Plugin for COBOL Copybook Reader - Fixed Length

Owned by priyanambiar
Last updated: Jul 28, 2016 by Patrick GuimaraisVersion comment
3 min read

 

Goal 

This is a source plugin that would allow users to read and process mainframe files defined using COBOL Copybook. This should be basic first implementation.

Checklist

  • User stories documented 
  • User stories reviewed 
  • Design documented 
  • Design reviewed 
  • Feature merged 
  • Examples and guides 
  • Integration tests 
  • Documentation for feature 
  • Short video demonstrating the feature

Use-case 

It’s basically used for reading flat file or dataset that is generated on a z/OS IBM mainframe based on a fixed length COBOL copybook. This will also work on AS/400 computers. So, if a customer has flat files on HDFS that can be parsed using simple COBOL copybook then applying the copybook one is able to read the file and its fields.

Conditions

  • Supports only fixed length binary format that matches the copybook

  • Binary data should be converted to Base64 encoded

  • First implementation will not be able to handle complex nested structures of COBOL copybook

  • Also will not handle Redefines or iterators in the structure.

  • Supports compressed files - Native Compressed Codec

Options

  • User should be able to copy paste or provide a file that gets loaded into text section for COBOL copybook

  • User should have the ability to select the fields that one wants into the output schema. So they should be able to specify the field.

References

Input Format implementation : here 

Design

  • If "AbstractFieldValue"(JRecord) type is binary, the data will be encoded to Base64 format.
    Integer.parseInt(new String(Base64.decodeBase64(Base64.encodeBase64(value.asString().getBytes()))), 2);

    or

    Base64.decodeInteger(Base64.encodeInteger(value.asBigInteger()));

It will depend on the field data type(int or BigInteger)

 

JRecord AbstractFieldValue type to JAVA primitive data type

JRecord AbstractFieldValue typeJAVA primitive data typeDescriptionComments

char, char just right , char null terminated,

char null padded

 java.lang.String  

num left justified, num right justified ,

num zero padded

int  
binary int, binary int positive, positive binary int fields  int

decode it using BASE64 format and then retrieve it.

Integer.parseInt(new String(Base64.decodeBase64(
Base64.encodeBase64(value.asString().getBytes()))), 2)

The Base64.decodeBase64() accepts either binary or String data, and therefore, first encoding and then decoding the values 

Decoding it directly results in improper values

decimal, Mainframe Packed Decimal,

Mainframe Packed Decimal, Mainframe Zoned Numeric,

Mainframe Packed Decimal(+ve)

 

 java.math.BigDecimal Since CDAP Schema.Type does not have a BigDecimal data type, converting everything to DOUBLE

Binary Integer Big Endian (Mainframe, AIX etc) -  

  1. Binary Integer Big Endian (Mainframe?),
  2. Binary Integer Big Endian (only +ve),Positive Integer Big Endian
  java.math.BigDecimal

 decode it using BASE64 format and then retrieve it.

Base64.decodeInteger(Base64.encodeInteger(filedValue.asBigInteger()))


The Base64.decodeBase64() accepts either binary or String data, and therefore, first encoding and then decoding the values 

Decoding it directly resulted in improper values

 

Since CDAP Schema.Type does not have BigInteger converting this to LONG
num any decimal, positive num any decimal, assumed decimaldouble  
Hexlong
Long.parseLong(value.asHex(), 16)
Since CDAP Schema.Type does not have Hex converting this to LONG
Boolean / (Y/N)java.lang.Boolean  
Default              java.lang.String  

Examples

Properties : 

referenceName         :  This will be used to uniquely identify this source for lineage, annotating metadata, etc.
copybookContents  :  Contents of the COBOL copybook file which will contain the data structure
binaryFilePath          :  Complete path of the .bin to be read.This will be a fixed length binary format file,that matches the copybook.
drop                           :  Comma-separated list of fields to drop. For example: 'field1,field2,field3'.
maxSplitSize             :  Maximum split-size for each mapper in the MapReduce. \n Job. Defaults to 128MB.

Example :

This example reads data from a local binary file "file:///home/cdap/DTAR020_FB.bin"  and parses it using the schema given in the text area "COBOL Copybook" 

It will drop field "DTAR020-DATE" and generate structured records with schema as specified in the text area.

{

"name": "CopybookReader",
"plugin": {

"name": "CopybookReader",
"type": "batchsource",
"properties": {

"drop" : "DTAR020-DATE",

"referenceName": "Copybook",

"copybookContents":

"000100* \n

000200* DTAR020 IS THE OUTPUT FROM DTAB020 FROM THE IML \n

000300* CENTRAL REPORTING SYSTEM \n

000400* \n

000500* CREATED BY BRUCE ARTHUR 19/12/90 \n

000600* \n

000700* RECORD LENGTH IS 27. \n

000800* \n

000900 03 DTAR020-KCODE-STORE-KEY. \n

001000 05 DTAR020-KEYCODE-NO PIC X(08). \n

001100 05 DTAR020-STORE-NO PIC S9(03) COMP-3. \n

001200 03 DTAR020-DATE PIC S9(07) COMP-3. \n

001300 03 DTAR020-DEPT-NO PIC S9(03) COMP-3. \n

001400 03 DTAR020-QTY-SOLD PIC S9(9) COMP-3. \n

001500 03 DTAR020-SALE-PRICE PIC S9(9)V99 COMP-3. ",

"binaryFilePath": "file:///home/cdap/DTAR020_FB.bin",

"maxSplitSize": "5"

}

}

}