WEBVTT

00:00.900 --> 00:08.040
Each layer here interacts only with the layer above and below it.

00:08.040 --> 00:11.250
But there must be some external interaction with the stacks here.

00:11.250 --> 00:19.110
So here I draw some diagrams that will show you two external connections and the link layer interacts

00:19.110 --> 00:24.870
with the physical network connections, transmitting the data in a physical medium.

00:25.050 --> 00:25.320
Right?

00:25.320 --> 00:32.970
So such as a process of electricity or light and the application layer interacts with the other application.

00:32.970 --> 00:39.450
And an application is a collection of related functionality that provides a service to a user.

00:39.630 --> 00:45.390
And in this figure you are seeing an example of an application that processes an email.

00:45.920 --> 00:54.800
And the service provided by the email application is sending and receiving of messages over a network.

00:54.800 --> 01:02.300
And here typically applications contains these components, which is the network communication.

01:03.190 --> 01:12.850
Uh, this component communicates over the network and processes incoming and outgoing data for a email

01:12.850 --> 01:13.630
application.

01:13.630 --> 01:23.830
The network communication is most likely standard protocol such as SMTP, POP3, IMAP or others.

01:23.830 --> 01:28.240
And we also have the content parsers here.

01:29.100 --> 01:29.320
Oops.

01:29.340 --> 01:30.780
Actually we are here.

01:30.810 --> 01:32.400
Content parsers.

01:32.400 --> 01:38.970
So data transferred over a network usually contains content that must be extracted and processed.

01:39.000 --> 01:47.520
So content might include textual data such as the body of an email, or it might be pictures or video.

01:47.730 --> 01:54.380
And we also have the user interface and this is the user interface that user interacts to it.

01:54.390 --> 02:03.820
So the UI allows the user to we received emails and, and to create a new emails for transmission In

02:03.820 --> 02:05.040
an email application.

02:05.040 --> 02:15.030
The UI might display emails using the HTML in a web browser and then I will also notify you that the

02:15.030 --> 02:19.530
user interacting with the UI doesn't have to be a human being.

02:19.530 --> 02:26.460
It could be another application that automates the sending and receiving of emails through a command

02:26.460 --> 02:27.420
line tool.