Objectives
In this page you will
see to:
* Identify
the limitations of EDI
* Identify
the need for XML as a standard data interchange format
* Identify
the differences between SGML, HTML, and XML
* Identify
the role of World Wide Web Consortium (W3C) in defining XML-related
specifications
* Create an
XML document
What is Electronic Data Interchange
* EDI refers
to the process of exchanging documents in a standard format between two
computer systems.
* EDI is
often used as a replacement for conventional business documents such as
purchase orders, requests for quotations, invoices, and shipping notices.
How Does EDI Work (Contd.)
* The sender
of information uses computer files to assemble the data needed for a
transaction.
* The
assembled data is the input to a software module that transforms the
transaction into the EDI standard format.
* The
resulting data file generated by the software module is transmitted to the
receiver via an intermediate channel company known as Value Added Network
(VAN).
* This data
file is treated as the input at the receiving end in which a software module
translates the data from the EDI format into a file that can be understood by
the receiver’s application system.
How Does EDI Work (Contd.)
* The above
process includes a number of security procedures. Data security is maintained
with the help of user identification numbers and passwords.
* The EDI
standards also allow a receiver to send an acknowledgement message to the
sender indicating successful receipt of information.
EDI Standards
* Two
standards of EDI are used widely.
* They are
ANSI X12 and UN/EDIFACT.
* ANSI X12
is the most widely used EDI standard in the United States.
* The rest
of the world uses the UN/EDIFACT standard.
* Many EDI
software packages support both the standards.
Hardware and Software Requirements for
Implementing EDI
* For
implementing EDI, you require EDI software and a modem (minimum 28.8k baud, 56k
baud recommended).
* You need
to convey transactions to and from your trading partners electronically.
* This can
be done either using the point-to-point communication method or using a VAN as
an intermediary between various trading partners.
* In the
point-to-point communication method, you use a telephone line to dial your
trading partner’s computer directly.
Benefits of EDI
* Reduction in data entry errors
* Elimination of communication lag
time between an agency and a customer
* Improved customer service
* Minimized costs of transferring
information
* Reduced order time
Limitations of EDI
* The
limitations of EDI are as follows:
3 Rigid
Transaction Set
3 Fixed
Business Rules
3 High
Costs
3 Slow
Pace of Standards Evolution
Introduction to XML
What
is XML
* eXtensible
Markup Language (XML) is a text-based markup language that enables you to store
data in a structured format by using meaningful tags.
* The term
"eXtensible" implies that you can extend your ability to describe a
document by defining meaningful tags for your application.
* XML is a
cross-platform, hardware, and software independent markup language.
* XML can be
used to address the problems faced by EDI.
Introduction to XML
Advantages of XML over EDI
* Some of
the advantages of XML over EDI are listed below:
3 Lower
Cost
ä XML
does not require a high priced VAN as in the case of EDI.
3 Customized
Business Rules
ä XML
enables you to store data in a structured format by allowing you to create
customized tags.
Advantages of XML over EDI (Contd.)
* Easy to
Interpret
3 XML
documents can be easily interpreted by the target systems by using a parser.
* Platform
Independent
3 As
XML documents are platform independent, a business unit can have transactions
with any other business unit irrespective of their data storage platform.
Difference between SGML, HTML, and XML
* A markup
language uses tags to indicate how a file should look when displayed on a Web
page.
* Some
examples of markup languages are Standard Generalized markup language (SGML)
and Hypertext Markup Language (HTML).
* SGML
allows documents to describe their own grammar by specifying the tag set used
in the document and the structural relationship that these tags represent.
* SGML
was complex and difficult for developers to master.
Difference between SGML, HTML, and XML
(Contd.)
* HTML
is based on SGML.
* In HTML, a
user has to work with a set of predefined tags that is understood by the
browser.
* XML is a
subset of SGML.
* HTML is
used for data presentation, whereas XML is used for data description and
definition. Thus, the purpose of these two markup languages is completely
different.
Advantages of XML
* The
advantages provided by XML are as follows:
3 Domain
Specific Vocabulary
3 Data
Interchange
3 Smart
Searches
3 Granular
Updates
3 User-Selected
View of Data
Introduction to World Wide Web
Consortium
* W3C is
responsible for the development of Web specifications (recommendations) that
describe communication protocols and the technologies for the Web.
* Role of
W3C in defining XML related specifications
3 W3C
has laid down certain rules that need to be followed by all XML applications.
Listed below are some of these rules:
ä XML
must be directly usable over the Internet.
ä XML
must support a wide variety of applications.
ä XML
must be compatible with SGML.
Introduction to World Wide Web
Consortium
(Contd.)
ä The
number of optional features in XML needs to be kept to the absolute minimum,
ideally zero.
ä XML
documents must be human-legible and clear.
ä
XML design must be formal and concise.
Problem
Statement 1.D.1
* CyberShoppe
requires a centralized repository of data about the products sold through its
e-commerce site. It has three branches, which maintain data on their local
computer systems. Data from all the three branches must be collated and housed
in a centralized location. This data must be made available to the Accounts and
Sales sections of these branches, regardless of the hardware and software
platforms being used at the branches. The sales personnel also require access
to the data using equipment, such as palmtops and cellular phones.
Problem
Statement 1.D.1 (Contd.)
* The
product details of CyberShoppe consist of the name of the product, a brief
description of the product, the price, and the available quantity on hand. Each
product is uniquely identified by a product ID.
Task
List
* Identify the method to store data
in a device-independent format.
