Legacy technologies in corporate environments – Alberto R. Schiesari – jan/2008 Legacy technologies in corporate environments

Legacy technologies in corporate environments – Alberto R. Schiesari – jan/2008

Legacy technologies in corporate environments


My background

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Experience since 1970 in InformationTechnology.

Companies where I’ve worked : Private and State companies; Banks; IT Services Providers;

Areas and activities in which I’ve been involved :IT Planning; Software Factory; Training; Appl Systems Dev & Maint (systems analysis and programming);Technical Support (system programmer).

And, since 1981I’m also an University Teacher (Computing Sciences courses)


Abstract

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ABSTRACT

Even today, most large corporations (in both developing and developed countries) still rely on 'legacy' technologies such as mainframes for daily operations. In this talk, I will present a review of the characteristics of the mainframes and related technology, the suppliers, the legacy systems user’s profile, and the roles that these technologies play, including software development and maintenance. Finally, I’ll present some trends we can observe in the corporations in the use of legacy systems.


Outline

1. Mainframe concept

1.1 In the sixties

1.2 Suppliers

1.3 Characteristics

2. Mainframe users

3. Mainframe legacy systems

3.1 Some words about software assets

3.2 Hardware and Software survival

3.3 Application Software survival

3.4 People

3.5 Trends

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1. Mainframe Concept

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1.1 In the sixties

1.2 Suppliers

1.3 Characteristics

2. Mainframe users





3.4 People

3.5 Trends



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Was once the 60’s…



1.1 In the 60’s

• There were no small systems

• 3rd generation computers:Integrated CircuitsOperating systemsMultiprogrammingCentralized processing

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We could see a bit with the naked eye


1.2 Mainframe suppliers


Sixties or a little later Today (mainframe related products)

IBM (System /360) IBM (z9 series)

Burroughs Univac RCA (sold to Univac)

Unisys

CDCNCRGEHoneywell

Cray Supercomputers

Siemens (joined with Fujitsu)

ICL (sold to Fujitsu)

Fujitsu, Hitachi, NEC Unix (or Unix-like) Servers,Supercomputers

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1.2 Mainframe suppliers

Who’s left today? Basically IBM.


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So, when we talk about Mainframes today, we’re talking about IBM systems, derived from IBM/360.

The concept is not necessarily attached to processing capacity or speed, but to the systems (and the product of their evolution) developed based on the technical characteristics of the original IBM mainframes.Hardware, base software (operating systems) and application systems.

/360 model 30 : (ex.) 64 K Ram, no virtual storage, 3 programs, 1 card reader/punch, 4 X 7.5 MB 2311 HD, 1403 printer (1100 lpm),

2420 magnetic tapes, typewriter consolehttp://www-03.ibm.com/ibm/history/exhibits/mainframe/mainframe_PP2030.html



IBM products today are servers that also do (the “old”) mainframe activities.

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1.2 Mainframe suppliers :

mainframes X servers X supercomputers

CPU = eServer zSeries 990, max 256 GB RAM, 2007 kg, 1,94 m height, 26.78 sq. ft footprint, 58.69 sq.ft clearance, 15.8 kw, 53.73 KBTU/hr

http://www-03.ibm.com/systems/z/hardware/z990/glance.html



Systems not derived from the IBM System/360 (even with similar processing power) are referred to as "servers“ or, in other cases, …

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HP Superdome Server , up to 64 processors, up to 2 TB memory, 77” height, 60” width, 48” depth

http://www.hp.com/products1/servers/scalableservers/superdome/comparison.html





… or, in other cases, supercomputers.

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CPU = Cray XT3 , 102200 GFlops ≈ 1/10 teraFlops

http://www.jlab.org/news/releases/2007/supercomputer.html





By the way…

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IBM Blue Gene /L Supercomputer73728 GB main memory, 478,200 GFlops = almost half aTeraFlop

# 1 in Top 10 [supercomputer] systems

http://www.top500.org





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Application systems programming

In the beginning was cards...

