OpenEdge Getting Started:<br />WebSpeed Essentials WebSpeed components

The components of the WebSpeed environment are the WebSpeed Workshop, the WebSpeed Messengers, and the WebSpeed Transaction Server. The WebSpeed environment can also include a NameServer, which can support both AppServer and WebSpeed transactions.

A default WebSpeed installation provides one predefined WebSpeed broker and one predefined NameServer. You can use these predefined components as templates from which you create and configure additional instances of the WebSpeed broker and, if needed, the NameServer.

WebSpeed Workshop

The WebSpeed WorkShop contains the tools that you use to develop and test WebSpeed applications. The default WebSpeed Workshop installation also includes a version of the WebSpeed Transaction Server scaled to support a single developer’s activities. The Workshop includes the following:

AppBuilder — The AppBuilder is a multi-purpose application development environment that supports a broad, integrated range of application and development options. You can use it as a visual programming environment to create character- or GUI-based client/server applications. In addition, you can use the AppBuilder for WebSpeed to create HTML-based Web applications.

The AppBuilder only runs in Windows platforms. You can configure it to work with a WebSpeed Transaction Server installed on a separate UNIX machine.

WebTools — You use the browser-based WebTools to access information on your server, such as the status of CGI Variables. You can also access database information, use the WebSpeed File tools, and access virtual system table data. You can use the Scripting Lab to write and test WebSpeed code, such as HTML that includes Embedded SpeedScript, and send operating system commands. With the Editor WebTool, you can create, open, save, and print files; check syntax; and compile code.

PRO*Tools — PRO*Tools is a set of utility programs that are useful for developing and running OpenEdge applications. For example, one of the PRO*Tools allows you to edit your PROPATH. The Color Changer, Screen Scaling Utility, and ProtoGen PRO*Tools do not apply to WebSpeed.

WebSpeed Transaction Server

The WebSpeed Transaction Server consists of the processes that handle the server-side activity of your WebSpeed applications:

WebSpeed agent — An application process that can execute Web objects, perform database transactions, and dynamically merge data into HTML format. The agent is the standard character Progress 4GL client running in batch mode.

Note: The agent process is inherently stateless. This means that the agent is only busy when a request is being processed. It will be idle at all other times.

WebSpeed broker — An application that can do the following:

For information on running WebSpeed from a client other than the HTML client (for example, an ActiveX page or a Java application), see the “Interfaces” area of the PSDN WebSpeed library at http://psdn.progress.com/library/webspeed.

Manage connections between clients and a pool of WebSpeed Agents.

Maintain the status of each agent in its pool and dynamically scale the number of agents according to changing demand.

Note: If you start a WebSpeed broker without specifying a username, the Broker inherits the account that the AdminServer is using. This is generally the system account, which might not have access to network drives.

WebSpeed Messenger

The WebSpeed Messenger listens for WebSpeed requests coming in to the Web server. The Messenger asks the NameServer where to send each request. Alternately, the Messenger can bypass the NameServer as described in the "NameServer" section. The Messenger then handles the transfer of data between the Web server and the WebSpeed Agent. There are Messengers for use on different Web servers: a CGI Messenger, an ISAPI Messenger, and an NSAPI Messenger.

There is also a Messenger that works with Microsoft’s Active Server Pages, the WSASP Messenger. Using the WSASP Messenger, you can call out of an Active Server Page to a WebSpeed application.

The WebSpeed Messenger always resides on the same machine with your Web server. Because the Messenger is not itself an OpenEdge application, it is sometimes the only part of the WebSpeed environment installed on a Web server machine. This is sometimes incorrectly described as a “Messenger-only deployment.” Your WebSpeed applications cannot run without a WebSpeed Transaction Server. “Messenger-only installation” is a more appropriate term for this setup.

NameServer

The NameServer is a basic part of the OpenEdge architecture. It maintains a list of available AppServers and WebSpeed Transaction Servers. Those servers register the application services that they provide with the NameServer. The NameServer can then direct client connection requests to a broker that supports a requested application service. This provides scalability and location transparency to your applications.

The NameServer can also provide load balancing and fault tolerance for OpenEdge server applications. Load balancing allows you to balance client workload among multiple brokers that support the same application service (that is, the same set of procedures and resources). This ability makes the NameServer very useful in deployed applications that handle large volumes of requests.

The NameServer works through the UDP network protocol. For various reasons, some network administrators might not want UDP on their networks. To accommodate this preference, the OpenEdge architecture includes a “No NameServer” connection procedure. If you employ the “No NameServer” connection procedure in a WebSpeed application, you must configure the WebSpeed Messenger to point directly to a specific WebSpeed broker. This approach can limit the scalability of your application. For more information, see Chapter 2, " Configuring WebSpeed."

Language support

The WebSpeed development environment also includes a programming language, SpeedScript, and a number of pre-coded conveniences, such as global variables, preprocessors, and APIs, to simplify your development. For more information on these elements, see Chapter 3, " Tools and Progress 4GL Support."