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 construct”  How much of this work can be done automatically?

What is Composition Based on? Possible standards  DAML-S Not complete  BPEL4WS Not dynamic “Providing this capability will require support from high-bandwidth information networking”  They expect it will be provided

Composition – 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  DAML-S (now OWL-S)  Describe semantics of services, “what they actually do” 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 technologies?  “Small-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 players  Most successful remain  Smaller companies differentiate based on functionality Big market examples  Search has three dominant companies  Online auctions has one

Finding Online Services As markets mature, number of choices decrease 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 security”  Design with security in mind Little discussion of possible failure  Only transactions are mentioned  Other types of failure are not mentioned

Failure You are providing a service with other peoples' code  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 1960s.”  Edit-compile-link procedural source code into a binary “...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