IBM zVM Module 8 CMS Pipelines 2004 IBM

IBM ^ z/VM Module 8: CMS Pipelines © 2004 IBM Corporation

IBM ^ Objectives § Describe the fundamental concepts behind CMS Pipelines § Explain what device drivers are and how they work § Explain the difference between running the PIPE command from a command prompt and from a REXX EXEC § Describe filters and how they are used within a CMS Pipeline © 2004 IBM Corporation

IBM ^ Objectives continued § Describe how to use the LOCATE and FIND commands to select records § Explain how to create your own filters using REXX § Show to use pipelines in EXECs and XEDIT macros in different subcommand environments § Describe the commands needed to create a SPOOL file to hold information © 2004 IBM Corporation

IBM ^ Objectives continued § List the commands needed to read information from a SPOOL file § Describe the CP commands that control the virtual reader § Describe what multistream pipelining is and how to use it © 2004 IBM Corporation

IBM ^ What is a Pipeline? © 2004 IBM Corporation

IBM ^ Device Drivers © 2004 IBM Corporation

IBM ^ The PIPE Command § PIPE: © 2004 IBM Corporation

IBM ^ Some Popular Device Drivers § The console filter reads from the terminal and types on it; for example: 4 Pipe console | console § CONSOLE can provide two functions: 4 Read input, when it is first in a pipeline specification 4 Type the input it gets, when it is not first § A device driver that writes to a device also writes the output to the pipeline. © 2004 IBM Corporation

IBM ^ Some Popular Device Drivers, continued § Reading and writing disk files: – ‘<‘ to read a file – ‘>’ to create or replace a file – ‘>>’ to append to or create a file § LITERAL: – A literal creates a record with the argument string and writes to a pipeline § Combining input drivers: – This allows the programmer to create a file at one location and append, copy, or overwrite the file later in the pipeline. © 2004 IBM Corporation

IBM ^ Using the PIPE Command Other Commands § The PIPE command is not part of the pipeline itself, therefore it is not considered a stage. § In the reading and writing example, the left-hand stage reads the file from disk and the right-hand stage appends to the file specified. § In the second example, we use the CONSOLE command to print the file to the screen. This is helpful when you want to see the file quickly. © 2004 IBM Corporation

IBM ^ Filters § A filter is an application in a pipeline that takes its input from the stage to the left and passes its output to the stage to the right. § The filters that are supplied with CMS Pipelines have many general-use functions. § A function can be anything. © 2004 IBM Corporation

IBM ^ Filters: XLATE - Change Characters XLATE: 4 This filter translates data passing through the pipeline on a character-by-character basis. 4 Some sample pipes: – Pipe literal ABCDEFG | xlate 1 -* lower | console – Pipe literal abcdefghi | xlate c-g = e e | console 4 This filter is also capable of altering multiple characters and character ranges in a single stage or pipe. © 2004 IBM Corporation

IBM ^ Filters: XLATE - Change Characters XLATE: /* Replace “%” with “. ” and */ /* Replace “!” with “ 0” and */ /* Replace “ 4” with “ 0” and */ /* Replace “+” with “-” */ “Pipe Literal Don’t forget that (2+2) / 10 = 40%! |”, ‘Xlate 1 -* %. ! 0 4 0 + - |’, ‘Console’ ____________________ Don’t forget that (2 -2) / 10 = 00. 0 © 2004 IBM Corporation

IBM ^ Making Records Longer or Shorter § CHOP truncates each record after a column. § PAD fills each record to the specified length with a pad character (the default is a blank). 4 Example: – Pipe disk Unknown Data | pad 256 | chop 256 | > Demo output A § You can combine chop and pad to create fixed format records. § Strip removes blanks from both the beginning and the end of records. © 2004 IBM Corporation

IBM ^ Reformat Records § SPLIT creates an output record for each blank-delimited word in its input record. § JOIN creates a single record from one or more input records. § FBLOCK reformats the input stream to fixed length records. © 2004 IBM Corporation

IBM ^ Edit and Rearrange Contents of Records © 2004 IBM Corporation

IBM ^ Buffer Filters § A filter that buffers a file reads all input records before writing output records. § The SORT filter must buffer the file by the nature of its processing. § Use BUFFER when a file must be buffered but not reordered. § Examples: 4 Pipe Disk INPUT FILE | Split | Sort unique | Console 4 Pipe console | buffer | stack © 2004 IBM Corporation

IBM ^ Selecting Records © 2004 IBM Corporation

IBM ^ Looking for Labels - FIND and NFIND © 2004 IBM Corporation

IBM ^ Discarding and Keeping Records § Use TAKE and DROP to retain or discard a specified number of records from the beginning or end of the file. § TAKE and DROP make it easy to select records based on their position in the file. § The DROP filter is the converse of TAKE, which allows you to delete the first or last n lines. © 2004 IBM Corporation

IBM ^ Writing REXX Filters § There are two types of REXX programs you can write to run in a pipeline: 4 One reads input records and writes output records, just like all other programs 4 The other kind is a subroutine pipeline § The REXX program ‘COPY REXX’ copies its input to the output. It can be used as a prototype for more complex filters. © 2004 IBM Corporation

