FTL Native Messages to JSON Translation Reference

This section details the translation between fields in FTL messages and equivalent fields in the JSON representations used on the Apache Kafka side of the Bridge for Apache Kafka (without schemas).

The Bridge for Apache Kafka connectors can use this translation scheme in either direction. However, they use this translation only when the configuration specifies the string converter without schemas.

Inbox

FTL inbox fields are not supported outside of FTL. The translation from FTL to JSON discards any inbox fields.

Field Translations

The table juxtaposes the Java code fragment that would create an FTL message against the equivalent JSON representation.

FTL (Java) JSON 
message.setLong("my-long",1);
 
"my-long": 1
 
long[] longArray = {1, 2, 3};
message.setArray("my-long-array", longArray);
 
"my-long-array": [ 1, 2, 3 ]
 
message.setString("my-string", "hello");
 
"my-string": "hello"
 
String[] stringArray = {"eeny", "meeny", "miny"};
message.setArray("my-string-array", stringArray);
 
"my-string-array":
  [ "eeny", "meeny", "miny" ]
 
message.setDouble("my-double", 9.9);
 
"my-double": { "_d_": 9.9 }
Note: An FTL double field translates as a JSON object with one field named "_d_". Its value must be either a JSON number, or one of the following special string values:
  • "Infinity" (positive infinity)
  • "-Infinity" (negative infinity)
  • "NaN" (not a number) 
double[] doubleArray =
  {1.1,
   Double.POSITIVE_INFINITY,
   Double.NEGATIVE_INFINITY,
   Double.NaN};
message.setArray("my-double-array", doubleArray);
 
"my-double-array": [
  { "_d_": 1.1 },
  { "_d_": "Infinity" }, 
  { "_d_": "-Infinity" },
  { "_d_": "NaN" }
]
 
TibDateTime dateTime = new TibDateTime();
dateTime.set(443815200, 0); 
message.setDateTime("my-dateTime", dateTime);
 
"my-dateTime": {
   "_m_": 443815200000
}
Note: An FTL TibDateTime field translates as a JSON object with one field named "_m_". Its value must be a JSON number, which represents the number of milliseconds since the UNIX Epoch.

The JSON representation excludes nanoseconds, truncating to the nearest millisecond. 

TibDateTime dt1 = new TibDateTime();
dt1.set(1168365600, 0);
TibDateTime dt2 = new TibDateTime();
dt2.set(1003860000, 0);
TibDateTime dt3 = new TibDateTime();
dt3.set(1003860000, 0);
TibDateTime[] dateTimeArray = {dt1, dt2, dt3};
message.setArray("my-dateTime-array", dateTimeArray);
 
"my-dateTime-array": [
  { "_m_": 1168365600000 },
  { "_m_": 1003860000000 }, 
  { "_m_": 1003860000000 } 
]
 
byte[] opaque = {'H', 'i'};
message.setOpaque("my-opaque", opaque);
 
"my-opaque": {
  "_o_": "SGk=" }
Note: An FTL opaque field translates as a JSON object with one field named "_o_". Its value is a JSON string containing base64-encoded binary data. 
Message nestedMessage = realm.createMessage(null);
nestedMessage.setLong("my-nested-message-long", 2);
message.setMessage("my-message", nestedMessage);
 
 "my-message": {
  "my-nested-message-long": 2 }
Note: A nested FTL message field is represented as a nested JSON object using the same JSON representation as any other FTL message. 
Message m1 = realm.createMessage(null);
m1.setString("m1-string", "ftl-is-great");
Message m2 = rlm.createMessage(null);
m2.setDouble("m2-double", 4.5);
Message m3 = rlm.createMessage(null);
m3.setLong("m3-long", 3);
Message[] messageArray = {m1, m2, m3};
message.setArray("my-message-array", messageArray);
 
 "my-message-array": [
  { "m1-string": "ftl-is-great" },
  { "m2-double":
      { "_d_": 4.5 } },
  { "m3-long": 3 }
]