 Students, in this module, I will discuss about the software architecture which has evolved over the last 60 or 70 years with reference to making the databases work on the internet. Things were not what we are seeing today, they started off very very differently because that was not the purpose for which the network or the internet is being used today. And of course, there were issues about the technology, about the processing power which I will discuss. So, a term terminal over here means that a teletype machine with little or no processing power and the client server environment which we are using today. So, I will give a very brief as a matter of fact an oversimplified historical overview of the last 70 years starting from the 1950s or may be 40s also. And this is overview is oversimplified just to give you an idea how things have evolved over the period of time. And of course, this has a benefit of hindsight also because what was happening during the last 60 or 70 years, it seemed apparently that there was no direction. But when we look back, we can see of course there was a direction also. So, let me first go over our time or temporal overview and then I will look at the pros and cons what has happened and in the positive sense what has increased, what has decreased of course in the positive sense and then I will do a comparison of the different architectures. So, if we look at how things have evolved, the computer age up to 50s mainframes and dumb terminals. Dumb terminals are the terminals, text terminals, teletype machines without any processing power and they are connected to the mainframe and they are running applications on the mainframe and there are many many issues with it. And then there was the rise of the operating system. Operating system instead of the programmers writing routines to do certain things, all of those things were made part of a larger program which kind of encapsulated the hardware and that program was the operating system. And that led to the structured programming also because there were many complaints about programming the projects not getting completed, so which I will discuss in the subsequent slide. And in the 1970s there was a revolution which was of the personal computers, PCs and the processing power moved out of the rooms onto the desktop. And in the 90s we have the world wide web, the growth of the internet and now we have the processing power in our palms, in our smartphones, in our touch phones and the future is open. So this is just a brief overview, historical overview. Now let's look at what has increased, what has decreased over this period of time. So the story so far there is a rapid increase in the processing power and the good news is that with this rapid increase in the processing power the cost has been decreasing. Now it costs less to have more processing power as compared to yesterday, as compared to last year. Then is the rapid increase in the bandwidth, in early days there was only the copper, now we have fiber optic, we have satellite communication, we have Wi-Fi and so on. The list goes on, we have ADSL also. And then of course is the decrease in the communication cost. It has become more affordable to transmit data over the internet. Sometime back it used to cost a lot to make a telephone call overseas, now we know it costs a fraction, a fraction of that amount. Then of course with all this there has been an increase in the computers and software applications and no wonder the person who was behind the operating system, who was behind these applications for a long time was the richest person in the world. But then is a growing backlog of software projects due to difficulties in programming. So we had the structured programming, further details is not part of this course. And persistent curious about the lack of productivity with many computerized programs and operations. But there is one thing more, customized software development costs a lot, even with structured programming, even with different routines and tools and utilities, it still costs a lot. And the complaints about difficulty in using computers have resulted in computer use become more intuitive, more user friendly, more widespread and it has been become popular with the children also. So this is just an overview, the positives and the negatives. Now let us compare, now what has happened over this period of time? There has been a tremendous change in the software architecture of the machines which are behind our web based database applications. So here is the comparison, now you can see certain major differences, now this is the which was used historically and this is what we have now. So you see that the operating system was only with the server, now we have the operating system with the server and we have something over the client over here also. So the client is, this is a dumb client, this is a smart client with CPU and processing power. Then of course we have the data displays here also, data displays here also, but we have this browser over here, the browser was no longer over here. Now we see that instead of all things jumbled together, they have been separated and we have HTML file, this is all public domain. So what is the benefit of all, the benefit of this architecture is that it now supports what we want it to do and it has resulted in proliferation of internet all over the world. So this is all I have for this module, thank you.