Sending the letter "A" over the internet - the first step
Posted on 2005-04-07
I asked this question a few hours ago...and realized that the way I asked it was TOO BIG of a question to be answered in one sitting.
So I am going to ask the same question again....but concentrate on a smaller (much smaller) piece of the pie.
Suppose I am in MSN Messenger chatting with someone.
I type the letter "A" and press the SEND key.
What I want to know is the very next thing that happens.
1) Following the OSI model......MSN Messenger would be the APPLICATION layer.
2) So....the letter "A" has to move from the APPLICATION layer to the PRESENTATION layer.
So how does this happen? How does the letter "A" get from the APPLICATION layer to the PRESENTATION layer?
I think it is reasonable to assume that at some point........the letter "A" is sitting somewhere in RAM memory.
So it is as simple as the APPLICATION layer telling the PRESENTATION layer....."I have some data that I want to send.....here is where the data is located in memory" ????? Or does the APPLICATION layer have to do more than this in order to hand off the letter "A" to the PRESENTATION layer? What is the PRESENTATION layer expecting?
At this point....what does the PRESENTATION layer do? I know that it has to somehow prepare the letter "A" to be received or sent to or handed-off to the SESSION layer.....so what does it do with the letter "A"?
Let's STOP here.......hopefully this is not too big of a chunk to bite off and explain.