Document revision date: 15 July 2002

COM for OpenVMS requires the OpenVMS Registry. Like its registry database counterpart on Windows NT systems, the OpenVMS Registry stores information about COM applications---specifically those COM applications running on OpenVMS. These COM for OpenVMS applications use the OpenVMS Registry to store CLSIDs (class IDs), startup information, security settings, and so on in the OpenVMS Registry database. COM for OpenVMS uses the Win32 APIs implemented on OpenVMS to read and write this information to the OpenVMS Registry.

COM for OpenVMS requires access to the OpenVMS Registry database. If COM for OpenVMS cannot access the OpenVMS Registry, COM for OpenVMS will not start. For more information about the OpenVMS Registry, see Chapter 12.

3.3 Using COM for OpenVMS

You can use COM for OpenVMS to do the following:

• Develop new COM for OpenVMS COM applications
• Encapsulate existing applications for use with COM for OpenVMS

The following sections discuss new application development and encapsulation in more detail.

An example of a COM application to encapsulate an existing OpenVMS application is included with this release. The example can be found in DCOM$EXAMPLES:[WRAPPER]. A README file describes the example and how to build it.

3.3.1 Developing New Applications

Your organization might use COM for OpenVMS to develop new applications under the following circumstances:

• You want to share data between an OpenVMS server and Windows NT clients in a two-tier client/server computing model.
• You want to share data and to place business logic in the middle tier of a three-tier computing environment.
  For example, you might have a Windows NT system as the client so you can take advantage of its graphical user interface. You could write business logic as a collection of COM objects on a middle-tier server; while the third-tier large-capacity, high-availability OpenVMS server provides database access.
• You want to share data between one or more OpenVMS systems or between OpenVMS and other non-Windows systems using COM.

The advantages of using COM for OpenVMS include:

• COM for OpenVMS provides a good programming model for programmers with C++ and object-oriented programming skills.
• COM for OpenVMS provides multivendor interoperability. COM is a standard with implementations available on a number of platforms today, and ports for additional platforms are in development.
• The COM for OpenVMS run-time provides automated data marshaling and unmarshaling.
• COM provides OLE Automation services to support communications with Microsoft Visual Basic® applications. Visual Basic is a very popular programming environment for client/server computing.
• COM provides version support for components so you can upgrade applications over time without breaking existing environments.

See Chapter 7 and Appendix C for examples of developing COM for OpenVMS applications.

3.3.2 Encapsulating Existing Applications

If you have monolithic applications written in procedural languages (such as Fortran and COBOL) with character-cell interfaces, you can put a COM "wrapper" or jacket around these applications to allow them either to run on new platforms or to remain on OpenVMS and run in a client/server environment.

The risk associated with completely reengineering some older applications is high. Many applications are large, complex, poorly documented, and not well understood by their current maintainers. Encapsulating a legacy application can be less risky than reengineering and can be the first step in a rewrite. Over time, pieces of the legacy application can be rewritten, while the older version of the application remains stable and available. Encapsulation also allows developers to reuse code, saving time and resources.

Disadvantages to encapsulation include more complex maintenance efforts and the inability to make changes to the underlying code. If the legacy application was unstable or hard to maintain, the encapsulated application will not be any better, and might be made worse because of the wrapper.

There are several layers of a traditional procedural application that you can encapsulate: the user interface (UI), the database, and the data manipulation routines.

• User interface
  If you choose to encapsulate the user interface, the UI could be supported on some other platform (for example, from a graphical user interface [GUI] on a Windows NT system).
  Encapsulating and moving the UI to the user's desktop can mean that the rest of the application remains on OpenVMS. Batch processing programs are well suited to user interface encapsulation. Applications that do screen management (for example, SMG or FMS) could have their older character-cell interface encapsulated using COM for OpenVMS, providing users access through newer Windows NT style dialog boxes.
• Database
  If you choose to encapsulate a database using COM for OpenVMS, the database could be accessed from parts of a distributed application running on other platforms. The advantage of this approach is that the programmer can keep the database on OpenVMS (a stable, 24x365 system), while the user interface and data access routines are on remote (and perhaps less reliable) systems.
• Database manipulation routines
  If you choose to encapsulate the database manipulation routines, the routines could be accessed from any other COM component in a heterogeneous computing environment.

