XML is an abbreviation which means Extensile Mark-up Language. It has been defined as “ A Text based meta linguistic communication, for the definition of computing machine linguistic communications which describe the Syntax and construction of informations ” [ 6 ]
The advantages of XML are that it has the ability to depict the construction of informations by itself. It can besides depict informations in tree formats and artworks, the information is besides portable. Though the major disadvantage is that due to transition of text it is slower to entree informations ; besides security jobs.
XML provides storage ( XML paperss ) Schemas, ( DTDs, XML Schemas, Relax NG ) question linguistic communications ( XQuery, Xpath, XQL, XML- QL, QUILT, e.t.c ) . programming interfaces ( SAX, DOM, JDOM )
The aim of XML is
XML database is used to hive away and recover XML paperss by utilizing the relational database system which is besides used for the same intent. There are 3 types of XML databases, these are explained below.
The construction of XML informations to be processed determines the pick of database to be used for an application. There are two categories of XML paperss which are: Data-centric XML paperss: These are paperss whose informations have a symmetrical construction like a relational database tabular array and are normally little sum of informations with less complex XML tickets, And Document-centric XML paperss: These are non so regular in construction and the information contains a mixture of XML tickets and text. The difference between these two is in their storage engineering.
1. Relational databases
These shop XML paperss in a relational database in the signifier of tabular arraies by tie ining each component of a tabular array with the component of another tabular array, there could be one or more tabular arraies that elements and properties. The XML paperss that are used for a peculiar database tabular array must fit the format.
2. XML-enabled databases
3. Native XML databases
Native XML databases store XML paperss, though non physically and they consist of an internal logical theoretical account that is based on XML. It supports XML question linguistic communications like XPATH or XQuery.
1.3 Storage OF XML DATA
For informations to be transferred from an XML papers to a database, the XML papers scheme ( DTD, XML Schemas, RELAX NG, etc. ) has to be mapped to the database scheme, the package for reassigning informations is so built on top of the function for informations transportation. XML query linguistic communications such as XPath and XQuery can besides be used by the package.
“ Several function techniques have been proposed for hive awaying XML paperss in level tabular arraies of relational databases. XML database systems store XML paperss in native storage directors. These systems relieve the processing from extra beds for mapping the logical informations to the physical layout, which finally slows down query processing, subtrees are besides stored in clustered physical pages, XML paperss are stored in pre-order traverse in order to constellate sub-elements together ” . [ 2 ]
1.4 XML Query Languages
“ XML question linguistic communications can be used over any XML papers. To utilize these with relational databases, the informations in the database must be modeled as XML, thereby leting questions over practical XML paperss. With XQuery, either a table-based function or an object-relational function can be used. If a table-based function is used, each tabular array is treated as a separate papers and joins between tabular arraies ( paperss ) are specified in the question itself, as in SQL. If an object relational
function is used, hierarchies of tabular arraies are treated as a individual papers and articulations are specified in the function.
With XPath, an object-relational function must be used to make questions across more than one tabular array. This is because XPath does non back up articulations across paperss. Therefore, if the table-based function was used, it would be possible to question merely one tabular array at a clip ” . [ 2 ]
1.5 XML Schema
The XML Schema is a particular XML linguistic communication that describes what a right papers may incorporate this helps to look into if a papers follows certain regulations or non and is a W3C recommendation. One of the advantages of XML Schema is that it provides assorted scope of datatypes that can be used, for illustration byte, int and float – twine types like twine, item, ID – day of the month and clip types – and types for hive awaying binary informations likes hexBinary. It can besides be used to declare user defined types and elements even from bing 1s.
Example of XML Schema
& lt ; ? xml version = ” 1.0 ” encoding = ” UTF -8 ” ? & gt ;
& lt ; xs: scheme xmlns: ten = ” hypertext transfer protocol // www.w3.org /2001/ XMLSchema “ & gt ;
& lt ; xs: component name = ” article “ & gt ;
& lt ; xs: complexType & gt ;
& lt ; xs: property name = ” rubric “ type = ” ten: twine “ / & gt ;
& lt ; xs: property name = ” writer “ type = ” ten: twine “ / & gt ;
& lt ; / ten: complexType & gt ;
& lt ; / ten: component & gt ;
& lt ; / ten: scheme & gt ;
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“ Augmented Reality ( AR ) allows the user to see the existent universe, with practical objects superimposed upon or composited with the existent universe. Therefore, AR supplements world, instead than wholly replacing it. Ideally, it would look to the user that the practical and existent objects coexisted in the same infinite. ” [ 10 ]
The chief characteristics of augmented world are that it is synergistic with existent clip, it registered in 3-D and lastly it combines the existent and practical.
Augmented Reality helps to better how the user Acts of the Apostless on existent life state of affairss and it besides influences his reading because there is a better apprehension when practical objects that ca n’t be seen with the physical eyes are displayed.
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Augmented world has a batch of advantages, its applications can be used in assorted facets of mundane life to function as ushers for an extra truth to the user because it allows a realistic interaction with the images generated in 3-D and in existent life.
Some illustrations of Fieldss where they are applicable are in Entertainment industry, where worlds are combined with practical backgrounds, in robot way planning, in note and visual image, in the nomadic industry where practical world gives direct aid to the user in several ways, so in the medical field where practical world is used by healthcare professionals for surgeries and in fabrication and fix, where the information contained in the user usher is displayed virtually for the user and so on. The potencies of Augmented world applications are virtually limitless
2.3 Data direction
“ Any important real-world application of Mobile augmented world will necessitate a big theoretical account of location referenced informations. While it may look that a natural attack is to develop application specific informations formats and direction schemes, it has been shown that such an attack really prevents reuse of the informations and finally produces extra complexness in developing and keeping the application. Therefore we developed a general theoretical account scheme and a 3-tier architecture to keep a cardinal informations shop and application particular reuse through dedicated transmutations ” . [ 7 ]
To incorporate the information from a assortment of beginnings, constructions of events and properties can be described in XML scheme, informations entree and distribution codification can besides be generated, XML can be used to depict the constituents of a particular scenario which are besides validated against the associated XML scheme. XML is a description platform that ‘s why it is chosen, since it is an unfastened and standardised Meta linguistic communication
ideally suited for hierarchal constructions. [ 4 ]
2.4 DATA MANIPULATION
First a theoretical account is defined for the informations format and the following measure is to feed the database by ascribing informations, so the information is structurally transformed and manipulated and in conclusion it is passed on to the user via the development of appropriate applications. [ 7 ]
“ The typical undertakings is to Import or extract information from beginning informations formats based on XML or other formats and map it to the informations theoretical account.
Non-XML beginning formats besides require the combination of an
appropriate parser with an XML generator to map the foreign ”
format to XML. [ 9 ]
2.5 THE Relationship
XML as the description platform for other linguistic communications, is a engineering is rather flexible that is why it is practically the most normally used for hive awaying informations particularly in the relational database direction systems ( RDMS ) which is a really effectual foundation for the execution of XML storage system.
Through the benefit of it ‘s flexibleness, the Augmented Reality 3D informations theoretical accounts are able to straight tie in with the elements of an XML construction due to the hierarchal model that exists in 3D informations theoretical accounts. The data definitions of Augmented Reality can so be separated by sphere and separately converted without disrupting the compatibility of the application, because of the flexibleness of XML engineering.
The ultimate final payment of XML is self description and systematic agreement through the usage of XML namespaces and XML scheme, there are besides a batch of package tools that can be used for analyzing and redacting XML paperss.
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