com.ibm.streams.operator.encoding

Interface JSONEncoding<O extends java.util.Map,A extends java.util.List>

Type Parameters:

O - Class representing a JSON object

A - Class representing a JSON array

public interface JSONEncoding<O extends java.util.Map,A extends java.util.List>

Interface to encode Tuples into JSON (JavaScript Object Notation) data structures.

Type mapping to JSON representation

Type.MetaType	JSON type
BOOLEAN	true|false
INT8, INT16, INT32, INT64, FLOAT32, FLOAT64, DECIMAL32, DECIMAL64, DECIMAL128	number
UINT8, UINT16, UINT32, UINT64	number (as the unsigned value)
RSTRING, USTRING, BSTRING	string
TIMESTAMP	number (from Timestamp.getTimeAsSeconds())
ENUM	string
TUPLE	object
MAP, BMAP	object
LIST, BLIST SET, BSET	array
BLOB, XML, COMPLEX32, COMPLEX64	not supported

Specific details of the object types used are shown by getAttributeObject(Tuple, Attribute).
For any SPL map the key type must be convertible to a String and the value type convertible to a JSON value. The value type is mapped according to the mapping table above.
For any SPL list or set type the elements of the JSON array follow the mapping table above for the SPL element type.

The interface interfaces with JSON libraries where the classes that represent JSON objects and arrays implement java.util.Map and java.util.List respectively, such as JSON4J and json-simple. A library specific instance is created using EncodingFactory.newJSONEncoding(Class, Class).
An JSON4J specific instance is obtained using EncodingFactory.getJSONEncoding().

Since:

InfoSphere® Streams Version 3.0

See Also:

EncodingFactory.getJSONEncoding(), EncodingFactory.getGenericJSONEncoding(), EncodingFactory.newJSONEncoding(Class, Class), http://www.json.org/

Method Summary

Methods

Modifier and Type	Method and Description
java.lang.String	encodeAsString(Tuple tuple) Encode all attributes for tuple into a string representation of a JSON object.
O	encodeTuple(Tuple tuple) Encode all attributes for tuple into a JSON object.
O	encodeTuple(Tuple tuple, O data) Encode all attributes for tuple as a JSON object.
java.lang.Object	getAttributeObject(Tuple tuple, Attribute attribute) Get an attribute value from tuple as object for a JSON object.
java.lang.Object	getAttributeObject(Tuple tuple, java.lang.String attributeName) Get an attribute value from tuple as an object for a JSON object.
A	newJSONArray() Return a new JSONObject.
O	newJSONObject() Return a new JSONObject.

Method Detail

getAttributeObject

java.lang.Object getAttributeObject(Tuple tuple,
                                  Attribute attribute)

Get an attribute value from tuple as object for a JSON object. The attribute's value is returned as a object that is an instance of Boolean, Number, String, O (JSON object) or A (JSON array).

Type mapping to JSON values

Type.MetaType	JSON value type
BOOLEAN	Boolean
INT8	Byte
INT16	Short
INT32	Integer
INT64	Long
FLOAT32	Float
FLOAT64	Double
DECIMAL32, DECIMAL64, DECIMAL128	java.math.BigDecimal
UINT8, UINT16	Integer (as the unsigned value)
UINT32	Long (as the unsigned value)
UINT64	java.math.BigInteger (as the unsigned value)
RSTRING, USTRING, BSTRING	String
ENUM	String
TUPLE	O (JSON object)
TIMESTAMP	java.math.BigDecimal (from Timestamp.getTimeAsSeconds())
MAP, BMAP	O (JSON object)
LIST, BLIST SET, BSET	A (JSON array)

Parameters:

tuple - Tuple to extract value from.

attribute - Attribute description. If attribute does not represent an attribute in tuple the behavior is undefined.

Returns:

An object that can be put into a JSON object or array

Throws:

java.lang.UnsupportedOperationException - Attribute cannot be represented in JSON.

getAttributeObject

java.lang.Object getAttributeObject(Tuple tuple,
                                  java.lang.String attributeName)

Get an attribute value from tuple as an object for a JSON object.

Parameters:

tuple - Tuple to extract value from.

attributeName - Attribute name.

Returns:

An object representing the attribute's value

See Also:

getAttributeObject(Tuple, Attribute)

newJSONObject

O newJSONObject()

Return a new JSONObject. Uses the no-arg constructor of O to create a new instance.

Returns:

A new instance of O

newJSONArray

A newJSONArray()

Return a new JSONObject. Uses the no-arg constructor of A to create a new instance.

Returns:

A new instance of A

encodeTuple

O encodeTuple(Tuple tuple,
            O data)

Encode all attributes for tuple as a JSON object. The keys for the JSON object are the attribute names and the values are objects from getAttributeObject(Tuple, Attribute).

Parameters:

tuple - Tuple to be encoded.

data - JSON object to be populated.

Returns:

data

See Also:

getAttributeObject(Tuple, Attribute)

encodeTuple

O encodeTuple(Tuple tuple)

Encode all attributes for tuple into a JSON object.

Parameters:

tuple - Tuple to be encoded.

Returns:

JSON object containing the attributes.

encodeAsString

java.lang.String encodeAsString(Tuple tuple)
                                throws java.io.IOException

Encode all attributes for tuple into a string representation of a JSON object.

Parameters:

tuple - Tuple to be encoded

Returns:

String representation of a JSON object

Throws:

java.io.IOException