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GTECH 731 Lab Session 13 11/2/10

GTECH 731 Lab Session 13 11/2/10. Quiz 2 Review XML. XML – Introduction. XML = Extensible Markup Language Language for describing data in a simple, straight forward format Saved as text file; anything that reads ASCII text file can read XML

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GTECH 731 Lab Session 13 11/2/10

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  1. GTECH 731Lab Session 13 11/2/10 Quiz 2 Review XML

  2. XML – Introduction • XML = Extensible Markup Language • Language for describing data in a simple, straight forward format • Saved as text file; anything that reads ASCII text file can read XML • Allows documents and data to be read on many different platforms • Can save information from many applications including MS Word, Excel, Powerpoint, or CorelDraw as well as custom programs • XML is not a database • Is Markup language, not a programming language • Does not do anything • Only stores information in defined format • Can provide data to instruct or guide the logic of a program • XML specification http://www.xml.com/axml/testaxml.htm • Other links on class website

  3. XML – File Content • Basic unit of XML Data “element” • Stored as “text string” and “marked-up” with surrounding tags in human readable format • Never binary data in XML file • Markup tags describe document’s structure • Tag names describe data element purpose (i.e., date, name, person etc.) • Elements associated with other elements in hierarchical structure • Meta-Markup language that can have any number of tags unlike HTML that has fixed number of tags • “Extensible” because users can define tags for elements as they need them • Customizable and usable in many different domains (i.e., web sites, data interchange, vector graphics, real estate etc.) • “Grammar” regulates naming and placement of tags in documents • “Well-formed” XML documents follows proper grammar

  4. XML – Application • XML “Application” • Not executable programs in usual sense of “application” • Set of agreed-upon “tags” used by organization or group of individuals to enhance interoperability between users • XML being “Applied” in particular domain • Real estate agency uses program that saves data to XML files, and posts information to website • XML Application restricts data elements to those relevant to domain • Might include “house”, “address”, “bedrooms”, “eat-in-kitchen” etc. • Program will open and save XML files with only those agreed-upon tags • Markups for particular XML Application defined in “document type definition” or DTD • Lists all legal Markups for that domain • Specifies where and how Markups can be used in a document • Document might contain DTD itself or pointer to centrally located DTD

  5. XML – Accessing Files • Software packages use an XML “parser” to access XML documents • “system.xml” namespace in Visual Studio C# environment provides tools for saving and extracting information in XML documents • Information retrieved from XML document divided into “elements” and “attributes” and passed to calling program piece by piece • Parser reports errors when violation of XML rules detected or when document “instance” of XML Application does not match with DTD • Documents that match DTD are valid; those that don’t are invalid • Validity errors are not necessarily fatal and an application can continue to parse the XML file if desired • XML documents that are not “well-formed” produce fatal errors • Applications that might use XML parsers include... • Web browsers, word processors, database servers, drawing programs, spreadsheets etc.

  6. XML – File Format • Documents “Marked-up” with “start” and “end” tags • Start tags begin with a “less-than” sign “<” followed by the element name and end with a “greater-than” sign “>” <ElementName> • End tags begin with a “less-than” sign and a forward slash “</” followed by the element name and end with a “greater-than” sign “>” </ElementName> • Everything between the start tag and end tag mark an element’s content • The following simple XML document provides for a single element of type “person” with content “Alan Turing” <person> start tag Alan Turing element content </person> end tag

  7. XML – File Format (cont’d) • Elements can have “attributes” • “name-value” pairs defined within the start tag of an element • Name is separated from value with equal sign • In the following example, “born” and “died” are attributes of the element “person” <person born = “1912/06/23” died=“1954/06/07” > Alan Turing </person> • When do you use “attributes” vs “elements” to hold data? • Depends on the use of the information and personal preference • Some believe attributes should be metadata about element information • Others say its too difficult to what is data or metadata • No steadfast rules

