[Bug 63521] New: javax.websocket.server.ServerContainer.addEndpoint(Class endpointClass) throws DeploymentException

[bu...@apache.org]

https://bz.apache.org/bugzilla/show_bug.cgi?id=63521

            Bug ID: 63521
           Summary: javax.websocket.server.ServerContainer.addEndpoint(Cla
                    ss<?> endpointClass) throws DeploymentException
           Product: Tomcat 8
           Version: 8.5.x-trunk
          Hardware: PC
            Status: NEW
          Severity: normal
          Priority: P2
         Component: WebSocket
          Assignee: dev@tomcat.apache.org
          Reporter: poli.m.georgieva@gmail.com
  Target Milestone: ----

Created attachment 36635
  --> https://bz.apache.org/bugzilla/attachment.cgi?id=36635&action=edit
Test application and patch.

Hello

Problem description:
The following API method is not working correctly on latest 8.5.x (and 9.0.x)
Tomcat versions.
javax.websocket.server.ServerContainer. void addEndpoint(Class<?>
endpointClass) [1]
The invocation of this method causes: 
javax.websocket.DeploymentException: Multiple Endpoints may not be deployed to
the same path [/websocket/echoAnnotation] : existing endpoint was [class
test.websocket.EchoAnnotation] and new endpoint is [class
test.websocket.EchoAnnotation]

Steps to reproduce: 
1. Deploy the attached test application ServerContainerTest.war
2. Request to ws://localhost:8080/ServerContainerTest/websocket/echoAnnotation
hangs. 

Problem analysis:
The issue is reproducible since v.8.5.38. Since then the DeploymentExceptions
started to cause failures of all the application endpoints (even already
successfully deployed).
The root issue causing the DeploymentException:  one and the same endpoint
class gets deployed twice - once deployed by the auto scan mechanism and then
via the programmatic approach. The second fails because the same path is
already used. This I think is a valid scenario according to the API
description[1] and the WebSocket specification.

What the spec says:
From JSR 356, section 6.4 Programmatic Server Deployment:
“It is recommended that developers use either the programmatic deployment API,
or base their application
on the scanning and ServerApplicationConfig mechanism, but not mix both
methods. Developers can
suppress a deployment by scan of the endpoints in the WAR file by providing a
ServerApplicationConfig
that returns empty sets from its methods. If however, the developer does mix
both modes of deployment, it is possible in the case of annotated endpoints,
for the same annotated endpoint to be submitted twice for deployment, once as a
result of a scan of
the WAR file, and once by means of the developer calling the programmatic
deployment API. In this case
of an attempt to deploy the same annotated endpoint class more than once, the
websocket implementation
must only deploy the annotated endpoint once, and ignore the duplicate
submission.”

Workaround is available:
Suppress the auto scan mechanism by providing a custom ServerApplicationConfig
implementation (returning empty sets).

Proposed solution:
A possible fix would be - when we detect duplicate paths to add a check if they
are for the same endpoint class and in this case ignore the second deployment
and omit the DeploymentException. 
An example patch plus junits adaptations are attached. 

Best Regards,
Polina

[1]
https://docs.oracle.com/javaee/7/api/javax/websocket/server/ServerContainer.html#addEndpoint-java.lang.Class-

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[Bug 63521] javax.websocket.server.ServerContainer.addEndpoint(Class endpointClass) throws DeploymentException

[bu...@apache.org]

https://bz.apache.org/bugzilla/show_bug.cgi?id=63521

Mark Thomas <ma...@apache.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Resolution|---                         |FIXED
             Status|NEW                         |RESOLVED

--- Comment #2 from Mark Thomas <ma...@apache.org> ---
Thanks for the report. I'd missed that in the spec.

Fixed in:
- master for 9.0.22 onwards
- 8.5.x for 8.5.43 onwards
- 7.0.x for 7.0.95 onwards

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[Bug 63521] javax.websocket.server.ServerContainer.addEndpoint(Class endpointClass) throws DeploymentException

[bu...@apache.org]

https://bz.apache.org/bugzilla/show_bug.cgi?id=63521

Mark Thomas <ma...@apache.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 OS|                            |All

--- Comment #1 from Mark Thomas <ma...@apache.org> ---
Checking for the same class is too broad. There are invalid circumstances (e.g.
duplicate programmatic deployment) that would then be allowed. I'm working on
implementing a narrower check.

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