[CXF-8249] SSE client refuses to accept valid stream

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 3.3.5, 3.2.12
• Fix Version/s: 3.3.6, 3.2.13, 3.4.0
• Component/s: JAX-RS
• Estimated Complexity: Unknown
• Assignee: Andriy Redko
• Reporter: Ihor Zahoruiko
• Created: 22/Mar/20 08:30
• Updated: 22/Dec/21 20:43
• Resolved: 22/Mar/20 22:14

Description

The standard (https://www.w3.org/TR/eventsource/#parsing-an-event-stream) defines that in the stream event fields (data, event, id etc.) a space after the colon is optional, i.e. both options are valid:

data:test
data: test

But SSE client does not accept stream events where format without a space after the colon (data:test).

In the class org.apache.cxf.jaxrs.sse.client.InboundSseEventProcessor line parsing is performed as

if (StringUtils.isEmpty(line) && builder != null) {
  ...
} else if (line.startsWith("event: ")) {
  ...
} else if (line.startsWith("id: ")) {
  ...
} else if (line.startsWith(": ")) {
  ...
} else if (line.startsWith("retry: ")) {
  ...
} else if (line.startsWith("data: ")) {
  ...
}

Why?

 

I use Spring with the SseEmitter class to generate an event stream, something like 

SseEmitter emitter = new SseEmitter ();
emitter.send ("test");

This class generate event using format "data:test", and I can't read this events in a client application where the SSE client is used.

If I change the line by adding a space, SSE client accept event....

emitter.send (" test");  // adding a space to get "data: test"

 

The SSE client in the client application: 

try (SseEventSource source = SseEventSource.target(someurl).build()) {
   source.register(
      (inboundSseEvent) -> System.out.println(inboundSseEvent.readData()
   );
   source.open();
} catch (Exception ex) {
}

Dependency in pom.xml 

<dependency>
  <groupId>org.apache.cxf</groupId>
  <artifactId>cxf-rt-rs-client</artifactId>
  <version>3.3.5</version>
</dependency>
<dependency>
  <groupId>org.apache.cxf</groupId>
  <artifactId>cxf-rt-rs-sse</artifactId>
  <version>3.3.5</version>
</dependency>