WEBVTT 00:04.960 --> 00:12.100 So, guys, let us start with our first method of establishing Interprocess communication and we will 00:12.100 --> 00:16.090 going to study Unix domain socket in this section of the course. 00:16.540 --> 00:23.020 So Unix domain sockets are used for carrying out inter-process communication between two processes which 00:23.020 --> 00:24.810 are running on the same machine. 00:24.880 --> 00:25.990 So note the word. 00:25.990 --> 00:32.560 Whenever we say inter-process communication, by default we mean the inter-process communication between 00:32.560 --> 00:35.590 the two processes running on the same machine. 00:35.890 --> 00:42.770 We shall discuss the implementation of Unix domain socket with respect to server and client process. 00:42.790 --> 00:50.090 So remember the two communicating processes are classified as server process and client process. 00:50.110 --> 00:55.960 So server process is a process which actually waits for the request from the client process. 00:55.990 --> 01:03.250 It is the responsibility of the client process to actually send the computation request to the server 01:03.250 --> 01:10.850 process and it is the responsibility of the server process to process the client request and send back 01:10.850 --> 01:12.650 the result back to the client. 01:12.980 --> 01:14.810 So always remember the two. 01:14.810 --> 01:20.210 Communicating processes can always be classified as server and client processes. 01:20.210 --> 01:27.550 Using Unix domain sockets, we can set up either a stream based communication or datagram based communication. 01:27.560 --> 01:28.910 Now let us see that. 01:28.910 --> 01:33.620 What is the difference between stream and datagram based communication? 01:34.370 --> 01:41.030 A stream based communication is a communication in which the two communicating processes actually involve 01:41.030 --> 01:46.340 in continuous exchange of data in the form of bytes. 01:46.910 --> 01:53.720 So, for example, it will be an example of a stream based communication when large files need to be 01:53.720 --> 01:56.690 moved or copied from one location to another. 01:56.690 --> 01:57.380 Right? 01:57.380 --> 02:03.110 So for example, copying a movie from one location of your hard drive to another location. 02:03.500 --> 02:10.460 So stream based communication is analogous to like flow of a water in a stream based communication. 02:10.460 --> 02:15.830 There is continuous flow of bytes from the sending process to the receiving process. 02:16.250 --> 02:21.170 Contrary to this, the other type of communication is a datagram based communication. 02:21.590 --> 02:24.470 In datagram based communication is small. 02:24.470 --> 02:30.650 Units of data needs to be moved from one process to another process within the system. 02:30.800 --> 02:37.670 So in Datagram based communication, the sending process actually sends the chunk of data or you can 02:37.670 --> 02:41.630 say the chunk of bytes of data to a receiving process. 02:43.140 --> 02:46.740 There is absolutely no continuous flow of bytes. 02:47.730 --> 02:54.570 Data is sent from the sending process to the receiving process in small, small individual units called 02:54.570 --> 02:55.770 datagrams. 02:56.190 --> 03:02.580 Now, next, let us discuss the steps involved in creating a socket based communication on a server 03:02.580 --> 03:03.570 process. 03:04.380 --> 03:11.070 So next we will going to discuss the implementation details regarding implementing Unix domain socket 03:11.070 --> 03:14.130 based communication on the server process. 03:14.250 --> 03:22.290 So you can see here listed is the steps for implementing socket based communication for server process. 03:22.500 --> 03:27.390 So we will discuss the code and we will discuss each of these steps. 03:27.990 --> 03:38.070 In a given sequence and try to understand that how you can implement Unix domain socket to create a 03:38.070 --> 03:39.390 server process. 03:39.690 --> 03:46.650 So on the right hand side, you can see the diagram which explains or capture the flowchart or steps 03:46.650 --> 03:54.080 to implement a socket programming based communication between the server and the client process. 03:54.090 --> 04:00.750 So you can see we have a server process here and the first step that the server process needs to do 04:00.750 --> 04:07.050 is to create a socket which is also called as master socket file descriptor or connection socket. 04:07.080 --> 04:09.300 The next step is the bind system call. 04:09.570 --> 04:16.590 In the next step the server needs to do bind followed by listen and then the server has to call the 04:16.590 --> 04:21.600 accept in order to wait for the connection from the new client. 04:22.170 --> 04:22.890 Right. 04:22.890 --> 04:30.100 And once the client connection request arrives using connect system call, you can see that the server 04:30.100 --> 04:32.830 process is unblocked from the accept system call. 04:32.830 --> 04:39.700 And then after that a server and the client process are actually engaged in the communication that is 04:39.730 --> 04:41.040 exchanging the data. 04:41.050 --> 04:48.280 So we will go through the code walk of implementing a server process and we will see that how each of 04:48.280 --> 04:53.050 these steps are implemented using Unix domain sockets. 04:54.310 --> 04:55.870 So let's start.