1.3 Some mainframe characteristics


1.3 Some mainframe characteristicsSystems designed initially with: • Batch processing• Primary input data using punched cards • (note that even the operating systems were batch-oriented)


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http://www.kloth.net/services/cardpunch.php




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Evolution: Need for online processing

3270 terminal characteristics □ (No mouse… only keyboard…no processing capability…) □ 24 lines X 80 columns = 1920 characters screen □ Each character is 8 x 20 dot-matrix □ Each field has his own attributes (color…, blinking, etc) □ Today : the mainframe applications normally think they’re communicating with a 3270 or similar, but there is an emulation program in the PCs, converting protocols □ Some differences with PC keyboards



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3270 keyboard

PC keyboard




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Typical 3270 screen


14:04:11 ***** NATURAL TEST UTILITIES ***** 14/06/2007Test Mode OFF - Debug Main Menu - Object RHALBE18 Code Function T Set test mode ON E Debug environment maintenance S Spy maintenance B Breakpoint maintenance W Watchpoint maintenance C Call statistics maintenance X Statement execution statistics maintenance V Variable maintenance L List object source ? Help . Exit Code .. _ Object name .. ________ Command ===> Enter-PF1---PF2---PF3---PF4---PF5---PF6---PF7---PF8---PF9---PF10--PF11--PF12--- Help Exit Last Flip Canc




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• Main Operating Systems “lines”

(MVT),…,OS/VS2, ..., MVS, ..., z/OS (DOS),…,DOS/VSE,…...…….., z/VSE

….….,VM, .........................., z/VM




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□ JCL (“script” language)□ Vsam (access method)□ Utilities, compilers □ etc…Are functionally quite similar to their previous versions (the internals were probably completely re-written)

//EPC##ARS JOB ('VERIFY'),'VERIFY',CLASS=1,MSGCLASS=X Job to be done //*-------------------------------------------------- comment//STEP1 EXEC PGM=IDCAMS Name of program to be executed //EMPLOYS DD DSN=DSVAABPS.FIN.A999,DISP=(OLD,KEEP) File # 1 program will use //SYSIN DD * File # 2 program will use (instream data) VERIFY FILE(EMPLOYS) this is the file #2 contents //SYSPRINT DD SYSOUT=* File # 3 program will use

Sintax : max. 80 positions (remember? Punched card...)



• Compatibility with previous environments provided, to preserve investments (and therefore, clients): applications developed decades ago can be run, in some cases even without recompiling, in the ultimate versions of hardware and software


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• Internal machine code EBCDIC (not ASCII) □ Data conversion needed in communication with PCs

• Text-oriented (normally no graphical processing; no graphical objects)

PC (Ascii code)

Out = “I LOVE YOU”

Hex’49204C4F564520594F55’

In = “ME TOO”

Hex’4D4520544F4F’

Mainframe (Ebcdic code)

In = “I LOVE YOU”

Hex’C940D3D6E540E8D6E4’

Out = “ME TOO”

Hex’D4C540E3D6D6’

I LOVE YOU

ME TOO



Evolution : online processing

For the application systems:

• IBM solution : a “driver” to manage online applications

• CICS = was (and still is...) responsible for managing the resources demanded by most online applications (storage, files, CPU use, locks,...)


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Batch applications1 address space each

Batch Job

Batch Job

Terminals and other remote objetcts

CICS

DB2 Dbms

Nucleus

Transactions (programs)

DB2

Vsam files

Online (realtime) applicationsAll in the Cics address space(s)

services

services

services

services

Operating System



CICS is not a programming language; user has a set of commands to demand services to CICS, and a host language is needed (ok, we can use it in another way, without a host

language, but just for development / test purposes…).

It can be Cobol, PL/I, C, … : CICS commands embedded in the host language commands

About CICS use, see http://websphere.sys-con.com/read/46839.htm


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Some alternatives to host language with CICS:

IBM = CSP (discontinued), Visual AGE.

