MQTT is a open source protocol on top of TCP which is widely used in
mobile communication and also for IoT (Internet of Things) today. This
will add an open source implementation of MQTT so that it becomes easier
for Netty users to implement an MQTT application.
For more information about the MQTT protocol, read this:
http://public.dhe.ibm.com/software/dw/webservices/ws-mqtt/mqtt-v3r1.html
Motivation:
maven-antrun-plugin does not redirect stdin, and thus it's impossible to
run interactive examples such as securechat-client and telnet-client.
org.codehaus.mojo:exec-maven-plugin redirects stdin, but it buffers
stdout and stderr, and thus an application output is not flushed timely.
Modifications:
Deploy a forked version of exec-maven-plugin which flushes output
buffers in a timely manner.
Result:
Interactive examples work. Launches faster than maven-antrun-plugin.
Motivation:
- dependencyVersionsDir property is not resolved during the build
process. The build doesn't fail because of this, but it creates an
ugly directory.
- All-in-one JAR contains libnetty-tcnative.so, which is not part of the
all-in-one JAR.
Modifications:
- Fix an incorrect property name
(dependencyVersionDir -> dependencyVersionsDir)
- Exclude libnetty-tcnative.so
- Remove unnecessary includes in source expanding configuration
Result:
- Cleaner pom.xml
- We do not ship libnetty-tcnative.so in all-in-one JAR anymore, which
is correct, because strictly speaking the native library belongs to
org.apache.tomcat.jni package.
Motivation:
exec-maven-plugin does not flush stdout and stderr, making the console
output from the examples invisible to users
Modification:
Use maven-antrun-plugin instead
Result:
A user sees the output from the examples immediately.
Motivation:
oss.sonatype.org refuses to promote an artifact if it doesn't have the
default JAR (the JAR without classifier.)
Modifications:
- Generate both the default JAR and the native JAR to make
oss.sonatype.org happy
- Rename the profile 'release' to 'restricted-release' which reflects
what it really does better
- Remove the redundant <quickbuild>true</quickbuild> in all/pom.xml
We specify the profile 'full' that triggers that property already
in maven-release-plugin configuration.
Result:
oss.sonatype.org is happy. Simpler pom.xml
Motivation:
Netty must be released from RHEL 6.5 x86_64 or compatible so that:
1) we ship x86_64 version of epoll transport officially, and
2) we ensure the ABI compatibility with older GLIBC versions.
The shared library built on a distribution with newer GLIBC will not
run on older distributions.
Modifications:
- When 'release' profile is active, perform an additional check using
maven-enforcer-plugin so that 'mvn release:*' fails when running on
non-RHEL6.5. This rule is active only when releasing, so a user
should not be affected.
- Simplify maven-release-plugin configuration by removing redundant
profiles such as 'linux'. 'linux' is automatically activated when
releasing because we now enforce the release occurs on linux-x86_64.
- Remove the no-osgi profile, which is unused
- Remove the reference to 'sonatype-oss-release' profile in all/pom.xml,
because we always specify 'release' profile when releasing
- Rename the profile 'linux-native' to 'linux' for brevity
- Upgrade oss-parent and maven-enforcer-plugin
Result:
No one can make a mistake to release Netty on an environment that can
produce incompatible or missing native library.
- Fixes#2003 properly
- Instead of using 'bundle' packaging, use 'jar' packaging. This is
more robust because some strict build tools fail to retrieve the
artifacts from a Maven repository unless their packaging is not 'jar'.
- All artifacts now contain META-INF/io.netty.version.properties, which
provides the detailed information about the build and repository.
- Removed OSGi testsuite temporarily because it gives false errors
during split package test and examination.
- Add io.netty.util.Version for easy retrieval of version information
The API changes made so far turned out to increase the memory footprint
and consumption while our intention was actually decreasing them.
Memory consumption issue:
When there are many connections which does not exchange data frequently,
the old Netty 4 API spent a lot more memory than 3 because it always
allocates per-handler buffer for each connection unless otherwise
explicitly stated by a user. In a usual real world load, a client
doesn't always send requests without pausing, so the idea of having a
buffer whose life cycle if bound to the life cycle of a connection
didn't work as expected.
