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Introduction to sockets, hi, everyone, and welcome back to the course.



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In this section, we're going to talk about sockets, which are one of the most important concepts when



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talking about connecting to different networks, specifically with Python.



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So a socket is the base of the IP.



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The sockets are used to connect to applications and make them communicate between themselves.



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You can imagine the socket as a tunnel between two applications that has a specific port name and so



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on and so forth.



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So using this to know one application actually has some bridge between itself and the other application,



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and then they can exchange data between themselves in order to have some role in the communication between



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those two applications.



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Of course, we're using the protocols that we already talked about in this and just sort of the FTB



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HTP and SMPTE protocols.



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Of course, there's our type of protocol that is used here, and you can find all of them online, of



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course.



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But these are the main protocols.



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We are going to be talking in this section and the main protocols with which we are going to conduct



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our tests.



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So in order for us to enable two applications to communicate between themselves, we, of course, need



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some type of components to enable this thing happening in reality.



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And for that reason, we created the concept of the server or the listener.



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So server usually turns on Eliseo's and listens for the communication on a specific port.



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And the port basically describes the tunnel is basically the number of the tunnel.



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So imagine the server as a machine or a virtual machine in our case that we simply turn on and it stays



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in a passive state until it is not awake from some other application that is calling on the port that



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is turned on.



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And here it comes the client.



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So normally the client connects us to the server.



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So while the server is on and waiting or listening, then we create a client that is awake in the server.



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So it calls a server or on the port that has been stated and basically starts sending requests and the



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requests you can imagine as messages.



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So it sends messages through that port to the server and then if the server understands these messages.



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So if you use the right protocols, then the server could respond with messages that are sent in from



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the server to the client.



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But usually the most important thing to remember here is that the client initiates the communication



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between the server itself.



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So we need a server that waits on certain port.



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And after that, we need the client to say to us.



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Okay, now I know that you're waiting for me.



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I'm here now.



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Let's communicate.



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And then the communication happens.



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Then we have, as I said, the trust transmission channel or this is the port or the tunnel that connects



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the server and the client.



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And we can say that this channel or tunnel or port you can go wherever you like, is basically an answer



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to a server and an exit to the client.



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So from the client, the signal where the messages exit from the client to this support, and then they



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enter the server through the same port.



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And finally we have the protocol, which is basically the topic of the conversation between the client



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and the server or the language with which they are communicating.



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So you can imagine the different protocols like the HTP or SMTP, as are different languages with which



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the application and the client can understand themselves.



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So if we talk about applications, there are, Trumaine, main applications that are basically using



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the sockets.



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The first application is a server, which is the application, as we said, that is waiting for connection.



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Then you hear the client, which is the application that connects to the server that is waiting.



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And then we have the client server, which are basically applications that are client and server at



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the same time.



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So when you run this type of applications, they are basically having internal clients and servers that



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consistently exchange information between themselves and updates on certain features of that application



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in order to provide you up to date data.



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So here, guys, I decided just to provide you a quick overview, just with three sentences, how the



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communication between client and server is working.



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And I know that I'm repeating this over and over again, but especially if you're new to the field of



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connecting.



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Different machines, it is very important to understand this concept before going into the actual coding,



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so always if you have any issues understanding about the processes that are happening in the codes that



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we were going to write in later on, please refer to the slide and read each of those three sentences,



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which are quite straightforward in my opinion.



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So the first one is the communication must be initiated by one of the programs, which is called Courland



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Program.



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The second program waits for the other one to initiate the communication and is called the server program,



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which is a program that is basically waiting for the client.



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And finally, we have the circuit, which is the basic topic of this section, which we have the circuit,



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which is a process that exits from the client machine and it goes straight to the server machine.



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In the main objective of the socket is that the server and the client read and the right information



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between themselves.



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Now, once you know what actually the sockets are and let's talk about the different types of sockets,



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because, of course, as anything else, the circuits have different types.



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And this is pretty much dependent on the protocols that they're using.



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So the socket that we're using here are going to be the Tsipi protocol sockets or the stream which basically



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uses the DCP protocol and provide security of the data transmission and security of the data reception.



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So by the transmission, I mean the data that is transmitted from the client or the server and the reception



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is basically the data that is received from the server.



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The other type of sockets are having asynchronous communications that is code.



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So did you run and this sockets are using UDP protocol and basically the packets of information here



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are travelling in the background type.



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But about this, we're going to talk later in more detail.



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But this is the basics about sockets and communication between clients and servers, guys.



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And I hope this lecture gave you a very good foundation for the code that we are going to be writing



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later on.



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And that's it.



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Thanks very much for watching and I will see you in the next lecture.