AMQ Clients 2.0 Release Notes
Release Notes for Red Hat AMQ Clients
Chapter 1. Features
- AMQ C++ now supports multithreaded operation on Windows.
- 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 https://access.redhat.com/support/offerings/techpreview/.
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_errorhandler is fired with an AMQP
unauthorized-accesserror. 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
2.3. AMQ JMS
ENTMQCL-605 - Support acknowledging individual messages
CLIENT_ACKNOWLEDGEmode 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
2.5. AMQ .NET
- AMQ .NET is now based on AMQP.Net Lite 2.1.1
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
userconnection option in order to use Kerberos authentication.
In this release, it is no longer necessary to set the
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_wakecauses segmentation fault
In earlier releases of the product, it was possible for the
pn_connection_wakeoperation 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
Due to a flaw in the option processing of the
container.create_receiver()method, the receiver name is not set when using the
Workaround: Set the receiver name using the
nameoption on the
connection.create_receiver()method instead of on the
4.2. AMQ Python
ENTMQCL-483 - Selectors with backslashes are invalid in non-Unicode strings
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
Container.schedule()fails if called from an event handler
Container.schedule()method will have no effect if it is called from inside a
schedule()from outside the
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++
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::ionamespaces and the following interfaces in the
API elements present in header files but not yet documented are considered unsettled and are subject to change.
Interfaces marked Deprecated in the API reference are scheduled for removal in a future release.
This release deprecates the following interfaces in the
void_function0- Use the
workclass or C++11 lambdas instead.
default_container- Use the
url_error- Use a third-party URL library instead.