Sending the letter "A" over the internet - the first step
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.
Some assumptions:
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.
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.
Some assumptions:
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.
SOLUTION
membership
This solution is only available to members.
To access this solution, you must be a member of Experts Exchange.
ASKER
Is there any way to find out EXACTLY how MSN Messenger works?
Is it documented somewhere?
Is it documented somewhere?
ASKER CERTIFIED SOLUTION
membership
This solution is only available to members.
To access this solution, you must be a member of Experts Exchange.
You do not have to use all layers, most application does not, I can not think of anything that actually uses all layers, the OSI stack is a theoretical description on how you can design networks, real networks does not have to map 100%. Many times one protocol can overlap 2 layers or not fit in very good. e.g. TCP is layer 3 and maybe 4.
MSN probably only uses 1 or 2 layers (expect for TCP/IP and layer 1 and 2), the application layer and maybe a session layer.