VRXDA v1.2     Distributed Connection Object for VX-REXX
        
        The VRXDA Distributed Connection Object allows you to create true 
        Client/Server applications with VX-REXX version 2.1 or greater. It 
        is a VX-REXX object developed using the ODK from WATCOM inc. and 
        SOM-1 and is automatically installed on the VX-REXX tooolbar. The 
        VRXDA Distributed Connection Object is fully enabled for drag drop 
        programming and will install a set of programming macros in your 
        VX-REXX system directory.

        The Distibuted Connection Object hides the complexity of the supported 
        communication protocols.

        Several methods of interprocess and cross-network communication are 
        available for OS/2. However, each has a different programming interface. 
        This means that a programmer must learn different ways to accomplish the 
        same task, depending on the protocol in use. 

        Using IBM* Distributed Application/2 services The Distibuted Connection 
        Object provides a single, consistent programming interface to aall of the 
        supported communication protocols. The programmer must therefore learn only 
        one interface in order to use multiple protocols.

        Ordinarily, the programmer must decide when writing an application which 
        communication protocol to use. If it becomes necessary to change protocols, 
        the application must be rewritten. 

        Because the Distibuted Connection Object uses the same APIs regardless of 
        the underlying protocol, the selection of protocol need not be made until 
        run time. This means that the protocol can be changed without access to 
        source code and without recompiling. 

        This also means that a distributed application can be developed and tested 
        first on a single machine using OS/2 named pipes and later moved to span a 
        network using NetBIOS or APPC without recoding. 
  
        The Distibuted Connection Object supports three communication protocols: 

            o Named pipes : A form of OS/2 interprocess communication that uses 
                            file-system calls to transfer data between processes 
                            running on the same workstation. Named-pipes 
                            connections across a network are not supported. 

            o NetBIOS     : A communications programming interface that supports 
                            peer-to-peer connections between applications running 
                            on a LAN. 

            o APPC        : Advanced Program-to-Program Communication, an 
                            implementation of the IBM* Systems Network Architecture 
                            (SNA) LU 6.2 protocol. APPC allows distribution of 
                            applications across an SNA network.

        The VRXDA Distributed Connection Object is shareware and can be registered 
        through the Shareware Registration database GO SWREG reg No 7276.

        ADD Consulting (CH)                              1995/08/25