DOCSLIB.ORG

Xlink:Href="Index.Xml#R102"

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Xlink:Href= DOM and XPath J. Schneeberger University of Applied Sciences Deggendorf [email protected] 1 Overview • DOM – Document Object Model • XPath – step and location path – axis – other concepts – node types, abbreviations, and data types – Functions • XLink and XPointer 2 DOM / XPath / XQuery • idea: uniform query language for parts of XML trees • DOM – first implementation in Netscape 2 – different in different browsers – standard by W3C – platform independent • XPath – Version 1: 1999 – Version 2 draft: 2004 – Version 2 standard: 2007 – Version 2 is supported by a few tools only 3 DOM Document Object Model Document Object Model (DOM) • W3C spezification • facilitates the XML/HTML documents tree structure • programming interface (API) in JavaScript for HTML and XML documents – Core DOM – base model for HTML and XML documents – XML DOM – model for XML documents – HTML DOM – model for HTML documents DOM nodes • the whole document is a node • each XML element is a node • the text within an XML element is a node • each attribute is an (attribute) node • comments are (comment) nodes 6 JavaScript DOM (Netscape) 7 In JavaScript / Browser • Load an XML file var xmlDoc; xmlDoc=new window.XMLHttpRequest(); xmlDoc.open("GET","books.xml",false); xmlDoc.send(""); • Load an XML string try { //Internet Explorer xmlDoc=new ActiveXObject("Microsoft.XMLDOM"); xmlDoc.async="false"; xmlDoc.loadXML(txt); return xmlDoc; } catch(e) { parser=new DOMParser(); xmlDoc=parser.parseFromString(txt,"text/xml"); return xmlDoc; } 8 DOM: properties and methods • Examples for properties – if x is a node: – x.nodeName – the name x – x.nodeValue – the value of x – x.parentNode – the parent node of x – x.childNodes – the child node of x – x.attributes – the attribute node of x • Examples of methods: – x.getElementsByTagName(name) returns all elements with name name – x.appendChild(node) inserts a child node below x – x.removeChild(node) removes a child node from x 9 Another JavaScript example txt = xmlDoc.getElementsByTagName("title")[0].childNodes[0].nodeValue • xmlDoc the dom node generated by the parser • getElementsByTagName("title")[0] the first element from the array of all <title> elements • childNodes[0] the first element in the array of child nodes • nodeValue the value of a node (e.g. some text) 10 Accessing DOM nodes • by getElementsByTagName() • Traversing the dom tree • Navigating the tree using the node relations 11 Event handler • A lot of HTML elemnts can be accessed by event handler – e.g: onAbort, onClick, onFocus, onLoad, onMouseover, onSelect, onSubmit, etc. • Event handlers may specify JavaScript expressions which are evaluated when the specified event occurs. • The evaluation order of event handlers may be tricky – e.g. if a button specifies all of the following: onClick, onFocus, onMouseover, onSubmit 12 Firefox DOM Inspector G. Görz, FAU, Informatik 8 G. Görz, FAU, Informatik 8 DOM specifications • Level 1: Core – HTML and XML document model – navigation in trees, tree modifications • Level 2: Style Sheet – change of format specs at tree nodes – event handler – functions for interaction – XML namespaces • Level 3: – load and save of documents – DTD and Schema support – views and formatting • Further Levels: windows and interaction [http://xml.coverpages.org/dom.html] 16 XPath Overview • DOM – Document Object Model • XPath – step and location path – axis – other concepts – node types, abbreviations, and data types – Functions • XLink and XPointer 18 Source • Parts from: Anders Møller, Michael I. Schwartzbach “An Introduction to XML and Web Technologies” Addison-Wesley, January 2006 • http://www.brics.dk/ixwt/ 19 What is XPath? • a notation to describe parts of trees • to navigate in trees • Is used by: – XSLT – programming language to transform XML – XML Schema (to define the uniqueness and the scope of elements) – XLink and XPointer 20 XPath • combination of path expressions (like those of a command shell) and simple programming language expressions – *.xml – all files with the extension “.xml“ – eg.: /body/table[@border="1"] • XSLT style sheets use XPath expressions in match and select elements <xsl:template match="/"> <xsl:value-of select="."