Considering the Application Layer
The video I provided this week provides a good layman's view of the application layer by simplifying the picture of three Web applications as if each were just one application layer in action. In reality, those applications use many different standard application layer protocols to do the things they do. The application layer is defined for many simple applications while many applications you think of are comprised of bundles of standard protocols. You certainly get a sense of how many standard applications there are available to you without having to write your own protocols just by looking at the Wikipedia page on the subject. They often have technical sounding names with promoted acronyms to help you remember them (like Data Distribution Service, DDS). One way of thinking about it is that the application layer becomes the operating system for any Web application you want to create. You can think of your sophisticated application as another layer on top of the available applications that are referenced in the Wiki. You can write and use your own new services and try to make a popular protocol out of them (and perhaps get them listed on the Wiki page in due time and show your friends and family).
The reading suggestion I provide for this week gives you a good overview of how those who write protocols for the application layer think about it. I give you the right to think about it in your own simplified way for now, but it would be great if you continued to dig in deeper to get a more techical understanding over time.
I won't make you read much more this week, but with the expectation you'll read each other through the Forums and spend more time on your final project. Your project is due July 23rd. Grading will be done on Tuesday, July 24th, so be sure to get all your class contribution done by then. I'll provide one final video to let you know how we all did (and show off your work) and to wish you well in your future endeavors. Do e-mail me with any questions. I will send you one-on-one comments via e-mail when they are specific to your work only.