GETTING MORE FROM MPE by Eugene and Vladimir Volokh, VESOFT (1135 S. Beverly Dr.,LA,CA,90035,USA) Presented at 1981 HPIUG Conference, Orlando, FL, USA Published in "Thoughts & Discourses on HP3000 Software", 1st-4rd ed. THE BIRTH OF MPEX In 1980, we were working as application programmers at an HP3000 site in Los Angeles; the application system we were developing was an Accounts Payable system in FORTRAN, but for the purposes of our discussion, it could just as well have been any application system in any language. The system was an average-sized one, starting with about 20 programs, growing to 25, 30, and finally stabilizing at about 35. And, while working on it, I discovered a rather disconcerting fact about the HP 3000: THE HP3000 IS NOT MADE FOR APPLICATION SYSTEMS DEVELOPMENT. After all, consider this: on the HP, you can compile a single program, list a single program, edit a single program, purge it, copy it, rename it, release it; but, when it comes to working on entire application systems, the HP just can't cut the mustard. For instance, let us say one changes the COPYLIB of a COBOL system; to put these changes into effect, it is necessary to recompile the entire application system. The only way to do this in MPE is to recompile the system program by program, a very time-consuming and error-prone task. What you really want to do is to execute a command such as %COBOL GL@.SOURCE, GL@.PUB i.e. 'compile via COBOL all the files that start with GL in the SOURCE group into files with the same name in PUB'. Similarly, you may sometimes want to list to the line printer all of your application sources. Instead of doing a /TEXT and /LIST ALL, OFFLINE of every source file in your application system, you would like to type a command like %EDIT GL@.SOURCE, LIST ALL,OFFLINE Other things that you ought to be able to do (but are not permitted to by MPE) on entire application systems spring to mind: %EDIT GL@.SOURCE, WHILE; FINDQ "QTY-SOLD"; LIST to find all the places where a given variable is mentioned in your application system, or %FCOPY GL@.SOURCE,GL@.ARCHIVE,NEW to do an online backup of your application sources. This is how VESOFT's MPEX/3000 was born -- out of a need to perform certain operations not just on single files, but on ENTIRE FILESETS, like GL@.SOURCE. THE MPEX FILESET As was discussed above, the MPEX fileset is the heart and soul of MPEX. Note that I say "MPEX fileset," not just "fileset." This is because MPEX filesets go far beyond the filesets available in MPE. In addition to ordinary MPE filesets like GL@.SOURCE K#######.@.@ @.@.@ MPEX filesets can also be "arithmetic expressions" of MPE filesets, where operators may be + (union) and - (exclusion): AP@+GL@.SOURCE <<all the files in either fileset>> AP@+GL@.SOURCE-@COPY.@ <<except those that end with COPY>> Thus, an MPEX command like %PURGE K#######.@.@+LOG####.PUB.SYS will purge all EDITOR/TDP K-files and all system log files (% is MPEX's prompt, and will be used to indicate MPEX commands). All the filesets that have been mentioned so far select files on the basis of their names ONLY. But, it is often desirable to select attributes other than file names; for instance, you may wish to find all the files in the system that are bigger than, say, 10,000 sectors. This can be accomplished by a command such as %LISTF @.@.@(DISCSPACE>10000),2 The part of the fileset that is enclosed in parentheses is the selection criterion, on the basis of which files are selected from the main fileset. There are many such selection criteria, and they may be ANDed together, as in this command: %LISTF @.@.@(DISCSPACE>10000 and ACCDATE<1/1/83),2 which finds all the files in the system (@.@.@) that use more than 10,000 sectors of disc space and haven't been accessed since January 1, 1983. Other selection criteria available are CODE (file code), CREATOR (file creator), CREDATE (creation date), DEVICE (logical device on which file resides), MODDATE (last modify date), OUTPRI (SPOOL file output priority), PMCAP (program file privileged mode capability), RSTDATE (last restore date), SAVABLE (amount of disc space savable), and SECURITY (file released vs. secured). Thus, an extreme example of an MPEX fileset may be found in a command like: %EDIT GL@.SOURCE+AP@-@COPY.