JSON schema to PL/I mapping
The DFHJS2LS utility program supports mappings between JSON schemas and PL/I data structures. Because the Enterprise PL/I compiler and older PL/I compilers differ, two language options are supported: PLI-ENTERPRISE and PLI-OTHER.
Rules for mapping schema element names to PL/I
-
Characters other than A-Z, a-z, 0-9, @, #, _, or $ are replaced
with '
X
'.For example,
monthly-total
becomesmonthlyXtotal
.You can use the MAPPING-OVERRIDES parameter to change the way other characters are handled. For example, if you set the value HYPHENS-AS-UNDERSCORES , any hyphen in the JSON schema is converted to an underscore instead of an X. For example,
monthly-total
becomesmonthly_total
. -
Duplicate names in the same scope are made unique by the addition
of one or two numeric digits to the second and subsequent
instances
of the name.
For example, three instances of
year
becomeyear
,year1
, andyear2
.Should the above behavior be undesirable the user can specify
MAPPING-OVERRIDES=NO-ARRAY-NAME-INDEXING
as input to the utility which disables the addition of one or two numeric digits to the second and subsequent instances of the name. -
A JSON schema specifies that a variable has varying cardinality
if it has a
"type"
value of"array"
, and the keywords"minItems"
and"maxItems"
are omitted or have different values. If the schema specifies that the variable has varying cardinality, then field names are created with suffixes of"_cont"
and"_num"
.For more information, see Variable arrays of elements in DFHJS2LS.
-
A JSON schema specifies that a variable is optional if it does
not appear in the
"required"
keyword array that is associated with the enclosing JSON schema"object"
type. For optional fields, an additional field is generated with a suffix of_num
added to the element name. At run time this is zero to indicate the value was absent from the JSON data, and non-zero if the value was present in the JSON data. - Field names are limited to 31 characters. If a generated name, including any prefix and suffix, exceeds this length, the element name is truncated.
Rules for mapping schema types to PL/I
- If the MAPPING-LEVEL parameter is set to 1.2 or higher and the CHAR-VARYING parameter is set to NULL, variable-length character data is mapped to null-terminated strings and an extra character is allocated for the null-terminator.
- If the MAPPING-LEVEL parameter is set to 1.2 or higher and the CHAR-VARYING parameter is not specified, by default variable-length character data is mapped to a VARYINGZ data type for Enterprise PL/I and VARYING data type for Other PL/I.
- Variable-length binary data is mapped to a VARYING data type if it less than 32 768 bytes and to a container if it is more than 32 768 bytes.
JSON Schema keyword | PL/I data description |
---|---|
All of:
|
Not supported |
|
This keyword is ignored, but it is assumed to be compatible with the draft 04 JSON Schema specification. |
|
These keywords are ignored. |
|
The "format" keyword is used to modify either the generated structure or run-time value. See the following information for the supported use of "format". |
|
Multidimensional arrays are supported from mapping level 4.3 or higher, and mixed type arrays are not supported.
If both
|
|
|
|
The only form of JSON object currently supported is a fixed set of named elements. This will generate a structure (or sub-structure) using the element names.
Any
element in the
|
|
The object is mapped as in the previous example, with additional fields that support
additional properties. The additionalProperties property is assumed to be false if
not set in the ADDITIONAL-PROPERTIES-DEFAULT parameter. If enabled, space is
allocated up to the value specified in the ADDITIONAL-PROPERTIES-MAX parameter.
The number of characters in each space is set by the ADDITIONAL-PROPERTIES-SIZE
parameter. Each individual property is mapped to a Note: There are several ways to configure JSON support in
CICS, including use of z/OS Connect for CICS. If you are using the older CICS Java Pipeline
technology,
Additional Properties are only supported if the
com.ibm.cics.json.enableAxis2Handlers JVM system property is not set to
true. |
|
None of these keywords are supported with JSON objects. |
|
where the value of z is based on m , but dependent on the settings of the CHAR-VARYING parameter.
m
is
based on the
|
|
When CCSID=1200 at mapping level 4.0 and higher:
where the value of z is based on m , but dependent on the settings of the CHAR-VARYING parameter.
m
is based on the
|
|
All
supported when
|
|
where
m is based on the
When CCSID=1200 at mapping level 4.0 and higher:
where
m
is
based on the
|
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where
m is based on the
|
|
where
m is based on the
|
|
When CCSID=1200 at mapping level 4.0 and higher:
where
m
is
based on the
|
|
Mapping level 1.1 and lower:
Mapping level 1.2 and higher:
where
|
|
"exclusiveMaximum" and "exclusiveMinimum" restrictions are passed
to the language structure only as a comment.
|
|
|
|
|
|
|
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|
|
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Mapping level 1.1 and lower:
Mapping level 1.2 and higher:
All mapping levels:
|
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Mapping level 1.1 and lower:
Mapping level 1.2 and higher:
All mapping levels:
|
|
Mapping level 1.1 and lower:
Mapping level 1.2 and higher:
|
|
FIXED DECIMAL(
n
,
m
)
|
|
Mapping levels 1.0 and 1.1:
Mapping level 1.2 and higher:
Note: The IBM® Hexadecimal Floating Point
(HFP) data representation is not exactly the same as the IEEE-754-1985 representation used for JSON.
Some values may not convert exactly from one representation to the other. Some extremely large or
small values might not be valid for float data types. Some values may lose precision when converted
to or from HFP representation. If precise conversions are important, consider replacing use of
DECIMAL FLOAT data types with fixed precision alternatives.
|
|
Mapping levels 1.0 and 1.1:
Mapping level 1.2 and higher:
Note: The IBM Hexadecimal Floating Point
(HFP) data representation is not exactly the same as the IEEE-754-1985 representation used for JSON.
Some values may not convert exactly from one representation to the other. Some extremely large or
small values might not be valid for float data types. Some values may lose precision when converted
to or from HFP representation. If precise conversions are important, consider replacing use of
DECIMAL FLOAT data types with fixed precision alternatives.
|
|
The logical paths through the array of options are merged together as
though a single Object had been defined of type It is possible for a JSON schema to define complex logical structures; however, the subtleties implied in the complex logical structures might be lost in the mapping to a language structure. The transformation process does not attempt to enforce the combinatorial rules from the schema; it only interacts with the language structure fields that indicate whether a given JSON property is present or absent. If the sub-options contain compatible definitions for the same property name, DFHJS2LS attempts to merge the associated pattern of constraints, though some subtleties might be lost in the process. For example, assume the following definition:
Most scenarios involving logical composition will map to simple language structures, but complicated logical composition might result in compromises during the mapping process. For best results, avoid using logical composition in a JSON schema to define alternative declarations for the same JSON property. |