PIPE AND FILTER GROUP 2 SHIMIRRAH REMBERT CHRISTOPER BELL ADEDOYIN OKE BRIAN ADIYIAH BRELAND BRANCH

ALSO KNOWN AS PIPELINE THIS IS THE PROCESS OF CHAIN OF EVENTS, WHERE THE OUTPUT OF AN ELEMENT IS THE INPUT OF THE NEXT ELEMENT IN BETWEEN THESE ELEMENTS THERE ARE FLOWS FILTER- TRANSFORMS THE DATA THROUGH THE PIPES THAT IT IS CONNECTED TO. A FILTER CAN HAVE AS MANY PIPES AS NEED BE. PIPE – PASSES DATA FROM ONE FILTER TO THE NEXT FILTERS WORK AT THE SAME TIME WITH DIFFERENT ASSIGNMENTS FILTERS CAN BE COMBINED WHAT IS PIPE AND FILTER

OTHER COMPONENTS PUMP- THE DATA SOURCE OR THE PRODUCER SINK- THE DATA TARGET OR THE CONSUMER KEN THOMSON- CREATOR OF UNIX THOMSON LIMITED THE ARCHITECTURE OF LINEAR PIPELINE ALONG WITH DOUG MCILROY. PIPE AND FILTER OVERVIEW

HIGH LEVEL DIAGRAM

UNIX STYLE EXAMPLE $ doyin | lpr –PclJ263 The | is a Unix pipe symbol used in command line. The standard output of the command to the left of the pipe gets sent as standard input of the command to the right of the pipe. It sends the stream of data to another program, in this case, a program called lpr which sends all incoming data to the printer in CLJ263.

$ CAT GROUP2.TXT INPUT STRING SHELL SIGNAL $ CAT GROUP2.TXT | WC IN THIS EXAMPLE, AT THE FIRST SHELL PROMPT, THE CONTENTS OF THE FILE GROUP2.TXT ARE DISPLAYED. HERE THE CAT COMMAND IS USED TO DISPLAY THE CONTENTS OF THE GROUP2.TXT FILE, BUT THE DISPLAY IS NOT SENT TO THE SCREEN; IT GOES THROUGH A PIPE TO THE WC (WORD COUNT) COMMAND. THE WC COMMAND THEN DOES ITS JOB AND COUNTS THE LINES, WORDS, AND CHARACTERS OF WHAT IT GOT AS INPUT. MORE EXAMPLE OF PIPE IN UNIX COMMAND LINE

FILTERS DOES SOME MANIPULATION TO TEXT OF A FILE. UNIX FILTERS USED ARE SED, AWK AND GREP $ CAT GROUP2.TXT INPUT STRING SHELL SIGNAL $ CAT GROUP2.TXT | SED -E "S/STRING/SIGNAL/G“ INPUT SIGNAL SHELL SIGNAL IN THIS EXAMPLE, THE FIRST SHELL PROMPT DISPLAYS THE CONTENTS OF THE GROUP2.TXT FILE. THE SECOND SHELL PROMPT, USES THE CAT COMMAND TO DISPLAY THE CONTENTS OF THE GROUP2.TXT FILE, AND SENDS THAT DISPLAY THROUGH A PIPE TO THE SED COMMAND. THE SED COMMAND CHANGED EVERY OCCURRENCE OF THE WORD "STRING" TO THE WORD "SIGNAL.“ THE SED TOOK AS INPUT THE INFORMATION IT GOT THROUGH THE PIPE. THE SED COMMAND DISPLAYED ITS OUTPUT TO THE SCREEN. EXAMPLE OF FILTERS IN UNIX

$ CAT GROUP2.TXT | SED -E "S/I/OOO/“ WWWNPUT STROOONG SHELL SOOOGNAL $ THE SHELL PROMPT, USES THE CAT COMMAND ON THE GROUP2.TXT FILE AND PIPES THE OUTPUT TO THE SED COMMAN TO CHANGE THE FIRST OCCURRENCE OF AN “I” ON EACH LINE TO “OOO” THE CONTENTS OF THE GROUP2.TXT FILE ITSELF WERE NOT CHANGED IN THE FILE. ONLY THE DISPLAY OF ITS CONTENTS CHANGED. ANOTHER FILTER EXAMPLE IS GREP COMMAND WHICH IS USED TO SEARCH FOR A PARTICULAR STRING IN A FILE JOHN S. GRAY “ INTERPROCESS COMMUNICATIONS IN UNIX.” THE NOOKS AND CRANNIES, DEC, MORE SED EXAMPLE

DESCRIPTION OF THE DESIGN OF PIPE AND FILTER CAN BE DONE IN VARIOUS WAYS AND HAVE SEVERAL PATHS HAS BACK-UP WITH 3 COMPONENTS: PUMP, FILTER, SINK. HELPS ELIMINATE DEADLOCKS IN THE OPERATING SYSTEM THE FILTER AND SYSTEM BENEFIT EACH OTHER NO RESTRICTIVE ORDER IN THE DESIGN INDEPENDENT FILTERS HELPS THE BINDING OF A REAL TIME SYSTEM PIPE AND FILTER ARE EFFICIENT AND PARALLEL ADVANTAGES

DOESN’T WORK WILL WITH SYSTEMS THAT INTERACT WITH USERS PIPE AND FILTER ARCHITECTURE IS A TYPE OF DIRECTED ACYCLIC GRAPH FILTERS CANNOT COMMUNICATE WITH OTHER COMPONENTS IN A PROGRAM DIRECTLY CONSUMES A LARGE MASS OF ENERGY CONCURRENT RUNNING TRANSPIRES DISADVANTAGES