Plan A

Update: The new Scriptus project by Ian Sollars has very similar goals to the Weaver engine. When Plan A gets resumed, it will probably be based on/in collaboration with his work.

Plan A is to build a prototype based on the JRE/Rhino/Narwhal platform.

Narwal will be the package manager and core library for weaverengine.

A sandboxed environment will be created for each user script that is executed.
A custom datastore API will be exposed, with granular security.
An ouput API will also be exposed, with granular security and injection prevention.

Libraries and frameworks

Visit the resources pages for details on why

So far, here are the top options (or only picks):

User code execution runtime: Rhino

User code syntax: JavaScript or CoffeeScript

Web framework: ? / Play / RingoJS / NitroJS / Narwhal
(Can be anything that runs on the JRE, although Rhino-based would probably be better)

Persistence engine: ?

Source code editing: ACE

Output syntax: Markdown variant

Visual code editor: Flow-layout, using a modified Jison/OMeta/PEG.js grammer to maintain whitespace and comments, and to allow bi-directional conversion.