  8. XML – File Format (cont’d) • XML documents are hierarchical trees with parent and child elements • All elements have exactly one parent except the root element that has no parent • Child element must be completely enclosed within a parent element start and end tags<person>root element (aka document element)<name>child of “person”; parent of “firstname” and “lastname”<firstname>Alan</firstname>child of “name”<lastname>Turing</lastname>child of “name”</name><profession>computer scientist</profession>child of “person”<profession>mathematician</profession>child of “person”<profession>cryptographer</profession>child of “person”</person>

  9. XML – File Format (cont’d) • Tree diagram of previous example person name profession profession profession firstname lastname computer scientist mathematician cryptographer Alan Turing Element Element Content

  10. XML – File Format (cont’d) • Elements can have both character data and child elements in “Mixed Content” elements • Character Only: <person>Alan Turing</person> • Child Elements Only: <name> <firstname>Alan</firstname> <lastname>Turing</lastname> </name> • Mixed Content: <sentence>My name is <name>Tony</name> and I live in <city>Ossining</city>.</sentence> • XML is case sensitive • <person> != <Person> != <PERSON> • Must close element with same name as it was opened with • <person> </person> OK • <person> </PERSON> not OK • Empty elements • Line Break: <br/> • Horizontal Rule: <hr/>

  11. XML – Name Rules • Rules for element and attribute names are the same • May contain ... • Standard English Alpha-numeric: A-Z, a-z, 0-9 • Non-English numbers and ideograms: ö, ç, ψ etc. • Punctuation characters: Underscore, Hyphen and Period • May not contain ... • Punctuation characters: Quotation marks, apostrophes, dollar signs, carets, percent symbols and semicolons • Colon is allowed but reserved for use in namespaces • White space of any kind such as space character, carriage return, line feed or non-breaking space • Can start with ... • Letters, ideograms or underscore • Not a number, hyphen or a period • There is no limit to name length

  12. XML – Entity References • “Entity References” are escape sequences to represent reserved characters within element content • Less-than sign “<” is always interpreted as the beginning of a tag • Use escape sequence &lt; to represent character within element content • Five predefined Entity References in XML include ... • Less-Than sign:&lt; • Ampersand: &amp; • Greater-Than sign: &gt; • Double Quotation: &quot; • Single Quotation or Apostrophe: &apos; • Only the &lt; (<) and &amp; (&) must be used instead of literal characters • &quot; and &apos;can be used when literal apostrophe or double quote might be mistaken for the ending of an attribute value

  13. XML – Declaration • XML documents should begin with an XML Declaration, but is optional • If document contains declaration, it must be first line in file • Includes name, version, encoding and standalone attributes <?xml version=“1.0” encoding=“US-ASCII” standalone=“yes”> • Version attribute • Always “1.0” as this is the most recent version • Encoding attribute • Provide name of encoding such as UTF-8 (8-bit Unicode Transformation Format), ASCII, ISO-8859_1 etc • Attribute is optional with UTF-8 as default • Standalone attribute • Refers to DTD location • If value is “yes”: Internal or no DTD • If value is “no”: external DTD is used • Optional attribute with default value of “no”