Non-IBM (Software AG) = Natural [+ Adabas] + Cics(Natural = programming language; can also be used to develop batch applications )(Adabas = DBMS)

Most mainframe online applications worldwide are created using these tools.


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Evolution : online processing

For development support : IBM solution = TSO

Menu Help ------------------------------------------------------------------------------ Utility Selection Panel 1 Library Compress or print data set. Print index listing. Print, rename, delete, browse, edit or view members 2 Data Set Allocate, rename, delete, catalog, uncatalog, or display information of an entire data set 3 Move/Copy Move, or copy members or data sets 4 Dslist Print or display (to process) list of data set names. Print or display VTOC information 5 Reset Reset statistics for members of ISPF library 6 Hardcopy Initiate hardcopy output 7 Transfer Download ISPF Client/Server or Transfer data set 8 Outlist Display, delete, or print held job output 9 Commands Create/change an application command table 11 Format Format definition for formatted data Edit/Browse 12 SuperC Compare data sets (Standard Dialog) 13 SuperCE Compare data sets Extended (Extended Dialog) 14 Search-For Search data sets for strings of data (Standard Dialog) 15 Search-ForE Search data sets for strings of data Extended (Extended Dialog) Option ===> F1=Help F2=Split F3=Exit F7=Backward F8=Forward F9=Swap F10=Actions F12=Cancel



Program Samples


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To produce this simple text screen …


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* 1 2 3 4 5 6 7 8 12345678901234567890123456789012345678901234567890123456789012345678901234567890 01 NERDC NESA Transaction 01 02 02 03 03 04 04 05 Date: 05 06 06 07 Time: 07 08 Termid: 08 09 Last Key: 09 10 10 11 11 12 12 13 13 14 14 15 15 16 16 17 17 18 18 19 19 20 20 21 21 22 Enter END to Terminate 22 23 23 24 24 12345678901234567890123456789012345678901234567890123456789012345678901234567890 * 1 2 3 4 5 6 7 8

Cobol CICS



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You have to specify this “physical map” …(believe it or not : in Assembler language;

OK… there are some cheap or easier alternatives to do the same…)

* NESA MAP. USED IN PROGRAM DCNESAMP. DCNESAS DFHMSD TYPE=MAP,MODE=INOUT,LANG=COBOL, + TIOAPFX=YES,STORAGE=AUTO DCNESAM DFHMDI SIZE=(24,80),CTRL=(FREEKB,PRINT) END DFHMDF POS=(1,1),ATTRB=(UNPROT,NORM,IC),LENGTH=3 DFHMDF POS=(1,5),ATTRB=(ASKIP,DRK),LENGTH=1 DFHMDF POS=(1,25),ATTRB=(ASKIP,NORM),LENGTH=22, + INITIAL='NERDC NESA Transaction' DFHMDF POS=(5,7),ATTRB=(ASKIP,NORM),LENGTH=5, + INITIAL='Date:' DATE DFHMDF POS=(5,20),ATTRB=(ASKIP,NORM),LENGTH=8 DATEJ DFHMDF POS=(6,20),ATTRB=(ASKIP,NORM),LENGTH=5 DFHMDF POS=(7,7),ATTRB=(ASKIP,NORM),LENGTH=5, + INITIAL='Time:' TIME DFHMDF POS=(7,20),ATTRB=(ASKIP,NORM),LENGTH=8 DFHMDF POS=(8,7),ATTRB=(ASKIP,NORM),LENGTH=7, + INITIAL='Termid:' TERMID DFHMDF POS=(8,20),ATTRB=(ASKIP,NORM),LENGTH=4 DFHMDF POS=(9,7),ATTRB=(ASKIP,NORM),LENGTH=9, + INITIAL='Last Key:' KEY DFHMDF POS=(9,20),ATTRB=(ASKIP,NORM),LENGTH=5 DFHMDF POS=(22,1),ATTRB=(ASKIP,NORM),LENGTH=22, + INITIAL='Enter END to Terminate' DFHMSD TYPE=FINAL END

More...

