Choosing security method for .net and java clients on different OSs

[pawel.krolak]

Hi guys!

I have to choose a security method for my web service. PLEASE HELP
ME... I have a problem... The definition is:

1. I have created web service with several methods e.g.
method 1: SignIn(login, passwd) (if needed)
method 2: id = PrepareSomething()
method 3: Something = GetPreparedSomething(id)
method 4: SignOut() (if needed)

2. Web Service is created using .NET 2.0 (VS 2005)/Windows 2003 server

3. There are about 5-10 clients using different platforms/OS (Windows/
Unix/Linux) and applications created in different languages
(mainly .NET 1.0/.NET 2.0, Java)

4. Web service is accessible in Internet.

5. Objects, that are returned by this web service, are rather small.

6. I have to secure this web service - only some users can access it.

What method of securing this web service should I choose? Do you have
any suggestions?

Thanks in advance for your help!
Pawel Krolak