Camel oneactivemq posta-final

CamelOne 2013 June 10-11 2013

Boston, MA

Apache ActiveMQ Internals

Christian Posta Senior Consultant and Architect

June 10, 2013

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Why are You Here?

•  Use ActiveMQ?

• What is ActiveMQ?

•  Dug into the code?

•  Interested in contributing back?

•  Understand configuration better

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Goals of Presentation •  Give back to community

•  Deliver understanding about architecture

•  Brief intro to ActiveMQ

•  Overview of architecture

•  Dive into major subcomponents

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Who am I?

•  Senior Consultant and Architect at Red Hat (formerly FuseSource)

•  Committer on ActiveMQ

•  Author: Essential Camel Components DZone Refcard

•  Christian Posta

•  Blog: http://christianposta.com/blog

•  Email: [email protected]

•  Twitter: @christianposta

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What is ActiveMQ?

•  OpenSource messaging broker

•  Apache v2 licensed

•  Very active community

•  Used at top companies

•  5.8.0 latest release (in JBoss A-MQ 6.0) ��5.9.0 on its way

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Features •  High performance

•  High availability

•  Light-weight

•  Multi-protocol

•  JMS compliant

•  Supported in production

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When to use ActiveMQ?

•  Asynchronous communication

•  Reliable message passing

•  Loose coupling

•  Heterogeneous integration

•  Real-time data

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This is ActiveMQ…

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How it’s built

•  Java project (supports Java 7!)

•  Maven project

•  Divided into client/broker and feature modules

•  Unit tests in activemq-unit-tests

•  mvn clean package –Dtest=false

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ActiveMQ Source

•  SVN at Apache: https://svn.apache.org/repos/asf/activemq/trunk/

•  Git at Apache: ��http://git.apache.org

•  Github: ��https://github.com/apache/activemq

•  Use git-svn and point directly to Apache SVN!

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Major Subcomponents

•  Transports and transport connectors

•  Broker core

•  Persistence adapters

•  Network of brokers / clustering

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Architecture

Broker CoreTransport

Transport

TransportJMX

NetworkConnectors

Security

Store

Adapter

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Transports��and ��

Transport Connectors

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Transport Connector

•  Let data in or out

•  Think of as “SocketServer” (which it is J)

•  Broker side

•  Highly configurable through URI

•  TransportConnector vs Transport

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Example Configuration

•  Broker side: ��<transportConnector uri=“tcp://0.0.0.0:61616” />

•  Broker side tuning: ��<transportConnector uri="tcp://0.0.0.0:0?transport.option=true”/>

•  Client side: ��ConnectionFactory("tcp://0.0.0.0:61616?soTimeout=xx”)

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Out of the box

•  TCP, NIO

•  UDP

•  SSL, SSL+NIO

•  VM

•  HTTP

• WebSockets

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Wire Formats

•  Part of transport

•  Encode/marshall

•  Decode/unmarshall

•  Creates Java objects

Wire

Broker

Transport

WireFormat

Socket

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Wire Formats

•  AMQP 1.0

•  OpenWire v1- v10

•  STOMP 1.0, 1.1, 1.2

•  MQTT 3.1

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Filters, Listeners

•  TransportFilter – decorator pattern to add specific functionality, implements Transport, TransportListener

•  TransportListener – callback for staged handling of incoming frame objects, on the way to broker

•  Examples: ��Stomp, inactivity heartbeat, negotiation, logging, mutex, etc

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Transports Architecture

Wire Broker

TransportListener

TransportFilterTransport

WireFormat

TransportFilter

TransportFilter

TransportListener

TransportListener

TransportListener

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Broker Core

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Broker Core

•  Regions, layers of brokers

•  Memory management

•  Message cursors

•  Threading

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Region Broker

•  Core of the broker

•  Create consumers

•  Create producers

•  Create destinations

•  Send messages to correct destination

RegionBroker

Router

Topic Region TempTopic Region

Queue Region

TempQueue Region

ConnectionStates Destinations ClientIDs

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Broker Filters

•  Decorate RegionBroker

•  How internal features like advisories and scheduling are implemented

•  Basis for broker plugins

•  http://activemq.apache.org/interceptors.html

•  http://activemq.apache.org/developing-plugins.html

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Broker Filters SchedulerBroker

