Alex Roytman: Hi! I'm Alex Roytman. I hope you enjoyed my introduction to Rich Internet Applications or RIA's and you're now starting to realize how friendly and full featured a browser interface can be. In contrast, traditional web applications are somewhat primitive compared to Rich applications. The interface is not nearly as robust and responsive. It is limited to clicking on Hyperlinks and submitting forms, and then waiting for the next page to load. Now, up onto a few years ago that's how most browser applications were built. They had these limitations, you didn't have panels, trees, tabs, intelligent grids, you had your basics buttons, text boxes and hyperlinks and every time you did something the entire page would reload. Now, you may wonder why word browser applications built this way.
Well, it's because browsers were not made for applications at all. Browsers were made for serving up documents or articles of information, which you could hyperlink together. And for that, we have Hypertext Markup Language or HTML. Well, eventually people realize that the information or the HTML in these articles could be dynamic and database driven and that let to building applications. So web servers were made to generate HTML on the fly and server side languages evolve to make it easy to operate HTML dynamically. So, you can now embed these languages into HTML and do all kinds of new tricks to output the HTML. But as you recall, HTML didn't have its roots in building applications, so it had to evolve and CSS or Cascading Style Sheets were introduced.
That gave it more capabilities as far as looking few of those. And then java script was introduced, a true programming language for the browser on the client side. So, these things allowed for applications to be creative. However, everyone quickly realized there some major issues with this paradigm. Everytime you need the server to do something, you would submit the request and the server would have to start from scratch and generate more dynamic HTML, which means the entire page would have to reload. So that interface is not very cohesive, everything was done one page at a time. And you also had to do a lot of work to keep track of sessions and state.
So, is there a better way? Well, as you may have a guessed Rich Internet Applications emerged as the better alternative. So, how do you build them? Well, would almost have to turn the pyramid upside down. We have the user interface load just one time, and then it can make request to service for data whenever it needs it. So in this paradigm, you only let your server code do backend business logic, data retrieval and data manipulation. You don't have to generate HTML or do anything as far as the user interface is concerned.
You will notice that I've multiple servers on my diagram that's because would RIA, it is very simple to request the data from more than one server or one type of technology at a time and integrate the information into one user interface. It means that your IBM i, iSeries or PG programs, Java, PHP, and even DotNet applications could all work together seamlessly. I hope you enjoyed this short explanation on how browser application development has evolved.
As always, feel free to post any comments or questions here at profoundlogic.tv and be sure to watch out for follow up videos on RIA's and other topics related to modernizing AS400 Legacy Systems and building modern web applications on the IBM i platform. Thank you and I'll talk to you again soon.
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