Trustworthy Semantic Webs Dr Bhavani Thuraisingham The University of Texas at Dallas Lecture 3 Semantic Web Web Services and Security Outline Today s Web From web to semantic web Applications and Technologies Layered Approach Web Services Introduction Today s Web High recall low precision Too many web pages resulting in searches many not relevant Sometimes low recall Results sensitive to vocabulary Different words even if they mean the same thing do not results in same web pages Results are single web pages not linked web pages From Today s Web to the Semantic Web Machine understandable web pages Activities on the web such as searching with little or no human intervention Technologies for knowledge management e commerce interoperability Solutions to the problems faced by today s web Retrieving appropriate web pages sensitive to vocabulary etc Semantic web applications including Layered Approach Tim Berners Lee s Vision www w3c org Applications Web Services Web Services refers to the technologies that allow for making connections Services are what you connect together using Web Services A service is the endpoint of a connection Also a service has some type of underlying computer system that supports the connection offered The combination of services internal and external to an organization make up a service oriented architecture Knowledge Management Corporation Need Searching extracting and maintaining information uncovering hidden dependencies viewing information Semantic web for knowledge management Organizing knowledge automated tools for maintaining knowledge question answering querying multiple documents controlling access to documents Business to Consumer E Commerce Users shopping on the web wrapper technology is used to extract information about user preferences etc and display the products to the user Use of semantic web Develop software agents that can interpret privacy requirements pricing and product information and display timely and correct information to the use also provides information about the reputation of shops Future negotiation among the behalf of the user Business to Business E Commerce Organizations work together and carrying out transactions such as collaborating on a product supply chains etc With today s web lack of standards for data exchange Use of semantic web XML is a big improvement but need to agree on vocabulary Future will be the use of ontologies to agree on meanings and interpretations Personal Agents Agents are essentially processes that have evolved from object oriented programming agent is an active objects Agents will use metadata to find resources on the web ontologies will be used to interpret statements logic will be used for drawing conclusions Agents will not completely replace humans but will make the tasks of the humans much easier Example John is a president of a company He needs to have a surgery for a serious but not a critical illness With current web he has to check each web page for relevant information make decisions depending on the information provided With the semantic web the agent will retrieve all the relevant information synthesize the information ask John if needed and then present the various options to John and also makes recommendations Semantic Web Technologies Explicit metadata XML RDF etc Ontologies e g OWL Logic Rules e g RuleML SWRL Explicit metadata Metadata is data about data Need metadata to be explicitly specified so that different groups and organizations will know what is on the web Using metadata one can then carry out various activities such as searching integration and executing actions Metadata specification languages include XML and RDF Ontologies Explicit and formal specification of conceptualization describes a domain of discourse Consists of concepts and prelateships between them Web searches can exploit ontologies to facilitate the search process Ontology languages include XML RDF OWL Ontology Engineering Tools and Techniques to Create Ontologies Specify Ontologies Maintain Ontologies Query Ontologies Evolve Ontologies Reuse Ontologies Incorporate features such as security data quality integrity Logic Logic can be used to specify facts as well as rules New facts and derived from existing facts based on the inference rules Descriptive Logic is the type of logic that has been developed for semantic web applications Example Logic based languages SWRL RuleML Semantic web vs Artificial Intelligence Goal of Artificial Intelligence is to build an intelligent agent exhibiting human level intelligence Goal of the semantic web is to enable machine understandable web pages Overview of Web Services Service Oriented Architectures Web Services Description Language UDDI SOAP WSDL with XML Security OASIS Federated identity Service Oriented Architectures SOA A service oriented architecture is essentially a collection of services These services communicate with each other A service is a function that is well defined self contained and does not depend on the context or state of other services The communication can involve either simple data passing or it could involve two or more services coordinating some activity Some means of connecting services to each other is needed The technology of web services is the most likely connection technology of service oriented architectures Web services essentially use XML Technology create a robust connection A service consumer sends a service request message to a service provider The service provider returns a response message to the service consumer The request and subsequent response connections are defined in some way that is understandable to both the service consumer and service provider A service provider can also be a service consumer Web Services BusinessEntity dsig Signature Query BusinessService UDDI PublisherAssertion BusinessService Service requestor tModel Service provider BindingTemplate Web Services Description Language The Web Services Description Language WSDL forms the basis for Web Services The steps involved in providing and consuming a service are A service provider describes its service using WSDL This definition is published to a directory of services The directory could use Universal Description Discovery and Integration UDDI Other forms of directories can also be used A service consumer issues one or more queries to the directory to locate a service and determine how to communicate with that service Part of the WSDL provided by the service provider is