* Identify the structure of the
document in which data is to be stored.
* Create an XML document to store
data.
* View the XML document in a browser.
Task
1: Identify the method to
store data in a
device-independent format.
Result
* XML
provides a way to store structured data that is capable of being recognized by
different kinds of devices. In other words, it enables device-independence.
Task
2: Identify the structure of the document in
which
data is to be stored.
* Before you
store data in an XML document, you need to organize it.
* An XML
document is composed of a number of components that can be used for
representing information. These components are:
3 Processing
Instruction
ä An
XML document usually begins with the XML declaration statement or the Processing
Instruction (PI).
ä The
PI provides information regarding the way in which the XML file should be
processed.
Task
2: Identify the structure…
(Contd.)
ä The
PI statement can be written as:
<?xml version="1.0"
encoding="UTF-8" ?>
ä In
the above example, the PI states that version 1.0 is used.
ä The
PI uses the encoding property to specify information about the encoding scheme
that is used to create the XML file.
Task
2: Identify the structure…
(Contd.)
3 Tag
ä Tags
are used to specify a name for a given piece of information.
ä Tags
usually occur in pairs.
ä Each
pair consists of a start tag and an end tag.
ä The start tag only contains the name of the
tag while the end tag includes a forward slash (/) before the name of the tag.
Task
2: Identify the structure…
(Contd.)
3 Elements
ä Elements
are the basic units that are used to identify and describe data in XML.
ä They
are the building blocks of an XML document.
ä Elements
are represented using tags.
ä An
XML document must always have a root element. All other elements are specified
within the opening and closing tags of the root element.
Task
2: Identify the structure…
(Contd.)
3 Content
ä The
information that is represented by the elements of an XML document is referred
to as the content of that element.
Task
2: Identify the structure…
(Contd.)
ä An
element can contain any of the following:
ä Character
or Data Content
ä
Elements can contain only textual information.
ä Element
Content
ä
Elements can contain other elements.
ä
The elements contained in another element are
called child elements.
ä
The containing element is called the parent
element.
Task
2: Identify the structure…
(Contd.)
ä Element
Content
ä
A parent element can contain many child
elements.
ä
All the
child elements of a parent element are siblings and are thus related to one
another.
ä Combination
ä
Elements can contain textual information as well
as other elements.
Task
2: Identify the structure…
(Contd.)
3 Attributes
ä Attributes
provide additional information about the elements for which they are declared.
ä An
attribute consists of a name-value pair.
ä Elements
can have one or more attributes. Attributes or attribute values can be either
mandatory or optional.
Task
2: Identify the structure…
(Contd.)
3 Attributes
ä While
deciding whether to represent information as an element or an attribute, you can
follow the guidelines given below:
ä If
the data must be displayed, you can represent it as an element. In general,
element attributes are used for intangible, abstract properties such as ID.
ä If
the data must be updated frequently, it is better represented as an element
because it is easier to edit elements than attributes with XML editing tools.
Task
2: Identify the structure…
(Contd.)
ä If
the value of a piece of information must be checked frequently, it may be
represented as an attribute.
Task
2: Identify the structure…
(Contd.)
3 Entities
ä An
entity can be described as a short cut to a set of information.
ä It
is a name that is associated with a block of data.
ä This
data can be a chunk of text or a reference to an external file that contains
textual or binary information.
ä XML
supports the use of three kinds of entities: internal, general, and parameter
entities.
Task
2: Identify the structure…
(Contd.)
ä Internal
Entities
ä An
internal entity consists of a name that is associated with a block of information.
ä This
can be identified easily as it is always preceded by an ampersand (&)
symbol and terminated with a semicolon.
Task
2: Identify the structure…
(Contd.)
3 Comments
ä Comments
are statements that are used to explain the code.
ä When
the code is executed, comment entries are ignored by the parser.
ä Comments
are not essential in an XML file.
Task
2: Identify the structure…
(Contd.)
Result
* Structure
of the XML document to be used for storing products data:
Task
3: Create an XML document
to store data.
* Rules for
Creating Well-formed XML Documents
3 Every
start tag must have an end tag.
3 Empty
tags must be closed using a forward slash (/).
3 All
attribute values must be given in double quotation marks.
3 Tags
must nest correctly.
3 XML
tags are case-sensitive. They must match each other in every implementation.
Task
4:View the XML document in
a browser.
Problem Statement 1.P.1
*The details of
books sold by CyberShoppe need to be stored at a centralized location. This
data needs to be made available to the various branches of CyberShoppe,
regardless of the platforms used at various branches. The book details consist of the title of the
book, the first and last names of the author of the book and the price of the
book. Each book is uniquely identified by a book ID.
Summary
In this lesson you learned
that,
* EDI is a
standard format used for the exchange of business data among heterogeneous
systems.
* XML is a
text-based markup language that enables you to store data in a structured
format using meaningful tags.
* XML is a
method of storing data in a device-independent format.
* HTML and
XML are subsets of SGML.
Summary
(Contd.)
* An XML
document consists of:
3 Processing
Instructions
3 Elements
3 Attributes
3 Entities
3 Comments
3 Content
Summary
(Contd.)
* The rules
that govern the creation of a well-formed XML document are as follows:
3 Every
start tag must have an end tag.
3 Empty
tags must be closed using a forward slash (/).
3 All
attribute values must be given in double quotation marks.
3 Tags
must nest correctly.
3 XML
tags are case-sensitive. They must match each other in every implementation.
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