AMFPHP AMF0 and AMF3

Question

What are the difference between them?

Answer 1

• AMF 0: Introduced in Flash Player 6 in 2001 and remained unchanged with the introduction of ActionScript 2.0 in Flash Player 7 and with the release of Flash Player 8.
• AMF 3: In Flash Player 9, Action Script 3.0 was introduced. The new data types and language features made possible by these improvements prompted AMF to be updated.
• AMFPHP: Is a free open-source PHP implementation of the Action Message Format(AMF).

Answer 2

Programs/Frameworks like AMFPHP/ZendAMF tend to fall back to AMF0 unless it uses a specific AMF3 feature. AMF 3 can pass a lot more things by reference, as well as supports sending a ByteArray and XML objects.

From the Specification:

• Object traits can now be sent by reference
• Strings can now be sent by reference
• int/uint type support
• flash.utils.ByteArray type support, can also be sent by reference
• flash.utils.IExternalizable support
• Variable length encoding scheme for integers to reduce data size
• References are sent using variable length integer
• String UTF-8 length uses variable length integer
• Array count uses variable length integer
• A single Array type marker covers both strict and ECMA Arrays
• Dates no longer send timezone information
• Dates can now be sent by reference
• XMLDocument UTF-8 length uses variable length integer
• XMLDocument can now be sent by reference
• XML type support, can also be sent by reference
• XML UTF-8 length uses variable length integer
• ByteArray type length uses variable length integer
• Boolean true and false are now sent as one byte type markers
• Unsupported type marker has been removed
• Reserved RecordSet and Movieclip type markers have been removed