Sockets/STREAMS/TLI ?

[ma at inmet.inmet.com]

I am building an application which needs to do RPC-like processing
across a SUN network, but I cannot use SUN's rpc facility itself;
I need to build mine from lower-level components.

The question is, WHICH set of lower-level components should I use?  I
gather that the underlying mechanism for SUN's rpc facility is
sockets, so that would be an obvious choice.  However, the SUN 4.1
documentation (in particular the Network Programming Guide) alludes to
the fact that SUN intends to ultimately discontinue support for
sockets, and warns the user to not use them directly for new software.

If that were true, what should one use instead?  The impression I
get from that very same Guide is that the answer is TLI.  However,
TLI is NOT available on pre-4.1 releases.  Is there something on that
level that IS available both now and in the future?  What comes to
mind is STREAMS.  However, I find it hard to figure out whether
STREAMS provide the same functionality as sockets and/or TLI, how
those three differ from one another, what each of them is good or bad
for, whether any of them are implemented in terms of the others, etc, etc...

I would very much appreciate an explanation of all of this, and some
advice about which of them to use.

Thanks in advance,

Malgosia Askanas (ma at inmet.inmet.com)