  14. XML File and Corresponding Image <tiObjectList> <Shape GeoType="FinalProject.tiPoint" Geometry="POINT (95 23)" ObjLineColor="Red" ObjLineThickness="1" ObjFillColor="" ObjSelected="False" /> <Shape GeoType="FinalProject.tiPoint" Geometry="POINT (97 56)" ObjLineColor="Red" ObjLineThickness="2" ObjFillColor="" ObjSelected="False" /> <Shape GeoType="FinalProject.tiPoint" Geometry="POINT (96 97)" ObjLineColor="Yellow" ObjLineThickness="3" ObjFillColor="" ObjSelected="False" /> <Shape GeoType="FinalProject.tiPoint" Geometry="POINT (92 140)" ObjLineColor="Yellow" ObjLineThickness="4" ObjFillColor="" ObjSelected="False" /> <Shape GeoType="FinalProject.tiPoint" Geometry="POINT (89 186)" ObjLineColor="Cyan" ObjLineThickness="5" ObjFillColor="" ObjSelected="False" /> <Shape GeoType="FinalProject.tiPoint" Geometry="POINT (89 227)" ObjLineColor="Magenta" ObjLineThickness="6" ObjFillColor="" ObjSelected="False" /> <Shape GeoType="FinalProject.tiPoint" Geometry="POINT (90 274)" ObjLineColor="Green" ObjLineThickness="7" ObjFillColor="" ObjSelected="False" /> <Shape GeoType="FinalProject.tiPoint" Geometry="POINT (90 322)" ObjLineColor="Green" ObjLineThickness="8" ObjFillColor="" ObjSelected="False" /> <Shape GeoType="FinalProject.tiPoint" Geometry="POINT (93 365)" ObjLineColor="Blue" ObjLineThickness="9" ObjFillColor="" ObjSelected="False" /> <Shape GeoType="FinalProject.tiPoint" Geometry="POINT (97 405)" ObjLineColor="Black" ObjLineThickness="10" ObjFillColor="" ObjSelected="False" /> <Shape GeoType="FinalProject.tiLineString" Geometry="LINESTRING (148 33, 196 132, 255 29, 319 133, 357 30)" ObjLineColor="Green" ObjLineThickness="8" ObjFillColor="" ObjSelected="False" /> <Shape GeoType="FinalProject.tiPolygon" Geometry="POLYGON ((180 287, 183 390, 399 401, 387 277, 276 220, 180 287))" ObjLineColor="Cyan" ObjLineThickness="4" ObjFillColor="Black" ObjSelected="False" /> </tiObjectList>

  15. XML File and Sample C# Code to Save File <tiObjectList> <Shape GeoType="FinalProject.tiPoint" Geometry="POINT (95 23)" ObjLineColor="Red" ObjLineThickness="1" ObjFillColor="" ObjSelected="False" /> <Shape GeoType="FinalProject.tiPoint" Geometry="POINT (97 56)" ObjLineColor="Red" ObjLineThickness="2" ObjFillColor="" ObjSelected="False" /> <Shape GeoType="FinalProject.tiPoint" Geometry="POINT (96 97)" ObjLineColor="Yellow" ObjLineThickness="3" ObjFillColor="" ObjSelected="False" /> <Shape GeoType="FinalProject.tiPoint" Geometry="POINT (92 140)" ObjLineColor="Yellow" ObjLineThickness="4" ObjFillColor="" ObjSelected="False" /> <Shape GeoType="FinalProject.tiPoint" Geometry="POINT (89 186)" ObjLineColor="Cyan" ObjLineThickness="5" ObjFillColor="" ObjSelected="False" /> <Shape GeoType="FinalProject.tiPoint" Geometry="POINT (89 227)" ObjLineColor="Magenta" ObjLineThickness="6" ObjFillColor="" ObjSelected="False" /> <Shape GeoType="FinalProject.tiPoint" Geometry="POINT (90 274)" ObjLineColor="Green" ObjLineThickness="7" ObjFillColor="" ObjSelected="False" /> <Shape GeoType="FinalProject.tiPoint" Geometry="POINT (90 322)" ObjLineColor="Green" ObjLineThickness="8" ObjFillColor="" ObjSelected="False" /> <Shape GeoType="FinalProject.tiPoint" Geometry="POINT (93 365)" ObjLineColor="Blue" ObjLineThickness="9" ObjFillColor="" ObjSelected="False" /> <Shape GeoType="FinalProject.tiPoint" Geometry="POINT (97 405)" ObjLineColor="Black" ObjLineThickness="10" ObjFillColor="" ObjSelected="False" /> <Shape GeoType="FinalProject.tiLineString" Geometry="LINESTRING (148 33, 196 132, 255 29, 319 133, 357 30)" ObjLineColor="Green" ObjLineThickness="8" ObjFillColor="" ObjSelected="False" /> <Shape GeoType="FinalProject.tiPolygon" Geometry="POLYGON ((180 287, 183 390, 399 401, 387 277, 276 220, 180 287))" ObjLineColor="Cyan" ObjLineThickness="4" ObjFillColor="Black" ObjSelected="False" /> </tiObjectList> usingSystem.Xml; // Required for Xml documents privatevoidsaveToolStripMenuItem_Click(object sender, EventArgs e) { SaveFileDialog saveFileDialog1 = newSaveFileDialog(); // Create a save file dialog XmlDocumentxmlDoc = newXmlDocument(); // Create an empty XML document if (saveFileDialog1.ShowDialog() == DialogResult.OK) // Show the dialog. If OK is clicked, // save the features to the selected file. { XmlElementelt = xmlDoc.CreateElement("tiObjectList"); // First, create a top-level element foreach (tiGeometry g in _tiGISObjectList._tiObjList) // Then go through each feature and create // a corresponding child element { XmlElementchildElt = xmlDoc.CreateElement("Shape"); // Shape will be the name of each element; childElt.SetAttribute("GeoType", g.GetType().ToString()); childElt.SetAttribute("Geometry", g.tiObject.ToText() ); childElt.SetAttribute("ObjLineColor", g.tiObjLineColor); // class, type, and geometry will be the attributes. childElt.SetAttribute("ObjLineThickness", g.tiObjLineThickness.ToString()); childElt.SetAttribute("ObjFillColor", g.tiObjFillColor); childElt.SetAttribute("ObjSelected", g.tiObjSelected.ToString()); elt.AppendChild(childElt); // Append the new element as a child element of the top-level element } xmlDoc.AppendChild(elt); // Append the top-level element to the document xmlDoc.Save(saveFileDialog1.FileName); // Write out the XML to a file. } saveFileDialog1.Dispose(); // Dispose of the save dialog object }

