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COBOL Copybook Format

MIME Type: application/flatfile

ID: flatfile

A COBOL copybook is a type of flat file that describes the layout of records and fields in a COBOL data file.

The Transform Message component provides settings for handling the COBOL copybook format. For example, you can import a COBOL definition into the Transform Message component and use it for your Copybook transformations.

COBOL copybook in DataWeave supports files of up to 15 MB, and the memory requirement is roughly 40 to 1. For example, a 1-MB file requires up to 40 MB of memory to process, so it’s important to consider this memory requirement in conjunction with your TPS needs for large copybook files. This is not an exact figure; the value might vary according to the complexity of the mapping instructions.

Importing a Copybook Definition

When you import a Copybook definition, the Transform Message component converts the definition to a flat file schema that you can reference with schemaPath property.

To import a copybook definition:

  1. Right-click the input payload in the Transform component in Studio, and select Set Metadata to open the Set Metadata Type dialog.

    Note that you need to create a metadata type before you can import a copybook definition.

  2. Provide a name for your copybook metadata, such as copybook.

  3. Select the Copybook type from the Type drop-down menu.

  4. Import your copybook definition file.

  5. Click Select.

    A selecting metadata type interface for importing a copybook definition file
    Figure 1. Importing a Copybook Definition File

For example, assume that you have a copybook definition file (mailing-record.cpy) that looks like this:

       01  MAILING-RECORD.
           05  COMPANY-NAME            PIC X(30).
           05  CONTACTS.
               10  PRESIDENT.
                   15  LAST-NAME       PIC X(15).
                   15  FIRST-NAME      PIC X(8).
               10  VP-MARKETING.
                   15  LAST-NAME       PIC X(15).
                   15  FIRST-NAME      PIC X(8).
               10  ALTERNATE-CONTACT.
                   15  TITLE           PIC X(10).
                   15  LAST-NAME       PIC X(15).
                   15  FIRST-NAME      PIC X(8).
           05  ADDRESS                 PIC X(15).
           05  CITY                    PIC X(15).
           05  STATE                   PIC XX.
           05  ZIP                     PIC 9(5).

  • Copybook definitions must always begin with a 01 entry. A separate record type is generated for each 01 definition in your copybook (there must be at least one 01 definition for the copybook to be usable, so add one using an arbitrary name at the start of the copybook if none is present). If there are multiple 01 definitions in the copybook file, you can select which definition to use in the transform from the dropdown list.

  • COBOL format requires definitions to only use columns 7-72 of each line. Data in columns 1-5 and past column 72 is ignored by the import process. Column 6 is a line continuation marker.

When you import the schema, the Transform component converts the copybook file to a flat file schema that it stores in the src/main/resources/schema folder of your Mule project. In flat file format, the copybook definition above looks like this:

form: COPYBOOK
id: 'MAILING-RECORD'
values:
- { name: 'COMPANY-NAME', type: String, length: 30 }
- name: 'CONTACTS'
  values:
  - name: 'PRESIDENT'
    values:
    - { name: 'LAST-NAME', type: String, length: 15 }
    - { name: 'FIRST-NAME', type: String, length: 8 }
  - name: 'VP-MARKETING'
    values:
    - { name: 'LAST-NAME', type: String, length: 15 }
    - { name: 'FIRST-NAME', type: String, length: 8 }
  - name: 'ALTERNATE-CONTACT'
    values:
    - { name: 'TITLE', type: String, length: 10 }
    - { name: 'LAST-NAME', type: String, length: 15 }
    - { name: 'FIRST-NAME', type: String, length: 8 }
- { name: 'ADDRESS', type: String, length: 15 }
- { name: 'CITY', type: String, length: 15 }
- { name: 'STATE', type: String, length: 2 }
- { name: 'ZIP', type: Integer, length: 5, format: { justify: ZEROES, sign: UNSIGNED } }

After importing the copybook, you can use the schemaPath property to reference the associated flat file through the output directive. For example: output application/flatfile schemaPath="src/main/resources/schemas/mailing-record.ffd"

Supported Copybook Features

Not all copybook features are supported by the COBOL Copybook format in DataWeave. In general, the format supports most common usages and simple patterns, including:

  • USAGE of DISPLAY, BINARY (COMP), COMP-5, and PACKED-DECIMAL (COMP-3). For character encoding restrictions, see Character Encodings.

