Unit 3 WEB TECHNOLOGIES

NAME OF STAFF :S.SAYI PRIYASS
NAME OF STUDENT :K.TAMIL MOZHIYAL
REGISTER NUMBER :CB17S 250446
CLASS :III-BCA-B
BATCH :2017-2020
YEAR :2020
SUBJECT CODE :MCA511

WHAT IS WEB SERVICES
 “The World Wide Web is more and more used for application to
application communication.
The programmatic interfaces made available are referred to as Web
services”
A Web service is a software system designed to support interoperable
machine-to-machine interaction over a network.
It has an interface described in a machine- format processble
(specifically WSDL).
Other systems interact with the Web service in a manner prescribed
by its description using SOAP messages, typically conveyed using
HTTP with an XML serialization in conjunction with other Web-related
standards.”

INTRODUCATION
 Contemporary Service-Oriented Architectures (SOA)
represents an architecture that promotes service-orientation through the
use of Web services.
 All functions, or services, are defined using a description language
and have invokable interface that are called to perform business
processes.
• Client
• Third party system
• Legacy
• Resources
• Modern Moves

Web service example
A stock quote service.
An application requires the current value of a stock, the
web service returns it.
A route finder for delivery of goods.
Given an initial and a final location, find the most cost-
effective delivery route.
A weather service, a map service, a web search service…
any composition of Web services.

Dickson Chiu 2006 Web Service-5
UDDI
Registry WSDL
Web
Service
SOAP
Service
Consumer
Points to description
Describes
ServiceFinds
Service
Communicates with
XML Messages
SOA Technologies

Why web services for important
From business standpoint
– Integration
• Within an organization
• Between companies
• Allows time/cost efficiencies
– Purchase orders
– Answering inquiries
– Processing shipment requests
• Do this without locking in to a single partner.

Issues distributed computing
platform
Platform Dependency
Management and Optimization
What do 99,99% availability mean?
How can I guarantee 3 seconds response time?
Who owns the Log? Who owns the context?
Load Balancing, Caching, Replication?
Change a Process: All or Nothing
Whole system fails when a component is upgraded
Versioning, Schema Evolution while process runs

How do we send a Java double value to a web service
using XML?
Is scientific notation allowed?
 How large can the value be?
Etc.
What if we want to send an object?
And what if the object contains references to other
objects?

Web services enterprises
The emergence of Web services is transforming traditional
enterprises. However, the industry hype surrounding these
technologies obscures the understanding of their impact and
implications to enterprises.
 The challenges and opportunities they present, how they fit
into the enterprise stack, how they relate to the business and
IT layers of the enterprise, as well as the existing and
emerging standards and their relevance.

XML fundamentals XML
XML Fundamentals:
 In this first of three chapters in Part One, we start with a discussion
of the fundamentals of the extensible Markup Language (XML), the
basic technology on which Web services are based.
 From network protocols up the stack to back-end databases, XML
in all its forms has had a commoditizing effect on enterprise
computing systems and being both platform and language
independent is a natural choice for the level of interoperability
required of Web services.

XML fundamentals XML
What is XML?
XML stands for Extensible Markup Language.
XML is a markup language like HTML and not a
programming language.
It uses tags, just like HTML.
XML is not a replacement for HTML.
XML was created to transport or store data.
XML is very easy to learn compared to learn any
programming language.

Some XML History:
XML is an application profile of an ISO standard SGML,
and most of XML comes from SGML unchanged.
XML version 1.0 was defined in 1998. It had many minor
revisions since then XML 1.0 is the recommended version.
XML version 1.1 was published in February of 2004, the
same day as version 1.0’s third edition. 1.0 is generally
suggested over 1.1 unless the project needs specific features
of 1.1.
There have been discussions of an XML 2.0, although no
organization has announced plans for work on such a
project.

XML vs. HTML:
There is no comparison between HTML and XML.
 They are completely different and are used in different
situations.
XML is a Data Interchange Format; it’s a way to structure and
store data and also to transport data.
XML was created to transport and store data and is more
behind the scenes.XML has no pre-defined tags.
HTML is used to display data in a browser and focus on
physical presentation. HTML has pre-defined tags.

Document structure
In the XML file structure, the first line is the declaration that
contains the document information like version information,
character set, etc.
Declaration must come first in the document.
Every opening tag should have a closing tag.
Each XML document has a root element.
Root element contains the child elements which can in turn
have sub-child elements.
All the sub-child elements in a child element are called
the siblings of each other.
Attributes like gender=”male” can also be given to the tags.

WEB SERVICES:
XML is a standard for data mark-up backed by the
World Wide Web Consortium, which has been branded
"the universal format for structured documents and data
on the Web.“
The entire XML suite of standards, models, and
processing technologies have been under development
since 1998 with the initial XML specification, and has
since been augmented by several additional supporting
standards and notes that have brought XML to its current
rich state.
In fact, though XML is undeniably a richly specified
technology, it has retained its simplicity and the entire

XML is for Structuring Data:
 Structured data includes things like spreadsheets,
address books, configuration parameters, financial
transactions, and technical drawings.
XML is a set of rules for designing text formats that support
the developer in creating structured data. Though it vaguely
resembles source code, XML is not a programming language,
but it does make it easy for a computer to generate data, read
data, and ensure that the data structure is unambiguous.
XML avoids common pitfalls in language design. It is
extensible, platform-independent, supports internationalization
and localization, and is fully Unicode-compliant.

