivers for JDBC and SAS/CONNECT installation package on the SAS Client-Side Components CD Volume 1:
SAS/CONNECT Driver for Java. This driver consists of the Java classes that enable you to communicate with a SAS/CONNECT server.
Tunnel feature. The tunnel feature is an optional CGI tool that enables you to locate your SAS server software on a machine other than your Web server.
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