  • PICTURE clauses for numeric values consisting only of:

    • '9' - One or more numeric character positions

    • 'S' - One optional sign character position, leading or trailing

    • 'V' - One optional decimal point

    • 'P' - One or more decimal scaling positions

  • PICTURE clauses for alphanumeric values consisting only of 'X' character positions

  • Repetition counts for '9', 'P', and 'X' characters in PICTURE clauses (as in 9(5) for a 5-digit numeric value)

  • OCCURS DEPENDING ON with controlVal property in schema. Note that if the control value is nested inside a containing structure, you need to manually modify the generated schema to specify the full path for the value in the form "container.value".

  • REDEFINES clause (used to provide different views of the same portion of record data - see details in section below)

Unsupported features include:

  • Alphanumeric-edited PICTURE clauses

  • Numeric-edited PICTURE clauses, including all forms of insertion, replacement, and zero suppression

  • Special level-numbers:

    • Level 66 - Alternate name for field or group

    • Level 77 - Independent data item

    • Level 88 - Condition names (equivalent to an enumeration of values)

  • SIGN clause at group level (only supported on elementary items with PICTURE clause)

  • USAGE of COMP-1 or COMP-2 and of clause at group level (only supported on elementary items with PICTURE clause)

  • VALUE clause (used to define a value of a data item or conditional name from a literal or another data item)

  • SYNC clause (used to align values within a record)

REDEFINES Support

REDEFINES facilitates dynamic interpretation of data in a record. When you import a copybook with REDEFINES present, the generated schema uses a special grouping with the name '*' (or '*1', '*2', and so on, if multiple REDEFINES groupings are present at the same level) to combine all the different interpretations. You use this special grouping name in your DataWeave expressions just as you use any other grouping name.

Use of REDEFINES groupings has higher overhead than normal copybook groupings, so MuleSoft recommends that you remove REDEFINES from your copybooks where possible before you import them into Studio.

Character Encodings

BINARY (COMP), COMP-5, or PACKED-DECIMAL (COMP-3) usages are only supported with single-byte character encodings, which use the entire range of 256 potential character codes. UTF-8 and other variable-length encodings are not supported for these usages (because they’re not single-byte), and ASCII is also not supported (because it doesn’t use the entire range). Supported character encodings include ISO-8859-1 (an extension of ASCII to full 8 bits) and other 8859 variations and EBCDIC (IBM037).

REDEFINES requires you to use a single-byte-per-character character encoding for the data, but any single-byte-per-character encoding can be used unless BINARY (COMP), COMP-5, or PACKED-DECIMAL (COMP-3) usages are included in the data.

Common Copybook Import Issues

The most common issue with copybook imports is a failure to follow the COBOL standard for input line regions. The copybook import parsing ignores the contents of columns 1-6 of each line, and ignores all lines with an '*' (asterisk) in column 7. It also ignores everything beyond column 72 in each line. This means that all your actual data definitions need to be within columns 8 through 72 of input lines.

Tabs in the input are not expanded because there is no defined standard for tab positions. Each tab character is treated as a single space character when counting copybook input columns.

Indentation is ignored when processing the copybook, with only level-numbers treated as significant. This is not normally a problem, but it means that copybooks might be accepted for import even though they are not accepted by COBOL compilers.

Both warnings and errors might be reported as a result of a copybook import. Warnings generally tell of unsupported or unrecognized features, which might or might not be significant. Errors are notifications of a problem that means the generated schema (if any) will not be a completely accurate representation of the copybook. You should review any warnings or errors reported and decide on the appropriate handling, which might be simply accepting the schema as generated, modifying the input copybook, or modifying the generated schema.

Configuration Properties

DataWeave supports the following configuration properties for this format.

Reader Properties

DataWeave accepts properties that provide instructions for reading input data in this format.

Parameter Type Default Description

allowLenientWithBinaryNotEndElement

Boolean

false

When the schema contains elements of type Binary or Packed, the lenient option does not allow short records, regardless of the last element’s format type. When you set this property to true, the validation applies only to cases in which the record ends with type Binary or Packed.

enforceRequires

Boolean

false

Error if required value missing. Valid values are true or false.

missingValues

String

nulls for copybook schema, spaces otherwise

Fill character used to represent missing values. To activate a non-default setting, set the useMissCharAsDefaultForFill property to true, and use one of the following values to missingValues:

  • none: Treat all data as actual values

  • spaces: Interpret a field consisting of only spaces as a missing value

  • zeroes: Interpret numeric fields consisting of only '0' characters and character fields consisting of only spaces as missing values

  • nulls: Interpret a field consisting only of 0 bytes as a missing value

notTruncateDependingOnSubjectNotPresent

Boolean

false

Fills the entire group when the DEPENDING ON subject is not present. Introduced in DataWeave 2.3 with the August 2021 release of Mule 4.3.0-20210622.

recordParsing

String

strict

Expected separation between lines/records:

  • strict: Line break expected at exact end of each record.

