Web Applications

define a distributed model of computation that suits the Web.
define canonical (language-independent?) object models for ... resources, application domains ...

Perspectives

servers - extensions
browsers - clients, viewers, configuration
agents - e.g. payment

Interests

distributed objects
plugin components
formalization of requirements and solutions

slide: Dimensions of APIs

slide: Hierarchical structure of DOM

intelligent navigation and information retrieval,
information and document maintenance,
user interfaces for Web-aware applications,
dynamic documents with user-defined applets,
declarative descriptions of agent behavior based on user preferences,
declarative modeling of coordinated and cooperative behavior of software agents, and
programming single and multi-agent systems.

modeling the behavior of cooperating agents,
generic means for realizing actual agents in a Web-aware context,
architectural support for programming agent-based systems.

Framework components

Web-aware agents

a methodology for developing agent-based applications, as well as
a logical foundation for modeling agent behavior; and in addition
guidelines for realizing actual agent applications, and
software components that can be used as building blocks, including
a language for programming agent behavior.

slide: Framework components

The DejaVU experience

Applications and the Web

Bringing music to the Web

Chatting on the Web

Animating the Web

Jamming (on) the Web

slide: The DejaVU experience

slide: The score in a plugin


    <SCORE>
      <TITLE>Corrente</TITLE>
      <COMPOSER>Antonio Vivaldi</COMPOSER>
      <STAFF>
        <MEASURE Sig="3,4" Key=F Clef=Gclef>
          <NOTE Pos="1,3" Stem=down>d6 4 0
          <REST Pos="3,6">C6 8 0
          <NOTE Pos="4,6" Stem=up>a5 8 0
          <NOTETUPLE Stem=down>
            <NOTE Pos="5,6">f5 8 0</NOTE>
            <NOTE Pos="6,6">a5 8 0</NOTE>
          </NOTETUPLE>
        </MEASURE>
        ...
      </STAFF>
    </SCORE>


    SCORE {
      margin-left : 30;
      margin-right : 30;
      margin-top : 80;
      margin-bottom : 20;
      page-height : 1000;
      page-width : 920;
    }
    TITLE {
      title-align : Center;
      title-font : -*-Times-Bold-R-Normal--*-240-*;
    }
    COMPOSER {
      composer-align : Center;
      composer-font : -*-Times-*-R-Normal--*-180-*;
    }

slide: An associated style sheet

registering and unregistering MIDI devices,
routing MIDI data between clients and MIDI devices, and
administration and security checks.

slide: The jam server

slide: Web components

viewer -- a widget for the inline display of several MIME types, such as HTML, VRML and Amuse score formats.
web -- an extension of the MIMEviewer with history and caching.
netclient -- the interface to the Internet, supporting several protocols.

It is a brave architect who, in today's environment, does not develop, or at least consider, an object-oriented design.

Architectural software styles

class of architectures

component types -- process, event, repository
runtime relations -- topology
semantic constraints -- immutability
communication and coordination -- connectors

slide: Architectural software styles

Themes and variations

technological constraints

OO -- simple call and return
CORBA -- independent components
WWW -- data centered
events -- independent components
logic -- virtual machine architecture

slide: Themes and variations

Architectural issues

managing growth, maintaining installed base
enhanced functionality -- synchronized multimedia
improved technological infrastructure -- HTTP-NG

slide: Architectural issues

Client NPP/Callbacks	Browser NPN/Calls
Instantiation and Destruction	Version Info
Stream Notification	Stream Creation and Destruction
Reading and Writing Streams	StreamAsFile
LiveConnect

Nevertheless, ignoring details, plugin architectures indicate what may become the dominant paradigm of the future, framework-like environments that are extensible by components following a clearly defined pattern or protocol; that is to say, components created according to the principles of object-oriented software development.

Objects and the Web

trends and technologies -- client/server + extensions
ObjectWeb -- CORBA/Java vs Microsoft

slide: Section 12.1: Objects and the Web

Programming the Web -- a search for APIs

models of computation
intelligent agents

slide: Section 12.2: Programming the Web -- a search for APIs

The DejaVU experience -- jamming (on) the Web

animating the Web -- an SGML-based approach
bringing music to the Web -- data formats + client-side plugin
jamming (on) the Web -- additional communication servers

slide: Section 12.3: The DejaVU experience -- jamming (on) the Web

Architecture revisited

OO -- simple call and return
CORBA -- independent components
WWW -- data centered
events -- independent components
logic -- virtual machine architecture

slide: Section 12.4: Architecture revisited

Describe the architecture of the Web. Explain the relevance of objects for the Web.
Sketch the Microsoft approach to the ObjectWeb. Discuss its pros and cons.
In what ways can Java and CORBA be deployed in Web applications?
Indicate how the computation model underlying the Web deviates from the computation models underlying, respectively, object systems and client-server systems.
What requirements can you think of for libraries or frameworks for developing Web applications?
Discuss the Document Object Model.
What are the requirements for a framework supporting intelligent agents?
Explain the issues that arise in extending the Web with additional media functionality. What solutions can you think of? Can you give an example?

slide: Questions

Æliens

2009