> <xsl:apply-templates select="/recipe/incredients/item"> 21 Spaghetti <recipe> <title>Spaghetti Carbonara</title> <incredients> <item weight="250g">spaghetti</item> <item weight="10g">butter</item> <item amount="3">egg</item> <item>garlic</item> </incredients> <preparation> Spaghetti carbonara is the classical .. <preparation/> <info> <difficulty>2</difficulty> <duration min="20" work="preparation"/> <duration min="20" work="total"/> </info> </recipe> 22 ... as XML tree recipe title incredients preparation info Spaghetti item item item item Spaghetti difficulty duration duration Carbonara Carbonara is.. .. weight Spaghetti weight butter amount eggs garlic 2 min work min work 250g 10g 3 20 prep.. 20 total 23 Location Path / Step 24 Location Path (1) • two kinds of location paths • relative path – one or more steps (from left to right), connected by “/“ – each step selects a set of nodes – relative to the context (i.e. the start node) – each node of this set is in the context for the next step – multiple result sets of a step are combined (set union). • absolute path – an absolute path consists of “/“ followed by a relative path – the “/“ absolute path selects the root node [http://www.w3.org/TR/xpath#location-paths] 25 Location Path (2) • a location path – evaluates to a sequence of nodes – the sequence is sorted in document order – the sequence will never contain duplicates • general form: step1 / step2 / ... / stepN 26 Evaluating a Location Path • A step maps a context node into a sequence • ƒThis also maps sequences to sequences – each node is used as context node – and is replaced with the result of applying the step • ƒ The path then applies each step in turn. 27 Example context descendant::C A B B C C D E E E F C E E E F F 28 Example descendant::C/child::E A B B C C D E E E F C E E E F F 29 Example descendant::C/child::E/child::F context A B B step 1 C C D step 2 E E E F C E E E F step 3 / result F 30 Context • The context of an XPath evaluation consists of – a context node (a node in an XML tree) – a context position and size (two nonnegative integers) – a set of variable bindings – a function library – a set of namespace declarations • ƒThe application determines the initial context • If the path starts with ‘/’ then – the initial context node is the root – the initial position and size are 1 31 XPath data model • Starting point is the XML Information Set (Infoset). I.e. the information found in a valid and parsed XML document. • In addition, the following holds for XPath: – All data types of XML Schema are supported. (complex and simple types). – Collection elements and complex values. – Typed atomic values. – Ordered and heterogeneous sequences. • http://www.w3.org/TR/xpath-datamodel/ 32 Location Step • The location path is a sequence of steps • A location step consists of – an axis – a node test – some predicates axis :: nodetest [expr1] [expr2] 33 Axis 34 Axis • An axis is a sequence of nodes • An axis is evaluated relative to a context • XPath names 12 axis: child parent self attribute ancestor descendant ancestor-or-self descendant-or-self preceding-sibling following-sibling preceding following 35 Axis Direction • Each Axis has a direction • forward – in document orientation – child, descendant, following-sibling, following, self, descendant-or-self • backward – inverse document orientation – parent, ancestor, preceding-sibling, preceding • without direction – depends on the implementation – attribute 36 parent axis A B B C C D E E E F C E E E F F 37 child axis A B B C C D E E E F C E E E F F 38 descendant axis A B B C C D E E E F C E E E F F 39 ancestor axis A B B C C D E E E F C E E E F F 40 following-sibling axis A B B C C D E E E F C E E E F F 41 preceding-sibling axis A B B C C D E E E F C E E E F F 42 following axis A B B C C D E E E F C E E E F F 43 preceding axis A B B C C D E E E F C E E E F F 44 axis ancestor self preceding following descendant 45 axis ancestor following-sibling self preceding-sibling preceding following descendant 46 Node Types, Abbreviations, and Data Types 47 Node Types • Element node – a node in the tree that corresponds to an element. • text node – text in the XML tree with no further subelements • attribute node – represents an attribute (with name and value) 48 Node Test node test selection text() a text node comment() a comment node <!