Tom Hensel - Introduction to AMF

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Copyright 2008 Adobe Systems Incorporated. All Rights Reserved. Adobe Con!dential.

Adobe MAX 2008

Introduction to AMF Wednesday, December 3rd

Tom Hensel

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Terms

AMF Action Message Format

Remote Procedure Call (RPC) An inter-process communication technology that allows a computer program to cause a

subroutine or procedure to execute in another address space (commonly on another computer on a shared network) without the programmer explicitly coding the details for this remote interaction [wikipedia]

Serialization In computer science, in the context of data storage and transmission, serialization is the

process of converting an object into a sequence of bits so that it can be stored on a storage medium (such as a !le, or a memory buffer) or transmitted across a network connection link. When the resulting series of bits is reread according to the serialization format, it can be used to create a semantically identical clone of the original object [wikipedia]

Often referred to as decoding and encoding of objects

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http://en.wikipedia.org/wiki/Inter-process_communication

http://en.wikipedia.org/wiki/Inter-process_communication

http://en.wikipedia.org/wiki/Computer_program

http://en.wikipedia.org/wiki/Computer_program

http://en.wikipedia.org/wiki/Subroutine

http://en.wikipedia.org/wiki/Subroutine

http://en.wikipedia.org/wiki/Address_space

http://en.wikipedia.org/wiki/Address_space

http://en.wikipedia.org/wiki/Computer_science

http://en.wikipedia.org/wiki/Computer_science

http://en.wikipedia.org/wiki/Object_%28computer_science%29

http://en.wikipedia.org/wiki/Object_%28computer_science%29

http://en.wikipedia.org/wiki/Computer_file

http://en.wikipedia.org/wiki/Computer_file

http://en.wikipedia.org/wiki/Computer_network

http://en.wikipedia.org/wiki/Computer_network

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De!nition

AMF is a binary format based loosely on the Simple Object Access Protocol (SOAP). It is used primarily to exchange data between an Adobe Flash application and a database, using a Remote Procedure Call (RPC)

AMF allows to serialize (and deserialize) ActionScript object graphs

Once serialized an AMF encoded object graph may be used to persist and retrieve the public state of an application across sessions or allow two endpoints to communicate through the exchange of strongly typed data

AMF0 also supports sending complex objects by reference which helps avoid sending redundant instances in an object graph as well as allowing endpoints to restore relationships and avoid circular references

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Purpose - AMF0

AMF was introduced in Flash Player 6 in 2001 and remained unchanged with the introduction of ActionScript 2.0 in Flash Player 7. The version header of this format was set to 0 and thus this version of the format is referred to as AMF0

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Purpose - AMF3

In Flash Player 9, Action Script 3.0 was introduced along with a new ActionScript Virtual Machine (AVM+) - the new data types and language features made possible by these improvements prompted AMF to be updated

Given the opportunity to release a new version of AMF, several optimizations were also made to the encoding format to remove redundant information from serialized data

This new version of the format is referred to as AMF3

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Speci!cations

Adobe Systems published the AMF binary data protocol speci!cation on December 13, 2007 and announced that it will support the developer community to make this protocol available for every major server platform Speci!cation of AMF0

download.macromedia.com/pub/labs/amf/amf0_spec_121207.pdf

Speci!cation of AMF3download.macromedia.com/pub/labs/amf/amf3_spec_121207.pdf

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http://download.macromedia.com/pub/labs/amf/amf0_spec_121207.pdf




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Bene!ts - Efficiency

AMF objects are very small Efficient Encoding and Decoding

AMF data is parsed directly to and from objects

Small Overhead

Binary Format

Optional compression (zlib)

Bandwidth and CPU usage is lower compared to HTML

JSON

YAML

XML

SOAP

WDDX

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Bene!ts - Efficiency

Lower bandwidth and CPU usage means Lower latency

Improved User Experience due to quicker response times Key Factor for User Acceptance

Essential for Near-Real-Time-Applications, e.g. Data Processing and Visualization Multi-User Applications Online-Games, MMO Interface and Sensor Input (i.e. Kiosk-Applications)

Bandwidth Usage

Bandwidth is still not free (and maybe never will)

Scales well (no accumulating overhead)

Suitable for low-bandwidth requirements

POTS, ISDN, GPRS, ...