Cobol CICS



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And this “logical map” …

* NESA MAP. USED IN PROGRAM DCNESAMP. DCNESAS DFHMSD TYPE=DSECT,MAP,MODE=INOUT,LANG=COBOL, + TIOAPFX=YES,STORAGE=AUTO DCNESAM DFHMDI SIZE=(24,80),CTRL=(FREEKB,PRINT) END DFHMDF POS=(1,1),ATTRB=(UNPROT,NORM,IC),LENGTH=3 DFHMDF POS=(1,5),ATTRB=(ASKIP,DRK),LENGTH=1 DFHMDF POS=(1,25),ATTRB=(ASKIP,NORM),LENGTH=22, + INITIAL='NERDC NESA Transaction' DFHMDF POS=(5,7),ATTRB=(ASKIP,NORM),LENGTH=5, + INITIAL='Date:' DATE DFHMDF POS=(5,20),ATTRB=(ASKIP,NORM),LENGTH=8 DATEJ DFHMDF POS=(6,20),ATTRB=(ASKIP,NORM),LENGTH=5 DFHMDF POS=(7,7),ATTRB=(ASKIP,NORM),LENGTH=5, + INITIAL='Time:' TIME DFHMDF POS=(7,20),ATTRB=(ASKIP,NORM),LENGTH=8 DFHMDF POS=(8,7),ATTRB=(ASKIP,NORM),LENGTH=7, + INITIAL='Termid:' TERMID DFHMDF POS=(8,20),ATTRB=(ASKIP,NORM),LENGTH=4 DFHMDF POS=(9,7),ATTRB=(ASKIP,NORM),LENGTH=9, + INITIAL='Last Key:' KEY DFHMDF POS=(9,20),ATTRB=(ASKIP,NORM),LENGTH=5 DFHMDF POS=(22,1),ATTRB=(ASKIP,NORM),LENGTH=22, + INITIAL='Enter END to Terminate' DFHMSD TYPE=FINAL END

And a program like that… (see next 2 pages)

Cobol CICS



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IDENTIFICATION DIVISION. PROGRAM-ID. DCNESAMP. AUTHOR. IMA GATOR. INSTALLATION. UF-NERDC, GAINESVILLE, FL. *REMARKS. * IBM VS COBOL II USING CICS COMMAND LEVEL INTERFACE * PURPOSE: THIS TRANSACTION DISPLAYS SYSTEM INFORMATION * AND LISTS THE LAST PFKEY THAT WAS ENTERED. ENVIRONMENT DIVISION. DATA DIVISION. WORKING-STORAGE SECTION. 01 WS-CONSTANTS. 05 WS-PROGRAM-ID PIC X(08) VALUE 'DCNESAMP'. 05 WS-TRANS-ID PIC X(04) VALUE 'NESA'. 05 WS-MAP-NAME PIC X(08) VALUE 'DCNESAM '. 05 WS-MAPSET-NAME PIC X(08) VALUE 'DCNESAS '. 05 WS-COMMAREA-LENGTH PIC S9(04) COMP VALUE +8 . 05 WS-MESSAGE-LENGTH PIC S9(04) COMP VALUE +79. 05 WS-ERRMSG PIC X(40) VALUE 'NESA TRANSACTION TERMINATED DUE TO ERROR'. 05 WS-ENDMSG PIC X(22) VALUE 'NESA TRANSACTION ENDED'. 01 WS-COMMAREA. 05 WS-CA-PGMID PIC X(08) VALUE SPACES. 01 WS-SWITCHES. 05 WS-FIRST-TIME-SW PIC X(01) VALUE 'Y'. 88 FIRST-TIME VALUE 'Y'. 88 NOT-FIRST-TIME VALUE 'N'. 05 WS-RETURN-TO-TRAN-SW PIC X(01) VALUE 'Y'. 88 RETURN-TO-TRAN VALUE 'Y'. 88 END-TRAN VALUE 'N'. 01 WS-HOLD-AREAS. 05 WS-MESSAGE PIC X(79) VALUE SPACES. 05 WS-ABSTIME PIC S9(16) COMP. 05 WS-SYSDATE PIC X(08) VALUE SPACES. 05 WS-SYSTIME PIC X(08) VALUE SPACES. 05 WS-EIBDATE PIC 9(05) VALUE ZERO. 05 WS-RESP PIC S9(08) COMP VALUE ZERO.

