DECnet Tasks

DECnet tasks allow applications on different nodes to work together. For most applications, your system manager will have already configured the applications, so the general user most often has no need to be concerned with the details.

However, as a general user, you can set up your own DECnet tasks to perform work on a remote node without logging in. This section demonstrates how to set up a simple DECnet task. This example shows the bare framework, which you can expand upon later as the need arises.

To use a DECnet task, you need only two things: network access to an account on a remote node and a command procedure that performs the work.

Creating a DECnet Task

A DECnet task takes the form of a command procedure. It resides on the remote node and executes in response to a certain type of network access. The command procedure can pass information back to the originating process, perform work on the remote node, or both.

Our task will simply pass the system time on the remote node back to the node which originated the request:

     $ !     $ ! The following DEFINE directs information which     $ ! would normally go to SYS$OUTPUT to go instead to     $ ! SYS$NET.  The logical name SYS$NET represents the     $ ! remote process that caused this procedure to     $ ! execute.  In this way, we can pass  information     $ ! back to the requesting process.     $ !     $ DEFINE SYS$OUTPUT SYS$NET     $ !     $ ! Now display the system time (on the node where     $ ! this command procedure resides), which will be     $ ! directed back to the originating process on SYS$NET     $ !     $ SHOW TIME     $ !     $ ! And we're done.     $ !     $ EXIT 

Simply place this command procedure in the SYS$LOGIN directory of the remote account under the name SHOWTIME.COM. Directories other than SYS$LOGIN are not supported.

Executing the Remote Task

To execute this DECnet task, you may use the DCL command TYPE (which displays the information returned by the task) with a special file access syntax shown below.

Replace the nodename, username, and password with those applicable to your configuration:

     $ TYPE TAMPA"SMITH password"::"task=showtime"       12-MAY-2003 17:26:09 

click to expand
Figure 14-1: A DECnet Task

Just as with DECnet file access, TAMPA"SMITH password" :: specifies the remote node TAMPA, using the SMITH account. This time, however, the addition of "task=showtime" causes the command procedure SHOWTIME.COM to be executed.

The command procedure executes on node TAMPA, not on your local node. Therefore, the time shown is the system time on TAMPA. Likewise, any work performed by the command procedure will be carried out on node TAMPA under the account TAMPA::SMITH. In this manner, you can maintain command procedures to perform various tasks on remote nodes simply by typing them.

If Your Task Did Not Work

If your task failed to work, there are a few likely explanations. Please compare your error message to those below:

     %TYPE-W-OPENIN, error opening TAMPA"smith password"::"task=showtime" as input     -RMS-E-ACC, ACP file access failed     -SYSTEM-F-LINKEXIT, network partner exited 

This probably means that your assignment of SYS$NET is missing or mistyped. Check your command procedure and compare it to the example. Other possible causes include network communications problems.

     %TYPE-W-OPENIN, error opening TAMPA"smith password"::"task=showtime" as input     -RMS-E-ACC, ACP file access failed     -SYSTEM-F-INVLOGIN, login information invalid at remote node 

This means that the username and password you supplied are not valid or that the account is disabled or has network access disallowed. Ensure that the username and password are valid.

     %TYPE-W-OPENIN, error opening TAMPA"smith password"::"task=showtime" as input     -RMS-E-ACC, ACP file access failed     -SYSTEM-F-NOSUCHOBJ, network object is unknown at remote node 

This means that the command procedure specified is not present. Did you spell its name correctly? Does it reside in the SYS$LOGIN directory of the account you specified?

     %TYPE-W-OPENIN, error opening TAMPA"smith password"::"task=showtime" as input     -RMS-E-ACC, ACP file access failed     -SYSTEM-F-NOSUCHNODE, remote node is unknown 

This means that the nodename you specified is unknown to the DECnet software. Check the nodename you entered.

     %TYPE-W-OPENIN, error opening TAMPA"smith password"::"task=showtime" as input     -RMS-E-ACC, ACP file access failed     -SYSTEM-F-UNREACHABLE, remote node is not currently reachable 

This means that the DECnet software knows of the node you specified, but there is currently no response from that node. The node may not be running, or there may be routing problems or other network problems preventing communication.



Getting Started with OpenVMS(c) A Guide for New Users
Getting Started with OpenVMS: A Guide for New Users (HP Technologies)
ISBN: 1555582796
EAN: 2147483647
Year: 2005
Pages: 215

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