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Mainframe Connector supports two versions of the copybook parser:

• Native copybook parser: The Native copybook parser implements an ANTLR4-based parser, supports COBOL copybooks, and is the recommended version of the parser.
• Legacy copybook parser: The Legacy copybook parser is an older version of the parser that has support for a very limited copybooks formats.

You can define which parser you want to use based on your copybook. For more information on defining the parser that you want to use, see Define the copybook parser.

Native copybook parser

The Native copybook parser is the latest version of the parser and is used by default. The native copybook parser implements an ANTLR4-based parser and supports COBOL copybooks.

This section lists the preprocessing tasks performed by the Native copybook parser. It also outlines the data types supported by the Native copybook parser and the restrictions for its use.

Preprocessing

Before parsing a copybook, the Native copybook parser preprocesses the data and performs the following tasks:

• Removes comment lines.
• Resolves line continuation.
• Blanks out line number areas and column 73 areas.
• Preserves preprocessor specific statements like EJECT, SPACE, and TITLE. These field are parsed, but ignored. Copybooks containing preprocessor parameters that can be used by COPY REPLACING are not supported by the Native copybook parser. In these copybooks, identifiers are surrounded by a colon (:).

Supported data types and restrictions

The following are the data types supported by the Native copybook parser and the restrictions for its use:

• Level 66 (ALIAS) or 77 (STANDALONE) are not supported.
• Use only PICTURE fields. The following PICTURE fields are supported:
  • Pic A, Pic, B, Pic G (DBCS), Pic N (national or DBCS), Pic U (UTF8), Pic X, and zoned decimal (max precision 38, max scale 38)
• IBM Hexadecimal floating point (HFP) is supported.
• REDEFINES are not supported.
• Use only the following COMP fields. ALIGN and OCCURS are not supported.
  • COMP
  • COMP4
  • BINARY
  • COMP3
  • PACKED-DECIMAL
• DATE and TIMESTAMP are supported.
• Null indicators are supported.
• Double-byte character set (DBCS) field Pic G and Pic N are supported and should be used instead of Pic T, which is now deprecated. To use the Pic N field as DBCS without specifying USAGE DISPLAY-1, you must set the NSYMBOL environment variable to DBCS. By default, NSYMBOL is set to NATIONAL which sets USAGE NATIONAL to Pic N fields that don't have a USAGE clause. Note that NSYMBOL can only be set to NATIONAL or DBCS.
• Variable-length character strings are supported.
• The SIGN clause is supported.
• You must justify all fields and use a single indentation level.
• Comments are supported.

Support for date and timestamp fields

Mainframe Connector supports moving date and timestamp data in and out of BigQuery. To do so, you must define environment variables that begin with the word SUFFIX in the following format:

SUFFIX_SUFFIX_STRING="command --format FORMAT --timezone TIMEZONE"

The following list describes the format in more detail:

• SUFFIX_SUFFIX_STRING: The environment variable that you can use to define date and timestamp data. The SUFFIX_STRING name corresponds to the suffixes -SUFFIX_STRING or _SUFFIX_STRING that should be interpreted as either a date or timestamp when used as a suffix of a field name in a copybook. Ensure that the SUFFIX_STRING doesn't contain a hyphen or underscore.
• command: Defines the decoder that should be used to parse the field. The supported commands are date-converter and timestamp-converter.
• --format: A parameter that defines the format of the date or timestamp. You can specify at most five different formats separated by commas. If multiple formats can match a given input, the first format that matches is used for loading to BigQuery. If multiple formats are specified for exporting, only the first format is used. For more information on valid formats, see Supported date and timestamp formats.
• --timezone: An optional parameter for the type TIMESTAMP. By default, the timezone is UTC. For more information about supported timezone formats, see Supported timezone formats.
• --omitsuffix (Optional): If this parameter is specified, -SUFFIX_STRING or _SUFFIX_STRING is removed from the field name appearing in BigQuery.

To add an alias for a SUFFIX_SUFFIX_STRING, you can set an environment variable SUFFIX_SUFFIX_ALIAS=$SUFFIX_SUFFIX_STRING.

Examples:

• If you define an environment variable as SUFFIX_DT8="date-converter --format yyyyMMdd", a field with suffix -DT8 or _DT8 will be a DATE type field in BigQuery, and its pattern will be yyyyMMdd.
• If you define an environment variable as SUFFIX_DT10="date-converter --format MM-dd-yyyy", a field with suffix -DT10 or _DT10 will be a DATE type field in BigQuery, and its pattern will be MM-dd-yyyy.
• If you define an environment variable as SUFFIX_DT="date-converter --format 'MM-dd-yyyy,MM/dd/yyyy'", a field with suffix -DT or _DT will be a DATE type field in BigQuery, and its pattern will be either MM-dd-yyyy or MM/dd/yyyy.
• If you define two environment variables as SUFFIX_TIMESTAMP="timestamp-converter --format yyyy-MM-dd SUFFIX_TIMESTAMP=timestamp-converter --format 'yyyy-MM-dd HH.mm.ss.SSSSSS' --timezone America/New_York" and SUFFIX_TS=$SUFFIX_TIMESTAMP, a field with one of the following suffixes: -TIMESTAMP, _TIMESTAMP, -TS, or _TS will be a TIMESTAMP type field in BigQuery, and its pattern will be yyyy-MM-dd HH:mm:ss.SSSSSS with timezone America/New_York.

Support for null indicators

Mainframe Connector supports null indicators starting with version 5.13.0. To use null indicators, you must define environment variables that begin with the word SUFFIX in the following format:

SUFFIX_NULL_INDICATOR_NAME="command --null-value NULL_VALUE --not-null-value NOT_NULL_VALUE"

NULL_INDICATOR_NAME corresponds to the suffixes -NULL_INDICATOR_NAME or _NULL_INDICATOR_NAME that are interpreted as a null indicator when used as a suffix of a field name in a copybook.