-- --> processing- <? ... > instruction() node() All elements enclosed by tags and also nodes consisting of text (between elements). * elements with arbitrary names QName elements with a qualifying name *:NCName elements with an arbitrary namespace and a qualifying name NCName:* elements with a qualifying namespace and an arbitrary name 49 Abbreviations for XPath expressions • attributes: @ • the context: . • the parent context: .. • the descendent axis: // • the child axis: (... by omission) 50 Abbreviations [http://www.brics.dk/ixwt/] 51 More Examples Abbreviation Long form * child::element() text() child::text() @maker attribute::maker @* attribute::* x//y child::x/descendant::y . self::node() .. parent::node() ../@maker parent::node()/attribute::maker car[5] child::car[position()=5] car[@maker="US"] child::car/self::node()[maker="US"] car[milage] child::car/self::node()[child::milage] 52 Atomization • A sequence may be atomized • This results in a sequence of atomic values • For element nodes this
Load more

Recommended publications
  • Describing Media Content of Binary Data in XML W3C Working Group Note 2 May 2005
    Table of Contents Describing Media Content of Binary Data in XML W3C Working Group Note 2 May 2005 This version: http://www.w3.org/TR/2005/NOTE-xml-media-types-20050502 Latest version: http://www.w3.org/TR/xml-media-types Previous version: http://www.w3.org/TR/2004/WD-xml-media-types-20041102 Editors: Anish Karmarkar, Oracle Ümit Yalç&#305;nalp, SAP (formerly of Oracle) Copyright © 2005 W3C ® (MIT, ERCIM, Keio), All Rights Reserved. W3C liability, trademark and document use rules apply. > >Abstract This document addresses the need to indicate the content-type associated with binary element content in an XML document and the need to specify, in XML Schema, the expected content-type(s) associated with binary element content. It is expected that the additional information about the content-type will be used for optimizing the handling of binary data that is part of a Web services message. Status of this Document This section describes the status of this document at the time of its publication. Other documents may supersede this document. A list of current W3C publications and the latest revision of this technical report can be found in the W3C technical reports index at http://www.w3.org/TR/. This document is a W3C Working Group Note. This document includes the resolution of the comments received on the Last Call Working Draft previously published. The comments on this document and their resolution can be found in the Web Services Description Working Group’s issues list and in the section C Change Log [p.11] . A diff-marked version against the previous version of this document is available.
    [Show full text]
  • XML Specifications Growth of the Web
    Web Services Standards Overview Dependencies Messaging Specifications SOAP 1.1 SOAP 1.2 Interoperability Business Process Specifications Management Specifications Presentation SOAP Message Transmission Optimization Mechanism WS-Notification the trademarks of their respective owners. of their respective the trademarks Management Using Web Management Of WS-BaseNotification Issues Business Process Execution WS-Choreography Model Web Service Choreography Web Service Choreography WS-Management Specifications Services (WSDM-MUWS) Web Services (WSDM-MOWS) Language for Web Services 1.1 Overview Interface Description Language AMD, Dell, Intel, Microsoft and Sun WS-Topics (BPEL4WS) · 1.1 · BEA Systems, IBM, (WSCI) · 1.0 · W3C 1.0 1.0 1.0 · W3C (CDL4WS) · 1.0 · W3C Microsystems Microsoft, SAP, Sun Microsystems, SAP, BEA Systems WS-BrokeredNotification Working Draft Candidate Recommendation OASIS OASIS Published Specification Web Services for Remote Security Resource Basic Profile Siebel Systems · OASIS-Standard and Intalio · Note OASIS-Standard OASIS-Standard Metadata Portlets (WSRP) WS-Addressing – Core 1.1 ̆ ̆ ̆ ̆ ̆ ̆ ̆ 2.0 WS-I Business Process Execution Language for Web Services WS-Choreography Model Overview defines the format Web Service Choreography Interface (WSCI) describes Web Service Choreography Description Language Web Service Distributed Management: Management Using Web Service Distributed Management: Management Of WS-Management describes a general SOAP-based WS-Addressing – WSDL Binding 1.1(BPEL4WS) provides a language for the formal
    [Show full text]
  • What Is XML Schema?
