Redirecting Files to Programs or Devices
Besides simply routing or returning files to the “reader” of an NJE user, you can have the NJE system invoke a script or a program that acts on the file. For example, to print the output file directly on a local or networkattached printer under the control of Common Unified Printing System (CUPS), the NJE system can be configured to intercept files routed to a pseudo- user such as “LPR.” For example, under VSE, the LDEST operand can be set to “LPR” rather than a user ID. When NJE receives a file with this destination, it could invoke the lpr command to send the file to CUPS for post-processing in such ways as:
- Directing it to a real printer
- Sending it as a fax
- Converting it to a PDF and storing it for later viewing (or staging it to CD or DVD)
- Sending it as an attachment to a prepared electronic mailing list.
Executing Batch Jobs on Linux
NJE provides interfaces to an open source batch execution facility known as NQS. This allows execution of jobs on the Unix or Linux-based platforms the NJE/IP Bridge supports. Compared to other batch systems, NQS is relatively primitive but can be used as the basis of a useful job execution environment. NQS expects scripts to be sent to it and for it to return the output of stdout and stderr to the user. There’s no file staging capability (yet). Figure 3 illustrates remote task execution. This file can be created on any . NJE node. In this example, we’ve used our VM system to prepare and submit the job.
Submitting a job for execution is a matter of sending the script to the user “JOB” on the remote NJE node. When the job is complete, the stdout and stderr files from the job are returned to the originating user. The figure shows two files returned to the originating user, with the file type set to the NQS job number and using the peek command to display the contents of stdout. The platform tools can then manipulate the returned files.
Sending Commands and Messages Between Nodes
NJE provides the facility to send commands and messages between nodes. For example, you can display POWER queues on a VSE system from your Linux system. Figure 4 shows the “D A” command initiated on Linux and executed on VSE. Similarly, users residing on NJE nodes may exchange messages with each other. Unlike file transmissions, there’s no store-and-forward mechanism. Messages that can’t be delivered immediately are discarded. Tools such as NetView, NetMaster, and Tivoli’s management suite can be used to centralize management of all NJE nodes.
Bringing It All Together
NJE continues to fill an important role in the modern IT infrastructure and its benefits can be extended to distributed environments. NJE facilitates robust system management and provides a set of functions that can be exploited to help standardize the automation of operations that are typically installation-unique. Z