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 he should be able to specify the field.

References

Input Format implementation : here 

Design

• Assumptions:

1. 1. .cbl file will have the schema in data structure
   2. Both data file and .cbl files would reside on HDFS
      
      

• For each AbstractLine read from the data file if the fields binary or binaryFile is true, the data will be encoded to Base64 format while reading
  

  for (ExternalField field : externalRecord.getRecordFields()) {
    AbstractFieldValue filedValue = line.getFieldValue(field.getName());
    if (filedValue.isBinary()) {
      value.put(field.getName(), new String(Base64.decodeBase64(Base64.encodeBase64String(
        filedValue.toString().getBytes()))));
    } else {
      value.put(field.getName(), filedValue.toString());
    }
  }

Examples

Properties : 

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.
fileStructure             : CopyBook file structure. For the current implementation only fixed length flat files will be read.

Example :

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

It will generate structured records with either the output schema (if specified by the user) or with the default schema as is specified in the text area.

{

"name": "CopyBookReader",
"plugin": {

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

"schema": "{\"type\":\"record\",\"name\":\"etlSchemaBody\",\"fields\":[{\"name\":\"DTAR020-KEYCODE-NO\",\"type\":\"int\"},{\"name\":\"DATE\",\"type\":[\"int\",\"null\"]},{\"name\":\"DTAR020-DEPT-NO\",\"type\":[\"int\",\"null\"]},{\"name\":\"DTAR020-QTY-SOLD\",\"type\":[\"int\",\"null\"]},{\"name\":\"DTAR020-SALE-PRICE\",\"type\":[\"double\",\"null\"]}]}",

"referenceName": "CopyBook",

"copybookContents": "000100* \n000200* DTAR020 IS THE OUTPUT FROM DTAB020 FROM THE IML \n000300* CENTRAL REPORTING SYSTEM \n000400* \n000500* CREATED BY BRUCE ARTHUR 19/12/90 \n000600* \n000700* RECORD LENGTH IS 27. \n000800* \n000900 03 DTAR020-KCODE-STORE-KEY. \n001000 05 DTAR020-KEYCODE-NO PIC X(08). \n001100 05 DTAR020-STORE-NO PIC S9(03) COMP-3. \n001200 03 DTAR020-DATE PIC S9(07) COMP-3. \n001300 03 DTAR020-DEPT-NO PIC S9(03) COMP-3. \n001400 03 DTAR020-QTY-SOLD PIC S9(9) COMP-3. \n001500 03 DTAR020-SALE-PRICE PIC S9(9)V99 COMP-3. ",

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

"fileStructure": ""

}

}

}

Sample .cbl file:

000600* 
000700* RECORD LENGTH IS 27. 
000800* 
000900 03 DTAR020-KCODE-STORE-KEY. 
001000 05 DTAR020-KEYCODE-NO PIC X(08). 
001100 05 DTAR020-STORE-NO PIC S9(03) COMP-3. 
001200 03 DTAR020-DATE PIC S9(07) COMP-3. 
001300 03 DTAR020-DEPT-NO PIC S9(03) COMP-3. 
001400 03 DTAR020-QTY-SOLD PIC S9(9) COMP-3. 
001500 03 DTAR020-SALE-PRICE PIC S9(9)V99 COMP-3.