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pwip interface

Occasional Contributor

pwip interface

hi guys,

can anyone give me some information about programming a pwip interface for the decnet stack. I have to use the callup and calldown vecotrs. But there is not much information available on the net. I have to make use of streams programming to write api's like bind, connect , accept etc by sending requests like T_BIND_REQ through mblk/dblk. Can anyone give me some leads as to how to start programming or any links which might be helpful for me

Robert Gezelter
Honored Contributor

Re: pwip interface


DECnet does not use the sockets API that is often used for TCP/IP.

The DECnet API is described in the OpenVMS Documentation set. This set is available on the OpenVMS www site at http://www.hp.com/go/openvms

In particular, the DECnet programming interface is covered in the documentation for DECnet Phase IV and Phase V. Phase IV programs will operate (within limitations) on Phase V nodes but not vice versa.

General OpenVMS programming concepts are, or course, covered in the main OpenVMS documentation set.

I recall making some DECUS presentations, both here and in Europe in the early 90's on the subject, but they are apparently among the backlog of materials that I have yet had the time to make available on my www site.

- Bob Gezelter, http://www.rlgsc.com
Honored Contributor

Re: pwip interface

That you're even asking this question and referencing these interfaces implies you're working at a very unusual level here, and some background on the application might be useful. Are you working with (or for?) HP here?

For those unfamiliar with it, PWIP is an interface used by PATHWORKS, Advanced Server and DECnet-Plus to operate over an IP transport; it's centrally an IP interface that's presented up to other network-related packages that need or want to link into the IP transport layer on the particular OpenVMS box. Very few packages tie into this layer, and the only folks coding here are usually either working on an IP package for OpenVMS, or are working directly with HP for low-level networking task. (The PWIPDRIVER interface documentation wasn't directly available, when last I looked.)

Conversely, if you're not working with HP here and have an existing DECnet application, then it will automatically and transparently operate over IP once the DECnet-Plus stack is installed and is configured to operate over IP and the PWIPDRIVER. Few (if any) changes are required here. You will program to the DECnet layers and existing DECnet APIs.

If you want to write your own DECnet software and want source examples, there are various resources available. To find source examples, you can look at the manuals (of course) and can also search for keywords such as /DECnet task programming/, and applications that are including strings such as /IO$_ACPCONTROL DECnet/ or such.

Start here for finding classic OpenVMS coding examples:


and use Google with any of the usual search strings including the site search keyword, such as the following:

site:mvb.saic.com io$_acpcontrol
site:mvb.saic.com DECnet task

mvb.saic.com is filled with OpenVMS source code.

The DECnet Phase IV manuals (which are probably easier reading if you're just starting out programming with DECnet) are here:


And you're not likely going to be coding to PWIP here. Either to DECnet, or to some other library.

And as Robert indicates, the socket library on Tru64 Unix did include DECnet, but the OpenVMS socket library does not.

HP has been doing very little (new) with DECnet other than maintaining it on current OpenVMS releases, so I'd not expect to see PWIP nor the C socket library sprout DECnet features any time. And if you're working with HP more directly here, ring up somebody affiliated with the TCP/IP engineering team and ask for the documentation on PWIPDRIVER.

And welcome to ITRC.

Stephen Hoffman
HoffmanLabs LLC
Hakan Zanderau ( Anders
Trusted Contributor

Re: pwip interface

The question is crossposted in Computing.Net


from another question that wistler posted at Computing.Net

>>> i am a student.....i am learning
>>> openvms.....i was given given an
>>> assignment ......this was one of the
>>> questions.....i did not understand the
>>> help for f$getdvi....can u please give
>>> me the script or explain in detail how
>>> to do this


Hakan Zanderau

Don't make it worse by guessing.........