CS 566 Web Semantics E-Commerce and Semantic Web

CS 566 Web Semantics E-Commerce and Semantic Web Antonis Misargopoulos misarg@csd. uoc. gr Athina Tziaki tziaki@csd. uoc. gr Professor Antoniou Grigoris June 2003 1

Introduction n n n The growth of a wide range of e-commerce services is contributing to the increasing international trading of products and services The ability to find, interrogate and exchange knowledge is fundamental for Business-to-Business (B 2 B) and Business-to. Customer (B 2 C) e-commerce Semantic Web brings structure to the content of Web pages Semantic Web is extension of the current Web, in which information is given a well-defined meaning It will be able to support automated electronic services using semantics-based descriptions Ontologies and metadata are becoming increasingly prevalent and important in a wide range of e-commerce applications RDF is the technical foundation of the Semantic Web which provides a generic core data model 2

When Semantic Web Approaches E-Commerce n n Semantic Web will enable automated agents to describe and carry out more intelligent tasks on behalf of the user Tim Berners-Lee, the inventor of the WWW, has conceived a fivelayer architecture for Semantic Web: ¨ The syntax layer – XML allows to markup arbitrary content by means of nested, attributed elements ¨ The data layer – RDF allows the encoding, exchange and reuse of structured metadata. Contrary to XML, RDF allows assigning global identifiers to resources and allows referring and extending statements made in other documents ¨ The ontology layer describe structurally heterogeneous and distributed information sources of interest ¨ The logic layer consists of rules that enable inferences ¨ The proof layer allows the explanation of given answers generated by automated agents. This will require the translation of agents internal reasoning mechanisms into some unifying proof representation language. 3

Ontologies n n While e-service approaches to e-commerce is to become widespread, standarisation of ontologies, message content and message protocols will be necessary Because of the great XML-like modelling languages release, the challenge is to create small standards for communities to describe information with meaning Ontologies can be seen as metadata that explicitly represent semantics of data in machine-processable way Ontology-based reasoning services help people and computers to access the information they need, and effectively communicate with each other 4

Semantic E-Commerce Lifecycle (1/10) Lifecycle Stages: Matchmaking: A trader locates other traders that it could potentially do business with. n ¨ Negotiation: The trader enters into negotiation with one or more of these potential business partners, to see if they can agree mutually acceptable terms of business. n ¨ n n This is done by some traders placing advertisements, and others making queries over these advertisements This is done through an interchange of negotiation proposals describing constraints on an acceptable deal. The outcome of this is an agreement. Contract Formation: The agreement is transformed into a legally binding contract Contract Fulfilment: The parties carry out the agreed transaction, within the parameters specified in the contract 5

Semantic E-Commerce Lifecycle (2/10) Matchmaking n n n Matchmaking is the process whereby potential trading partners become aware of each other’s existence Provides an associated partially specified service description that defines the set of possible services the provider can offer which are of the interest to the buyers Despite different architectures and communication protocols: we can identify clear roles which are common to all of them. we have a repository of information about services or service requirements, which is maintained by the repository host. ¨ agents adopting advertiser role are willing to advertise descriptions of services in the repository. They may be buyers, advertising a service request, or may be marketplaces offering environments where such services can be traded. ¨ agents adopting the seeker role similarly wish to locate appropriate advertisers. Seekers can query a repository, via the repository host, and may be able to browse the repository. ¨ ¨ 6

Semantic E-Commerce Lifecycle (3/10) Negotiation n n Negotiation stage of the e-commerce interaction lifecycle refines the abstract service specification from the matchmaking phase to a concrete agreement between two parties Negotiation can be one-to-one, one-to-many or many-to-many Negotiation protocols determine the interchange of messages which take place during the negotiation, and the roles by which the negotiation must abide In each case there at least two negotiation participants trying to make a deal with each other There is at least one (possible more) negotiation host, responsible for enforcing the rules of the negotiation and ensuring it goes normally 7

