I need to write an X.25 application for a Sun platform to communicate
with an X.29 host.

I'm trying to decide what interface to use.
I've found the following candidates:

- TLI - seems like the right approach - introduced for exactly this
reason - to integrate OSI protocols into unix. Unfortunately, I
can't find any evidence that Sun supports X.25 as a supported
transport service for TLI.

Using it with the OSI stack is an option - but significantly
increases the configuration complexity and probably cost.

- sockets - seems like a good approach - why not? The BSD interface
was clearly defined to be protocol independent. And it looks like
Sun has implemented it in that sense. But Sun strongly discourages
it, promoting the NLI instead. They don't explain why, though.

- NLI - network layer interface - this is directly connected with
steams. This is the preferred interface, according to Sun, for X.25
programming. And I know streams - I've written streams device
drivers - 15 years ago. But it seems an unnecessarily low level
programming interface to just send dialog data back and forth.
Do I have to lose the abstract socket interface that is so mature?

More to the point, can I build a simple loopback testing
environment ("hello world") without Solstice being installed?

- DLPI - I can't figure this one out, but it doesn't seem very
encouraged by Sun or better than NLI.

Any opinions or advice on this will be appreciated.