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From OpenLaszlo

Contents 1 Requirements 1.1 SWF9 runtime 1.2 DHTML runtime 2 Conceptual Design 2.1 Changes to Language definition 2.2 Architectural changes 2.3 SWF9 backend and runtime 2.4 DHTML backend and runtime 3 Architecture 3.1 Two-pass compiler 3.1.1 1. Compile LZX to ECMA4~ 3.1.2 2. Compile ECMA4~ to native 3.2 OLR 4 Design Principles 4.1 Reduce complexity by focusing on SOLO deployment 4.2 Build discrete components that can be used outside OpenLaszlo 5 Details

Requirements

(MOVED TO LEGALS_PROJECT_PLAN)

SWF9 runtime

• executes ActionScript 3.0 plus support libraries
  • AS3 is a dialect of the ECMA Release 4 proposal

DHTML runtime

• Initially our target browsers will be Windows IE 6.0.xx, Netscape 4.7 (?), and Mozilla Firefox 1.0/1.5.

• (Fill in market penetration numbers to support.)

• Baseline requirements therefore are:
  • ECMA3
  •  ?? what version of HTML - HTML 4.0 or XHTML? DOM2? CSS2?

• Conceptually two separate DHTML runtimes: Javascript 1.2 / JScript 5.6, and Javascript 1.5.

Conceptual Design

Changes to Language definition

• Good performance on SWF9 is likely to require use of new language features in AS3/ECMA4: class-based object model, static typing, and sealed classes.
• This argues for repositioning LZX on top of ECMA4
  • Benefit is that future ECMA4-based runtimes (e.g. Firefox 2.0) will require relatively little support for OpenLaszlo compatibility
  • Certain ECMA4 features can be compiled away for ECMA3 targets
    • static typing
    • sealed classes
  • Other features can be emulated
    • class-based object model
• Runtime: Lightweight Views. Use Sprites instead of MovieClip?
• Runtime: View States. swf9 supports an equivalent to the LZX state mechanism. Can this be used directly?

Architectural changes

SWF9 backend and runtime

DHTML backend and runtime

Architecture

Two-pass compiler

1. Compile LZX to ECMA4~

2. Compile ECMA4~ to native

• Two conceptual sub-stages: ECMA4~ to native source, native source to binary where needed:

Source Transform	Binary Generation	Notes
ECMA4 to AS2	AS2 to SWF6-8 (3.x front end)	Either our 3.x backend or MTASC
ECMA4 to AS3	AS3 to SWF9	minimal source transform + flex2, eventually our own backend
ECMA4 to JScript 5.6	(no binary)	Supports Win IE 6, 7?
ECMA4 to Javascript 1.5	(no binary)	Supports Firefox 1.0/1.5

OLR

• OLR mostly written in ECMA4, with a kernel of runtime-specific/native code (AS2, AS3, JScript, etc).
• Kernel(s) include:
  • runtime support for drawing, interaction, data processing (XML), and networking
  • ECMA4 object runtimes for AS2, JScript 5.6, Javascript 1.5

Design Principles

Reduce complexity by focusing on SOLO deployment

• focus is on SOLO deployment
  • non-SOLO deployment support TBD

Build discrete components that can be used outside OpenLaszlo

• We will attempt to separate components that might be reused by other opensource projects, including:
  • backends for converting ECMA3/4 to native ECMA dialect
    • e.g. ECMA3/4-to-AS3/SWF9
  • ECMA4 object model simulation in JScript 5.6, Javascript 1.5
  • Community support will probably be required to fully separate these components

Details

• The project plan is Legals_Project_Plan.
• Details of our multiple-runtime architecture are in Multiple Runtimes Infrastructure.
• SWF9 work is detailed at SWF9 Target.
• DHTML work is detailed in DHTML Target.