Semantic E-Commerce Lifecycle (4/10) Negotiation n n Before negotiation can begin, the parties have already agreed roughly what the negotiation is about. So, this places a restriction on the parameters and values to be negotiated, which is called negotiation template The negotiation template refers to a common ontology accepted by all participants in the negotiation. It defines a schema for valid negotiation proposals that participants submit to each other The result of the negotiation process is an agreement 8

Semantic E-Commerce Lifecycle (5/10) Standardization take place at 3 levels: n n n Standards for business-specific ontologies which describe goods, services and contracts being traded Standards for specifying the format of advertisements, proposals, contracts and other constructs which are used during B 2 B interactions Standards that specify the protocols which traders use to interact with each other during different phases of the B 2 B lifecycle 9

Semantic E-Commerce Lifecycle (6/10) Description Language for B 2 B E-Commerce Lifecycle Requirements: n n Description should offer a high degree of flexibility and expressiveness Descriptions need to share a common semantics Descriptions should easily lend themselves to performing the operations described in the negotiation and matchmaking sections Descriptions should express restrictions and constraints 10

Semantic E-Commerce Lifecycle (7/10) Description Language for B 2 B E-Commerce Lifecycle Why DAML+OIL is a good candidate? n n DAML+OIL offers support for types, which greatly enhances the expressiveness and modularity of the descriptions DAML+OIL offers support for ontologies. It is almost integrated with tools such as Oil. Ed and Protégé which make the generation of new ontologies for service descriptions much easier All the operations can be expressed in terms of the subsumption operation. DAML+OIL descriptions lend themselves very well DAML+OIL offers some support for expressing constraints 11

Semantic E-Commerce Lifecycle (8/10) n. The Description Ontology: Description class is a common superclass for Advertisement, Query, Template and Proposal n. The PC Ontology: PC class is a subclass of Product and must have at most one Processor and one amount of memory Description Language for B 2 B E-Commerce Lifecycle Using DAML+OIL 12

Semantic E-Commerce Lifecycle (9/10) n. The Service Ontology: Two services are defined in this ontology: Sales and Delivery n. The Participant Ontology: Public information about prospective advertisers and negotiators. Built from information that individuals or companies are requested to provide at registration time. Description Language for B 2 B E-Commerce Lifecycle Using DAML+OIL Such information is then used at matchmaking and negotiation time to verify compatibility of advertisements and proposals. 13

Semantic E-Commerce Lifecycle (10/10) Description Language for B 2 B E-Commerce Lifecycle Agreement Instance Example 14

E-commerce issues (1/2) q q q Many consumers do not trust the Internet to provide robust security for online transactions, and many businesses neither trust e-commerce systems nor believe they will be able to evaluate or control their business risk when using them Lack of automation – human intervention is required for browsing, selecting, ordering and paying for products Current e-commerce sites do not include semantic representations of data, services, processes, or business models that are readable by software programs (agents) 15

E-commerce issues (2/2) Three technologies will bring e-commerce to the next generation by increasing efficiency, compatibility, autonomy, and security: Mobile Agents: Automate Electronic Transactions q Security and Trust: Build a Web of Trust q XML: Create a Semantic Web q 16

Mobile Agents: Automate Electronic Transactions q Mobile software agents are programs that act on behalf of a user or another program and, for a specified mission, are able to migrate from host to host on a network q Numerous applications could benefit from mobile agent technology, such as Internet information retrieval and network management q However, the greatest potential for mobile agents has been e- commerce applications in which the agents automate and facilitate the phases of Brokering of a transaction ü Negotiation of a transaction ü Payment of a transaction ü Delivery of a transaction ü 17

