1. Middleware IS 8030 – Integrated Computing Environments Dr. Hoganson Middleware What is middleware? A software interface glue that resides between the operating system (or network operating system) and the application in distributed client/server systems. Client Application Middle- ware NOS Physical NW Layers Server Application Middle- ware NOS Physical NW Layers

2. Middleware IS 8030 – Integrated Computing Environments Dr. Hoganson Vertical Integration: –Between layers in each stack –Each layer interfaces with its neighbors –Between application and middleware is the API: Application Programming Interface Horizontal Integration –Between equivalent layers located at client and server –Middleware achieves horizontal integration between client and server middleware

3. Middleware IS 8030 – Integrated Computing Environments Dr. Hoganson Interfaces Middleware must be compatible with and interface with the network operating system Middleware must be able to interface with the API Compatibility issues

4. Middleware IS 8030 – Integrated Computing Environments Dr. Hoganson Middleware Tiers Server Application Middle- ware B NOS Physical NW Layers Server Application Middle- ware A NOS Physical NW Layers Client Application Middle -ware A NOS Physical NW Layers Middle -ware B 2 Tier Middleware Architecture

5. Middleware IS 8030 – Integrated Computing Environments Dr. Hoganson Middleware Tiers Server Application Middle- ware A NOS Physical NW Layers Client Application Client Middleware NOS Physical NW Layers Application Middle- ware A NOS Physical NW Layers Middle- ware B n -Tier Middleware Architecture (three tiers) Server Application Middle- ware B NOS Physical NW Layers Client Middle- ware

6. Middleware IS 8030 – Integrated Computing Environments Dr. Hoganson Simple Example of n-Tiers Server Application Middle- ware A SQL NOS Physical NW Layers Client Application Client Middleware Browser NOS Physical NW Layers Application SQL server NOS Physical NW Layers VB n -Tier Middleware Architecture (3-Tier) Server Application Middle- ware B VB NOS Physical NW Layers Client Middle- ware HTML

7. Middleware IS 8030 – Integrated Computing Environments Dr. Hoganson N-Tier architecture Simplifies client software –Development –Configuration & Maintenance – fewer products & protocols –(true cost of computing includes ALL personnel support costs) Fewer client resources consumed (less memory and processing power) De-couples the development of the server systems from the client interface Facilitates platform independence