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AMQ Clients 2.0 Release Notes

Red Hat AMQ 7.1

Release Notes for Red Hat AMQ Clients


These release notes contain the latest information about new features, enhancements, fixes, and issues contained in the AMQ Clients 2.0 release.

Chapter 1. Features

  • AMQ C++ now supports multithreaded operation on Windows.
  • AMQ JavaScript now supports Node.js versions 4, 6, and 8.
  • AMQ JMS now offers more fine-grained control of message acknowledgment.
  • AMQ .NET now supports .NET Core on Windows and Red Hat Enterprise Linux.
  • This release improves the performance and efficiency of AMQP encoding and decoding.
  • A new Ruby messaging client, AMQ Ruby, is now available in Technology Preview.

The AMQ Ruby client is a Technology Preview feature only. Technology Preview features are not supported with Red Hat production service level agreements (SLAs) and might not be functionally complete. Red Hat does not recommend using them in production. These features provide early access to upcoming product features, enabling customers to test functionality and provide feedback during the development process.

For more information about the support scope of Red Hat Technology Preview features, see

Chapter 2. Enhancements

2.1. AMQ C++

  • ENTMQCL-536 - Provide a way to intercept authentication failure

    Authentication failures are now distinguished from other connection failures during reconnect. If authentication fails, the on_transport_error handler is fired with an AMQP unauthorized-access error. Connections configured to reconnect will terminate on this error but continue to retry after other connection errors.

  • AMQ C++ is now based on Qpid Proton 0.22.0

2.2. AMQ JavaScript

2.3. AMQ JMS

  • ENTMQCL-605 - Support acknowledging individual messages

    The JMS CLIENT_ACKNOWLEDGE mode enables explicit message acknowledgment using the Message.acknowledge() method. This method acknowledges all the messages previously received on the session at the time it is called.

    AMQ JMS now has an "individual acknowledge" mode that makes Message.acknowledge() apply only to the message it is called on.

  • ENTMQCL-568 - Support a no-acknowledge mode at the session level

    The client now offers a "no acknowledge" mode to enable presettled (at-most-once) message delivery on a per-session basis.

  • ENTMQCL-556 - Try each endpoint before delaying for next reconnect cycle

    The client now tries to connect to each endpoint in the failover set before delaying between reconnect cycles, rather than delaying between each endpoint.

  • AMQ JMS is now based on Qpid JMS 0.31.0

2.4. AMQ Python

  • ENTMQCL-573 - Exclude user and password in logging of connection URLs

    If a user or password are provided in a connection URL, they are now omitted in any printed representation of the connection.

  • AMQ Python is now based on Qpid Proton 0.22.0

2.5. AMQ .NET

Chapter 3. Resolved Issues

3.1. AMQ C++

  • ENTMQCL-584 - Kerberos authentication cannot proceed if the user option is not set

    In earlier releases of the product, it was necessary to supply a value to the user connection option in order to use Kerberos authentication.

    In this release, it is no longer necessary to set the user option.

  • ENTMQCL-565 - Windows build does not compile the examples that require C++11

    In earlier releases of the product, compiling the C++11 examples was not supported on Windows.

    In this release, the C++11 examples are supported on Windows.

  • ENTMQCL-600 - Epoll proactor pointer NULL in pn_connection_wake causes segmentation fault

    In earlier releases of the product, it was possible for the pn_connection_wake operation to fail during reconnect and trigger a segmentation fault.

    In this release, the operation no longer fails.

  • ENTMQCL-601 - Container continues to run after container.stop() called from main thread

    In earlier releases of the product, the container.stop() operation failed when called before any connections were established.

    In this release, the operation can safely be called before connecting.

3.2. AMQ JMS

  • ENTMQCL-571 - Missed connect error on start can lead to hung failover reconnect cycle

    In earlier releases of the product, it was possible for the client to miss a connection error and hang during reconnect.

    In this release, the client no longer hangs due to the missed error.

  • ENTMQCL-606 - Connection fails using Kerberos against Interconnect

    In earlier releases of the product, the client did not handle an empty SASL challenge from AMQ Interconnect during Kerberos authentication. This prevented the client from establishing the connection.