Security and Trust: Build a Web of Trust q Most of the security issues, such as confidentiality, authentication, integrity, and non - repudiation, are addressed by well-known cryptographic algorithms and protocols q However, even if we have a secure channel connecting us to a party whose identity can be verified, we still have no way to confirm the trustworthiness of that party q To meet this challenge, we need a trust management mechanism to manage the histories and reputation of parties involved in the business to create a web of trust q While the mobile agent automates the electronic transactions, it also introduces new security threats 18

XML: Create a Semantic Web q Today’s Web is a vast unstructured mass of information q HTML was designed to provide a usable interface for humans, rather than to communicate with other machines. While HTML reflects the structure and limited presentation of a Web page, it conveys nothing about the meaning of the marked document q Search engines and software programs have difficulty using information that is not semantically encoded q Today, several industry-focused initiatives have been formed to work on standards based on XML for interoperable frameworks for ecommerce application domains q Rules range from how to offer items for sale, to making payment choices, delivering products, generating receipts, and resolving problems 19

Integration Problems of XML-Based Catalogs for B 2 B Electronic Commerce q Electronic marketplaces for Business-to-Business (B 2 B) electronic commerce bring together many online suppliers and buyers q Each individual participant can potentially use his own format to represent the products in his product catalog q A B 2 B mediator has to integrate both suppliers’ and buyers’ formats to allow them to do contracting with one another q Given the dominance of XML, e-commerce integration technology must be based on the XML low-level integration architecture provided by the W 3 C consortium with XSLT and XPath languages 20

Product Description Standards (1/2) q x. CBL 3. 0 developed by Commerce One 2, Inc ¨ Provides a comprehensive set of standardized XML document formats, allowing buyers, suppliers and service providers to integrate their existing systems quickly and efficiently in the electronic marketplaces q Internet Open Trading Protocol (IOTP) was developed within the Internet Engineering Task Force (IETF 3) consortium ¨ Provides the data structures and communication protocols for payment transactions: purchase, refund, authentication, deposit, and other protocols that occur in electronic commerce 21

Product Description Standards (2/2) q Open Applications Group Integration Specification (OAGIS) q Provides data structures, messaging formats and protocols for business integration. OAGIS defines a vocabulary of business terms and more than 90 different types of business documents can be exchanged q Real Estate Data Interchange Standard (RETS) q Defines a protocol for implementing transactions, and incorporates an XML specification for general-purpose interchange. It also provides a compressed data interchange format and specification to allow the interchange of machineinterpretable property information 22

Catalog Integration (1/3) q If a marketplace mediates between n suppliers and m buyers, then it must be able to map each of the n suppliers’ catalogs into m buyers’ formats performing nxm mappings q The numbers n and m may be high enough to make the problem of creating and maintaining these catalog integration rules nontrivial 23

Catalog Integration (2/3) q Unified Catalog (the UC), only requires the marketplace to perform mapping between each supplier or buyer catalog and the UC, and therefore requires only n+m mappings q There are two opposing strategies for selecting the elements for inclusion in the UC: a) The unified catalog stores the minimum core number of attributes for each product b) The unified catalog stores the maximum possible number of attributes 24

Catalog Integration (3/3) In both strategies the UC can change if we add a new catalogue q In strategy (a) The addition of a more detailed catalog will not change the UC ¨ The addition of a less detailed catalog will reduce the granularity level of the UC. As a result, this strategy bounds the granularity level of the UC to the less detailed catalog, which is unacceptable for most B 2 B systems ¨ q In strategy (b) ¨ The addition of a new catalog that is less detailed than the UC will not influence the latter ¨ The addition of a more detailed catalog will require updates to the UC so that it will not be less detailed than the former 25

Integration at the XML Catalog Level (1/5) Four types of mapping between the attributes of C 1 and C 2 are possible: q one-to-one mapping (1: 1) § It occurs when the element of C 1 has a semantic equivalent in C 2, i. e. element State. Or. Region in IOTP standard is equivalent to Province in the UC. If the element is encoded by an XML attribute in C 1 and by an XML element in C 2 then the rule can be expressed as follows (from IOTP to UC): <xsl: for-each select="Postal. Address"> … <Province> <xsl: value-of select="@State. Or. Region"/> </Province> … </xsl: for-each> 26

Integration at the XML Catalog Level (2/5) q one-to-many mapping (1: n) § It occurs when an element in C 1 has to be translated into several elements in C 2. For example, ADDRLINE in OAGIS semantically corresponds to the pair of attributes Street and House in the UC § XSLT rules must be extended with small XPath expressions (element parsers) that will split the elements as required <ADDRLINE>De Boelelaan, 1081 a</ADDRLINE> <ADDRESS> <ADDRLINE> <STREET>De Boelelaan</STREET> <HOUSE>1081 a</HOUSE> </ADDRLINE> … </ADDRESS> <STREET> <xsl: variable name="addrline" select="ADDRLINE"/> <xsl: value-of select="substring-before($addrline, ', ')"/> </ STREET > <HOUSE> <xsl: variable name="addrline" select="ADDRLINE"/> <xsl: value-of select="substring-after($addrline, ', ')"/> </ HOUSE > 27

Integration at the XML Catalog Level (3/5) q many-to-one mapping (n: 1) § It occurs when two or more elements from C 1 have to be translated into one element in C 2. For example, the Street and House elements in the UC must be translated into the element ADDRLINE in OAGIS. This can be done by means of XSLT in the following way: <xsl: for-each select="address"> <ADDRLINE> <xsl: value-of select="Street"/>, <xsl: value-of select="House"/> </ADDRLINE> … </xsl: for-each> <ADDRLINE>De Boelelaan, 1081 a</ADDRLINE> 28

Integration at the XML Catalog Level (4/5) q Many to-many mapping (n: n) § It occurs when a piece of a description is spread over several elements without evident partitioning of information between them. For example, Street, House, and PObox elements of the UC correspond to the pair (Address. Line 1, Address. Line 2) in IOTP without any indication where street, house, and postbox information should be stored within these two address lines. Mapping of a structured UC record into a less structured IOTP record can be done straightforwardly: <xsl: for-each select="address"> <Address. Line 1><xsl: value-of select="Street"/> <xsl: value-of select="House"/></Address. Line 1> <Address. Line 2>P. O. Box <xsl: value-of select="PObox"/> </Address. Line 2> … </xsl: for-each> 29

Integration at the XML Catalog Level (5/5) n n If an element was mapped into the UC with one 1: n mapping then the reverse mapping will require one n: 1 mapping Most of the rules (89%) represent one-to-one mappings, while the other types only appear in special cases, once or twice for each catalog standard 30

Existing Frameworks and Applications MOMIS n SEMANTICEDGE n KAON n ONTOWEB n ONTOKNOWLEDGE n 31

MOMIS Architecture MOMIS (Mediator envir. Onment for Multiple Information Systems) is a mediator-based system aiming to extract and integrate information from heterogeneous data sources, such as relational, object, semi-structured sources (XML) 33

Semantic. Edge (1/2) q Semantic. Edge has developed a state of the art multilingual natural language (text and voice) dialog system capable of handling dialogs with humans wanting to access information, for example, to purchase products and services q The technology extends naturally to Customer Relations Management (CRM) and other e-business functions q This technology depends on several distinct technology areas within Artificial Intelligence: natural language processing, including deep language processing and statistical analyses; machine learning, including inductive learning; speech recognition; automated dialog generation, both user and content specific; and knowledge representation and ontologies 34

Semantic. Edge (2/2) q The system mediates between humans and information. q That is, it mediates between an information space and a human’s conceptualization of that information space; for example, between a product space and a customer’s conceptualization of that product space, and how they will consequently go about searching and querying that product space q Users hold negotiations with the system, which is mediating access to the product spaces, and it will ask questions of them. q This requires the system to have the ability to guide those dialogs according to a representation of that product space. q This ability to a large extent is supported by ontologies Financial Application demo 35

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