The following list describes the parameters you can use with these environment variables:

• command: The value must be null-indicator.
• null-value: The value null indicator signals that the referenced field is null. The value of --null-value must be either a string or decimal number.
• not-null-value: (Optional) When specified, the value null indicator signals that the referenced field is not null. If this parameter is not set, any value that is not value-null is accepted. The value of not-null-value must be either a string or decimal number.
• keep: (Optional) When specified, the null-indicator field is kept as a column in the Optimized Row Columnar (ORC) file format. By default, this field is not kept in the ORC format.
• -force-type: (Optional) Supports two options -- bytes and binary that force a field to be decoded as either bytes or binary, respectively. For bytes, the values for null and not-null are expressed as HEX (for example, FA3AB5). HIGH and LOW constants are available that are equivalent to all FF or all 00. For binary, the values are regular integers.

If the null-indicator doesn't have a referenced field, Mainframe Connector displays an error message and stops processing the files.

Examples:

Copybook snippet

10 COL1-NID1            PIC S9(4) USAGE COMP.
10 COL1                 PIC S9(6) USAGE COMP.

10 FIELD       PIC        X(10).
10 FIELD-NID2  PIC        X(1).

10 COL2       PIC        X(10).
10 COL2-NULL  PIC        X(1).

Environment variables definition

SUFFIX_NID1="null-indicator --null-value -1 --not-null-value 0"
# Copybook fields with NID1 suffix null indicator configuration.
SUFFIX_NID2="null-indicator --null-value '?'"
# Copybook fields with NID2 suffix null indicator configuration.
SUFFIX_NULL="null-indicator --null-value '?' --keep"
# Copybook fields with NULL suffix null indicator configuration.

Support for DBCS fields

Ensure the following when using DBCS fields:

• When you use PIC G or Pic N DBCS fields, you must provide one of the following valid multi-byte character set (MBCS) encodings in the encoding option or in the ENCODING environment variable when using the gsutil cp or bq export commands:
  • x-IBM930
  • x-IBM933
  • x-IBM935
  • x-IBM937
  • x-IBM939
  • x-IBM942
  • x-IBM942C
  • x-IBM943
  • x-IBM943C
  • x-IBM949
  • x-IBM949C
  • x-IBM950
  • x-IBM964
  • x-IBM970
  • x-IBM1364
• When a copybook field only contains DBCS bytes, but these bytes are not surrounded by shift-out (0x0E) and shift-in (0x0F), you must add the suffix _DBCS to the field name to ensure that these bytes are decoded as DBCS bytes.

For example, if your data corresponding to the copybook field 03 FLD01 PIC N USAGE DISPLAY-1 contains bytes 0x43 and 0xC5 in encoding x-IBM930 that are not surrounded by 0x0E and 0x0F, you must rename the copybook field name to 03 FLD01-DBCS PIC N USAGE DISPLAY-1 in order to correctly decode the DBCS data.

Support for variable-length character strings

The Native copybook parser supports the following struct fields:

• 10 var
• 15 var-LEN PIC 9(4) USAGE COMP
• 15 var-TEXT PIC X(n)

The first field in the struct field is the length of the second field, the string field. You might have to add some padding to the end of the record based on the record length as shown in the following figure.

[Padding added to variable-length character strings.] Figure 1. Padding added to variable-length character strings.

Mainframe Connector removes the suffix from the variable name before saving the data in BigQuery. In this example, the variable name will be var.

To use struct fields, set the environment variable BQSH_FEATURE_VARIABLE_LENGTH_ENABLED to either yes or true.

When using struct fields, ensure the following:

• The suffix of the first parameter in the struct is -LEN. If you want to use a different suffix, you must set the environment variable BQSH_FEATURE_VARIABLE_LENGTH_LEN_SUFFIX to the suffix that you want to use.
• The suffix of the second parameter in the struct is -TEXT. If you want to use a different suffix you must set the environment variable BQSH_FEATURE_VARIABLE_LENGTH_DATA_SUFFIX to the suffix that you want to use.

Unsupported fields and constructs

The following sections describe fields and constructs are not supported by the

• COBOL constructs
• Data types

COBOL constructs

COBOL constructs even though these constructs are not supported. If you use these constructs in your copybook, Mainframe Connector shows an error.

• dataAlignedClause
• dataBlankWhenZeroClause
• dataCommonOwnLocalClause
• dataIntegerStringClause
• dataJustifiedClause
• dataOccursClause
• dataReceivedByClause
• dataRecordAreaClause
• dataRenamesClause
• dataSignClause
• dataSynchronizedClause
• dataThreadLocalClause
• dataTypeClause
• dataTypeDefClause
• dataUsingClause

Data types

COBOL data types like COMP-1 and COMP-2 are supported.

Legacy copybook parser

The legacy copybook parser is an older version of the parser that supports non-COBOL features. If you are using DSL-based copybook the legacy parser might be more suitable as the Native copybook parser might cause errors.

You can use copybook DD with the following restrictions:

• Level 66 (ALIAS) or 77 (STANDALONE) are not supported.
• REDEFINES are not supported.
• Comment lines are not supported.
• Fields of length 10 whose name ends with DATE or DT are dates. Decoding is different for those fields.
• Use only the following COMP fields. ALIGN and OCCURS are not supported.
  • COMP
  • COMP4
  • BINARY
  • COMP3
  • PACKED-DECIMAL
• Use only PICTURE fields. Define PICTURE fields on the same line, directly after the field name.
• You must justify all fields and use a single level. Comments are not supported.
• Ensure that columns 1 to 6 always contain blanks.