@(CODE="EDTCT"), LIST ALL,OFFLINE which lists to the line printer all files in GL@.SOURCE and AP@ that have file code EDTCT except those that end with "COPY." Thus, the MPEX fileset is a very powerful tool that can select files based on a number of different relevant criteria. FROM PROGRAMMER'S TOOL TO SYSTEM MANAGEMENT TOOL The first few MPEX commands that were talked about (COBOL, EDIT, and FCOPY) are mostly programmer and project leader tools, that can greatly enhance the program development process. However, MPEX and MPEX filesets offer quite a bit for the account and system manager, too. One command that has already been mentioned, PURGE, is often a handy command for the system manager. With a command like %PURGE K#######.@.@+LOG####.PUB.SYS which purges all EDITOR/TDP K-files and system log files, the system manager can save quite a bit of space occupied by these files, which are usually useless. Or, the system manager can do a :STORE @.@.@;*TAPE;DATE<1/1/83 :RUN MPEX.PUB.VESOFT %PURGE @.@.@(ACCDATE<1/1/83) to archive to tape all the files that haven't been accessed since January 1, 1983 and then purge them. Other uses for the PURGE command include %PURGE @.@.ACCOUNT to clear out all the files in the specified account without removing the accounting structure. This command can often be used instead of :PURGEACCT ACCOUNT, which destroys the accounting structure, and thus makes files from that account difficult to restore. Another feature of the PURGE command, useful for system operators, is based on the fact that MPEX allows spool-file filesets as well as permanent file filesets. Thus a command like %PURGE $STDLIST.@.@-@.@.PROD(SPOOL.OUTPRI=1) will purge all the $STDLISTs in the system that have output priority 1 except those in the PROD account (the :SPOOL at the end of the fileset indicates that this is a spool-file fileset). In addition to the PURGE command, other MPE commands that have been extended to allow filesets include RELEASE, SECURE, RENAME, and ALTSEC. However, not only do these commands accommodate filesets, but they also make the account or system manager's life easier by waiving HP's restriction that these commands may be performed by the creator of the file only. After all, if a user has read and write access to a file, he can copy it and purge the original -- he should certainly be allowed to RENAME it. Thus, by replacing HP's rather illogical creator-only restriction by one that permits anyone who has read, write, and execute access to RELEASE, SECURE, RENAME, and ALTSEC a file, MPEX makes life easier for its users without compromising system security. MORE FOR THE SYSTEM MANAGER -- THE LISTF COMMAND MPE's :LISTF command already permits filesets; however, MPEX's extended %LISTF command permits MPEX's extended filesets, with + filesets, - filesets, and selection criteria. Thus, as was shown above, you can use the %LISTF command on a fileset with selection criteria to find all files that use more than a certain amount of disc space, or all files that haven't been accessed since a given date, etc. This ability to list all files by disc space used, last access date, etc. makes MPEX a very powerful system manager tool, especially in the area of saving disc space -- one of our customers reported that he saved 50 megabytes of disc space by using the %LISTF command alone! But, there is more to the %LISTF command than just the ability to list MPEX filesets. Say you use the last access date as a selection criterion; it is only reasonable that you should be able to list the last access date in addition to selecting on it. With a command like %LISTF @.@.@(ACCDATE<1/1/83),3 you can! New modes, mode 3 to list creator id, last access date, last modify date, creation date, and last restore date; mode 4 to list various disc space utilization information (including device class, extent map, suggested blocking factor, etc.); and mode 5 to list program file information (capabilities, maxdata, stack size, group/account that last ran this program, etc.) have been added, letting the MPEX user list much file information that is otherwise unavailable. Thus, the %LISTF command, with the ability to specify MPEX filesets and its new modes, is a very powerful system manager tool. ALTERING FILE ATTRIBUTES WITH MPEX To complement the ability to select on many file attributes and list those attributes via the new modes of the %LISTF command, MPEX also allows its users to alter vital file attributes. For instance, let us say that one wants to move a database set (called GLDB05) to device 2 to minimize head contention. With MPEX, you can do this very easily: %ALTFILE GLDB05, DEV=2 Of course, this command, like all MPEX commands, can be applied to filesets as well as single files. Or, let us