Generic exception is thrown when publishing a JetStream message

[joschiwald]

Better identify JetStream connection and /communication errors.

Versions of io.nats:jnats and nats-server:

io.nats:jnats: 2.16.1
nats-server: 2.8.4

OS/Container environment:

Client: Windows 10
Server: alpine docker image

Steps or code to reproduce the issue:

1. Start a nats-server with default configuration and no streams configured
2. Publish a JetStream message

natsConn.jetStream().publish("test", myMessageBytes)

Expected result:

The publish function throws a JetStreamApiException with the right error code.

Actual result:

The publish function throws an IOException
https://github.com/nats-io/nats.java/blob/main/src/main/java/io/nats/client/impl/NatsJetStream.java#L153

[scottf]

For now you need to look at the getMessage() that came back in the IOException

Error Publishing: 503 No Responders Available For Request

Changing this would be a breaking change since JetStreamApiException is not an IOException

I'm changing this issue to an enhancement instead of a bug.

[joschiwald]

This is my first approach to solve this issue. I'll test it next week when I have access to my development environment.

diff --git a/src/main/java/io/nats/client/api/ApiResponse.java b/src/main/java/io/nats/client/api/ApiResponse.java
index 5257cb4c..2353759f 100644
--- a/src/main/java/io/nats/client/api/ApiResponse.java
+++ b/src/main/java/io/nats/client/api/ApiResponse.java
@@ -31,7 +31,15 @@ public abstract class ApiResponse<T> {
     private final Error error;
 
     public ApiResponse(Message msg) {
-        this(new String(msg.getData(), UTF_8));
+        if (msg.isStatusMessage()) {
+            json = null;
+            error = Error.convert(msg.getStatus());
+            type = NO_TYPE;
+        } else {
+            json = new String(msg.getData(), UTF_8);
+            error = json == null ? null : Error.optionalInstance(json);
+            type = json == null ? NO_TYPE : JsonUtils.readString(json, TYPE_RE, NO_TYPE);
+        }
     }
 
     public ApiResponse(String json) {
diff --git a/src/main/java/io/nats/client/impl/NatsJetStream.java b/src/main/java/io/nats/client/impl/NatsJetStream.java
index d0145571..8e339cce 100644
--- a/src/main/java/io/nats/client/impl/NatsJetStream.java
+++ b/src/main/java/io/nats/client/impl/NatsJetStream.java
@@ -149,10 +149,6 @@ public class NatsJetStream extends NatsJetStreamImplBase implements JetStream {
     }
 
     private PublishAck processPublishResponse(Message resp, PublishOptions options) throws IOException, JetStreamApiException {
-        if (resp.isStatusMessage()) {
-            throw new IOException("Error Publishing: " + resp.getStatus().getCode() + " " + resp.getStatus().getMessage());
-        }
-
         PublishAck ack = new PublishAck(resp);
         String ackStream = ack.getStream();
         String pubStream = options == null ? null : options.getStream();

[scottf]

Yes, something like that would work, but again, we cannot change the type of exception thrown without a major version release as it would be a breaking change.

[scottf]

Also see #858

[scottf]

@joschiwald I'm thinking about how to fix this in a backward compatible manner. I could add a connection option that is essentially "better error messages" and behave differently if the user sets this option. What do you think?

[joschiwald]

I like the idea. With that option we could remove the workaround with exception mapping from our code 😊I hope this is doable without having to add to much bloat to your codebase.