C and C++ to JSON Schema mapping

The JSON web services assistant with parameters MAPPING-MODE=LS2JS and LANG=C or LANG=CPP will map between C or C++ data types and JSON Schema definitions.

C and C++ names are converted to JSON names according to the following rules:
  1. Characters that are not valid in JSON property names are replaced with 'X'.

    For example, monthly-total becomes monthlyXtotal.

  2. Duplicate names are made unique by the addition of one or more numeric digits.

    For example, two instances of year become year and year1.

JSON web services assistant maps C and C++ data types to schema elements according to the following table. C and C++ types that are not shown in the table are not supported by JSON web services assistant. The _Packed qualifier is supported for structures. These restrictions apply:
  • Header files must contain a top level struct instance.
  • You cannot declare a structure type that contains itself as a member.
  • The following C and C++ data types are not supported:
    • decimal
    • long double
    • wchar_t (C++ only)
  • The following are ignored if they are present in the header file.
    Storage class specifiers:
    • auto
    • register
    • static
    • extern
    • mutable
    Qualifiers
    • const
    • volatile
    • _Export (C++ only)
    Function specifiers
    • inline (C++ only)
    • virtual (C++ only)
    Initial values
  • The header file must not contain these items:
    • Unions
    • Class declarations
    • Enumeration data types
    • Pointer type variables
    • Template declarations
    • Predefined macros; that is, macros with names that start and end with two underscore characters (__)
    • The line continuation sequence (a \ symbol that is immediately followed by a newline character)
    • Prototype function declarators
    • Preprocessor directives
    • Bit fields
    • The __cdecl (or _cdecl) keyword (C++ only)
  • The application programmer must use a 32-bit compiler to ensure that an int maps to 4 bytes.
  • The following C++ reserved keywords are not supported:
    • explicit
    • using
    • namespace
    • typename
    • typeid
C and C++ data type Schema simpleType
char[z] 
"type":"string"
"maxlength":z
char16_t[n] 
"type":"string"
"maxlength":n

At run time, CICS® TG populates the application data structure field with UTF-16 data.
char[8]

Supported when DATETIME=PACKED15

 
"type":"string"
"format":"date-time"
The format of the timestamp is defined by RFC3339.
char
short
int
long
long long
 
"type":"integer",
"minimum":- (n + 1),
"maximum":n
where n is the maximum value that can be represented by the primitive.
unsigned char
unsigned short
unsigned int
unsigned long
unsigned long long
 
"type":"integer",
"minimum":0,
"maximum":n
where n is the maximum value that can be represented by the primitive.		 
bool
(C++ only)		 
"type":"boolean"
 
float
 
"type":"number",
"description":"float"
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 float data types with fixed precision alternatives.
 
double
 
"type":"number",
"description":"double"
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 double data types. Some values may lose precision when converted to or from HFP representation. If precise conversions are important, consider replacing use of double data types with fixed precision alternatives.
type name[n] For primitives: 
"type":"array"
"maxItems":n
"minItems":n
"items":{
   "type":"object",
   "properties":{
      name:{
         type JSON
      }
   }
   "required":[
      name
   ]
}
For structs: 
"type":"array"
"maxItems":n
"minItems":n
"items":{
  type JSON
}
Where type JSON is the JSON Schema representation of the C or C++ type.