COBOL File Organizations File Naming Using File Status This chapter explains the available COBOL file organizations and gives examples of using them. Using only COBOL syntax, COBOL programs can create, update and read files of four different organizations:.
Line sequential Line Sequential files are a special type of sequential file. They correspond to simple text files as produced by the standard editor provided with your operating system.
Record sequential Sequential files are the simplest form of COBOL file. Records are placed in the file in the order they are written, and can only be read back in the same order.
Relative Files Every record in a relative file can be accessed directly without having to read through any other records. Each record is identified by a unique ordinal number both when it is written and when it is read back. Indexed Indexed files are the most complex form of COBOL file which can be handled directly by COBOL syntax. Records in an indexed file are identified by a unique user-defined key when written. Each record can contain any number of user-defined keys which can be used to read the record, either directly or in key sequence. A sequential file is a file in which the records can only be accessed sequentially.
Records are always added to the end of the file. In line sequential files, each record in the file is separated from the next by a record delimiter. On DOS, Windows and OS/2 this is a carriage return (x'0D') and a line feed (x'0A') character. On UNIX it is just the line feed (x'0A') character.
These characters are inserted after the last non-space character in each record so line sequential files always contain variable-length records. Report files are line sequential, since most PC printers require the carriage return and/or line feed characters at the end of each record. Most PC editors produce line sequential files, and these files can therefore be edited with almost any PC editor. The primary use of line sequential files is for display-only data.
Caution: We recommend that you do not use line sequential files for binary or packed data fields. Line sequential files are also known as text files, or flat ASCII files. When you declare a file as line sequential in COBOL, you do so through the SELECT clause. Example Creating a line sequential file: file-control. Select lineseq assign to 'line.dat' organization is line sequential. File section. Fd lineseq record contains 80 characters.
01 lineseq-fd-record pic x(80). Record sequential files are nearly always simply called sequential files, since record sequential is the default for a sequential file.
Records in a record sequential file can be either fixed or variable in length. Variable-length records save disk space. There are many applications that can benefit from the use of variable-length records.
A common example is where your application generates many small records, with occasional large ones. If you make the record length as long as the largest record, you waste a lot of disk space. The way to prevent this waste is to use variable-length records. When you declare a file as record sequential in COBOL, you do so through the SELECT clause. Example Creating a record sequential file with fixed-length records. Select recseq assign to 'recseq.dat' organization is record sequential. File section.
Fd recseq record contains 80 characters. 01 recseq-fd-record pic x(80). Note: In place of the ORGANIZATION clause above, you could use: organization is sequential Or, you could simply omit the ORGANIZATION clause, as record sequential is the default file organization (if the SEQUENTIAL directive is not set). Example Creating a record sequential file with variable-length records. File control. Select recseqv assign to 'recseqv.dat' organization is sequential. File section.
Fd recseqv recording mode is v record varying from 3 to 80 characters. 01 recseqv-fd-record pic x occurs 3 to 80 times depending on ws-record-length. Working-storage section. 01 ws-record-length pic 99.
With relative file organization, you can access records sequentially or randomly. For sequential access, you simply do a sequential READ to get the next record in the file. For random access, you specify the ordinal number of the record in the file. Relative files have a fixed-length file format. You can declare that you want the records to have a recording mode of 'variable' but even if you do this, the system assumes the maximum record length for all WRITE statements to the file, and pads the unused character positions. So, when you are in a situation where you have a lot to gain by using variable-length records, you should avoid relative files because they are always fixed format.
Relative files have the fastest access time of all the file types used by this COBOL system so, if speed of access is the most important consideration, you should consider using relative files. With relative files, you can have numeric keys, but you cannot key on fields.
If you need to access data randomly based on certain fields, you must use indexed files. Example Creating a relative file with a record length of 80 characters: file-control.
How To Read Cobol Code
Select relfil assign to 'relfil.dat' organization is relative access mode is random relative key is relfil-key. File section. Fd relfil record contains 80 characters. 01 recseq-fd-record pic x(80).
Working-storage section. 01 relfil-key pic 9(8) comp-x.
Note: The relative key field is relfil-key. When you are randomly accessing this file, there is no KEY IS field on the READ statement. The number in relfil-key determines which record is read. (For sequential access, a simple READ statement gets the next record.) Indexed file access enables you to access records either randomly or sequentially, using one or more key fields in the individual records. Key comparisons are made on a byte-by-byte basis from right to left using the ASCII collating sequence. COBOL indexed files are actually made up of two physical files: a data file and an index file.
