Part 1: Distributed System Architectures

Business e-environments are evolving such that it is often impossible to know who is doing what and where. Today, many of our corporations operate globally, 24 hours a day, seven days a week. We see a rapid melding of a global economy. Work and tasks are quickly updated and changed based on global information, often reducing business cycle times to a fraction of previous work-time. The term, information economy, has been used to describe the integration of communication and data technology into information technology using the Internet as the communication method.

Global corporations can only work through information technology, and the only way technology can work is through information systems which are readily available, flexible to changing environments, regularly monitored, and represent the "real world". Distributed systems technology allows corporations to create the information systems which can be adapted for the needs of 21st century business.
It would be difficult to find any large computer-based system today without some type of distributed system. Most information systems distribute processing over several processors. Worldwide, the top priority in the next decade will be updating architectures for implementing or improving distributed computing platforms.

The primary characteristics of a distributed system is the ability to share resources, run programs concurrently, and provide systems to run on large and small systems. They also must have a high level of fault tolerance and the ability to hide the distributed processing from the user (transparency).

In 1994, Peter Deutch published 8 fallacies of Distributed Computing. For years Distributed Data Services were built with these in mind:

1. The network is reliable 2
2. Latency is zero
3. Bandwidth is infinite
4. Network is secure
5. Topology doesn't change
6. There is one administrator
7. Transport cost is zero
8. The network is homogeneous

We have learned a lot in 15 years. We now know that we need to revisit Deutch's list. We are savvier on what it takes to implement a distributed system. The evolution of distributed software engineering has had a significant impact on the implementation of distributed systems. Distributed systems include files systems, database systems, operating systems, and the Internet.

The characteristics of the DDS include the hardware, operating systems, languages and applications, middleware (abstract level between software components), and the virtual machines which communicate with each other.

Distributed Systems offer different configurations for building their concurrency -simultaneous users on many computers. All, however, need to be scalable where resources can be added or deleted. Another key factor for DDS is the ability to provide a high level of security. This includes securing data from unauthorized entry, denial of attacks, data attacks which affects data integrity. There also needs to be a high level of fault tolerance - recovery from failures (using hardware and data redundancy and software rollbacks).

Attachment:- Lecture.pdf