IBM ^ Pipeline Input and Output in a REXX Program § Two of the most important REXX interface commands are READ and WRITE. § The READTO command has a single argument: the name of the variable you wish to be set to the contents of the next input record. § The OUTPUT command is followed by the data you wish to write; you can compute the output data as a REXX expression or you can write a literal. © 2004 IBM Corporation

IBM ^ How to Use Filters © 2004 IBM Corporation

IBM ^ How to Use Filters, continued © 2004 IBM Corporation

IBM ^ Using Pipelines in EXECs and XEDIT Macros © 2004 IBM Corporation

IBM ^ Using Pipelines in EXECs and XEDIT Macros continued § VAR handles the special case where you want to read and write a single record with the contents of a REXX variable. § When you run the pipeline shown in the notes, the SCRIPT macro reads a line from the stack and inserts it in the document. © 2004 IBM Corporation

IBM ^ Getting Information about Files § STATE and STATEW provide information about selected files. § STATEW only searches minidisks that are accessed in write mode. § The underlying CMS commands allow asterisks for components of a file name, so you can find the first occurrence of a certain type of file. © 2004 IBM Corporation

IBM ^ Subcommand Environments § There can be several subcommand environments active in your session, such as XEDIT, CMS, and ISPF. § The SUBCOM device driver takes as an argument the name of a subcommand environment, which is used for execution and displaying output. © 2004 IBM Corporation

IBM ^ Accessing Files in XEDIT © 2004 IBM Corporation

IBM ^ More REXX Interface Commands © 2004 IBM Corporation

IBM ^ More REXX Interface Commands § CALLPIPE replaces a stage with a pipeline. § The asterisk followed by a colon, which seems to be a stage by itself, is called a connector. § Connectors are the magic that tells CALLPIPE to take the input and output for the stage issuing the command connect it to a new pipeline. § CALLPIPE returns when all stages of the new pipeline have completed. © 2004 IBM Corporation

IBM ^ Output Device Driver - Creating a SPOOL File § Three device drivers write lines on unit record devices. § Some output device drivers include: 4 Printmc For a virtual printer 4 Punch For a virtual punch 4 Uro Can write to either device § For complete control, you must issue SPOOL, TAG, and CLOSE commands as required. © 2004 IBM Corporation

IBM ^ Unit Record Input - Reader SPOOL Files § SPOOL files in your virtual reader can come from several sources that have different formats; for example: 4 virtual card punch 4 virtual printer 4 CP-generated SPOOL files, such as a VMDUMP 4 read from a real card reader § A reader reads a file and writes a line to the pipeline for each CCW in the SPOOL file. © 2004 IBM Corporation

IBM ^ CP Commands to Control the Virtual Reader § The characteristics of a virtual reader can be set by the CP command SPOOL, which can control: 4 CLASS 4 NOCOUNT & CONT 4 NOHOLD & HOLD § A printer file is probably easier to handle than a punch file because you often want to retain the carriage control provided by the printer. § Punch files are more complicated because a punch file usually has more than plain data records. © 2004 IBM Corporation

IBM ^ Example: Process Reader Files © 2004 IBM Corporation

IBM ^ Multistream Pipelines © 2004 IBM Corporation

IBM ^ Examples of Multistream Pipelines © 2004 IBM Corporation

IBM ^ Specifying Multistream Pipelines © 2004 IBM Corporation

IBM ^ Combining Streams © 2004 IBM Corporation

IBM ^ Combining Streams continued © 2004 IBM Corporation

IBM ^ Pipeline Stalls © 2004 IBM Corporation

IBM ^ Conclusion § Each section of this module deals with an aspect of CMS Pipelines. § The pipeline concepts discussed were: 4 Device drivers 4 Filters 4 Selecting records 4 Writing REXX filters 4 Using pipeline macros 4 Unit record input and output § These topics help students learn the necessary elements for creating their own pipelines. © 2004 IBM Corporation

IBM ^ Glossary CHOP: – truncates each record after a column FBLOCK: – reformats the input stream to fixed length records Filter: – a stage in a pipeline that takes its input from the stage to the left of it and passes its output to the stage to the right of it JOIN: – creates a single record from one or more input records © 2004 IBM Corporation

IBM ^ Glossary LOCATE: – writes only the records that contain a specific string NLOCATE: – writes all records that do not contain the string specified as the argument PAD: – fills each record to the specified length with a pad character Pipeline: – a series of programs that data passes through. SPLIT: – creates an output record for each blank-delimited word in its input records © 2004 IBM Corporation

IBM ^ Glossary SORT: – orders the input in ascending or descending order UNPACK: – converts a file from the packed format supported by COPYFILE and XEDIT to plain records VAR: – handles the special case where you want to read and write a single record with the contents of a REXX variable XLATE: – translates data passing through the pipeline on a character by character basis © 2004 IBM Corporation

IBM ^ References Hartmann, J. , L. Kraines, and J. Lynn. CMS Pipelines Tutorial. GG 66 -3158 -00, February 1990. IBM. z/VM: CMS Pipelines User’s Guide. SC 24 -5970 -00, February 2001. IBM. z/VM: CMS Command Utility Reference. SC 24 -601002, May 2002. © 2004 IBM Corporation