COPY DFHAID. COPY DCNESASD. LINKAGE SECTION. 01 DFHCOMMAREA PIC X(08). PROCEDURE DIVISION. 0000-PROGRAM-DCNESAMP. PERFORM 1000-INITIALIZE. IF NOT-FIRST-TIME PERFORM 2000-RECEIVE-MAP. PERFORM 3000-SEND-MAP. IF RETURN-TO-TRAN PERFORM 8000-RETURN ELSE PERFORM 9000-END-TRANSACTION. GOBACK. 1000-INITIALIZE. EXEC CICS HANDLE CONDITION ERROR(9200-HANDLE-ERROR) END-EXEC. IF EIBCALEN = 0 MOVE LOW-VALUES TO DCNESAMO MOVE WS-PROGRAM-ID TO WS-CA-PGMID ELSE IF EIBCALEN = WS-COMMAREA-LENGTH MOVE 'N' TO WS-FIRST-TIME-SW MOVE DFHCOMMAREA TO WS-COMMAREA ELSE PERFORM 9200-HANDLE-ERROR. 2000-RECEIVE-MAP. MOVE LOW-VALUES TO DCNESAMI. EXEC CICS RECEIVE MAP(WS-MAP-NAME) MAPSET(WS-MAPSET-NAME) INTO(DCNESAMI) RESP(WS-RESP) END-EXEC. IF ENDI = 'END' OR 'end' MOVE 'N' TO WS-RETURN-TO-TRAN-SW.

More...

Cobol as the host languag

eCobol CICS

In red, the CICS

embedded commands



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That’s it

3000-SEND-MAP. PERFORM 3100-PROCESS-EIBAID. EXEC CICS ASKTIME ABSTIME(WS-ABSTIME) RESP(WS-RESP) END-EXEC. EXEC CICS FORMATTIME ABSTIME(WS-ABSTIME) MMDDYY(WS-SYSDATE) DATESEP('/') TIME(WS-SYSTIME) TIMESEP(':') RESP(WS-RESP) END-EXEC. MOVE WS-SYSDATE TO DATEO. MOVE WS-SYSTIME TO TIMEO. MOVE EIBDATE TO WS-EIBDATE. MOVE WS-EIBDATE TO DATEJO. MOVE EIBTRMID TO TERMIDO. IF FIRST-TIME OR EIBAID = DFHCLEAR OR DFHCLRP EXEC CICS SEND MAP(WS-MAP-NAME) MAPSET(WS-MAPSET-NAME) FROM(DCNESAMO) ERASE FREEKB END-EXEC ELSE EXEC CICS SEND MAP(WS-MAP-NAME) MAPSET(WS-MAPSET-NAME) FROM(DCNESAMO) ERASEAUP FREEKB DATAONLY END-EXEC.