Encapsulating an OpenVMS application using COM for OpenVMS means that you write a COM for OpenVMS server that talks to the application being encapsulated. The COM for OpenVMS server passes arguments to the application in the order and format that the application expects. The COM for OpenVMS server then intercepts the output from the application and directs it to the display device, user interface, or other routines.

This chapter provides a list of the contents of the COM for OpenVMS kit, a list of prerequisite software, and preinstallation requirements. It also describes how to install COM for OpenVMS and includes postinstallation instructions.

4.1 Contents of the COM Version 1.2 for OpenVMS Kit

COM Version 1.2 for OpenVMS contains the following:

• Software
  • COM for OpenVMS run-time libraries
  • COM for OpenVMS MIDL compiler and header files
  • COM for OpenVMS configuration utilities
  • Active Template Library Version 3.0
  • Sample applications
• Documentation
  • COM, Registry, and Events for OpenVMS Developer's Guide (in PostScript, HTML, and PDF formats)

The following software is required:

• For OpenVMS systems
  • OpenVMS Version 7.2-1 or higher
  • For COM for OpenVMS application development:
    Compaq C++ Version 6.0 or higher
    To build ATL applications on OpenVMS:
    Compaq C++ Version 6.2-016 or higher
  • Compaq TCP/IP Services for OpenVMS Version 5.0 or equivalent
  • Compaq DECwindows Motif for OpenVMS (see Section 4.2.1)
  • Compaq Advanced Server for OpenVMS Version 7.3 or higher
    (Compaq Advanced Server for OpenVMS is not required if you are running COM for OpenVMS in unauthenticated mode.)
  • Before installing COM for OpenVMS check that you have the required free global pages, global sections, and disk blocks. The following table lists the requirements.

    Software	Global pages	Global sections	Disk blocks
    COM for OpenVMS	11,000	27	57000
    RPC Runtime	3,300	14	N/A

    For Advanced Server requirements: See the Compaq Advanced Server for OpenVMS Server Installation and Configuration Guide.
    For TCP/IP requirements: See the Compaq TCP/IP Services for OpenVMS Installation and Configuration document.

• For Windows NT systems
  • Windows NT 4.0 with Service Pack 3 or higher installed
  • Microsoft Visual C++ or Visual Basic (for Windows NT client development and information about MIDL compiler). See the Microsoft website for compiler version requirements.
  • TCP/IP enabled (needed for OpenVMS connectivity)

You must install DECwindows Motif for OpenVMS on any system running COM for OpenVMS. If you already have DECwindows Motif installed on your system, you do not need to do anything else. If you do not have DECwindows Motif installed on your system, you can find the installation kit for DECwindows Motif on the OpenVMS CD-ROM in the [KITS.DWMOTIFxxx_KIT] directory, where xxx is a DECwindows Motif version, such as 125 or 126.

The following sections describe COM Version 1.2 for OpenVMS installation and upgrade options.

Use the following procedure:

1. Install OpenVMS Version 7.2-1 or higher. For this procedure, see the OpenVMS Alpha Version 7.x Upgrade and Installation Manual.
2. Install TCP/IP Services. For this procedure, see the Compaq TCP/IP Services for OpenVMS Installation and Configuration manual or your TCP/IP supplier's documentation.
3. Boot the installed system from the system disk.
4. Install COM Version 1.2 for OpenVMS. For this procedure, see Section 4.9.
5. Install Compaq Advanced Server for OpenVMS. For this procedure, see the Compaq Advanced Server for OpenVMS Server Installation and Configuration Guide.
6. Configure TCP/IP Services (set up for startup and reboot); then start TCP/IP. You must configure the PWIP driver for Compaq Advanced Server for OpenVMS to use TCP/IP Services. For information about configuring TCP/IP, see the Compaq TCP/IP Services for OpenVMS Installation and Configuration manual or your TCP/IP supplier's documentation.
7. Configure the OpenVMS Registry as follows:
   • Run REG$CONFIG.COM to configure the OpenVMS Registry. See Section 13.2.
   • Edit the SYLOGICALS.COM file to define the SYS$REGISTRY logical as follows:

     $ DEFINE/SYSTEM SYS$REGISTRY directory-specification

8. Start OpenVMS Registry by running the REG$STARTUP.COM file.
9. If you want to run DCE, start DCE now.

   Note You do not need DCE to run COM for OpenVMS, but if your environment uses DCE, Compaq recommends that you start DCE now.