Memory footprint issue:
The old Netty 4 API decreased overall memory footprint by a great deal
in many cases. It was mainly because the old Netty 4 API did not
allocate a new buffer and event object for each read. Instead, it
created a new buffer for each handler in a pipeline. This works pretty
well as long as the number of handlers in a pipeline is only a few.
However, for a highly modular application with many handlers which
handles connections which lasts for relatively short period, it actually
makes the memory footprint issue much worse.
Changes:
All in all, this is about retaining all the good changes we made in 4 so
far such as better thread model and going back to the way how we dealt
with message events in 3.
To fix the memory consumption/footprint issue mentioned above, we made a
hard decision to break the backward compatibility again with the
following changes:
- Remove MessageBuf
- Merge Buf into ByteBuf
- Merge ChannelInboundByte/MessageHandler and ChannelStateHandler into ChannelInboundHandler
- Similar changes were made to the adapter classes
- Merge ChannelOutboundByte/MessageHandler and ChannelOperationHandler into ChannelOutboundHandler
- Similar changes were made to the adapter classes
- Introduce MessageList which is similar to `MessageEvent` in Netty 3
- Replace inboundBufferUpdated(ctx) with messageReceived(ctx, MessageList)
- Replace flush(ctx, promise) with write(ctx, MessageList, promise)
- Remove ByteToByteEncoder/Decoder/Codec
- Replaced by MessageToByteEncoder<ByteBuf>, ByteToMessageDecoder<ByteBuf>, and ByteMessageCodec<ByteBuf>
- Merge EmbeddedByteChannel and EmbeddedMessageChannel into EmbeddedChannel
- Add SimpleChannelInboundHandler which is sometimes more useful than
ChannelInboundHandlerAdapter
- Bring back Channel.isWritable() from Netty 3
- Add ChannelInboundHandler.channelWritabilityChanges() event
- Add RecvByteBufAllocator configuration property
- Similar to ReceiveBufferSizePredictor in Netty 3
- Some existing configuration properties such as
DatagramChannelConfig.receivePacketSize is gone now.
- Remove suspend/resumeIntermediaryDeallocation() in ByteBuf
This change would have been impossible without @normanmaurer's help. He
fixed, ported, and improved many parts of the changes.
- Borrow SLF4J API which is the best of the best
- InternalLoggerFactory now automatically detects the logging framework
using static class loading. It tries SLF4J, Log4J, and then falls back
to java.util.logging.
- Remove OsgiLogger because it is very likely that OSGi container
already provides a bridge for existing logging frameworks
- Remove JBossLogger because the latest JBossLogger implementation seems
to implement SLF4J binding
- Upgrade SLF4J to 1.7.2
- Remove tests for the untestable logging frameworks
- Remove TestAny
First cut at implementing a generic abstraction layer for pluggable
metrics providers. This first cut is closely modeled after Yammer
Metrics. It remains to be seen if it is indeed flexibel enough to
support other providers.
Provide a default implementation of this new abstraction layer
based on Yammer Metrics.
Support pluggable Monitoring Providers using Java 6's ServiceLoader.
Use this new abstraction layer to provide stats on (a) number of
Timeouts executed per second and (b) distribution of absolute
deviation between scheduled and actual Timeout execution time in
HashedWheelTimer.
* Interface ValueDistributionMonitor, a monitor for histograms.
* Interface EventRateMonitor, a monitor for measuring the rate per time
unit of specific events.
* Interface ValueMonitor, a monitor for tracking an arbitrary datum's
current value
* Interface CounterMonitor, a monitor for incrementing/decrementing a
long value
* Interface MonitorRegistry, a registry for monitors that serves as the
interface between Netty and concrete metrics providers as e.g. Yammer
Metrics.
* Interface MonitorRegistryFactory, to be implemented by metrics
providers.
* Document how to use Netty's new monitoring support in javadocs for
package io.netty.monitor.