The index file is created automatically, and has an extension of.idx; the data file can have any other extension, although.dat is very common. Records in indexed files can be either fixed or variable in length. Whenever you need to provide users with many different views of a file, you need indexed files. In your programs, this implies the need for random access, keyed on one or more fields in the records. Example Creating an indexed file with fixed-length 80-byte records keyed on the first five bytes of each record: file-control. Select isamfil assign to 'isamfil.dat' organization is indexed access mode is dynamic record key is isamfil-fd-key. File section.
Fd isamfil record contains 80 characters. 01 isamfil-fd-record. 05 isamfil-fd-key pic x(5). 05 isamfil-fd-data pic x(75). Creating an indexed file with variable-length records, varying in length from 5 to 80 bytes: file-control. Select isamvar assign to 'isamvar.dat' organization is indexed access mode is dynamic record key is isamvar-fd-key.
File section. Record is varying in size from 5 to 80 characters depending on ws-record-count. 01 isamvar-fd-record. 05 isamvar-fd-key pic x(5). 05 isamvar-fd-data pic x(75).
Working-storage section. 01 ws-record-count pic 99 comp-x.
Note: The keys defined for the file must all lie in the fixed part of the record. When using COBOL, you can open data files in one program, and perform file operations (such as READ and WRITE) in another, as long as all the programs are in the same run unit.
This is called using external files.
The INX file extension can be a lot of different things. Old FoxPro index files, Microfocus Cobol files, etc. Hard to tell you much without seeing the file. If the file contains data that was downloaded from an AS/400 or IBM mainframe, bear in mind that it could be EBCDIC. Can you post one of the smaller files, perhaps? If we can see it, we can probably provide a lot more information.
BTW, why did you post this in the AS/400 and Mainframe zones? Sounds like these are PC files from your post. Gary Patterson. Gary - thank you for your reply. In answer to your questions.
1) I agree, I am not sure what the.INX file means here. I have attached the file for you to see. Please note, I added the.txt extension, so that the 'add file' button would allow me to upload the file. 2) Quite honestly, I had no idea which zone to post a 'Cobol' question to. I just created my question, and checked off a few of the zones that Experts-Exchange defaulted to. So my apologies - you are correct, this doesn't belong in the AS/400 zone, and it IS a PC question.
Developing a tool that parses these indexed files is not trivial, so there are not a lot of free tools to do this. It is pretty easy to do using an RM COBOL program or the RM COBOL built-in utilities. The popular tools and services can be relatively costly.
For example, my company does data conversion work, and we typically charge a couple hundred per file, so it only takes a few files and that $2,000 for Data Viewer starts to look like a pretty good deal. I found a thread that talks about some ways to access this data: It mentions an old Delphi tool that may dump the data, though not very fancy: It also mentions the RUNCOBOL command from the RM COBOL runtime has a RECOVER2 option that can be used to dump data from an indexed file. Gary Patterson. Gary P - Thank you for your reply and research. I have 10 -12 files that I am interested in, so you are right - the 'pay for each' solution would not be cost effective. I followed the janes.demo.co.uk link, and the RUNCOBOL command sounds promising.
Specifically: 'If you are trying to read a RM/Cobol index file into a flat file (without the index keys), you might use the utility that is provided with the runtime. Command line= (runtime folder) RUNCOBOL (runtimefolder) RECOVER2 A='(indexfile)' This should create a non-indexed file with only the data. ' Gary - can you please help me with: 1) How can I tell on my customer's linux server if they have the runtime? 2) How do I find the runtime folder? My customer is using a legacy Point of Sale solution, which is what this is all about. Is it a decent assumption that if they can run their POS cobol soltuion, that the runtime must be installed? Please forgive the newbie questions.
I work every day of my life in MSSQL, and do not know one wit about Cobol. Any help greatly appreciated. (And you have already been incredibly helpful).
Thanks so much for you help. Regards, Tom D. Giltjr and Gary P - I was at customer site yesterday, and was able to locate and run the 'recover2' cobol util to read a Cobol Indexed file. Unfortunately, the results are less than perfect. I do have files, but they are missing line breaks.
I am attaching a Cust sample. This is definitely much closer, but I still don't have a file that I can work with. It appears that each new record begins after the indicator ' '. I'm just not sure how to parse this to make this a useful/readable file. Any suggestions greatly appreciated. The ' ' are really how your text editor represents the 'characters' in those positions. Notepad uses skinny little rectangles.
