1 - Motivation

Question 1

What is a middleware and what are its goals?

Answer 1

System that supports development, deployment, and execution of complex information systems, facilitating interaction and integration of application and components.

Programming abstraction: distribution, autonomy, heterogeneity are transparent to programmer (provided by infrastructure).
Infrastructure: code that is either generated by a preprocessor or accessed via an API.

Principles: distribution made transparent, standardization to overcome heterogeneity, application logic independent from infrastructure.

DBIS perspective: anything on top of DB.

Question 2

What are the challenges imposed to the architecture of information systems and how does the middleware help?

Answer 2

Distribution, autonomy, heterogeneity, performance, scalability, high availability, complexity.

Abstraction + infrastructure.

Question 3

How does the Web influence the architecture of information systems (IS)?

Answer 3

In the scope of IS: web is a platform for connecting remote clients and applications across the Internet.

• Beyond terminals/legacy interfaces, leveraging advantages of web technologies.
• Universal (thin) client for any IS: browser.

Requirements: dynamic content provided by DB; session concept (track interaction of a client)

Question 4

Give an overview of general types of middleware

Answer 4

• DB-Gateways: abstract heterogeneity of underlying data sources (drivers)
• RPC/RMI
• Transaction monitors
• Object brokers
• Web services

Middleware occurs in every IS layer, connecting e.g.: databases, 3-tier systems within company, business partners across boundaries.