    72076_FM 3/22/02 10:39 AM Page i XML Schema Essentials R. Allen Wyke Andrew Watt Wiley Computer Publishing John Wiley & Sons, Inc. 72076_AppB 3/22/02 10:47 AM Page 378 72076_FM 3/22/02 10:39 AM Page i XML Schema Essentials R. Allen Wyke Andrew Watt Wiley Computer Publishing John Wiley & Sons, Inc. 72076_FM 3/22/02 10:39 AM Page ii Publisher: Robert Ipsen Editor: Cary Sullivan Developmental Editor: Scott Amerman Associate Managing Editor: Penny Linskey Associate New Media Editor: Brian Snapp Text Design & Composition: D&G Limited, LLC Designations used by companies to distinguish their products are often claimed as trademarks. In all instances where John Wiley & Sons, Inc., is aware of a claim, the product names appear in initial capital or ALL CAPITAL LETTERS. Readers, however, should contact the appropriate companies for more complete information regarding trademarks and registration. This book is printed on acid-free paper. Copyright © 2002 by R. Allen Wyke and Andrew Watt. All rights reserved. Published by John Wiley & Sons, Inc. Published simultaneously in Canada. No part of this publication may be reproduced, stored in a retrieval system or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, scanning or otherwise, except as permitted under Sections 107 or 108 of the 1976 United States Copy- right Act, without either the prior written permission of the Publisher, or authorization through payment of the appropriate per-copy fee to the Copyright Clearance Center, 222 Rosewood Drive, Danvers, MA 01923, (978) 750-8400, fax (978) 750-4744. Requests to the Publisher for permission should be addressed to the Permissions Department, John Wiley & Sons, Inc., 605 Third Avenue, New York, NY 10158-0012, (212) 850-6011, fax (212) 850- 6008, E-Mail: PERMREQ @ WILEY.COM.
    [Show full text]
  • Command Injection in XML Signatures and Encryption Bradley W
    Command Injection in XML Signatures and Encryption Bradley W. Hill Information Security Partners, July 12, 2007 [email protected] Abstract. The XML Digital Signature1 (XMLDSIG) and XML Encryption2 (XMLENC) standards are complex protocols for securing XML and other content. Among its complexities, the XMLDSIG standard specifies various “Transform” algorithms to identify, manipulate and canonicalize signed content and key material. Unfortunately, the defined transforms have not been rigorously constrained to prevent their use as attack vectors, and denial of service or even arbitrary code execution are probable in implementations that have not specifically guarded against such risks. Attacks against the processing application can be embedded in the KeyInfo portion of a signature, making them inherently unauthenticated, or in the SignedInfo block. Although tampering with the SignedInfo should be detectable, a defective implied order of operations in the specification may still allow unauthenticated attacks here. The ability to execute arbitrary code and perform file system operations with a malicious, invalid signature has been confirmed by the researcher in at least two independent XMLDSIG implementations, and other implementations may be similarly vulnerable. This paper describes the vulnerabilities in detail and offers advice for remediation. The most damaging attack is also likely to apply in other contexts where XSLT is accepted as input, and should be considered by all implementers of complex XML processing systems. Categories and Subject Descriptors Primary Classification: K.6.5 Security and Protection Subject: Invasive software Unauthorized access Authentication Additional Classification: D.2.3 Coding Tools and Techniques (REVISED) Subject: Standards D.2.1 Requirements/Specifications (D.3.1) Subject: Languages Tools General Terms: Security, Reliability, Verification, and Design.
