Unit-V: XML
Introduction to XML, uses of XML, simple XML, XML key components, DTD and Schemas, Well formed, using XML with application.XML, XSL and XSLT. Introduction to XSL, XML transformed simple example, XSL elements, transforming with XSLT
Introduction to XML
XML stands for Extensible Markup Language. It is a markup language that is designed to store and transport data. Unlike HTML, which is primarily used for displaying content on web pages, XML is used to describe data and its structure.
XML uses tags to describe the data and its structure. These tags are similar to HTML tags, but whereas HTML tags describe how the content should be displayed, XML tags describe the data itself. XML tags can be customized to suit the needs of the user, and can be used to represent any type of data.
XML is often used in web development to transfer data between applications or systems. It is a platform-independent format, which means it can be used on any operating system or device. It is also human-readable, which makes it easy to understand and work with.
Overall, XML is a powerful tool for describing, storing, and transporting data in a flexible and customizable way.
uses of XML
XML (eXtensible Markup Language) has a wide range of uses in various fields such as:
Data exchange: XML is widely used for data exchange between different applications and platforms. This is because XML is a flexible and platform-independent language, which can be easily read by both humans and machines.
Web services: XML is used for creating web services that can be accessed over the internet. XML-based web services use standard protocols such as SOAP (Simple Object Access Protocol), WSDL (Web Services Description Language), and UDDI (Universal Description, Discovery and Integration) for communication.
Document management: XML is used for creating structured documents that can be easily searched, sorted, and filtered. This is because XML allows developers to define custom tags and attributes that can be used to describe the structure and content of the document.
Configuration files: XML is used for storing configuration data in many software applications. This is because XML allows developers to define custom tags and attributes that can be used to store and retrieve configuration data.
Database management: XML can be used to store and exchange data between databases. This is because XML provides a standard way of representing data that can be easily read and understood by different database management systems.
Electronic data interchange (EDI): XML is used for exchanging business data between different organizations. This is because XML allows developers to define custom tags and attributes that can be used to describe the structure and content of the business data.
simple XML
Simple XML, also known as Simple Object Access Protocol (SOAP), is a lightweight protocol for exchanging structured data between applications over the internet. It is based on the Extensible Markup Language (XML) and is designed to be platform and programming language independent. Simple XML uses XML to encode messages and supports a wide range of data types, making it a flexible and versatile protocol. It is commonly used in web services and other distributed computing applications.
XML key components,
The key components of XML are:
Tags: Tags are the building blocks of XML documents. They define the structure of the document and are enclosed in angle brackets (< >).
Attributes: Attributes provide additional information about an element. They are always specified within the start tag of an element.
Elements: Elements are the fundamental units of an XML document. They define the structure of the document and are made up of tags, attributes, and content.
Namespaces: Namespaces are used to avoid naming conflicts between elements and attributes. They allow the same name to be used in different contexts without ambiguity.
DTDs and XSDs: DTDs (Document Type Definitions) and XSDs (XML Schema Definitions) are used to define the structure and content of an XML document. They provide a set of rules that must be followed to create valid XML documents.
Processing instructions: Processing instructions are used to provide instructions to applications that process the XML document.
Comments: Comments provide a way to add information to an XML document that is not processed by the application. They are enclosed in <!-- -->.
DTD and Schemas
DTD (Document Type Definition) and XML Schema are two methods for defining the structure and content of an XML document.
DTD is a set of rules that defines the structure and elements of an XML document. It is used to validate XML documents against a specific set of rules. DTDs define the elements, attributes, and entities that can be used in an XML document, and the order in which they can appear. DTD is used to validate the structure of an XML document, ensuring that it conforms to the rules specified in the DTD.
XML Schema is an alternative to DTD that provides a more powerful and flexible way to define the structure and content of an XML document. XML Schema is written in XML and defines the data types, elements, and attributes that can be used in an XML document. XML Schema provides more precise control over the data that can be contained in an XML document and allows for more complex data structures and data types than DTD.
In summary, both DTD and XML Schema are used to define the structure and content of an XML document. DTD is simpler and easier to use, but provides less control and flexibility than XML Schema. XML Schema is more complex, but allows for more precise control over the structure and content of an XML document.
Well formed
In XML, a document is considered "well-formed" if it follows the syntax rules defined by the XML specification. These rules include:
The document must have only one root element
All elements must be properly nested (i.e., no overlapping elements)
All elements must have opening and closing tags
All attribute values must be enclosed in quotation marks
All tags must be in lowercase
If a document violates any of these rules, it is not considered well-formed and will not be valid according to XML standards.
using XML with application.XML
XML (Extensible Markup Language) is a popular data format used for exchanging data between applications over the internet. XML can be used with various applications like web services, databases, and programming languages. The following are some of the ways in which XML can be used with applications:
XML with Web Services: XML is widely used in web services to exchange data between different applications. Web services use XML to represent data in a standardized way, making it easier to share data between different platforms and programming languages.
XML with Databases: Many databases support the storage and retrieval of XML data. XML can be used to store data in a structured format in databases, making it easier to query and retrieve specific data.
XML with Programming Languages: XML can be used with programming languages like Java, C#, and Python. These languages provide APIs that can be used to parse and manipulate XML data.
XML with Content Management Systems (CMS): XML can be used with content management systems to store and manage structured data like articles, products, and categories.
In summary, XML can be used in a wide range of applications, and its flexibility makes it an ideal format for exchanging data between different systems and platforms.
.XML, XSL and XSLT
XML, XSL, and XSLT are all related technologies used for manipulating and transforming XML documents.
XML (Extensible Markup Language) is a markup language used for storing and exchanging structured data. XML documents contain both data and metadata, which describes the structure and format of the data.