It looks like each record begins with ASCII x0517 and ends with x0517 (a.k.a.ENQ and ETB). You may want to get notepad and the plugin hex editor to allow you to see what is really there. There are other hex characters (like FF/SOH/ENQ/STX) that are used to separate various fields within a logical record. It also seems that 'logical' records span across physical records.
Once you figure out what hex characters are used you could write a little program to sperate out the logicall records and then break down the individual fields. However, you may have to guess at what some of these fields are.
How To Read Cobol Dump
Some are obvious: First name, Last Name, Address, phone, year(s). Some make no sense at all. Tom, Yes, it is a reasonable assumption that they have the runtime installed.
Do you have file layout documentation? If not, your job is liable to be complex unless the database is very simple. These type of COBOL indexed files don't contain metadata. This means that the field definitions (names, data type, length, scale, etc) are defined in the programs themselves, not the files, and that you generally need the COBOL source code or some sort of file layout documentation in order to interpret what you see in the files. Does your customer have source code for these files? If so a COBOL programmer can convert them pretty easily.
Additionally, the record structures are often more complex than what you see in a normalized SQL database, and you may find that one 'file' really represents what you would normally define as several tables in SQL. When you run the recover2 utility, it extracts the data out and separates it from the index information. From there, it is up to you to write a program that parses the file, or to use a utility Like Data Viewer (above) to help you parse the file. A few hints: The recover2 output data appears to be null padded (x20) into fixed-length fields in most case, and the record delimiter does appear to be x0517, as giltjr indicates. There also appear to be a pair of nulls between each record. Viewing the file in hex as giltjr suggests, will shed more light on the layout for you. You should probably contact the POS system vendor and see if source code or file layout documentation is available, or if they have a conversion or extract tool.
I take it that you've already looked through the application for any 'data export' options? What is the name of the package in question? Anyway, I don't think this is as small a project as you originally thought it was.
I know we often charge over $10K for a conversion like this when we do them for our customers, and significantly more if file layouts information and source are both unavailable. Depending on the application, it can be - Gary Patterson. Gary and giltjr, thank you both again, for your responses, suggestions, and insights here.
As Gary has stated in the last entry, this is definitely more involved than I gave it credit for. I have contacted the vendor, and though they do not have an export tool, they are offereing to extract data for us, if we specify exactly what we are looking for. Apart from working with the vendor, the 'Siber DataViewer' was starting to look like my best option, despite the $2,000 price tag.
I am splitting the points here, which doesn't begin to acknowledge how much I appreciate both of your help and comments. I wish there was an 'assign 10,000 points button', because I would click it for both of you. Thanks again. You have my appreciation and respect for your excellence on this topic, and your time and willingness to share that with me. Regards, Tom D / Mpls, MN.
Reading COBOL Layouts, Tutorial: How to read a COBOL layout. Converting IBM EBCDIC,packed,comp-3,signed fields,implied decimal,occurs,redefined pic and more Reading COBOL Layouts: Need to convert COBOL data? That's our business!
Introduction: This tutorial on how to read a COBOL layout was written specifically for customers of Disc Interchange Service Company who have had a conversion performed and have received a COBOL layout with the data. It is intended to give you enough information to read most simple layouts.
It does not cover all topics or everything you would find in a complex layout, and it is intended to explain COBOL layouts only so you can use your converted data, not so you can write COBOL programs. If you need more detail, please refer to one of the many fine COBOL books available. Most COBOL data files and most of the conversions DISC performs originate on EBCDIC machines, so our discussion assumes an EBCDIC platform. We will discuss some EBCDIC to ASCII conversion issues. This tutorial teaches mostly by example, and progresses from basic rules to simple layouts to more complex layouts. Later examples build on previous examples.
To read the article from the beginning, click on Part 1 below. If you only want to review a specific topic, click on the one of interest in the index below. This tutorial consists of the following 7 sections: Part 1 Introduces you to the elements of a COBOL record layout.
Part 2 Presents some simple COBOL layouts and introduces the concept of groups. Part 3 Discusses what redefined fields are and how they are used. Part 4 Discusses several types of character and binary numeric fields, and the handling of signs and decimal points. Part 5 Introduces tables and the OCCURS and OCCURS DEPENDING ON clauses.
Part 6 Discusses redefined records and multiple record types in a file. Part 7 Conclusion, and notes from the author. Additional Information For more articles on data conversion, see our. Our COBOL Conversion Services Disc Interchange Service Company's primary business is converting mainframe COBOL files. From the simplest mailing list to the most complex financial data, we have the tools to properly convert and Q.C.