   
   For this procedure, see the Compaq DCE Installation and Configuration Guide.
   For more information about OpenVMS external authentication, see Section 5.1.
10. Configure Compaq Advanced Server for OpenVMS. You need to reboot to finish Compaq Advanced Server for OpenVMS configuration. You must reboot 0 to n times, depending on your system configuration. For this procedure, see the Compaq Advanced Server for OpenVMS Server Installation and Configuration Guide.
11. Start Compaq Advanced Server for OpenVMS (set up for startup on reboot). For this procedure, see the Compaq Advanced Server for OpenVMS Server Installation and Configuration Guide.
12. Start the ACME server. Use the following command:

    $ @SYS$STARTUP:NTA$STARTUP_NT_ACME

13. Start RPC. Use the following command:

    $ @SYS$STARTUP:DCE$RPC_STARTUP.COM

14. Configure COM for OpenVMS. For this procedure, see Section 4.10 and Section 6.2.
    • Populate the OpenVMS Registry. For this procedure, see Section 6.2. Use option 3 to populate the OpenVMS Registry database.
    • Create any OpenVMS and Compaq Advanced Server for OpenVMS accounts needed by the COM for OpenVMS Service Control Manager. For more information, see Section 6.2. Use option 8 to create the accounts.
15. Edit the SYLOGICALS.COM file and add the following line:

    $ DEFINE DCOM$TO_BE_STARTED TRUE

16. Start COM for OpenVMS. For this procedure, see Section 4.11.

Use the following procedure:

1. Upgrade to OpenVMS Version 7.2-1 or higher. For this procedure, see the OpenVMS Alpha Version 7.x Upgrade and Installation Manual.
2. If you need to upgrade TCP/IP, upgrade TCP/IP now. For this procedure, see the Compaq TCP/IP Services for OpenVMS Installation and Configuration manual or your TCP/IP supplier's documentation.
3. Boot the upgraded system from the system disk.
4. Upgrade COM for OpenVMS. For this procedure, see Section 4.9.
5. Install or upgrade Compaq Advanced Server for OpenVMS. You must reboot 0 to n times, depending on your system configuration. For this procedure, see the Compaq Advanced Server for OpenVMS Server Installation and Configuration Guide.
6. Start TCP/IP unless you have enabled TCP/IP to start on a reboot. For this procedure, see the Compaq TCP/IP Services for OpenVMS Installation and Configuration manual or your TCP/IP supplier's documentation.
7. Start the OpenVMS Registry unless you have enabled the OpenVMS Registry to start on a reboot. For this procedure, see Section 13.2.
8. If you want to run DCE, start DCE now.

   Note You do not need DCE to run COM for OpenVMS, but if your environment uses DCE, Compaq recommends that you start DCE now.

   
   For this procedure, see the Compaq DCE Installation and Configuration Guide.
   For more information about OpenVMS external authentication, see Section 5.1.
9. Configure Compaq Advanced Server for OpenVMS. You must reboot to finish Compaq Advanced Server for OpenVMS configuration. You need to reboot 0 to n times, depending on your system configuration. For this procedure, see the Compaq Advanced Server for OpenVMS Server Installation and Configuration Guide.
10. Start Compaq Advanced Server for OpenVMS (set up for startup on reboot). For this procedure, see the Compaq Advanced Server for OpenVMS Server Installation and Configuration Guide.
11. Start the ACME server. Use the following command:

    $ @SYS$STARTUP:NTA$STARTUP_NT_ACME

12. Start RPC. Use the following command:

    $ @SYS$STARTUP:DCE$RPC_STARTUP.COM

13. See Appendix D for detailed information about upgrading from COM Version 1.0 for OpenVMS to COM Version 1.2 for OpenVMS.
14. Configure COM for OpenVMS. For this procedure, see Section 4.10 and Section 6.2.
    • Populate the OpenVMS Registry. For this procedure, see Section 6.2. Use option 3 to populate the OpenVMS Registry database.
    • Create any OpenVMS and Compaq Advanced Server for OpenVMS accounts needed by the COM for OpenVMS Service Control Manager. For more information, see Section 6.2. Use option 8 to create the accounts.
15. Edit the SYLOGICALS.COM file and add the following line:

