Overview: Architecture

The RPC Broker is considered to be part of the infrastructure of VISTA. It establishes a common and consistent foundation for client/server applications being written as part of VISTA.

The RPC Broker is a bridge connecting the client application front-end on the workstation (e.g., Delphi GUI applications) to the M-based data and business rules on the server. It links one part of a program running on a workstation to its counterpart on the server. Therefore, the RPC Broker assists in opening the traditionally proprietary VISTA software to Commercial Off-the-Shelf (COTS) and Hybrid Open Systems Technology (HOST) products.

The RPC Broker includes the following:

• A common communications driver interface that handles the device-specific characteristics of the supported communications protocol.
  
  
• An interface component separate from the communications driver that interprets the message, executes the required code, and eventually returns data to the communications driver.
  
  
• A common file that all applications use to store the information on the queries to which they respond (i.e., REMOTE PROCEDURE file [#8994]).
  
  
• Architecture that supports multiple GUI and client front-ends.

This version of the Broker also includes the Broker Development Kit (BDK). The BDK provides VISTA application programmers with the following features:

• The capability to develop new VISTA client/server software using the Broker Delphi component (i.e., TRPCBroker) in the 32-bit environment (e.g., create Delphi-based GUI client/server VISTA applications).

  Please note that version 1.1 of the Broker supports Delphi V. 3.0 as well as Delphi V. 2.0. However, the next version of the Broker will no longer provide support for Delphi V. 2.0.

• Support for COTS/HOST client/server software using the Broker Dynamic Link Library (DLL).

The RPC Broker does the following:

• Operates in a 32-bit environment (i.e., client workstations running Microsoft Windows 95 or Windows NT operating systems) while supporting VISTA applications previously developed in the 16-bit environment (e.g., PCMM).
  
  
• Provides support for single signon. Users need only sign on once when accessing both a VISTA roll-and-scroll (e.g., Lab, Pharmacy) and a VISTA client/server GUI-based application (e.g., PCMM, CPRS) on the same workstation, regardless of which application is started first.
  
  
• Provides new and enhanced Broker management and configuration tools (e.g., new debugging tools, new RPC BROKER SITE PARAMETERS file (#8994.1), enhanced Broker Listener).