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COBOL Data files? Are you talking about compiled data? Or like a data file that it reads. COBOL defines data structures at the top of the program, usually they are sequential. There is also random access files, but still you need to know the file format (been many years since I dealt with binary files in COBOL). If you have the original source you can figure out the data format for a file, whether its sequential or random, but otherwise, who/waht created it doesn't matter.
'EricJ' wrote in message news:[email protected]. Hi i need to access cobol data files from.net, the files have no or.vix extention (i think thats a acucobol or something like that) (/me has completely no experience in cobol) i heard that there should be an odbc connection for that.
Dous anyone have any ideas on how to do this?? - Juchtmans Eric Omnipack.
Hi EricJ, There are so many 'Cobol' file. I think you can shift it by first knowing if it is a kind of PC cobol or that it is mainframe Cobol. This link was very easy to find But you have to be sure of what Cobol it is, there was also a lot of MS, CIS and a lot of other cobol on a PC. There are no 'Cobol' files every company uses there own format or sometimes 2 files to get one (text and index). Cor 'EricJ' schreef in bericht news:[email protected]. Hi i need to access cobol data files from.net, the files have no or.vix extention (i think thats a acucobol or something like that) (/me has completely no experience in cobol) i heard that there should be an odbc connection for that. Dous anyone have any ideas on how to do this??
- Juchtmans Eric Omnipack. Hi, If you are talking about Acucobol you will need an OleDb provider or ODBC driver. Link to ODBC provider: I've found I don't have a clue if it works or not (it should work via Data.Odbc namespace). Miha Markic - RightHand.NET consulting & software development miha at rthand com 'EricJ' wrote in message news:[email protected]. Hi i need to access cobol data files from.net, the files have no or.vix extention (i think thats a acucobol or something like that) (/me has completely no experience in cobol) i heard that there should be an odbc connection for that. Dous anyone have any ideas on how to do this?? - Juchtmans Eric Omnipack.
The files that it reads have a look at my reply to cor 'CJ Taylor' wrote in message news:[email protected]. COBOL Data files? Are you talking about compiled data? Or like a data file that it reads. COBOL defines data structures at the top of the program, usually they are sequential. There is also random access files, but still you need to know the file format (been many years since I dealt with binary files in COBOL).
If you have the original source you can figure out the data format for a file, whether its sequential or random, but otherwise, who/waht created it doesn't matter. 'EricJ' wrote in message news:[email protected]. Hi i need to access cobol data files from.net, the files have no or.vix extention (i think thats a acucobol or something like that) (/me has completely no experience in cobol) i heard that there should be an odbc connection for that. Dous anyone have any ideas on how to do this?? - Juchtmans Eric Omnipack. That was w i was thinking but i cant find it douwnloadable (prefferebly free) or an other sollution thats free 'Miha Markic' wrote in message news:[email protected].
Hi, If you are talking about Acucobol you will need an OleDb provider or ODBC driver. Link to ODBC provider: I've found I don't have a clue if it works or not (it should work via Data.Odbc namespace). Miha Markic - RightHand.NET consulting & software development miha at rthand com 'EricJ' wrote in message news:[email protected]. Hi i need to access cobol data files from.net, the files have no or.vix extention (i think thats a acucobol or something like that) (/me has completely no experience in cobol) i heard that there should be an odbc connection for that. Dous anyone have any ideas on how to do this?? - Juchtmans Eric Omnipack.
Eric, COBOL files usually are fixed length records. If this is the case, the simpliest way to read the files is not the a data adapter but rather read the file as fixed length binary record, then break apart the record into the individual fields. If the construct a structure that matches the field layout of the record this may help.
For the binary numbers you must be careful that the byte order is correct. For the text you must be careful that the characters are ASCII and not some other coding like EBCDIC. I have done just this for IBM mainframe files to PC. Pat -Original Message- hi i need to access cobol data files from.net, the files have no or.vixextention (i think thats a acucobol or something like that) (/me hascompletely no experience in cobol) i heard that there should be an odbc connection for that. Dous anyone have any ideas on how to do this?? - Juchtmans Eric Omnipack. Pff, i found a acuserver thing on 1 of the servers i'll look into that (venting frustration a bit, its a maze here and no-one that works here exept me knows anything about computers so they are no help.
