GT2003Stefano

Talk by Stefano Mazzocchi at the 2003 GetTogether: How I see Cocoon - a visual journey.

Raw notes taken collaboratively during the talk.

Stefano takes the stage

Says he could not come last year because of ApacheCon.

Shows an unusual presentation, in the very good sense, very graphical, mostly photos and short comments.

A written report will not do justice to this talk. You had to be there.

What is Cocoon:

• Cocoon is designed for People, not machines - empower all the different kinds of people who work on projects

• Guided by Open Standards (but not trapped by them)

• Free to make mistakes, in public

• Creative & original, not afraid to copy good stuff

• Looks to the past for inspiration or warnings

  • Like GOTO was found harmful in the past, finite state machines for web apps might be the next thing that we find harmful...

• No fear of innovation

• Balance, between innovation & compatibility

  • It will not collapse beneath your feet, because we need it to work too

• Modular, adaptable, etc. yet solid

• Care for details

  • It's ok to take six months to polish the sitemap contracts

• Self-organising organism

Concepts

• "Creativity is making the complicated simple" - Charles Mingus

• Separation of concerns - simple yet very powerful concept

  • Seperating overlaps in responsibilities

  • Allow people to do what they do best and leave the rest to others

  • Pyramid of contracts

  • Concern Islands, kept seperate

    • Management

    • Logic

    • Content

    • Style

Design

• "To create, one must first question everything" - Eileen Grey

• Architecture of Cocoon (shows diagram)

  • Many different web clients (browser, PDA, cell phone, TV, agent, etc)

  • Try doing this in JSP

  • Back-end: web services, data sources, content repositories

  • Two interfaces:

    • Command Line

    • Servlet

(Stefano shows another diagram)

• Cache is essential to performance

• Pipeline components can allow you to create a complete site without writing a single line of Java code

• Blocks (Another diagram)

  • Cocoon 2.1 without Blocks is limited, we have distribution problems with it as everything possible has to be contained.

  • (Real) Blocks will be components at the application level

  • User connects to the Block Deployer (command-line, GUI, web-based tool...time will tell) to select the required Blocks for a given application

  • Block deployer can automatically download required (dependant) blocks at runtime

  • Cocoon keeps seperation between blocks that are not dependent (allows easy versioning and hot-deploy scenarios)

  • Possible scenario: install a complete web site as a Block

  • Rely on dependencies between Blocks

• Blocks wiring (Diagram)

  • Connect website paths to specific blocks

  • Connect 'Behaviours' (Interfaces) automatically, hot deployable, polymorphically

  • Extension mechanism, so you can overlaod a Block from another one (whether this is logic, content or style)

• Blocks will become available in Cocoon 2.2

• The design is completed

• Please start planning to use them

Flow (Another diagram)

• Continuations are not new, they have been use on the web as early as 1995 in Lisp and Scheme (Paul Graham)

• A logic engine, connected to the SiteMap

• Based on JavaScript (current implementation)

• Took the ideas of Continuations from Scheme

  • Pauses the flow script while the user fills in their data

  • Not something that has normally been possible for web programming environments

  • (Discussion on why FSM is not good)

  • Very fast prototyping, increases productivity

  • Pipeline Teeing with Flowscript (Another diagram)

    • processPipelineTo ()

    • Your FlowSript can use a Pipeline to output to a Source (Disc etc.)

Stefano gives a very clear explanation of Flowscript with Continuations - looks like today might be the Day of the Web Application for many Cocooners

Diagram 6 shows how the results of a pipeline can be saved as well as being sent (maybe after further processing) to the client.

Sitemap Components

Now we're into 'normal' stuff, explaining generators, transformers, serializers etc...

New for 2.2 will be "pipeline snippets", assembled into "virtual components"

• Several components put together, that can be reused elsewhere in your sitemap, as if it were a single component.

• Virtual Generator: Generator followed by optional Transformers

• Virtual Transformer: One or several Transformers

• Virtual Serializer: Optional Transformers followed by a Serializer

Goes on to describe the current components: Readers, Selectors.

call: call resources, (javascript) functions or continuations.

Redirect to a different URL. Mount a different sitemap (isolating parts of a project, or teams etc.)

Sitemap notation

"Example sitemap" page shows an overview Stefano's notation for the sitemap - it would be good for Cocoon documentation or articles writers to standardize on a notation, this one looks good!

Brings talk to an end, with a famous photo of himself as the "evil fairy"

Audience questions:

• Someone talks about MIT's haystack project ( http://haystack.lcs.mit.edu/), which is supposed to become the killer app of the web (smiles all around). Did we look at this for inspiration?

  • Not really says Stefano, but we're always looking at similar projects for inspiration.

(Gianugo on chat) "a huge bloated desktop replacement but with a few nice concepts"