    In this release, the client handles the empty challenge, and the connection can be established.

3.3. AMQ Python

  • ENTMQCL-620 - Application property keys are incorrectly encoded as AMQP binary

    In earlier releases of the product, the client encoded the keys of message application properties as AMQP binary data. AMQP specifies that they be AMQP string data instead.

    In this release, the keys are encoded as AMQP strings.

3.4. AMQ .NET

  • ENTMQCL-500 - Receive does not raise exception when link closed with error

    In earlier releases of the product, it was possible for pipelined protocol state events to prevent the client from raising link errors to the API user.

    In this release, the link errors are raised when the link is closed.

Chapter 4. Known Issues

4.1. AMQ C++

  • ENTMQCL-604 - Receiver name is not set when using the container.create_receiver() method

    Due to a flaw in the option processing of the container.create_receiver() method, the receiver name is not set when using the name option.

    Workaround: Set the receiver name using the name option on the connection.create_receiver() method instead of on the container.create_receiver() method.

4.2. AMQ Python

  • ENTMQCL-483 - Selectors with backslashes are invalid in non-Unicode strings

    The Selector option on Container.create_receiver() accepts a string. If the string is not supplied as Unicode (in Python 2, u"somestring"), any elements escaped with backslashes might not be processed correctly.

    Workaround: Users of Python 2 should use an explicit Unicode string in filter declarations to avoid the problem.

  • ENTMQCL-546 - Transactions introduce unexpected link events

    Starting a transaction internally opens a sending link for controlling the transaction. This special link can trigger extra application events.

    Workaround: Code using transactions should ensure link handler functions are processing the link they expect.

4.3. AMQ Ruby

  • ENTMQCL-690 - Container.schedule() fails if called from an event handler

    The Container.schedule() method will have no effect if it is called from inside a MessagingHandler callback function.

    Workaround: Call schedule() from outside the MessagingHandler callback functions.

Chapter 5. Important Notes

5.1. Preferred Clients

In general, AMQ clients that support the AMQP 1.0 standard are preferred for new application development. However, the following exceptions apply.

  • If your implementation requires distributed transactions, use the AMQ Core Protocol JMS client.
  • If you require MQTT or STOMP in your domain (for IoT applications, for instance), use community-supported MQTT or STOMP clients.

The considerations above do not necessarily apply if you are already using:

  • The AMQ OpenWire JMS client (the JMS implementation previously provided in A-MQ 6)
  • The AMQ Core Protocol JMS client (the JMS implementation previously provided with HornetQ)

5.2. Legacy Clients

  • Deprecation of the CMS and NMS APIs

    The ActiveMQ CMS and NMS messaging APIs are deprecated in AMQ 7. It is recommended that users of the CMS API migrate to AMQ C++, and users of the NMS API migrate to AMQ .NET. The CMS and NMS APIs might have reduced functionality in AMQ 7.

  • The Core API is unsupported

    The Artemis Core API client is not supported. This client is distinct from the AMQ Core Protocol JMS client, which is supported.

5.3. AMQ C++

  • Unsettled interfaces

    The AMQ C++ messaging API includes classes and methods that are not yet proven and can change in future releases. Be aware that use of these interfaces might require changes to your application code in the future.

    These interfaces are marked Unsettled API in the API reference. They include the interfaces in the proton::codec and proton::io namespaces and the following interfaces in the proton namespace.

    • listen_handler
    • reconnect_options
    • ssl_certificate, ssl_client_options, and ssl_server_options
    • work_queue and work
    • The on_connection_wake method on messaging_handler
    • The wake method on connection
    • The on_sender_drain_start and on_sender_drain_finish methods on messaging_handler
    • The draining and return_credit methods on sender
    • The draining and drain methods on receiver

    API elements present in header files but not yet documented are considered unsettled and are subject to change.

  • Deprecated interfaces

    Interfaces marked Deprecated in the API reference are scheduled for removal in a future release.

    This release deprecates the following interfaces in the proton namespace.

    • void_function0 - Use the work class or C++11 lambdas instead.
    • default_container - Use the container class instead.
    • url and url_error - Use a third-party URL library instead.

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