XML Resembles HTML:
o Like HTML, XML makes use of tags (words surrounded by
angle brackets, "<" and ">") and attributes (of the
form name="value"). While HTML specifies what each tag and
attribute means and often how the text between them will render in
a browser, XML uses the tags only to delimit pieces of data and
leaves the interpretation of the data completely to the application
that reads it.

XML is Human Readable, but Humans Shouldn't Read
It:
 Programs that produce structured data often store that data on
disk, using either a binary or text format. An advantage of a textual
format is that it allows people, if necessary, to look at the data without
the program that produced it, using tools like text editors.
XML files are text files that people shouldn't have to read, but may
read as and when the need arises. Care must be taken when manually
editing XML since its rules are strict.
The official XML specification forbids applications from trying to
second-guess the creator of a broken XML file; if the file is broken, an
application has to stop and report an error.

XML is Verbose:
 Since XML is a textual format and uses tags to delimit
the data, XML files are nearly always larger than
comparable binary formats. That was a conscious decision
by the designers of XML. The advantages of a text format
are evident, and the disadvantages can usually be
compensated at a different level by compression
applications.
XML is a Suite of Technologies:
 XML 1.0 is the specification that defines what "tags"
and "attributes" are. Beyond that specification, the XML
family is a growing set of modules that offer useful
services to accomplish important and frequently demanded
tasks.

XML is Modular:
XML allows you to define a new document format by combining and
reusing other formats. Since two formats developed independently may
have elements or attributes with the same name, care must be taken
when combining those formats.
To eliminate name confusion when combining formats, XML
provides a namespace mechanism that is supported in all XML-based
technologies.
XML is License-Free, Platform-Independent, and Well-
Supported:
Basing Web services on XML is similar to basing a database strategy
on SQL you still have to build your own database, programs, and
procedures that manipulate it, but there are many tools and commodity
components available to help. since XML is license-free, Web services
can be built without incurring royalty payments.

What is namespaces:
•As an example, let's assume we have an RDB with a table of the
following structure (employee Table, section Table). What kind of
SQL statement would you create to obtain a list of Employee ID,
Employee Department Name, and Employee Name? If we merged
employee Table and section Table with the sec ID column, then we
would be able to obtain a list of employee IDs, employee departments
and employee names. However, since the name column and sec ID
column exist in both tables, we would have to designate the table name
before the name and sec ID columns, or designate the alias of the table
in order to clarify the table of the name and sec ID columns in
question.

Solving the Name Conflict Using a Prefix:
Name conflicts in XML can easily be avoided using a name prefix.
This XML carries information about an HTML table, and a piece of
furniture:
<h:table>
<h:tr>
<h:td>Apples</h:td>
<h:td>Bananas</h:td>
</h:tr>
</h:table>
<f:table>
<f:name>African Coffee Table</f:name>
<f:width>80</f:width>
<f:length>120</f:length>
</f:table>

XML Namespaces - The xmlns Attribute:
When using prefixes in XML, a namespace for the prefix must be
defined.The namespace can be defined by an xmlns attribute in the start
tag of an element.
The namespace declaration has the following syntax. Xmlns :
prefix="URI".
<root>
<h:table xmlns : h="http://www.w3.org/TR/html4/">
<h:tr>
<h:td>Apples</h:td>
<h:td>Bananas</h:td>
</h:tr>
</h:table>
<f:table xmlns :f="https://www.w3schools.com/furniture">
<f:name>African Coffee Table</f:name>
<f:width>80</f:width>
<f:length>120</f:length> </f:table>
</root >

Uniform Resource Identifier (URI):
A Uniform Resource Identifier (URI) is a string of characters which
identifies an Internet Resource.
The most common URI is the Uniform Resource Locator (URL)
which identifies an Internet domain address.
 Another, not so common type of URI is the Uniform Resource
Name (URN)

Default Namespaces:
Defining a default namespace for an element saves us from using
prefixes in all the child elements. It has the following syntax:
xmlns="namespace URI"
This XML carries HTML table information:
<table xmlns="http://www.w3.org/TR/html4/">
<tr>
<td>Apples</td>
<td>Bananas</td>
</tr>
</table>
This XML carries information about a piece of furniture:
<table xmlns="https://www.w3schools.com/furniture">
<name>African Coffee Table</name>
<width>80</width>
<length>120</length>
</table>

Namespaces in Real Use:
XSLT is a language that can be used to transform XML documents into other formats.
The XML document below, is a document used to transform XML into HTML. The
namespace "http://www.w3.org/1999/XSL/Transform" identifies XSLT elements inside
an HTML document:
<html>
<body>
<h2>My CD Collection</h2>
<table border="1">
<tr>
<th style="text-align : left">Title</th>
<th style="text-align : left">Artist</th>
</tr>
<xsl : for-each select="catalog/cd">
<tr>
<td><xsl : value-of select="title"/></td>
<td><xsl : value-of select="artist"/></td>
</tr>
</xsl : for-each>
</table>
</body>
</html>