  • lenient: Line break is used, but records can be shorter or longer than the schema specifies. Do not use lenient if your payload lacks line breaks. The other options to recordParsing support records that lack line breaks.

  • noTerminator: Records follow one another with no separation. This option is preferred for fixed-length records that lack a line break.

  • singleRecord: Entire input is a single record.

Note that schemas with type Binary or Packed don’t allow for line break detection, so setting recordParsing to lenient only allows long records to be handled, not short ones. These schemas also currently only work with certain single-byte character encodings (so not with UTF-8 or any multibyte format).

schemaPath (Required)

String

null

Schema definition. Location in your local disk of the schema file used to parse your input.

segmentIdent

String

null

Segment identifier in the schema for fixed width or copybook schemas (only needed when parsing a single segment/record definition and if the schema includes multiple segment definitions).

structureIdent

String

null

Structure identifier in schema for flatfile schemas (only needed when parsing a structure definition, and if the schema includes multiple structure definitions)

truncateDependingOn

Boolean

false

Truncate COBOL copybook DEPENDING ON values to the length used. Valid values are true or false.

useMissCharAsDefaultForFill

Boolean

false

By default, the flat file reader and writer use spaces for missing characters and ignore the setting of the missingValues property. When you set this property to true, the reader honors the setting of the missingValues property. Introduced in DataWeave 2.3 (2.3.0-20210823) for the September 2021 release of Mule 4.3.0-20210823. Valid values are true or false.

zonedDecimalStrict

Boolean

false

Use the strict ASCII form of sign encoding for COBOL copybook zoned decimal values. Valid values are true or false.

Writer Properties

DataWeave accepts properties that provide instructions for writing output data in this format.

Parameter Type Default Description

bufferSize

Number

8192

Size of the buffer writer.

deferred

Boolean

false

When set to true, DataWeave generates the output as a data stream, and the script’s execution is deferred until it is consumed. Valid values are true or false.

encoding

String

null

Encoding to be used by this writer, such as UTF-8.

enforceRequires

Boolean

false

Error if a required value is missing. Valid values are true or false.

missingValues

String

NULLS for copybook schema, SPACES otherwise

Fill character used to represent missing values. To activate a non-default setting, use useMissCharAsDefaultForFill, and use one of the following values to missingValues:

  • NONE: Write nothing for missing values.

  • SPACES: Fill the field with spaces.

  • ZEROES: Fill numeric fields with 0 characters and character fields with space characters.

  • NULLS: Fill the field with 0 bytes.

notTruncateDependingOnSubjectNotPresent

Boolean

false

Fills the entire group when the DEPENDING ON subject is not present. Introduced in DataWeave 2.3 with the August 2021 release of Mule 4.3.0-20210622.

recordTerminator

String

System property line.separator

Record separator line break. Valid values:

  • lf

  • cr

  • crlf

  • none

Note that in Mule versions 4.0.4 and later, this is only used as a separator when there are multiple records. Values translate directly to character codes (none leaves no termination on each record).

retainEmptyStringFieldsOnParsing

false

When set to true, this property makes the reader retain fields that lack values and set their values to an empty string. Introduced in the January 2023 version of DataWeave 2.3 for Mule version 4.3.0-20221212.

schemaPath (Required)

String

null

Schema definition. Path where the schema file to be used is located.

segmentIdent

String

null

Segment identifier in the schema for fixed width or copybook schemas (only needed when writing a single segment/record definition, and if the schema includes multiple segment definitions).

structureIdent

String

null

Structure identifier in schema for flatfile schemas (only needed when writing a structure definition and if the schema includes multiple structure definitions)

trimValues

Boolean

false

Trim string values longer than the field length by truncating trailing characters. Valid values are true or false.

trimValues

Boolean

false

Indicates whether trim values are longer than the field width. Valid Options are true or false.

truncateDependingOn

Boolean

false

Truncate COBOL copybook DEPENDING ON values to the length used. Valid values are true or false.

useMissCharAsDefaultForFill

Boolean

false

By default, the flat file reader and writer use spaces for missing characters and ignore the setting of the missingValues property. When you set this property to true, the writer honors the setting of the missingValues property. Introduced in DataWeave 2.3 (2.3.0-20210823) for the September 2021 release of Mule 4.3.0-20210823.

zonedDecimalStrict

Supported MIME Types

The COBOL Copybook format supports the following MIME types.

MIME Type

*/flatfile