JSON parser and domain
JSON (JavaScript Object Notation) is a simple data-interchange format based on a subset of the JavaScript programming language.
IBM® App Connect Enterprise supports a JSON domain. Messages in the JSON domain are processed by the JSON parser and serializer. The JSON parser interprets a bit stream by using the JSON grammar, and generates a corresponding JSON domain logical message tree. When processing data for output, the JSON serializer generates a JSON formatted bit stream from a JSON domain logical message tree.
JSON messages can be validated against a JSON schema file or OpenAPI definition during parsing. JSON message trees can be validated against a JSON schema file or OpenAPI definition during writing or mid-flow.
You can use the JSON editor in the IBM App Connect Enterprise Toolkit to edit JSON files; however, the validation capability of the editor has a number of limitations and should not be used to validate your JSON documents. For information about how to validate JSON documents, see JSON validation.
- Objects (name-value pairs) with the following types:
- String
- Number
- Boolean
- Null
- Ordered collections of values (arrays)
The JSON parser accepts only a JSON object or a JSON array as the top-level value type in both an input bit stream and an output bit stream. It is not possible to use the JSON parser to output a JSON string literal, number, Boolean, or null value without first embedding it in an object or array.
For more information about JSON message structure, see JSON message details. For more information about JSON parser parameters, see Parameter values for the JSON parser.
- UTF-8
- UTF-16BE
- UTF-16LE
- UTF-32BE
- UTF-32LE
If a UTF-* CCSID is explicitly specified, the JSON parser tolerates the corresponding Byte Order Mark (BOM) at the beginning of the data stream.
JSON data streams are parsed into a logical message tree under
the Data
element below the JSON
parser
root. The logical tree structure is shown in the Example JSON message.
The Data
element can be accessed and manipulated from ESQL as
JSON.Data
, from Java™ as
JSON/Data
, from the Graphical Data Mapping editor by using the Add User-Defined
function to define JSON->Data
, or from XPath as $Body/Data
.
The JSON parser issues an error if a bit stream is not formatted according to the JSON grammar.
The JSON serializer serializes message trees into a JSON format data stream. The CCSID can be defined by either the integration node properties tree, or by transport headers in the message assembly. If no CCSID is defined, the serializer defaults to the queue manager default CCSID for all nodes except HTTP nodes, which default to UTF-8 encoding.
When the JSON serializer is invoked through an ASBITSTREAM
function
call, the CCSID is defined by the CCSID parameter. If no CCSID parameter
is provided, or if the value is set to 0, the JSON serializer defaults
to using UTF-8 encoding.
If you code the ASBITSTREAM function with the parser mode option set to FolderBitStream to parse a JSON domain message tree to a bit stream, the generated bit stream is a JSON format that is built from the target element and its children.
To process messages with the JSON parser, select JSON as the Message Domain on the relevant node in the message flow. The XSLTransform node does not support the JSON domain.
The integration node sets the HTTP Content-Type header to application/json
when
it serializes a JSON message tree, unless an explicit value is set by the message flow.
JSON objects are modeled in the integration node message tree as a sequence of NameValue elements. The parser builds the message tree in the order in which it encounters the members in the bit stream. The serializer writes the object members into the bit stream in the tree order.
- An array that contains simple values; for
example:
"array1" : [ "thing1", 1 ]
The following message tree is produced:(0x01001000:Array): array1 = ( (0x03000000:NameValue):Item = 'thing1' (CHARACTER) (0x03000000:NameValue):Item = 1 (INTEGER) )
The JSON parser assigns the name
Item
to the NameValue elements. - An array that contains objects; for
example:
"array2" : [ {"a" : 1}, {"b" : 2} ]
The following message tree is produced:(0x01001000:Array):array2 = ( (0x01000000:Object):Item = ( (0x03000000:NameValue):a = 1 (INTEGER) ) (0x01000000:Object):Item = ( (0x03000000:NameValue):b = 2 (INTEGER) ) )
- A multidimensional array; for example:
"array3" : [ [1.1], [2.1] ]
The following message tree is produced:(0x01001000:Array):array3 = ( (0x01001000:Array):Item = ( (0x03000000:NameValue):Item = 1.1E+0 (FLOAT) ) (0x01001000:Array):Item = ( (0x03000000:NameValue):Item = 2.1E+0 (FLOAT) ) )
Example JSON message
The following example shows a simple JSON message:
{
"name" : "John Doe",
"age" : -1.0,
"known" : false,
"address" : { "street" : null,
"city" : "unknown" },
"belongings" : ["item1", "item2", "item3"]
}
This JSON input produces the following integration node logical message tree:
(0x01000000:Object):JSON = ( ['json' : 0xd55fc8]
(0x01000000:Object):Data = (
(0x03000000:NameValue):name = 'John Doe' (CHARACTER)
(0x03000000:NameValue):age = -1E+0 (FLOAT)
(0x03000000:NameValue):known = FALSE (BOOLEAN)
(0x01000000:Object ):address = (
(0x03000000:NameValue):street = NULL
(0x03000000:NameValue):city = 'unknown' (CHARACTER)
)
(0x01001000:Array ):belongings = (
(0x03000000:NameValue):Item = 'item1' (CHARACTER)
(0x03000000:NameValue):Item = 'item2' (CHARACTER)
(0x03000000:NameValue):Item = 'item3' (CHARACTER)
)
)
)