3100-PROCESS-EIBAID. IF EIBAID = DFHNULL MOVE 'NULL ' TO KEYO ELSE IF EIBAID = DFHENTER MOVE 'ENTER' TO KEYO ELSE IF EIBAID = DFHPA1 MOVE 'PA1 ' TO KEYO ELSE IF EIBAID = DFHPA2 MOVE 'PA2 ' TO KEYO ELSE IF EIBAID = DFHPA3 MOVE 'PA3 ' TO KEYO ELSE IF EIBAID = DFHPF1 MOVE 'PF1 ' TO KEYO ELSE IF EIBAID = DFHPF2 MOVE 'PF2 ' TO KEYO ELSE MOVE 'OTHER' TO KEYO. 8000-RETURN. EXEC CICS RETURN TRANSID(WS-TRANS-ID) COMMAREA(WS-COMMAREA) LENGTH(WS-COMMAREA-LENGTH) END-EXEC. 9000-END-TRANSACTION. MOVE WS-ENDMSG TO WS-MESSAGE. PERFORM 9900-TERMINATE. 9200-HANDLE-ERROR. MOVE WS-ERRMSG TO WS-MESSAGE. PERFORM 9900-TERMINATE. 9900-TERMINATE. EXEC CICS SEND FROM(WS-MESSAGE) LENGTH(WS-MESSAGE-LENGTH) ERASE END-EXEC. EXEC CICS SEND CONTROL FREEKB END-EXEC. EXEC CICS RETURN END-EXEC.

Cobol as the host languag

eCobol CICS

In red, the CICS

embedded commands



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EZEM90 TEST ==> ENTER = Continue PF3 = Exit ............................. FUNCTION SELECTION ............................. Enter application name => Enter function number => 2 1 Syntax check using the preprocessor 2 Run the application Run Options Trace => YES Stop on statement count => 01000 Select statements to stop on => NO Stop PF key => Initialization file (name) => Delayed preprocessing => YES Change execution defaults => NO

CSP



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Visual Age



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0010 DEFINE DATA LOCAL 0030 1 #I (N4) INIT<-1> 0040 1 #TL-A (N3) 0050 1 #AX-A (N3) 0060 1 #TL-B (N3) 0070 1 #AX-B (N3) 0080 1 #FUNA (N5) 0090 1 #FUNB (N5) 0100 END-DEFINE 0120 SET KEY ALL 0140 INPUT USING MAP 'ZZDICOTO' 0160 INPUT USING MAP 'ZZDICOT3' 0180 IF #TL-A = 0 0190 REINPUT ' ENTER VALUE FOR A' 0200 END-IF 0210 IF #TL-B = 0 0220 REINPUT ' ENTER VALUE FOR B' 0230 END-IF 0250 #AX-A := #TL-A 0260 #AX-B := #TL-B 0270 INPUT NO ERASE 1/24 'THE FUCTION WILL BE X * X - 5' 0290 #FUNA := (#AX-A * #AX-A) - 5 0300 #FUNB := (#AX-B * #AX-B) - 5 0320 IF *PF-KEY = 'ENTR' 0330 INPUT USING MAP 'ZZDICOT2' 0340 IF (#FUNA * #FUNB) < 0 THEN 0350 INPUT NO ERASE 13/28 'THERE IS ROOT' 0360 ELSE 0370 INPUT NO ERASE 13/28 'THERE IS NO ROOT' 0380 END-IF 0390 END-IF 0410 END

Natural



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Natural A little bit easier to build the map…

Ob _ Ob D CLS ATT DEL CLS ATT DEL . . T D Blnk T I ? . . A D _ A I ) . . A N ª M D & . . M I : O D + . . O I ( . . 001 --010---+----+----+---030---+----+----+---050---+----+----+---070---+---- ?NOME : (XXXXXXXXXXXXXXXXXXXXXXXXXXXXXX ?ENDERECO : (XXXXXXXXXXXXXXXXXXXXXXXXXXXXXX ?TELEFONE : (XXXXXXXXXXXXXXXXXXXXXXXXXXXXXX Enter-PF1---PF2---PF3---PF4---PF5---PF6---PF7---PF8---PF9---PF10--PF11--PF12--- Help Mset Exit Test Edit -- - + Full < > Let

NOME : ENDERECO : TELEFONE :


2. Mainframe Users

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1.1 In the sixties

1.2 Suppliers

1.3 Characteristics

2. Mainframe users





3.4 People

3.5 Trends


Who, since the 60’s, are the users?