Before i started working here everithing was done out house (if i got it right by 6 different companies some things in cobol, some things in vb on sqlserver7, some things in??? Dos thing.)) eric 'Cor' wrote in message news:[email protected]. Hi Eric I think it is definetaly acu yes. When you look on Google with AcuODBC you find a lot, but if it is free I think you have to search for yourself. This link I could not read.
But Herfried is a specialist in getting software from this kind of sites he said somewhile ago in the VB.language newsgroup. The idea is as follows if a user selects a product in my app and the product dousnt exist i have to look at the cobol files to c if the product exists there, i it dous get the product info from cobol and add it to my sql server. I'm affraid converting the cobol files all the time wont be performant, keep in mind that this happens a lot since the systems are used together but the cobol app is still the main application. I need structured access to the cobol data, from what i have seen so far i think that the acuserver (acucobol acuodbc) can do this for me, i just have to find a way to get it working;) but i'm working on that. Eric 'Cor' wrote in message news:%[email protected]. Hi Ericj, Mostly the structure of the not index file is not that difficult to analyse. That is sometimes also a good way to go.
You can read it than first streaming converting it to a format you want to use.
COBOL is an endangered language. But it once ran 80% of the world's business systems: thousands of mission-critical applications that still exist today. Some companies want to upgrade and transition their COBOL applications to more modern frameworks; others want to stick with COBOL's relatively stable platform. In either case, hiring managers are willing to pay a premium for candidates who know how to take on COBOL's challenges. For this reason, programmers are learning COBOL again. This course is designed to help new and experienced programmers alike add COBOL (or add COBOL back) to their skill set. Peggy Fisher shows how to get a COBOL development environment up and running and how to start programming.
She reviews COBOL's data types and constants, control structures, file storage and processing methods, tables, and strings. Challenges issued along the way will help you practice what you've learned. Instructor. Peggy Fisher is a programmer and full-time staff author at Lynda.com. She is also a strong supporter of women in STEM.
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Peggy Fisher is a full-time staff author at Lynda.com in the Developer segment. Her main focus is Application Programming in Java, Arduino, and C.
She has also worked on courses in COBOL and Discrete Mathematics. Previously she was a faculty member at Penn State University's College of Information Sciences and Technology. She started out as a programmer working for a large insurance company, but after 18 years she left her job as a director of information technology to pursue her true passion teaching.
She earned a master's degree in math education, and went on to teach high school math and computer science in Pennsylvania. In 2012, Peggy accepted a position as an instructional designer at Penn State, and shortly thereafter began teaching Intro to Application Programming with Java. As one of the few female programming teachers, she serves as a mentor to incoming female freshmen who are considering a career in programming. She was also the K–12 outreach coordinator for the college, where she scheduled, ran, and taught summer camps for middle school and high school students.
In a PBS NewsHour interview, she expressed that all students should take at least one programming class either in high school or college. Peggy enjoys constantly learning and finding new and exciting ways to bring technology to life in and outside of the classroom, such as using Arduino microcontrollers or Lego Mindstorms, to help make learning hands-on and fun. Related courses. By: Mike Figliuolo Course. 38m 59s. By: Simon Allardice Course.
3h 1m 16s. By: Mark Niemann-Ross Course. 3h 24m 29s. By: David Gassner Course. 3h 33m 2s.
Course Transcript - Reading files sequentially is probably the most common access method for COBOL programs. Files can be both input and/or output from a program. Let's look at this sample program called Employee. Notice that I have the Notepad window split, so we can see the employee file along with the program simultaneously. This can be done in Notepad using the view menu.
You go to View, and then you can choose Move, and Move to other view. This program is designed to read the employee file, keep a running total of all salaries, and print out a report of employees and the total salary amount. My test file only has eight records in it, but that will be easy for us to double check when we run the program to make sure every record gets read. To read the file, we must assign the file in the environment division.
The environment division, starting on line four, more specifically in the file control paragraph, which is located in the INPUT-OUTPUT SECTION. As you can see in the example on line seven. Practice while you learn with exercise files. Watch this course anytime, anywhere.
Course Contents. Introduction Introduction. 1. Getting Started 1. Getting Started. 2. Describing Data 2.
Describing Data. 3. Control Structures 3. Control Structures. 4. Sequential Files 4. Sequential Files.
5. Advance Sequential Files 5. Advance Sequential Files. 6. Direct Access Files 6. Direct Access Files.
How To Read Cobol Programs
7. Tables in COBOL 7. Tables in COBOL. 8. String Handling 8. String Handling. Conclusion Conclusion.
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