    [Show full text]
  • Describing Media Content of Binary Data in XML W3C Working Group Note 4 May 2005
    Table of Contents Describing Media Content of Binary Data in XML W3C Working Group Note 4 May 2005 This version: http://www.w3.org/TR/2005/NOTE-xml-media-types-20050504 Latest version: http://www.w3.org/TR/xml-media-types Previous version: http://www.w3.org/TR/2005/NOTE-xml-media-types-20050502 Editors: Anish Karmarkar, Oracle Ümit Yalç&#305;nalp, SAP Copyright © 2005 W3C ® (MIT, ERCIM, Keio), All Rights Reserved. W3C liability, trademark and document use rules apply. > >Abstract This document addresses the need to indicate the content-type associated with binary element content in an XML document and the need to specify, in XML Schema, the expected content-type(s) associated with binary element content. It is expected that the additional information about the content-type will be used for optimizing the handling of binary data that is part of a Web services message. Status of this Document This section describes the status of this document at the time of its publication. Other documents may supersede this document. A list of current W3C publications and the latest revision of this technical report can be found in the W3C technical reports index at http://www.w3.org/TR/. This document is a W3C Working Group Note. This document includes the resolution of the comments received on the Last Call Working Draft previously published. The comments on this document and their resolution can be found in the Web Services Description Working Group’s issues list. There is no technical difference between this document and the 2 May 2005 version; the acknowledgement section has been updated to thank external contributors.
    [Show full text]
  • XML Information Set
    XML Information Set XML Information Set W3C Recommendation 24 October 2001 This version: http://www.w3.org/TR/2001/REC-xml-infoset-20011024 Latest version: http://www.w3.org/TR/xml-infoset Previous version: http://www.w3.org/TR/2001/PR-xml-infoset-20010810 Editors: John Cowan, [email protected] Richard Tobin, [email protected] Copyright ©1999, 2000, 2001 W3C® (MIT, INRIA, Keio), All Rights Reserved. W3C liability, trademark, document use and software licensing rules apply. Abstract This specification provides a set of definitions for use in other specifications that need to refer to the information in an XML document. Status of this Document This section describes the status of this document at the time of its publication. Other documents may supersede this document. The latest status of this document series is maintained at the W3C. This is the W3C Recommendation of the XML Information Set. This document has been reviewed by W3C Members and other interested parties and has been endorsed by the Director as a W3C Recommendation. It is a stable document and may be used as reference material or cited as a normative reference from another document. W3C's role in making the Recommendation is to draw attention to the specification and to promote its widespread deployment. This enhances the functionality and interoperability of the file:///C|/Documents%20and%20Settings/immdca01/Desktop/xml-infoset.html (1 of 16) [8/12/2002 10:38:58 AM] XML Information Set Web. This document has been produced by the W3C XML Core Working Group as part of the XML Activity in the W3C Architecture Domain.
    [Show full text]
  • 5241 Index 0939-0964.Qxd 29/08/02 5.30 Pm Page 941
    5241_index_0939-0964.qxd 29/08/02 5.30 pm Page 941 INDEX 941 5241_index_0939-0964.qxd 29/08/02 5.30 pm Page 942 Index 942 Regular A Alternatives, 362 Analysis Patterns: Reusable Expression ABSENT value, 67 Object Models, 521 Symbols abstract attribute, 62, 64–66 ancestor (XPath axis), 54 of complexType element, ancestor-or-self (XPath axis), . escape character, 368, 369 247–248, 512, 719 54 . metacharacter, 361 of element element, 148–149 Annotation, 82 ? metacharacter, 361, 375 mapping to object-oriented defined, 390 ( metacharacter, 361 language, 513–514 mapping to object-oriented ) metacharacter, 361 Abstract language, 521 { metacharacter, 361 attribute type, 934 Microsoft use of term, } metacharacter, 361 defined, 58 821–822 + metacharacter, 361, 375 element type, 16, 17, 18, 934 properties of, 411 * metacharacter, 361, 375 object, corresponding to docu- annotation content option ^ metacharacter, 379 ment, 14 for schema element, 115 \ metacharacter, 361 uses of term, 238, 931–932 annotation element, 82, 83, | metacharacter, 361 Abstract character, 67 254, 260, 722, 859 \. escape character, 366 Abstract document attributes of, 118 \? escape character, 366 document information item content options for, 118–119 \( escape character, 367 view of, 62 example of use of, 117 \) escape character, 367 infoset view of, 62 function of, 116, 124, 128 \{ escape character, 367 makeup of, 59 nested, 83–84 \} escape character, 367 properties of, 66 Anonymous component, 82 \+ escape character, 367 Abstract element, 14–15 any element, 859 \- escape character,
    [Show full text]