say that the file DATAFILE, which has room for 10,000 records, is currently at 9987, and is in danger of imminent overflow. With MPEX, you can expand the file with one command: %ALTFILE DATAFILE, FLIMIT=15000 Alternatively, if the file has room for 15,000 records, but contains only 600 records, much of the room allocated for this file is wasted. With MPEX, one can do a %ALTFILE DATAFILE, FLIMIT=1000 to decrease the file limit, a %ALTFILE DATAFILE, SQUEEZE to set the file limit to the end of file (saving as much space as possible), or a %ALTFILE DATAFILE, EXTENTS=32 to increase the number of extents of the file, thus decreasing the size of each individual extent and thus minimizing the amount of space wasted by the file without decreasing the file's file limit. The EXTENTS keyword is especially applicable to V/3000 forms files, which are built with file limits of 4000, 8000, or 16,000 and only 8 extents; thus, a small V/3000 forms file can waste from 500 to 2,000 sectors of disc space! A command of the form %ALTFILE @.@.@(CODE=VFORM), EXTENTS=32 will change all the V/3000 forms files in the system to have 32 extents, thus potentially saving a lot of disc space. These keywords (FLIMIT, SQUEEZE, and EXTENTS) in addition to the BLKFACT keyword, which changes a file's blocking factor, and BLKFACT=BEST, which automatically sets the file's blocking factor to the one yielding the most disc space savings, are also very powerful disc space saving options; one MPEX user reported that by using the %LISTF and %ALTFILE commands they saved 150 megabytes of disc space! In addition to the attributes mentioned above, other file attributes can be changed; for instance, let us say that your trusted programmer, John, leaves your shop. Naturally, being a security-conscious system manager, you immediately remove the user JOHN from the system, only to find that he has created many files and several databases. What you want is to change the creator id of all files created by JOHN to MGR. With MPEX, this is easy: %ALTFILE @.@(CREATOR="JOHN"), CREATOR=MGR Other file attributes, such as file code, lockword, and various program file attributes, can also be changed with this command, one of the most powerful in the MPEX arsenal. ACCESSING MPEX FROM WITHIN EDITOR One major problem with HP's EDITOR is that one cannot compile, prepare, or execute programs from within it. Thus, to make a simple program modification, the programmer has to enter EDITOR, /TEXT the file, make the modification, /KEEP the file, /EXIT EDITOR, compile it, find a compilation error, re-enter EDITOR, re-/TEXT the file, and so on. What would be really desirable is the ability to compile the file from EDITOR without /EXITing and having to re-text the source file when one re-enters EDITOR. MPEX, however, permits its users to compile, :PREP, :RUN, and even execute UDCs from within it. And, VESOFT also provides a method of executing MPEX commands from within EDITOR (by prefixing them with a %). Thus, a programmer may "live" in EDITOR, doing all his compilation and testing from within EDITOR via MPEX. An example programmer session would thus be: :RUN EDITOR.PUB.VESOFT;LIB=P <<special version of EDITOR>> /TEXT SRCFILE << make modifications >> /KEEP /%COBOL SRCFILE,PRGFILE <<MPEX command, includes :PREP>> << compile fails, workfile still contains SRCFILE, make more modifications without re-/TEXTing the file >> /KEEP /%COBOL SRCFILE,PRGFILE << compile now succeeds >> /%RUN PRGFILE Thus, the programmer saves the overhead of entering EDITOR, /EXITing EDITOR, and re-/TEXTing the file every time he needs to do a compile. Thus, even if one does not use any of the fileset-handling features of MPEX (which are also available from within EDITOR via the same % interface), one can still derive great benefit from MPEX. SUMMARY Thus, MPEX provides the user with many desirable and needed features, including the ability to * Compile, EDIT, FCOPY, RENAME, PURGE, RELEASE filesets. * Select on the basis of various file attributes. * List various file attributes. * Change various file attributes. * Waive certain annoying and unneeded security provisions in the RENAME, RELEASE, SECURE, and ALTSEC commands. * PURGE filesets of spool files. * Execute MPEX commands, compiles, :PREPs, :RUNs, and UDCs from within the EDITOR. * Save a lot of disc space. * And much, much more. MPEX thus proves itself to be an exceptionally powerful and useful tool for the program developer and the system manager.
Go to Adager's index of technical papers