The Client Building Block
- Runs the client side of the application
- It runs on the OS that provides a GUI or an OOUI and that can access distributed services, wherever they may be.
- The client also runs a component of the Distributed System Management (DSM) element.
The Server Building Block
- Runs the server side of the application
- The server application typically runs on top of some shrink-wrapped server software package.
- The five contending server platforms for creating the next generation of client/server applications are SQL database severs, TP Monitors, groupware servers, Object servers and the Web server.
- The server side depends on the OS to interface with the middleware building block.
- The server also runs DSM component
- It may be a simple agent or a shared object database etc.
The Middleware Building Block
- Runs on both the client and server sides of an application
- This broken into three category
- Transport Stacks
- Service-specific middleware
- Middleware is the nervous system of the client/server infrastructure
- This also has the DSM component
- Runs on every node in the client/server network.
- A managing workstation collects information from all its agents on the network and displays it graphically.
- The managing workstation can also instruct its agents to perform actions on its behalf.
- Server-to-server interactions are usually client/server in nature – servers are clients to other servers.
- However, some server-to-server interactions require specialized server middleware. For example, Two-Phase commit protocol may be used to coordinate a transaction that executes on multiple servers.
- Servers on mail backbone will use special server-to-server middleware for doing store-and-forward type messaging.
- But most modern software follows the client/server paradigm.