Presentation (discussant)


5 Νοε 2013 (πριν από 5 χρόνια και 5 μήνες)

89 εμφανίσεις

Turning Software into a Service

The Critique

Paul Kopacz

Brian Moore

Dynamic Composition

Heavy emphasis

“...we seek to devise a suitable mechanism for
creating new forms of service on demand”

“...lets the set of services a business uses evolve
without any user interaction as the business and it's
context change”

The most interesting idea in their paper

Is Dynamic Composition Possible?

They hope so

No references to studies

No limits imposed on composition

No details on what composition will do

No Silver Bullet

by Fred Brooks

"I believe the hard part of building software to be
the specification, design, and testing of this
conceptual constr

How much of this work can be done

What is Composition Based on?

Possible standards


Not complete


Not dynamic

“Providing this capability will require support
from high
bandwidth information networking”

They expect it will be provided


The Question

Can you propose an approach based on
unfinished standards?

What if the standards never work?

Unproven and untested with real applications

Adoption of Technology

Widely used standards inadequate

The most complete stack is based on ebXML

e.g. Contract negotiation

Semantic Web technology

S (now OWL

Describe semantics of services, “what they actually

Even these are lacking

Adoption of Technology

Semantic Web and ebXML based technology
not widely used in industry

They are highly complex

The authors need them to be more complex

Can regular developers use these

scale specialist
services providers”

Will smaller development firms have the resources?

Online Service Vendors

“Such a model would open up new markets”

Assume functionally identical services from
multiple providers

Various choices for services to compose from

Vendors differentiate based on non
functional terms
(price, reliability, speed, etc.)

Online Services Today

Internet enables worldwide competition

Mature markets contain small numbers of

Most successful remain

Smaller companies differentiate based on

Big market examples

Search has three dominant companies

Online auctions has one

Finding Online Services

As markets mature, number of choices

Will automatic binding still work with services
differentiated based on functionality?

Does it even make sense to do this?

Is their complex model necessary?

Security and Reliability

“...because it concentrates instead on other
areas, our current model does not include

Design with security in mind

Little discussion of possible failure

Only transactions are mentioned

Other types of failure are not mentioned


You are providing a service with other peoples'

Why should you trust it?

How do you make sure it behaves as advertised?

This is all done dynamically

Dynamic error checking?

Who do you trust?

Programming and the Web

“...the basic paradigm for constructing and
maintaining software has altered little since the

link procedural source code into a

“...the practices used to develop and implement
a Web site differ little from those traditionally
employed for constructing software and are just
as error prone.”

Programming and the Web

Web programming is where the departure is
most evident

J2EE containers

Scripting/Interpreted languages

Composition and pipelining

Ignoring what is currently being done