Middleware - creating the illusion The Martian C/S book (Part 3)

Transparency: creating a seamless C/S system Location: redirection Namespace Containment Logon Replication Distributed access Distributed time Failure Administrative

Security OS security insufficient Forgeries & Trojan Horses Authentication –passwords –Kerberos (trusted third party)Kerberos Authorization –Access Control Lists –Win95, Un*x, NT Audit trails Encryption Cryptographic checksums

RPC hide the intricacy behind “stub” RPC runtime or middleware Server stub and procedure Fig 9-1 Problems –Containment transparency –Client-stub Server-stub Interface –Failures –Binding or how does a client find the server static, dynamic, automatic

MOM Store and forward Removes direct connection requirement More versitile Comparison: –MOM vs. RPC –Post office vs Telephone –Asynchronous vs. Synchronous –Call-return vs. Queued –Persistent vs. transitory –Slow vs. Fast –Adaptable vs. dedicated

Transport Stacks