Big companies: both government and private

Private : banks and most of the Top 500

Industries : (most of them migrated to SAP or other ERP systems)

Companies like that normally have a long life; most of them are alive today. Some solutions and processes they use were set long time ago.

The IT systems – software - is one of them.

2. Mainframe Users

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Note that it’s unlike a younger company, born in the 80’s or 90’s: in this case, the IT solutions and processes implemented were based on new designs, new architectures (web, for instance), new development environments.

2. Mainframe Users

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3. Mainframe Legacy Systems

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1.1 In the sixties

1.2 Suppliers

1.3 Characteristics

2. Mainframe users





3.4 People

3.5 Trends


Let’s try to figure out the mainframe market, in Brazil, nowadays:

40 large or medium sized banks 50 government entities (both federal and state)100 of the top 500 private Brazilian companies

190 companies working with mainframe-based applications

(Worldwide = it’s a significant # of active mainframes)


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3.1 Some words about the software assets


Let’s try to figure out the size of the software assets of these companies (mainframe software):

(* = numbers based upon my experience)

Assuming :a) 1000 LOCs / program average (*)

b) $125 / Function Point(Capers Jones, SPR)See http://www.boston-spin.org/slides/031-Oct02-talk.ppt

c) 1 FPs = 80 LOCs (3rd generation language default, Caper Jones, SPR)See http://www.spr.com/products/programming.shtm


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User type # Programs

(*)LOCs Total # FPs

$ Total

Large size Bank 200,000 200,000,000 2.500,000 300 M

Medium size Bank

100,000 100,000,000 1,250,000 150 M

State company 50,000 50,000,000 625,000 70 M

Big company 20,000 20,000,000 250,000 30 M


The cost to change the application using new technologies, with new designs, is too

expensive.

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There’s a kind of “supplier commitment” to provide compatibility with previous versions (backward compatibility); there is no reason for great concerns about obsolete environments; programs “always” run on new equipment.

Hardware has the ability to run (host) many operating systems / virtual machines.

There is also the backward compatibility “commitment” with the base software (operating systems, compilers, dbms, etc.)


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3.3 Application Software survival - Reliability

• It is well known that the more a software is tested, the more it is error-free and, thus, reliable.

• Mainframe software technologies do not change substantially.

• In the mainframe area, quickly releasing new products and new versions isn’t as fundamental as it is in the other platforms (remember: there is no competition…).

• There is enough time to do the necessary tests.

• The products are released in very reliable versions.


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3.3 Application Software survival - Reliability

• Unavailability in a net PC and in a server supporting thousands of workstations is quite different.

• Unscheduled boots rarely occur

• There is a small number of interfacing components; to track and correct errors is easier


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3.4 Application Software survival - People

• People who designed, developed, worked on the systems leave the company.

• There’s a need to replace these technicians.

• In Universities, there’s practically no more training on Mainframe technologies: CICS, Cobol, batch programming logic – for example, how to create a report, controlling lines, pages, breaks, etc? Do you know OOP? Forget it!


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3.4 Application Software survival - People

• How do companies deal with this point? Internal training Ex. 6 months programme with:

Mainframe conceptsProgramming logicJCL and utilitiesCobolPL/ICICSDB2TSO / Roscoe

Training suppliers


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3.5 Application Software survival – Trends

• Batch applications:

They’ll probably continue the same way

I bet: 20 years from now you’ll see a batch system running in a quantum computer, “reading” 80 byte records as cards…


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• Online applications:

Break the application into layers

Change the application “foreground layer” (front end) by web based application

Leave the mainframe as a DB Server and “background layer” Server

Probably all terminal I/O operations migrating to the PC based applications

Probably all DB operations left in the mainframes


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PC based Mainframe

DBMS services, other file services

CICS Data validation;

CICS services;

demand services to

DBMS

Data validation;

OK, demand

services to Mainframe

Terminal input and

output


Questions ?

Questions

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Documents

Legacy technologies in corporate environments – Alberto R. Schiesari – jan/2008 Legacy technologies in corporate environments