  16. Sample C# Code to Open File privatevoidopenToolStripMenuItem_Click(object sender, EventArgs e) { OpenFileDialog openFileDialog1 = newOpenFileDialog(); // Create a open file dialog XmlDocumentxmlDoc = newXmlDocument(); // Create an empty XML document if (openFileDialog1.ShowDialog() == DialogResult.OK) // Show the dialog. If OK is clicked, // save the features to the selected file. { xmlDoc.Load(openFileDialog1.FileName); // Load the Xml document from the given file. XmlElementelt = xmlDoc.DocumentElement; // get top-level element _tiGISObjectList._tiObjList.Clear(); // clear out current object list foreach (XmlElementchildEltinelt.ChildNodes) // go through XML child elements & add // a corresponding geometry { StringtempGeoType = childElt.GetAttribute("GeoType"); StringtempGeo = childElt.GetAttribute("Geometry"); StringtempObjCol = childElt.GetAttribute("ObjLineColor"); StringtempObjLineThickness = childElt.GetAttribute("ObjLineThickness"); StringtempObjFillCol = childElt.GetAttribute("ObjFillColor"); StringtempSelected = childElt.GetAttribute("ObjSelected"); switch (tempGeoType) { case"FinalProject.tiPoint": { _tiGISObjectList._tiObjList.Add(newtiPoint(tempObjCol,Convert.ToInt16(tempObjLineThickness),tempGeo)); _tiGISObjectList._tiObjList[_tiGISObjectList._tiObjList.Count - 1].tiObjSelected = Convert.ToBoolean(tempSelected); break; } case"FinalProject.tiLineString": { _tiGISObjectList._tiObjList.Add(newtiLineString(tempObjCol,Convert.ToInt16(tempObjLineThickness), tempGeo)); _tiGISObjectList._tiObjList[_tiGISObjectList._tiObjList.Count - 1].tiObjSelected = Convert.ToBoolean(tempSelected); break; } case"FinalProject.tiPolygon": { _tiGISObjectList._tiObjList.Add(newtiPolygon (tempObjCol, tempObjFillCol,Convert.ToInt16(tempObjLineThickness), tempGeo)); _tiGISObjectList._tiObjList[_tiGISObjectList._tiObjList.Count - 1].tiObjSelected = Convert.ToBoolean(tempSelected); break; } } } } openFileDialog1.Dispose(); // Dispose of the open dialog object tiPictureBox.Refresh(); //redraw scene }

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