Progress
Installation and Configuration Guide
Version 9
for UNIX
Client/Server and Progress AppServer In the Network Environment
The Progress client/server architecture fits naturally into a network environment, allowing clients and servers to run together in many different (heterogeneous) hardware and operating system environments. On a network, the Progress client and server processes are distributed to separate nodes where they communicate through a common network protocol. Some nodes run client processes, while others run server processes. One advantage of this is that adding users or databases has minimal impact on the machine resources used by others. Each has its own resources devoted only to its client or server tasks. Another advantage is that a single Progress application can take advantage of the strengths of a multi-machine, multi-operating system environment, without regard to differences in file resources on the separate machines. Remote Progress clients and servers interact transparently, regardless of the type of machine environment in which they run. The result is a cooperative application environment with many more possibilities for expansion.
Progress Network Support
Table 7–3 describes the network types that Progress supports.
Table 7–3: Progress Network Type Options For Progress Network Type (-N) Description SNA Allows some UNIX clients to access a Progress AS/400 server using the APPC protocol suite (Advanced Program to Program Communication using SNA Logical Unit (LU) type 6.2). For more information, see the Progress/400 Product Guide . TCP Allows client and server operations among UNIX and Windows systems that communicate using TCP/IP. In a Progress AppServer configuration, the client connection to the application server is always TCP. The Progress AppServer supports all of the client/server network types for the connection of the application server to the database server.
Sample Network Configurations
The following figures show sample configurations for Progress on a LAN. Your configuration might differ depending on your requirements.
Figure 7–6 shows the simplest Progress network configuration: a database server machine and application workstation. Although the figure shows only one database server machine and workstation, there can be more than one of each.
Figure 7–6: Simple Progress Network Configuration
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This configuration is a TCP/IP network without file servers. There are no shared resources except the Progress database. There is a hard disk on both the workstation and database server machine. A printer is also attached to the workstation. Progress is installed on each node.
A workstation in this configuration often supports multiple users and clients (for example, a system with multiple terminals) that share the local printer and Progress application. The database server machine is usually a high-performance back-end processor that can also support local self-service clients. This network configuration, with the Progress database local to the database server machine, ensures full database integrity. With all files stored local to each node, it generally (but not always) provides the highest performance on a LAN.
Figure 7–7 shows a dedicated network file server, dedicated Progress database server machine, and application workstations. Although the figure shows a limited number of workstations, file servers, and database server machines, there can be more of each.
Figure 7–7: Network File Server For Application Files
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This is a configuration typical for LANs with file servers and network operating systems. A hard disk and a printer are attached to the network file server, and an additional hard disk is attached to the Progress database server machine. The Progress database is on the disk drive that is locally attached to the Progress database server machine. Progress and all application procedures are installed on the file server and shared by all other nodes.
This network configuration ensures full database integrity and high performance, limited only by network and application performance capabilities.
Figure 7–8 shows a network file server doubling as a Progress database server machine and disk-optional application workstations. Although the figure shows a limited number of workstations, file servers, and database server machines, there can be more of each.
Figure 7–8: Network File Server As a Database Server
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This is a configuration you might find on a LAN with a powerful file server running a multi-tasking operating system. Progress, application procedures, and the Progress database are all installed on the file server and are shared by the other nodes.
This network configuration provides full database integrity and acceptable performance on a file server with high-speed CPU and I/O resources.
NOTE: Avoid doubling a network file server as a database server machine on low-capacity nodes or on nodes where the database server machine can run only in an emulated environment.Figure 7–9 shows database files residing on a network file server.
CAUTION: On Linux systems, Progress Software recommends you store the database on a disk that is locally connected to the database server. Do not mount the database files on a network file system.This network configuration runs the risk of compromising database integrity if the network file server or database server machine crashes, because the before-image (BI) file must be on the network file server, making synchronous writes to it impossible. Performance also depends on whether network file server I/O efficiency compensates for traffic across the network.
Figure 7–9: Network File Server For Application and Database Files
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Figure 7–10 shows the simplest LAN configuration with the Progress AppServer. The Progress AppServer enables you to distribute portions of your business application throughout your enterprise. The flexible, modular use of computer resources provides greater performance.
An application server running on the application server machine connects through shared memory to a Progress database and has access to a set of procedure files. A Progress 4GL application runs at the application workstation, connects to the application server running on the Progress AppServer machine, and sends the requests to the application server to run remote procedures. The procedure execution and database access occur in a remote Progress session context.
Figure 7–10: LAN Configuration With the Progress AppServer
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In more complex implementations of the Progress AppServer, an application server can connect to another application server in order to connect with a database. For more information about the Progress AppServer, see Building Distributed Applications Using the Progress AppServer .
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