How to determine the type of thrift message?

Question

I have a pipeline that has two kind of thrift message coming in

I can try deserializing each individually and see if it runs into error

TDeserializer deserializer = new TDeserializer(new TSimpleJSONProtocol.Factory());

try {
   Type1Msg t1 = new Type1Msg();
   deserializer.deserialize(t1, json, "UTF-8");
   return t1
} catch() {

}

try {
   Type2Msg t2 = new Type2Msg();
   deserializer.deserialize(t1, json, "UTF-8");
   return t2
} catch() {

}

Is there a idiomatic way of achieving deserializing multiple message type in thrift?

I've never used Thrift, but a quick perusal of the Javadoc suggests you want a `TUnion` — Jim Garrison, Nov 16 '21 at 20:38
..but its abstract and constructor is protected ;(;(;(and has very poor javadoc) — xerx593, Nov 16 '21 at 20:49
if, you *knew* the (message) class name, you could do `TBase obj = (TBase) Class.forName(className).getConstructor().newInstance();` [like here(eof)](https://www.programcreek.com/java-api-examples/?code=pinterest%2Fsinger%2Fsinger-master%2Fsinger%2Fsrc%2Fmain%2Fjava%2Fcom%2Fpinterest%2Fsinger%2Ftools%2FThriftLogDumper.java) ..but you probably don't!(?) — xerx593, Nov 16 '21 at 20:51
different approach: Why do you have (only) one pipeline(/endpoint) for two message types!? ;) (if you cannot infer from the "endpoint", check the option to infer it from the "message/payload") — xerx593, Nov 16 '21 at 20:53

score 0 · Answer 1 · answered Nov 18 '21 at 12:49

I answered it for Python already over here, but in fact the topic is language-agnostic.

Use a Thrift union, alternatively a struct with non-required fields will also work:

union varying {
  1 : Type1Msg msg1
  2 : Type2Msg msg2
  // room for more 
}

How to determine the type of thrift message?

1 Answers1