Active Components as a Method for Coupling Data and Services – A Database-Driven Application Development Process

Active Components as a Method for Coupling
Data and Services – A Database-Driven
Application Development Process
Beat Signer and Moira C. Norrie
Department of Computer Science
Vrije Universiteit Brussel
1050 Brussels, Belgium

http://vub.academia.edu/BeatSigner
2 December 2005

Motivation
package org.penAndPaper;
import java.io.IOException;
...

public class PaperPoint {

Rectangle slide1
= new Rectangle(10,10,70,50);

// if input within slide1 then
// execute application logic

}

ICOODB, July 3, 2009 Beat Signer - Department of Computer Science - bsigner@vub.ac.be

Problems
 No separation of data objects (e.g design elements) and
application logic
 changes to the design require a recompilation
 limited reusability of application logic
 Authoring of paper interface requires programming
 designer has to be a programmer
 programming rather than authoring approach
 Design elements cannot easily be reused with different
application logic variants
 replication of code


Active Component Approach
 Database driven application development where the
database contains
 data objects
 active components (application logic)
 Data objects can be associated with active components at
 instance level
 type level
 role level (classification)
 Access to data object might trigger the execution of an
active component
 active component runtime environment
 database-driven application logic on server and/or client side


Active Component
 Active component contains data about a service
 name
 identifier
 timeout
 parameters
- key/value string pairs

 Active component runtime environment executes the
corresponding application logic
 service binding
 initialisation


Active Component Runtime Environment


Active Component Registry

 Binding of identifier to stub and logic components
 Reconfigurable at runtime


Server-side Functionality


Client-side Functionality


Client- and Server-side Funtionality


Active Component Stub and Logic


Active Component Example
package org.ximtec.iserver.activecomponent.logic;
public class CommandLine extends EmptyLogic {
}

package org.ximtec.iserver.activecomponent.stub;
import java.io.IOException;
...
public class CommandLineStub extends SingleEventStub {
public static final String PARAM_COMMAND = "command";

public void finish() {
try {
Runtime.getRuntime().exec(getParameter(PARAM_COMMAND));
}
catch (IOException e) {
LOGGER.log(Level.SEVERE, Constant.EMPTY_STRING, e);
}
} // finish
}


Active Component Stub Example ...


Client and Server AC Interaction


Active Components
Button Image

Slider Sound

Slider2D Movie

DateSelector SQLClient

Browser XCMRequest

MapSelector CommandLine

Capture PaperPointControl

CaptureAndIcr PaperPointAnnot

CaptureAndSpeak ...


Slider / Slider2D Active Component


Slider2D Active Component
 Slider2D active component properties
 startValueX
 endValueX
 stepsizeX
 invertedX
 startValueY
 endValueY
 stepsizeY
 invertedY


Authoring


Active Component Editor
PP_SLIDE_SELECTOR

Show slide 1

command showSlide

slide 1


Other Use Cases
 Rich internet applications
 active component runtime environment within browser
 "Internet of Things"
 active component runtime environment for augmented
physical objects
 lightweight solution for database updates (e.g. sensor data)
 Implicit service execution at object access time
 service associated at instance, type or role level
 media service components


Media Service
 No longer deal with "raw" media types


Ongoing and Future Work
 Integration of concepts into the ODBMS
 role-driven service invocation
 separation of intrinsic (type) and extrinsic object behaviour
 Communication between different active components
 AC runtime environments for alternative programming
languages


Conclusions
 Database-driven application development
 reusability due to separation of data objects and services (ACs)
 flexible configuration of active component services
 instance, type and role-driven service invocation
 Client- and server-side execution of application logic
 autonomous component-based client-server interaction
 Automatic deployment of services to the client side
 simplifies updates of client-side application logic
 Authoring rather than programming approach
 rapid prototyping (growing set of active components)


Further Information
 Beat Signer, Fundamental Concepts for Interactive
Paper and Cross-Media Information Spaces,
ISBN 978-3-8370-2713-6, May 2008


Active Components as a Method for Coupling Data and Services – A Database-Driven Application Development Process

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