  • SWAD-Europe Deliverable 5.1: Schema Technology Survey
    Sat Jun 05 2004 23:47:40 Europe/London SWAD-Europe Deliverable 5.1: Schema Technology Survey Project name: Semantic Web Advanced Development for Europe (SWAD-Europe) Project Number: IST-2001-34732 Workpackage name: 5. Integration with XML Technology Workpackage description: ☞http://www.w3.org/2001/sw/Europe/plan/workpackages/live/esw-wp-5.html Deliverable title: SWAD-Europe: Schema Technology Survey URI: ☞http://www.w3.org/2001/sw/Europe/reports/xml_schema_tools_techniques_report Authors: Stephen Buswell, Dan Brickley, Brian Matthews Abstract: This report surveys the state of schema annotation and mapping technology. It takes a practical approach by targeting the work to the needs of developers, providing background to support our attempts to answer frequently asked questions on this subject. The report first reviews previous work on 'bridging languages', giving an overview of the major approaches and uses that to motivate further technical work to progress the state of the art in this area. Status: Snapshot release for discussion and editorial work. Further revisions are planned during WP4. Comments on this document are welcome and should be sent to the ☞[email protected] list. An archive of this list is available at ☞http://lists.w3.org/Archives/Public/public-esw/ This report is part of ☞SWAD-Europe ☞Work package 5: Integration with XML Technology and addresses the topic of Schema annotation, and the relationship(s) between RDF and XML technologies. The variety of so-called 'schema languages' for the Web has caused some confusion. This document attempts to place them in context, and explore the state of the art in tools for mapping data between the different approaches.
    [Show full text]
  • XML Tutorial Description
    Introduction to XML Tutorial Description With your HTML knowledge, you have a solid foundation for working with markup languages. However, unlike HTML, XML is more flexible, Bebo White allowing for custom tag creation. This course [email protected] introduces the fundamentals of XML and its related technologies so that you can create your own markup language. InterLab 2006 FermiLab October 2006 Topics* What Is Markup? • XML well-formed documents • Information added to a text to make its structure • Validation concepts comprehensible • DTD syntax and constructs • Pre-computer markup (punctuational and presentational) • W3C Schema syntax and constructs • Word divisions • XSL(T) syntax and processing • Punctuation • XPath addressing language • Copy-editor and typesetters marks • Development and design considerations • Formatting conventions • XML processing model • XML development and processing tools * Tutorial plus references Computer Markup (1/3) Computer Markup (2/3) • Any kind of codes added to a document • Declarative markup (cont) • Typesetting (presentational markup) • Names and structure • Macros embedded in ASCII • Framework for indirection • Commands to define the layout • Finer level of detail (most human-legible signals are • MS Word, TeX, RTF, Scribe, Script, nroff, etc. overloaded) • *Hello* Æ Hello • Independent of presentation (abstract) ••/Hello//Hello/ Æ Hello • Often called “semantic” • Declarative markup • HTML (sometimes) ••XMLXML Computer Markup (3/3) Markup – ISO-Definitions • Semantic Markup • Markup – Text
    [Show full text]
  • Exploring the XML World
    Lars Strandén SP Swedish National Testing and Research Institute develops and transfers Exploring the XML World technology for improving competitiveness and quality in industry, and for safety, conservation of resources and good environment in society as a whole. With - A survey for dependable systems Swedens widest and most sophisticated range of equipment and expertise for technical investigation, measurement, testing and certfi cation, we perform research and development in close liaison with universities, institutes of technology and international partners. SP is a EU-notifi ed body and accredited test laboratory. Our headquarters are in Borås, in the west part of Sweden. SP Swedish National Testing and Research Institute SP Swedish National Testing SP Electronics SP REPORT 2004:04 ISBN 91-7848-976-8 ISSN 0284-5172 SP Swedish National Testing and Research Institute Box 857 SE-501 15 BORÅS, SWEDEN Telephone: + 46 33 16 50 00, Telefax: +46 33 13 55 02 SP Electronics E-mail: [email protected], Internet: www.sp.se SP REPORT 2004:04 Lars Strandén Exploring the XML World - A survey for dependable systems 2 Abstract Exploring the XML World - A survey for dependable systems The report gives an overview of and an introduction to the XML world i.e. the definition of XML and how it can be applied. The content shall not be considered a development tutorial since this is better covered by books and information available on the Internet. Instead this report takes a top-down perspective and focuses on the possibilities when using XML e.g. concerning functionality, tools and supporting standards. Getting started with XML is very easy and the threshold is low.
