Interactive Systems Technical Design Seminar work: Web Services Janne Ojanaho

ISTD 2003, Web Services Topic overview What is a web service? Why they are important? General system illustration Practical example Limitations and weaknesses Links to additional information Future developments

ISTD 2003, Web Services Introduction Web service is a functional software resource accessable via network Core mechanisms use standards like XML and HTTP; systems are easy and fast to implement

ISTD 2003, Web Services Why web services are important? They provide platform and language independent communication mechanism Services support dynamic binding; they can be located runtime from specific registries When similar interfaces are applied to similar service types, clients can communicate in uniform manner

ISTD 2003, Web Services Implementation Web services communicate using SOAP (Simple Object Access Protocol) Services can be listed in UDDI (Universal Discovery, Description and Integration) directory using WSDL (Web Services Description Language)

ISTD 2003, Web Services Practical example (Imaginary) Use case: Client wants to book cheapest flight from Oulu to Helsinki 1. Client queries possible airlines from nearest UDDI registry 2. Registry returns WSDL descriptions for Finnair and Flying Finn, both implementing the same, predefined service interface 3. Client queries flight price from Finnair 4. Client queries flight price from Flying Finn 5. Client compares received information 6. Client selects Flying Finn since it’s cheaper and places order

ISTD 2003, Web Services Limitations and weaknesses Since most of the information is described in XML-based languages, it takes a lot of bandwidth Faster networks needed Compression can be used to some extent XML processing consumes hardware resources that some devices might not have much (e.g. phones and PDAs) Faster devices needed Standards still evolving Uniform service descriptions are not globally agreed

ISTD 2003, Web Services Selected Industrial Players Microsoft.NET product family support for web services Sun Java family support for web services IBM Websphere – integrated kit for creating, discovering, invoking and testing web services

ISTD 2003, Web Services Some International Projects W3C web services working groups Standards for architecture, protocols etc. Apache project Many open source implementations related to web servives (SOAP implementation Axis, Web services invocation framework WSIF etc.)

ISTD 2003, Web Services Academic activity in Finland University of Helsinki, Semantic Computing Research group (SeCo) Semantic web services ” Our goal is to investigate how Semantic Web techniques could add content and intelligent features to Web Services based on open standards such as UDDI, WSDL, and SOAP ”

ISTD 2003, Web Services Future Developments Semantic web Enhances communication between machines by adding metadata (information about information) to web ”an extension of the current web in which information is given well defined meaning, enhancing the capability of computers and people to work in co-operation” ”an idea of having data on the web defined and linked in a way, that it can be processed by machines - not just for display purposes, but for using it in various knowledge based applications” Intelligent agents performing routine tasks using web services (and semantic web) automatic information search, discovery and formulation negotiations on behalf of user on goods planned to be purchased