XSL (Extensible Stylesheet Language) is a stylesheet language used for transforming XML documents into other formats, such as HTML, PDF, or plain text. XSL stylesheets define how the content of an XML document should be displayed or processed, including how to apply formatting, conditional logic, and data manipulation.
XSLT (XSL Transformations) is a language used for transforming XML documents into other XML documents or other formats using XSL stylesheets. XSLT is a declarative programming language that defines rules for transforming the structure and content of an XML document.
Together, these technologies enable developers to create, manipulate, and transform XML documents for a wide range of applications and use cases. For example, an XML document can be transformed into HTML for display in a web browser, or transformed into a different XML document for use in a different application or system.
Introduction to XSL, XML transformed simple example
XSL (eXtensible Stylesheet Language) is a language used to transform XML documents into other formats, such as HTML, XHTML, or plain text. XSL documents consist of two main components: the template rules for transforming the input document, and the output format in which the result will be generated.
To demonstrate a simple example of XML transformation using XSL, consider the following XML document representing a list of books:
xml
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<?xml version="1.0" encoding="UTF-8"?>
<library>
<book>
<title>The Catcher in the Rye</title>
<author>J.D. Salinger</author>
<year>1951</year>
</book>
<book>
<title>To Kill a Mockingbird</title>
<author>Harper Lee</author>
<year>1960</year>
</book>
</library>
Suppose we want to transform this XML document into an HTML table displaying the book titles, authors, and publication years. We can use an XSL document to specify the transformation rules:
xml
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<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:template match="/">
<html>
<body>
<h2>Book List</h2>
<table border="1">
<tr bgcolor="#9acd32">
<th>Title</th>
<th>Author</th>
<th>Year</th>
</tr>
<xsl:for-each select="library/book">
<tr>
<td><xsl:value-of select="title"/></td>
<td><xsl:value-of select="author"/></td>
<td><xsl:value-of select="year"/></td>
</tr>
</xsl:for-each>
</table>
</body>
</html>
</xsl:template>
</xsl:stylesheet>
In this XSL document, the xsl:template element specifies that the root node of the input document will be transformed into an HTML document. Within this template, we define an HTML table with a header row and a loop over each book element in the input document. For each book, we create a new row in the HTML table and populate the cells with the corresponding values for title, author, and year.
When we apply this XSL document to the XML document using an XSLT processor, the output will be an HTML document that looks like this:
html
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<html>
<body>
<h2>Book List</h2>
<table border="1">
<tr bgcolor="#9acd32">
<th>Title</th>
<th>Author</th>
<th>Year</th>
</tr>
<tr>
<td>The Catcher in the Rye</td>
<td>J.D. Salinger</td>
<td>1951</td>
</tr>
<tr>
<td>To Kill a Mockingbird</td>
<td>Harper Lee</td>
<td>1960</td>
</tr>
</table>
</body>
</html>
XSL elements
XSL (Extensible Stylesheet Language) is used to transform an XML document into a different output format, such as HTML or PDF. XSL is comprised of XSLT (XSL Transformations) and XPath. XSLT is a language used for transforming XML documents, while XPath is used to navigate XML documents and select specific elements and attributes.
XSLT uses a set of elements to define the transformation rules for an XML document. Some of the most commonly used XSL elements are:
xsl:stylesheet - This is the root element of an XSLT document and is used to define the namespace for the XSLT document.
xsl:template - This element defines a template for transforming a specific element in the XML document. It includes the match attribute, which specifies the element to be transformed.
xsl:value-of - This element is used to extract the value of an XML element and insert it into the output document.
xsl:if - This element is used to apply a condition to the transformation. It includes a test attribute that specifies the condition to be evaluated.
xsl:for-each - This element is used to iterate over a set of XML elements and apply the same transformation to each one.
xsl:apply-templates - This element is used to apply templates to the child elements of the current element being transformed.
xsl:attribute - This element is used to create an attribute in the output document.
xsl:choose - This element is used to specify a set of conditions and transformations to be applied based on the condition that is true.
These are just a few of the many XSL elements that can be used in an XSLT document. By using these elements and others, you can transform an XML document into the desired output format.
transforming with XSLT
XSLT stands for Extensible Stylesheet Language Transformations. It is a language for transforming XML documents into other formats, such as HTML or plain text, using XSLT stylesheets.
To transform an XML document using XSLT, a few steps need to be followed:
Create an XML document that contains the data you want to transform.
Create an XSLT stylesheet that defines how the XML data should be transformed.
Use a transformation tool to apply the stylesheet to the XML document.
Here's a simple example of an XSLT stylesheet that transforms an XML document:
xml
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<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:template match="/">
<html>
<body>
<xsl:apply-templates/>
</body>
</html>
</xsl:template>
<xsl:template match="person">
<h2>
<xsl:value-of select="@name"/>
</h2>
<p>
<xsl:value-of select="address"/>
</p>
</xsl:template>
</xsl:stylesheet>
This stylesheet has two templates. The first template matches the root element of the XML document and creates an HTML document with a body element. The second template matches the person element of the XML document and creates an HTML header element with the person's name and a paragraph element with their address.
When this stylesheet is applied to an XML document that looks like this:
xml
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<?xml version="1.0" encoding="UTF-8"?>
<people>
<person name="John Doe">
<address>123 Main St</address>
</person>
<person name="Jane Doe">
<address>456 Elm St</address>
</person>
</people>
The result will be an HTML document that looks like this:
css
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<html>
<body>
<h2>John Doe</h2>
<p>123 Main St</p>
<h2>Jane Doe</h2>
<p>456 Elm St</p>
</body>
</html>
This is just a simple example of how XSLT can be used to transform XML documents. XSLT provides many more features for manipulating and transforming XML data, including conditional processing, looping, and grouping.
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