    $ DEFINE DCOM$TO_BE_STARTED TRUE

16. Start COM for OpenVMS. For this procedure, see Section 4.11.

Use the following procedure:

1. Install OpenVMS Version 7.2-1 or higher on all system disks as required. For this procedure, see the OpenVMS Alpha Version 7.x Upgrade and Installation Manual.
2. Install TCP/IP. For this procedure, see the Compaq TCP/IP Services for OpenVMS Installation and Configuration manual or your TCP/IP supplier's documentation.
3. Boot the installed system from the system disk.
4. Install COM Version 1.2 for OpenVMS. For this procedure, see Section 4.9.
5. Install Compaq Advanced Server for OpenVMS on this node in the cluster. For this procedure, see the Compaq Advanced Server for OpenVMS Server Installation and Configuration Guide.

   Note You must install Compaq Advanced Server for OpenVMS on at least one Alpha node in the cluster. On the other nodes, you can either install Compaq Advanced Server for OpenVMS or select External Authentication images (only) .

6. Configure TCP/IP (set up for startup on reboot on each node) and start TCP/IP. You must configure the PWIP driver for Compaq Advanced Server for OpenVMS to use TCP/IP. For information about configuring TCP/IP, see the Compaq TCP/IP Services for OpenVMS Installation and Configuration manual or your TCP/IP supplier's documentation.
7. Configure the OpenVMS Registry:
   • Run REG$CONFIG.COM to configure the OpenVMS Registry. You need to configure the OpenVMS Registry only once for the cluster. See Section 13.2.
   • Set the SYS$REGISTRY logical to DEFINE/SYSTEM on every Alpha node in the cluster that will run the OpenVMS Registry server.
   • Edit the SYLOGICALS.COM file on every node in the cluster as follows:
     • If the cluster uses a single, cluster-common SYLOGICALS.COM file that is called by each node's SYLOGICALS.COM file, you do not need to make any changes.
     • On those nodes where you do not want the OpenVMS Registry server to run, add the following line to the SYLOGICALS.COM file:

       $ DEFINE/SYSTEM REG$TO_BE_STARTED FALSE

     
     Compaq Advanced Server for OpenVMS requires that the OpenVMS Registry be running on a node in the cluster.
8. Configure DCE.

   Note You do not need DCE to run COM for OpenVMS, but if your environment uses DCE, Compaq recommends that you start DCE now.

   
   For this procedure, see the Compaq DCE Installation and Configuration Guide.
9. If you want to run DCE, start DCE now. You must configure DCE on each node on which you want to run DCE.
   For more information about OpenVMS external authentication, see Section 5.1.
10. Configure and start Compaq Advanced Server for OpenVMS. For this procedure, see the Compaq Advanced Server for OpenVMS Server Installation and Configuration Guide.
    If this node is running Compaq Advanced Server for OpenVMS, set up Compaq Advanced Server for OpenVMS for startup on reboot (edit the SYS$STARTUP file as necessary). You must reboot 0 to n times as needed, depending on your system configuration.
    If this node is not running Compaq Advanced Server for OpenVMS, edit the SYLOGICALS.COM file and define the PWRK$ACME_SERVER logical. For this procedure, see the Compaq Advanced Server for OpenVMS Server Installation and Configuration Guide. For more information about the PWRK$ACME_SERVER logical, see Table 8-2.
11. Start the ACME server. Use the following command:

    $ @SYS$STARTUP:NTA$STARTUP_NT_ACME

12. Start RPC. Use the following command:

    $ @SYS$STARTUP:DCE$RPC_STARTUP.COM

13. Configure COM for OpenVMS. For this procedure, see Section 4.10 and Section 6.2.
    • Populate the OpenVMS Registry. For this procedure, see Section 6.2. Use option 3 to populate the OpenVMS Registry database. You need to populate the OpenVMS Registry only once in a cluster.
    • Create any OpenVMS and Compaq Advanced Server for OpenVMS accounts needed by the COM for OpenVMS Service Control Manager. For more information, see Section 6.2. Use option 8 to create the accounts. You need to create these accounts only once in a cluster.
14. Edit the SYLOGICALS.COM file and add the following line:

    $ DEFINE DCOM$TO_BE_STARTED TRUE

15. Start COM for OpenVMS. For this procedure, see Section 4.11.

	privacy and legal statement
6539PRO_002.HTML