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Bene!ts - Reference Tables

In AMF 3, Strings, Complex Objects and an Object Type's Traits can be sent by reference Complex Objects are de!ned as

Anonymous Objects, typed Objects

Arrays

Dates

XMLDocument, XML

ByteArrays

Instead of sending redundant information AMF can simply refer to an earlier occurrence of a complex object

Transparent Reference Caching No Client-side logic required Again, lower bandwidth and CPU usage, lower latency

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Bene!ts - Ease of Use

Well-documented Speci!cations available

Many examples and code samples available

Promoted by Adobe (supported)

Easy to implement Most of the work is done automagically

No Parsing required

Less possibly erroneous logic needed Dont Repeat Yourself (DRY)

Strong-typed result objects Syntax Completion everywhere Smooth Team-Work Error handling is included

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Bene!ts - Pitfalls

Ubercomplex types can not be serialized DisplayObject

and all of it‘s descendants

Native Types and Custom classes are supported Mapping a AMF serialized object back to a custom class is possible, but

The custom class needs to be instanced when the AMF object is unserialized

Compression (zlib) Lower bandwidth usage, but

Higher latency and CPU usage

Compressing binary data is not as efficient as compressing text (i.e. XML)

Do not use compression on larger chunks of data if near real-time response times are required

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Downsides (and workarounds)

Binary Format Not readable by humans

Use a HTTP transport channel for testing, or

Use suitable tools to capture and decode

Less complex clients means a more complex backend Higher skill requirements for the backend developers (J2EE, Python, Ruby, ...)

Client design can not !x faulty backend design

Plan and design both ends carefully and verify your decisions

Create diagrams and documentation

Embrace team-work

Lack of understanding in not-so-agile enterprises Do not push your bosses, convince them by facts (they might save time and money)

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Benchmarks

Apache JMeter Capture AMF packets containing the clients requests !rst (tcpdump, Charles, ...)

JMeter replays packets and measures response times

Produces nicely looking graphs

Integration in NetBeans (great for J2EE Backend Developers)

Not for beginners!

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Benchmarks

James Ward‘s „Census“ Benchmarkwww.jamesward.com/census/ Source Code available (GPLv2)

Perfect to convince your bosses that AMF is the right thing

Thanks James!

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http://www.jamesward.com/census/

http://www.jamesward.com/census/

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Transport - Basic

No additional Port required Most of the time Port 80 is used

No !rewall issues on basic setups

Various Transport Channel Types Flex SDK offers !ne-grained channel con!guration

Simple AMF or HTTP channels

AMF channels transport data in the binary AMF format and HTTP channels transport data in AMFX, a text-based XML representation of AMF

AMF channels provide better performanceUsing a HTTP channel instead of an AMF channel is only recommended when there are auditing or compliance requirements that preclude the use of binary data

over the network or the contents of messages should be easily human-readable over the network

(debugging)

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Transport - Advanced

Advanced HTTP and AMF Channels

‚Piggybacking‘ provides lightweight pseudo polling: Rather than the client channel polling the server on a !xed interval the client sends a non-command message to the server which sends any pending data along with the response to the client message

‚Long-polling‘ sends a request to the server, but a response is not returned to the client until one is available (similar to „Comet“)

Streaming RTMP, AMF, and HTTP channels

Less protocol overhead (connection is kept alive)

RTMP allows message pushing No polling at all Lowest latency

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Server Side

PHP PHP Extension

AMFEXT Written in C, fast encoding and decoding of AMF0 and AMF3 messages Looking for a new maintainer since July 2008

PHP Frameworks

AMFPHP Simple and powerful Works since Flash MX 2004 Optional support for AMFEXT

CakeAMFPHP Easy to use with CakePHP, requires AMFEXT Development stalled

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Server Side

SabreAMF Server and Client PHP5 only Compliant to PHP Strict Mode

WebORB for PHP Well documented, commercial support available Management Console includes Service Browser, Testing and Security Management Code Generators for ActionScript Remoting, Cairngorm and PureMVC

Zend AMF Easy to use with Zend Framework PHP is very widespread Promoted by Adobe

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Server Side

Cold Fusion Supports serialization to AMF

Easy to use

Supported by Adobe

WebORB for Cold Fusion Supports AJAX, Flash, Flex and Silverlight

Provides easy to use interfaces to Featuresof Cold Fusion

Coming soon!

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Server Side

.NET amf.net

Implemented as an HttpHandler, easy to install

Very simple

WebORB for .NET

Easy to install (only on Microsoft IIS)

Commercial support available

FluorineFx

Supports RTMP

Template based code generator

Includes a Service Browser

Blaze Data Services for .NET (BlazeDS.NET)

Upcoming port, announced on MAX 2008, stay tuned

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Server Side

Python PyAMF

Integration with Python web frameworks like Django, Pylons, Twisted, CherryPy, ... Scales well if used with mod_python, mod_wsgi, ...

Possible to run on Google App Engine

RTMPy is a protocol for Twisted Based on PyAMF Implementing RTMP Still in development

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http://pyamf.org/wiki/DjangoHowto

http://pyamf.org/wiki/DjangoHowto

http://pyamf.org/wiki/PylonsHowto

http://pyamf.org/wiki/PylonsHowto

http://pyamf.org/wiki/TwistedHowto

http://pyamf.org/wiki/TwistedHowto

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Server Side

Ruby Ruby on Rails

RubyAMF Very easy for Rails Developers to get started Flexible and extensible Scales well if Rails is used with Thin, lighttpd, nginx, Phusion Passenger (mod_rails), ...

