Binary String Types

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XSD defines the following types that are mapped to a C binary type structure:

hexBinary

base64Binary

The type of structure used depends on whether or not a length facet is applied to the type. If a length facet is not used, or the length is a very large value (> 32K), a built-in type containing a pointer to a dynamic memory buffer is used to hold the binary data. The definition of this type in osSysTypes.h is as follows:

	typedef struct OSDynOctStr {
 
	   OSUINT32     numocts;
 
	   const OSOCTET* data;
 
	} OSDynOctStr;
 

The numocts member holds the length of the binary string and the data member holds the actual data.

For C++, a built-in class definition is used that extends this structure:

	class OSDynOctStrClass : public OSRTBaseType {
 
	 protected:
 
		OSUINT32 numocts;
 
		const OSOCTET* data;
 
	 public:
 
	   ...
 
	} ;
 

This class provides methods for getting and setting the data values as well as initialization through constructors and other utility methods.

If a length facet is used that restricts the size of the binary string to a value less than 32K, a custom type is generated that contains a static array to hold the data. The general form of this type is as follows:

      typedef struct TypeName {
 
         OSUINT32     numocts;
 
         OSOCTET      data[length];
 
      } TypeName;
 

In this case, TypeName would be the name of the type defined in the XSD specification and length would be the value of the length facet.

In the case of C++, a class is generated:

      class TypeName : public OSRTBaseType {
 
         OSUINT32     numocts;
 
         OSOCTET      data[length];
 
	   ...
 
      } ;
 

The general mappings for each case are as follows:

Dynamic Case (no length facet):

XSD type:	<xsd:simpleType name="TypeName"> <restriction base="xsd:hexBinary"/> </xsd:simpleType>
Generated C code:	typedef OSDynOctStr TypeName;
Generated C++ code:	class TypeName : public OSDynOctStrClass { ... } ;

Static Case (length restricted to 32K or less):

XSD type:	<xsd:simpleType name="TypeName"> <xsd:restriction base="xsd:hexBinary"> <xsd:length value="length"/> </xsd:restriction> </xsd:simpleType>
Generated C code:	typedef struct TypeName { OSUINT32 numocts; OSOCTET data[length]; } TypeName;
Generated C++ code:	class TypeName : public OSRTBaseType { OSUINT32 numocts; OSOCTET data[length]; ... } ;

Note: in the static case, the maxLength facet will cause the same code to be generated with maxLength used for the size of the array.