TransactionBroker

AdvisoryBroker

RegionBroker

Router

Send message

Add Consumer

Add Connection

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System Usage

•  Allocate resources for the broker

•  Persistent, Non-Persistent, in Memory Cache

<systemUsage> <systemUsage> <memoryUsage> <memoryUsage limit="64 mb"/> </memoryUsage> <storeUsage> <storeUsage limit="100 gb"/> </storeUsage> <tempUsage> <tempUsage limit="50 gb"/> </tempUsage> </systemUsage> </systemUsage>

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Memory Usage JVM Heap Space

Messages (MemoryUsage)

Queue Queue Queue Queue

ActiveMQ Objects

Index Cache Threads

16 MB 16 MB 16 MB

256 MB

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Message Cursors

•  Buffers for tracking position

•  Consumer Subscriptions

•  VMPendingMessageCursor

•  FilePendingMessageCursor

•  Store Cursors + PrefetchSubscriptions

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Store Cursors

http://activemq.apache.org/message-cursors.html

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Store Cursors

http://activemq.apache.org/message-cursors.html

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Threading

•  Producer connections

•  Dispatching within destinations

•  Consumer connections

•  Store write threads

•  Ancillary broker tasks (expiration, producer flow control, scheduled messages, etc)

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Threads

TCP

TCP

Queue Dispatch Thread

Consumer Transport Thread

Producer Transport Thread

Queue

Consumer Connection

Subscription

Producer Connection

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TCP

TCP

Consumer Transport Thread


Queue

Consumer Connection

Subscription

Producer Connection

<policyEntry queue=“>” optimizedDispatched=“true” >

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TCP

TCP


Queue

Consumer Connection

Subscription

Producer Connection

<policyEntry queue=“>” optimizedDispatched=“true” >

tcp://host:port?jms.dispatchAsync=false

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Persistence Adapter

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Persistence Adapters

•  Add reliability to message delivery

•  Optimized databases

•  Pluggable implementations

•  Out of the box:

•  KahaDB

•  LevelDB

•  JDBC

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Persistence Adapter

Locker

Queue Store Topic Store

Journal

Index Redo

File System / RDBMS

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Lockers

•  Used for master election

•  SharedFileLocker

•  DatabaseLocker, LeaseDatabaseLocker

•  ZooKeeper based for replicated LevelDB ��new in upcoming 5.9.0, not available yet

•  Your own!

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Message Stores

•  Topic vs Queue stores

•  Difference use cases

•  Storage vs broadcast

•  Relatively cheap

Topic StoreTopic Store

Topic Store

Journal

Index Redo

File System

Queue StoreQueue Store

Queue Store

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Store implementation

•  Journal

•  Index

•  Redo/write ahead log

Index Journal

Redo Log

X X X X

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Network of Brokers

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Network of Brokers

•  Connect brokers together

•  Achieve scale

•  Store and forward

Broker

Message

Broker

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Networking components

•  Network Connector

•  Discovery Agents

•  Bridge

•  Advisory messages/static destination filters

•  Proxy Consumers

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Advisory Messages

•  Advisory Topics

•  Internal events��ActiveMQ.Advisory.Connection��ActiveMQ.Advisory.Consumer

•  Event driven

•  Replay upon first connect

•  Necessary for Dynamic Demand Forwarding

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Dynamic Demand Forwarding

Broker

Message

Broker

Producer

Message

Consumer

Message

establish demand

forward message

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Bridging in Detail

Broker A

Broker B

Forward Msg

AdvisoriesQueue

CQueue

Producer Consumer

Bridge

C

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Wrap Up •  Checkout the ActiveMQ wiki: ��

http://activemq.apache.org

•  Mailing list: ��[email protected]

•  Book: ActiveMQ in Action��http://www.manning.com/snyder/

•  Blog��http://christianposta.com/blog

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Questions?

Technology

Camel oneactivemq posta-final