Currently using a MPGW service with request type "non-xml" and trying to convert JSON to JSONx (XML).

Some JSON payloads with Unicode character are throwing error in DataPower with error message:

"Invalid string syntax"

Some other JSON payloads with Unicode are processed by JSON parser without any issue.

Is there any way to parse all these JSON payloads successfully in DataPower?

In short answer, some of the Unicode characters are not valid XML characters after the JSONx conversion.

For longer answer:

According JSON spec the character encoding is a hexadecimal number:

https://tools.ietf.org/html/rfc8259#section-7

Certain Unicode character such as \u000a (Line Feed) is a XML character:

Other Unicode characters such as \u000b (Line Tabulation) and \u0010 (Data Link Escape) is not:

https://en.wikipedia.org/wiki/C0_and_C1_control_codes

Example of common XML ASCII control characters are \u0009, \u000a and \u000d for XML 1.0:

https://www.w3.org/TR/REC-xml/#charsets

It is not possible for JSONx conversion to process JSON with string characters that are not valid XML characters.

The reason is because after parsing JSON, there is no escaping anymore, and each JSON character is internally a parsed XML character.

Changing the request type to "json" is not a valid solution either:

The same JSON payload would also fail because request type JSON does implicit conversion of input to JSONX, which gets stored in __JSONASJSONX context.

https://www.ibm.com/support/knowledgecenter/SS9H2Y_7.7.0/com.ibm.dp.doc/request-type_webtokenservice.html

To workaround this, it is necessary to use GatewayScript to process JSON that cannot be processed with JSONx because of the XML spec.

Some JSON payloads with Unicode character are throwing error in DataPower with error message:

Some JSON payloads with Unicode character are throwing error in DataPower with error message: