Future Web - behind semantics

The general{common} definition of concept semantics is a studying values. (the Word semantics occurs from the Greek concept semantikos, i.e. "great value", and in a basis of the last lays a word sema, i.e. a sign). Semantic technologies Web help to allocate the helpful information from the data, maintenances{contents} of documents or codes of applications, leaning{basing} on open standards. If the computer understands semantics of the document it does not mean, that he simply interprets a character set, contained in the document. It means, that the computer understands sense of the document.

Semantic technologies Web outline the general{common} frameworks, allowing to carry out data exchange and their repeated use in various applications, corporations and even communities. Semantic technologies Web is an effective way of data presentation on the Internet. Such structure also can be identified with a database which is connected on a global scale to the maintenance{contents} of documents in intenete symbolically. And this communication{connection} is carried out by way, to understandable computers. Semantic technologies represent values with the help ontologii and provide the argument, using communications{connections}, rules, logic and the conditions stipulated in ontologii.

Semantic technologies Web

The following concern to semantic technologies Web:

* The global circuit of names (URI);

* Standard syntax of the description of the data (RDF);

* Standard ways of the description of properties of the data (circuit RDF);

* Standard ways of the description of communications{connections} between objects of the data (ontologija, determined with the help of ontologic language Web (Web Ontology Language)).

Below in more detail each of these technologies is considered{examined}.

The global circuit of names - URI

URI is simply identifier Web, i.e. the addresses beginning with http or ftp. Any user can create URI, but the property rights to them are precisely organized, therefore they represent ideal base technology for construction of a wide-area network. Actually, the Internet is such structure: everything, that has URI, it is considered taking place in a wide-area network. Any object, the circuit or model of the data of a semantic network should have own unique (URI address.

The universal index of resources (Uniform Resource Locator, abbr. URL) is URI which, besides identification of a resource, specifies a way of action or performance of a resource by the description of the basic mechanism of access to it{him} or his{its} positions in a network. For example, URL http://www.webifysolutions.com < =http%3A%2F%2Fwww.webifysolutions.com> is URI which identifies a resource (a home page of company Webify Solutions) and specifies, that his{its} performance (i.e. as a set of the coded symbols) can be received current code HTML of a home page under report HTTP from network www.webifysolutions.com site.

The universal name of a resource (Uniform Resource Name, abbr. URN) is URI which identifies a resource with the help of a name in the certain space of names. It allows to speak about a resource without use of his{its} site or removal of links to him{it}. For example, URN urn:ISBN:1-0-7666-98-0 is URI which, it is similar to number{room} ISBN, allows to mention the book, but thus does not specify, where and as she{it} can be got.

Standard syntax of the description of given{data} - RDF

RDF is a specification which defines{determines} model of performance of the world and syntax for serialization and an exchange of this model. The consortium of a worldnet (World Wide Web Consortium, abbr. W3C) has developed XML-serialization for RDF. RDF XML is a standard format of an exchange for RDF in a semantic network though he is not the only thing. For example, Notation3 is an excellent{a different} test alternative serialization.

RDF provides a consecutive standard way of the description and job practically with any Internet - resources: from text pages and schedules up to audio-files and video clips. He offers syntactic opportunities for interaction of networks and forms a base layer for creation of a semantic network. RDF defines{determines} the controlled columns of communications{connections} submitted by three object - atribut-znachenie. For example, the object About has attribute And with value V.

In listing 1 example RDF XML is submitted.

Listing 1. Example RDF XML

<? xml version = " 1.0"?>

<rdf:RDF xmlns:rdf = " http: // www.w3.org/1999/02/22-rdf-syntax-ns * "

xmlns:contact = " http: // www.w3.org/2000/05/contact * ">

<contact:Company rdf:about = " http: // www.w3.org/Organization/contact*WebifySolutions ">

<contact:name> Webify Solutions </contact:name>

<contact:mailbox rdf:resource = "mailto:info@webifysolutions.com"/>

<contact:phone> 1-800-4WEBIFY </contact:phone>

</contact:Company>

</rdf:RDF>

Element RDF in listing 1 bears{carries} the information on a resource, in this case it is the company http: // www.w3.org/Organization/contact*WebifySolutions. The company can be identified on URI http: // www.w3.org/Organization/contact*WebifySolutions, its{her} name - Webify Solutions, her{it} e-mail - info@webifysolutions.com, and a phone number - 1-800-4WEBIFY.

On fig. 1 it is shown controlled columns of the communications{connections}, representing the same information.

Standard ways of the description of properties of the data - circuit RDF

Circuit RDF is semantic expansion RDF. She provides mechanisms of the description of the connected resources, and also actually these communications{connections}.

The system of classes and properties of circuit RDF is similar to system of types of languages of object-oriented programming, such, for example, as Java, but differs from many other systems. So, descriptive language of dictionary RDF defines{determines} properties in terms of that class of resources to which these properties concern. Other systems describe a class in terms of properties of his{its} elements.

RDF and circuit RDF are based on XML and circuit XML. Existence of standards for the description of the data (RDF) and their attributes (circuit RDF) allows to create packages of easily accessible tools for reading and uses of the data from numerous sources. As far as deeply various applications can exchange the data and use them, sometimes is called as syntactic interaction of networks (syntactic interoperability). The and widespread{distributed} these tools of job with the data are more standardized, the above the degree of syntactic interaction of networks and that becomes easier and more attractive use of the approach on the basis of semantic networks in comparison with dot integration decisions.

The link to a full package of models of the data and specifications of circuit RDF of consortium W3C it is possible to find Resources in section.

Standard ways of the description of communications{connections} between objects of the data: ontologija, determined with the help of ontologic language Web

Syntactic interaction of networks - a necessary condition that plural applications could "understand" really the data and work with them as with the information. It also a necessary condition for correct check of the data. Syntactic interaction of networks demands transformation ("mehppirovanija") between terms for what the content - analysis, in turn, is necessary.

Such content - analysis demands formal and detailed specifications of models of domains which define{determine} used terms and their communications{connections}. Similar formal models of domains sometimes are called ontologijami. They define{determine} models of the classes given in terms, subclasses and properties.

Ontologic language Web (Web Ontology Language), recommended consortium W3C, helps in expression ontologij. Working ontologic language (Ontology Working Language, abbr. OWL) adds more than dictionary opportunities for the description of properties and classes, than RDF or circuit RDF. In particular, he allows to describe communications{connections} between classes (for example, neperekryvaemost`), capacity of set (for example, " it is equally one "), equality, richer typology of properties and their characteristics (for example, symmetry).

Ontologic language Web on basis OWL is developed for use by applications which should work with the maintenance{contents} of the information, instead of simply give its{her} user. OWL improves opportunities of automatic interpretation of contents of the Internet in comparison with that can provide XML, RDF and circuit RDF. It occurs due to that OWL gives additional dictionary opportunities alongside with formal semantics. OWL includes three sublanguages: full OWL (OWL Full), OWL DL and facilitated OWL (OWL Lite) (are listed in decreasing order their expressive opportunities).

* The full version of ontologic language Web on basis OWL is called OWL Full. This language uses all basic elements of language OWL and allows to combine in their casual image with RDF and circuit RDF. Full OWL it is compatible " from below upwards " with RDF, both sintaksicheski, and semanticheski: any resolved{allowed} document RDF is also resolved{allowed} document OWL Full. It is improbable, that any intellectual software are capable to support all opportunities OWL Full as this language offers a maximum of expressive means and syntactic freedom RDF at absence of computing guarantees.

* OWL DL it is intended for those users for whom the maximum of expressive means without loss of computing opportunities is necessary. OWL DL is a sublanguage of designs of language OWL Full with some restrictions, such as division of types (type separation) (for example, the class cannot be simultaneously individual element or property, and property cannot simultaneously be an individual element or a class).

* OWL Lite it is intended for users for whom the classification hierarchy and simple restrictive opportunities is necessary. Advantage of this language are the big ease of his{its} understanding and introduction in comparison with two others. But at the same time his{its} expressive opportunities are much lower. For example, though OWL Lite also supports restrictions of capacity of set, unique allowable values of this parameter are 0 or 1.

Examples ontologij are catalogues of sites of interactive purchases, such as Amazon.com, standard terminology of this or that sphere of activity, for example, UNSPSC - The United Nations Standard Products and Services Code (system of standard products and services of the United Nations), or various taksonomicheskie systems of the Internet, such as categories of a site " My Yahoo ".

In the following sections it will be more in detail told about various components OWL.

Components of ontologic language Web on basis OWL

Basic components OWL include classes, properties and individual elements.

Classes

Classes are mainframes ontologii OWL. The class is a concept in the domain. Classes usually form taksonomicheskuju hierarchy (i.e. system a subclass - nadklass).

Classes are defined{determined} with the help of an element owl:Class. In language OWL exists two beforehand certain classes: owl:Thing and owl:Nothing. First of them is most the general{common} and includes everything, the second is an empty class. Any class determined by the user, is a subclass of a class owl:Thing and nadklassom a class owl:Nothing. Examples of classes in the field of a banking can include classes the Bill (Account) or the Client (Customer).

In listing 2 the example of class OWL is submitted.

Listing 2. An example of class OWL

<owl:Class rdf:ID = "SavingsAccount">

<rdfs:subclassOf rdf:resource = " * Account "/>

</owl:Class>

The code in listing 2 specifies, that element SavingAccount is the class being a subclass of class Account.

OWL supports six basic ways of the description of classes. The most simple is a class with a name (named). Other types are classes of crossings (intersection), associations (union), additions (complement), restrictions (restrictions) and classes of transfers (enumerated). In listing 2 two of these ways of the description of classes are submitted: the class of restrictions defines{determines} SavingAccount as a subclass of a class with name Account. The link to a full package of specifications of classes W3C OWL it is possible to find Resources in section.

Properties

Properties include two basic categories:

* Properties of object (Object properties) which connect individual elements among themselves;

* Properties of types of the data (Datatype properties) which connect individual elements with values of types of the data, such as integers, numbers from a floating point and a line. For definition of types of data OWL uses circuit XML.

Property can include the domain and some area connected to it{him}. Any property gets in one of the following categories:

* Functional: for any object property can accept only one value (for example, age, growth or weight of the person);

* Back - functional: two various individual elements cannot have the same value. For example, at each person the unique number{room} of the bank bill or so-called SSN (social security number) 1;

* Symmetric: if property connects an element And with an element In from this it is possible to draw a conclusion, that it also connects an element In with A.Primery's element of symmetric properties include expressions such as " is the brother (sister) " or " same, as ";

* Transitive: if property connects an element And with an element In, and an element In with an element With it is possible to assume, that it also connects an element And with S.Naprimer's element if And is higher In, and In higher With And is higher With.

To classes and properties various restrictions can be applied. For example, restrictions of capacity of set specify number of communications{connections} in which the class or an individual element can participate.

The link to a full package of specifications W3C OWL it is possible to find Resources in section.

Individual elements

Individual elements are elements of classes; properties can connect them with each other. For example, individual element Smith can be described as an element belonging to class Person (individual). Property hasEmployer (has the employer) can connect it{him} with other individual element - Webify Solutions, specifying in such a manner that Smith works in company Webify Solutions.

In listing 3 the example of individual element OWL is resulted.

Listing 3. Individual element OWL

<owl:Thing rdf:about = "SmithAccount">

<rdfs:type = " * Account "/>

</owl:Class>

The element rdf:type is property RDF which connects an individual element with that class to which he belongs. Listing 3 specifies, that element SmithAccount belongs to type Account.

Value ontologii for business

IT-systems organize values with the help of relational models of the data, the flat files, object-oriented models or specially developed models of the data. From time to time, in connection with changes of business - requirements, there is a necessity of addition of new elements and communications{connections} for relational models of the data or object-oriented models.

Moreover, if the organization uses plural applications from various suppliers it is necessary to copy the same models in all databases of applications. For example, the bank offers a set of various products for service of various categories of clients. To the corporate client service on detection of swindle can be demanded, and to the usual consumer there are enough functionalities of interactive realization of bank operations with the help of the Internet. Usually the bank gets applications from several suppliers, but each of them repeats same the general{common} information - numbers{rooms} of bills, names of clients, etc. - in the database. As the organization adds new products for satisfaction of growing searches of business, the same surplus information is distributed on all corporation.

A lot of services is the general{common} for all applications, for example, viewing of bank transactions and electronic translations. Each of these services also is duplicated in a format inherent in this or that application that conducts to necessity of realization of dot integration.

If the bank accepts the approach based on ontologii he can collect and represent the general{common} information on products in neutral in relation to language to the form and save this information in central repositories. With the help such the general{common} adapted ontologii the organization can provide uniform standardized data presentation for all applications. Such standardized performance allows to take precisely the necessary information and without problems to carry out corporate integration as business - processes and various sources of the data can be connected ("mehppirovany") with each other to the help of the general{common} metamodel. Thus, communicating ontologija excludes necessity for dot integration and simplifies integration of applications, reducing redundancy of the data and providing the same semantic value for all applications that facilitates maintenance of functioning of bank and his{its} updating.

Advantages of semantic networks to the Internet

The Internet is largest of ever existing information repositories, and his{its} maintenance{contents} all time grows and is submitted in the diversified languages and practically in all fields of knowledge. But finally all becomes more difficult to find sense in all these contents. Search engines are capable to find the information containing certain words, but this information not always appears that is required. Any element always appears missed. Search is based on the maintenance{contents} of pages, but not on semantic value of this maintenance{contents} or the information on page.

As soon as the semantic Internet will be created, he will enable marking of the maintenance{contents} of the Internet, the description of each element of the information and maintenance of semantic value of these elements. Thus, search engines become more effective, than now, and users can find that information which is necessary for them. The organizations rendering various services, are capable to index them with special value. And users be able to operatively find these services, using software on the basis of the Internet and to use them for the advantage{benefit} or in a combination to other services.

Role and value of semantic technologies for SOA

In appropriate way to model and operate SOA (service - guided by architecture), corporate architects should support active performance of the services accessible to corporation. In particular, for revealing and the organization of the services, architects should use the best practices in modelling and association of services with use of the metadata, to transform business - logic to the metadata for dynamic association and to carry out management with the help of the metadata. Ontologija provides very powerful and floppy way for aggregation, visualization and normalization of this layer of services with the help of the metadata.

Ontologija is a network of concepts, communications{connections} and restrictions which provide a context for the data and information, and also for processes. Ontologija promotes improvement of detection of services, modelling, association, intermediary and semantic interaction of networks. She will improve for users ways of search, studying and interaction with complex{difficult} information spaces of the metadata. Business - ontologija is a formal specification of business - concepts and their interrelations which improves machine relationships of cause and effect and interactions. Business - ontologija connects systems, using the metadata, in many respects is similar to how the database unites the isolated data. Such abstraction provides flexibility and mobility as allows to change easily interfaces, and also to add new resources and users, and even in an operating time of system.

Semantics is the future service - guided of integration. Semantic technologies provide existence of the certain level of abstraction above existing IT-technologies. This level allows to carry out communication{connection} of the data, maintenances{contents} and processes between various kinds of business and isolated IT-structures. At last, from the point of view of interaction of people, semantic technologies add a new level of semantic portals which provide much more analytical, corresponding to a subject and a context of interaction, than what are accessible with the help of traditional dot approaches to the integration, used in information portals.

The conclusion

In given clause{article} the basic standards making technologies of semantic networks, and also the reasons inducing the organizations to use these technologies have been submitted. With the help of the given technologies of the organization can create the uniform unified data presentation in all applications that allows to find precisely the necessary information, simplifies corporate integration and integration SOA, reduces redundancy of the data and provides unity of semantic values in all applications. All this, in turn, facilitates development, support and updating of applications within the limits of corporation.