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Internet Domain UDP Sockets Datagram sockets unreliable , full duplex , packet oriented communication channel unreliable means there is no sequence numbering no connection establishment server has only one socket , no master socket like tcp , only has data socket Connection-Orietned Datagram Sockets = but client can call connect method , with this state you don't have to specify server address U..

short connections = something like echo it is very short term connection long connections = telnet , ssh is very long term connection it goes on until client send quit message to server Socket communciation end point to which an application can write data and from which an application can read data. Stream Sockets provide a reliable , full duplex , steram oriented communciation channel. do not s..

Application Layer Consist of process that use the NW(Network) Porvides progamming interface used for building a program Protocols used are http, telnet, ftp, smtp, ssh Addresses are string based URIs (URL, URN) Transport Layer Provides host to host communication Protocols used are TCP ,UDP , RAW 16 bits Port numbers are used for addressing Internet Layer Break data into fragments small enough fo..

#include #include #include #include #include #include #include #include void* f1(void * arg); int main(int argc, char* argv[]){ if(argc != 3){ printf("Invalid number of arguments. Must pass two file names.\n"); exit(1); } pthread_t tid1, tid2; void *rv1, *rv2; pthread_create(&tid1, NULL, f1, (void*)argv[1]); pthread_create(&tid2, NULL, f1, (void*)argv[2]); pthread_join(tid1, &rv1); pthread_join(..

Shared Memory allows 2 or more processes to share a memory region or segment of memory for reading and writing purposes the problem with pipes, fifo and message queue is that mode switches are involved as the data has to apss from one process buffer to the kernel buffer and then to another process buffer since access to user-space memory does not require a mode switch , thereofre , shared memory..

Message Queues = can be used to pass messages between related or unrelated processes executing on same machine. Message queues are somewhat like pipes and fifos , but differ in 2 important aspects. 1. mesage boundaries are preserved, so that readers and writers communciate in units of messages. 2. message queues are kerenl persistent A message queue can be thought of as a linked list of messages..

pipe system call Creating pipe is similar to opening 2 files. A successful call to pipe() returns 2 open file descriptors in the array fd. one contains the read descriptor of the pipe, fd[0] , and the other contains the write descriptor fo the pipe fd[1]. if pipe(fd) fails it returns -1. to make parent process writer and child process reader we close fd[0] from parent process and close fd[1] for..

kill system call int kill(pid_t pid, int sig); if sig is zero than normal error checking is performed but no signal is sent. Used to determine if a specified process still exists. if it doesn't exist, a -1 is returned and errno is set to ESRCH if pid > 0 , the signal is sent to the process with the process ID specified by first argument if pid == 0 the signal is sent to every process in the same..

Inter Process Communciation (IPC) Process Persistence Exists as long as it is held open by a process Pipes and FIFOs TCP, UDP sockets Mutex , condition variables , read write locks POSIX memroy based semaphores Kernel Persistence Exists until kernel reboots or IPC objects is explicitly deleted Message Queues , semaphores & shared memory are at least kernel persistent File system Persistence Exis..

Temporal Multi-threading = Only one thread of instruction can execute in any given pipeline stage at a time Simultaneous Multi-threading (SMT/HT) = More than one thread of insturction can execute in any given pipeline stage at a time (super scalar architecture) #include #include #include #include #include struct mystruct{ char character; int count; }; void * f1(void *); int main(){ pthread_t tid..