WebORB for Rails Based on Ruby on Rails Tight integration of ActiveRecord Commercial support available

RubyIZUMI

RTMP Server for streaming Flash video/audio (H.264)

Based on EventMachine (fast single-threaded socket engine)

Experimental - not ready for production use

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Server Side

Java RED5

Mainly for Audio- and Video Streaming

Supports AMF Remoting, too

Blaze Data Services (BlazeDS)

Open Source (GPLv3) Shares codebase (messaging and remoting)

with LiveCycle Data Services SE

Rich set of features

Supports streaming channels over HTTP

Includes Tomcat 6 Application Server (easy to deploy)

LiveCycle Data Services Community Edition Certi!ed builds of BlazeDS Developer and Enterprise Support

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Server Side

Granite Data Services (GraniteDS)

Lightweight and stable, scales well

Dedicated Service Factories: integrates with EJB3, Seam, Spring, Guice, Warp, POJO, ...

‚Granite Eclipse Builder‘ for Code Generation in Eclipse

Includes a Client-side framework (‚Tide‘) Service Locator Pattern (inspired by Cairngorm) Offline Data Caching (similar to Live Cycle Data Services ES)

Supports ‚Long polling‘ Data Push over HTTP (‚Gravity‘)

Server-side compilation of MXML (‚Granite Web Compiler‘)

Upcoming support for GlassFish and TopLink (instead of Hibernate)

WebORB for Java

Integrates with Spring, EJB, Pojo, ...

Commerical support available (Enterprise Edition)

Supports Microsoft Silverlight, too

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Server Side

Currently, only Adobe LiveCycle Data Services ES implement all protocols, channel types and security options shown Feature Comparison of LiveCycle Data Services ES and BlazeDS

sujitreddyg.wordpress.com/2008/01/31/blazeds-and-lcds-feature-difference/

Adobe LiveCycle Data Services ES Based on J2EE

Very powerful

Data Synchronization

Con%ict Resolution

Offline Data Caching

Very expensive

One-CPU license available for production use (formerly know as LiveCycle Data Services Express); Multi-CPU developer licenses available on request

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http://sujitreddyg.wordpress.com/2008/01/31/blazeds-and-lcds-feature-difference/

http://sujitreddyg.wordpress.com/2008/01/31/blazeds-and-lcds-feature-difference/

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Tools

Client Development Flex SDK is everything you need

Flex Builder

Flash CS4

Power%asher FDT

Your choice!

Frameworks

PureMVC

Cairngorm

Guttershark

Mate

Many, many more

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Tools

Debugging, Testing Firebug

Recommended for every day use

Does not decode AMF

Limited to HTTP (AMFX)

Charles

Multi-protocol local proxy Deciphers SSL/TLS Supports RTMP Decodes AMF

Easy to use

Affordable Shareware

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Tools

Debugging, Testing ServiceCapture

Similar to Charles but more simple, Shareware

tcpdump

Weapon of choice for UNIX experts (geeks)

WireShark

Full %edged network analyzer

Captures and dissects mostly everything on the wire

Does not decode AMF

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Showcase

Mercedes Benz - Focus on Fashion Server Tiers

Application Server MySQL 5 Ruby on Rails 2.0

ActiveRecord RubyAMF Plugin

Web Server (Assets)

Streaming Server (Videos)

Application

Adobe Flash Platform Application built using Flex 3 SDK

PureMVC Framework (Model-View-Controller Pattern) uses RemoteObject over a AMF channel

Content Modules built in Flash CS3

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Showcase

mercedes-benz.de/focus-on-fashion

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Showcase

mercedes-benz.de/focus-on-fashion

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Showcase

User Experience

Quick response times Server-side caching of database queries Application-side caching

Assets (Browser-Cache) Data (RAM)

Rich and mixed media

Stylish people, fast cars

Developer Experience

Rapid implementation of a prototype

Lightweight application logic

Transparent, strong-typed data model (Value Objects everywhere) Interdisciplinary team-work PureMVC rocks

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Summary

Efficiency Enhanced User Experience

Greater User Acceptance

Helps to save the planet (lower energy consumption)

Ease of Use Intuitive way of working with data

Less hassle, higher quality

Have more time for creative ideas, or

Spend more time with your loved ones

AMF is not always the right thing Consider alternatives (E4X, SWX, JSON, ...)

Proof your design by a working prototype

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Questions and Answers

Please ask!

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Keep in touch

Elephant Sevenwww.e-7.com

Yeebase Open Source Publishingwww.yeebase.com

[email protected]

XINGwww.xing.com/pro!le/Tom_Hensel

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http://www.e-7.com/

http://www.e-7.com/

http://www.yeebase.com/

http://www.yeebase.com/

mailto:[email protected]?subject=Introduction%20to%20AMF:%20

mailto:[email protected]?subject=Introduction%20to%20AMF:%20

https://www.xing.com/profile/Tom_Hensel

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Tom Hensel - Introduction to AMF

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