Subject: Some general questions

From: "Bill Skiba" <[email-masked]>
Date: Fri, 26 Mar 1999 10:48:40 -0500

I've only recently become aware of the existence of SLP, and am currently
studying the RFC and draft documents to determine its applicability to a
project my company is doing for a client.  I have some general questions
that someone might be able to shed some light on.  I know that these
questions should also be directed to other parties, but I thought I'd post
them here to try to get a broader perspective:

Have there been any implementations of SLP that I could use to get started
in developing demo-level applications to help evaluate the technology?  For
example, is there sample code for DA's, SA's and/or UA's?  I see there's a
draft for an API definition - is this based on an available implementation?
Is there any known commercial support in the embedded workd for developing
SA's, or would we be pretty much on our own developing code from scratch?

What is the relationship, if any, between SLP and the Sun's Jini technology?
Although I know very little about the details of Jini, its device discovery
capability seems to be quite similar to SLP in many respects.

What is the relationship between SLP and IPX/SPX and Novell's networking
products?  It seems like SLP is intended to provide an open and
standardized way to do some things in the TCP/IP family that already exist
in the IPX/SPX world.

What is the relationship between SLP and the Salutation architecture?  The
Salutation consortium evidently has said that SLP fits within their
architecture, but it isn't clear exactly what this means or how it would
work.

---

From: James Kempf <[email-masked]>
Date: Tue, 30 Mar 1999 08:30:14 -0800 (PST)

>example, is there sample code for DA's, SA's and/or UA's?  

There is a UA and SA implementation in C available from www.srvloc.org.
The SA has no API, the UA implements the API from the API draft. It
runs on Linux, Solaris or Win32 (NT and Win95) and is designed
specifically for embedded systems. Currently, it is free for
noncommercial use. Later this week, it will be updated to reflect the version of
SLP that was approved by the IESG as a proposed standard. 
There is also a DA being developed by Matt Peterson, a student
at Utah Valley College. His Web page at:

 http://aros.net/~mtpkwp/slpdad/index.html
 
contains more information. It is designed for Linux. 

>I see there's a

The API draft has been tracked by our implementation for Solaris, which
has not yet been released.

>SA's, or would we be pretty much on our own developing code from scratch?

You could use the implementation at www.srvloc.org. As mentioned, it
is currently free for noncommercial use, but we are trying to get
it licensable through Sun's community source license or open source.

>capability seems to be quite similar to SLP in many respects.

Jini contains much more than service discovery, however, the service
discovery part is very similar. One difference is that the device
that is advertising services must embed a JVM for Jini to work, 
whereas with SLP, it can be implemented in any language. Some devices
may not have enough resources to embed a JVM. We have
developed a bridge that allows nonJVM devices advertising through
SLP to make their services available to Jini clients. Contact
Jon Bostrom ([email-masked]) for more information. 

>standardized way to do some things in the TCP/IP family that already exist

In Netware 5, Novell has implemented SLPv1 to replace the IPX SAP protocol.
SLP is Novell's service location solution for IP networks.

>architecture, but it isn't clear exactly what this means or how it would

In draft 2.1 of the Salutation architecture, the Salutation Consoritium
has added SLP along with it's proprietary subnet-limited broadcast
protocol to find services off the subnet. If a Salutation manager
discovers an SLP DA, it uses the DA to find services located off the
subnet. On the subnet, however, it continues to use the Salutation
broadcast protocol, for backward compatibility reasons.

There will be a book coming out in early May on SLP, called
"Service Location Protocol For Enterprise Networks: Implementing and Deploying a 
Dynamic Service Finder" by Pete St. Pierre and myself published
by John Wiley and Sons. It contains alot of details on implementation
and management of SLP, gleaned from our experience over that past
couple years working with the protocol. We also talk a little about
existing products.

		jak