    [Show full text]
  • Chapter 7 XML.Pptx
    Prof. Dr.-Ing. Stefan Deßloch AG Heterogene Informationssysteme Geb. 36, Raum 329 Tel. 0631/205 3275 [email protected] Chapter 7 - XML XML Origin and Usages n Defined by the WWW Consortium (W3C) n Originally intended as a document markup language, not a database language n Documents have tags giving extra information about sections of the document n For example: n <title> XML </title> n <slide> XML Origin and Usages </slide> n Meta-language: used to define arbitrary XML languages/vocabularies (e.g. XHTML) n Derived from SGML (Standard Generalized Markup Language) n standard for document description n enables document interchange in publishing, office, engineering, … n main idea: separate form from structure n XML is simpler to use than SGML n roughly 20% complexity achieves 80% functionality © Prof.Dr.-Ing. Stefan Deßloch XML Origin and Usages (cont.) n XML documents are to some extent self-describing n Tags represent metadata n Metadata and data are combined in the same document n semi-structured data modeling n Example <bank> <account> <account-number> A-101 </account-number> <branch-name> Downtown </branch-name> <balance> 500 </balance> </account> <depositor> <account-number> A-101 </account-number> <customer-name> Johnson </customer-name> </depositor> </bank> © Prof.Dr.-Ing. Stefan Deßloch Forces Driving XML n Document Processing n Goal: use document in various, evolving systems n structure – content – layout n grammar: markup vocabulary for mixed content n Data Bases and Data Exchange n Goal: data independence n structured, typed data – schema-driven – integrity constraints n Semi-structured Data and Information Integration n Goal: integrate autonomous data sources n data source schema not known in detail – schemata are dynamic n schema might be revealed through analysis only after data processing © Prof.Dr.-Ing.
    [Show full text]
  • Guidelines for the Use of Extensible Markup Language (XML) Within IETF Protocols
    Network Working Group S. Hollenbeck Request for Comments: 3470 VeriSign, Inc. BCP: 70 M. Rose Category: Best Current Practice Dover Beach Consulting, Inc. L. Masinter Adobe Systems Incorporated January 2003 Guidelines for the Use of Extensible Markup Language (XML) within IETF Protocols Status of this Memo This document specifies an Internet Best Current Practices for the Internet Community, and requests discussion and suggestions for improvements. Distribution of this memo is unlimited. Copyright Notice Copyright © The Internet Society (2003). All Rights Reserved. Abstract The Extensible Markup Language (XML) is a framework for structuring data. While it evolved from Standard Generalized Markup Language (SGML) -- a markup language primarily focused on structuring documents -- XML has evolved to be a widely-used mechanism for representing structured data. There are a wide variety of Internet protocols being developed; many have need for a representation for structured data relevant to their application. There has been much interest in the use of XML as a representation method. This document describes basic XML concepts, analyzes various alternatives in the use of XML, and provides guidelines for the use of XML within IETF standards-track protocols. Conventions Used In This Document This document recommends, as policy, what specifications for Internet protocols -- and, in particular, IETF standards track protocol documents -- should include as normative language within them. The capitalized keywords "SHOULD", "MUST", "REQUIRED", etc. are used in the sense of how they would be used within other documents with the meanings as specified in BCP 14, RFC 2119 [1]. RFC 3470 XML Within IETF Protocols January 2003 Table of Contents 1 Introduction and Overview....................................................................................................................................
    [Show full text]