NAMESPACES AND VISUAL INHERITANCE:
Inheritance namespaces:
INTRODUCTION Namespaces:
 allow you to organize a large number of classes into a hierarchical
structure, which promotes code reuse and inheritance among classes.
Without namespaces, a project quickly becomes cluttered with classes
and other objects that are all on the same root namespace .
 Moving classes into namespaces that grow out of your own custom
root namespace allows you to keep classes separate.
WHAT IS A NAMESPACE?
 A namespace is a hierarchical structure for organizing classes. You can
create and use any namespace name that you want in your programs

 VISUAL INHERITANCE:
INTRODUCTION Visual inheritance is a new feature in VB.NET, which
allows you to reuse forms and controls between projects. Ideally, you
would compile a form or control as a component into a.DLL file, so it
could be shared. For demonstration purposes, I’ll just show you how to
inherit one form into another, within the same project.
 CREATING A REUSABLE FORM :Create a new Window
Application called Visual Inheritance. Add four controls to the default
Form1: a Label, a Text Box, and two Button controls. Now, double-click
the first button to open up the default event for the button and type the
following code: If TextBox1.Text.Length > 0 Then Msg Box(“Hello, “ &
TextBox1.Text & “!

REUSING THE REUSABLE FORM:
 Creating inherited forms is fairly easy, because VB.NET
has a menu item that does all the work for you. And actually,
you can do it yourself because the code that VB.
NET generates is extremely short, as you’ll see. Select
Project, Add Inherited Form.
The Add New Item dialog appears, with the Inherited Form
template already selected.

Schema Overview
Elements
Cardinality
Simple Types
Complex Types
Compositors
Global Types
Attributes
mixed Content

Overview:
An XML schema, commonly Known as an Xml Schema
Definition (XSD), formally describes what a given XML document
can contain, in the same way that a database schema describes the
date that can be contain in a database.
The XML schema defines the shape, or structure, of an XML
document, along with rules for data content and semantics such as
what fields an element an contain which sub elements it can
contain and how many item can be present.
It can also describe the type and values that can be placed into
each elements or attributes.
 The XML data constrains are called facets and include rules
such as min and max length.

XML schema abstract:
This report presents a series of BT user stories which chart our
experience in using XML Schema to describe messages exchanged by
Web services.
We explain how the value of a standard is greatly diminished, even
one as widely used as XML Schema, when it is implemented
inconsistently and offer best practices in conjunction with test cases
targeted at description as the best way of communicating which aspects
of schema maybe relied upon to interoperate.

structure of the global cache:
 the global cache consists of both WSDL documents and XML
schema documents
 the global cache of WSDL documents contains all WSDL
documents that have been imported into API Gateway
 The global cache of schema documents contains:
 user defined catalog-This contains all user defined schema
documents that have been imported into API Gateway.
 System catalog-This contains all common schemas that are
preloaded during API Gateway installation.

manage WSDL and XML schema documents:
Overview:
 WSDL files contain XML schemas that define the elements that
appear in SOAP messages. When you import a WSDL file to register a
web service, the imported WSDL file, and any XML schemas included in
the WSDL, are added to a global cache of WSDL and XML schema
documents.
 If you select a cached WSDL file or XML schema in a Schema
Validation filter, API Gateway can retrieve it from the cache instead of
fetching it from its original location. This improves the runtime
performance of the filter, and also ensures that an administrator has
complete control over the schemas used to validate messages.
 API Gateway can maintain multiple versions of WSDL and XML
schema documents in the global cache, and keeps an explicit version
history as they change over time.

document object model:
document object model (DOM) is a cross-platform and language-
independent interface that treats an XML or HTML documents as a
tree structure wherein each node is an object representing a part of
the document. The DOM represents a document with a logical tree.
each branch of the tree ends in a node, and each node contains
objects. DOM methods allow programmatic access to the tree; with
them one can change the structure, style or content of a document.
Nodes an have event handlers attached to them. Once an event is
triggered, the event handlers get executed
xslt (Extensible style sheet language transformations) is a language
for documents into other XML documents, or other formats such
tranforming XMl as HTML for web pages, plain text or XSL
formatting objects, which may sub sequency be converted to other
formats, such as PDF, Postscript and png

XSLT
Introduction:
oXsl(extensible style sheet language) is a styling language for XML
oxslt stands for XSL transformation
oThis tutorial will teach you how to use XSL t to transform XML
documents into other formats

XPATH
 XPATH(xml path language) is a query language for selecting
nodes from an xml document in addtion path maybe used to compute
values
The global cache consists of both WSDL documents and XML
schema documents
The global cache of WSDL documents contains all WSDL
documents that have been imported into API Gateway
The global cache of schema documents contains:
user defined catalog-This contains all user defined schema
documents that have been imported into API Gateway.
System catalog-This contains all common schemas that are
preloaded during API Gateway installation.

Unit 3 WEB TECHNOLOGIES

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