Working as sessions

Hi!

Well, I'm looking for comments about a problem:

I have a webservice where I want my users to log in into the system, and
if they are logged on they can use any of the methods that the
webservice has, which is the best solution? send with every webservice
call the username and password (md5ed of course) and validate this
information in every call? or any other ideas?

Thanks!
Pablo
-- 
Pablo Fischer Sandoval (pablo [arroba/at] pablo.com.mx)
Fingerprint:  5973 0F10 543F 54AE 1E41  EC81 0840 A10A 74A4 E5C0
http://www.pablo.com.mx 
http://www.debianmexico.org

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