WEB Architecture
advertisement
Basic WEB Architecture
1
Data Driven WEB Architecture
2
Recent WEB Applications Architecture
3
Client Tier
4
Service Tier
5
The Web as a Platform
for Running Applications
6
Service Oriented Application (SOA)
7
Service Oriented Application (SOA)
8
Service Oriented Application (SOA)
9
Service Oriented Application (SOA)
10
Service Oriented Application (SOA)
11
Front-End
12
Front-End
13
Service Oriented Application (SOA)
14
Middle Layer – Data Link
15
Service Oriented Application (SOA)
16
Back-End- Server Site
17
GROUP DISCUSSION
W
H
A
T
T
O
D
O
?
18
What is XML?
eXtensible Markup Language, is a
specification for creating custom markup
languages
W3C Recommendation
Primary purpose is to help computers to share
data
XML is meta-language. This means that you
use it for creating languages.
XML is an extensive concept.
XML Document
Every XML-document is text-based
=> sharing data between different computers!
=> sharing data in Internet!
=> platform independence!
Binary vs. Text
Problems with Binary format
– Platform depence
– Firewalls
– Hard to debug
– Inspecting the file can be hard
Since XML is text-based, it does not have the
problems mentioned above.
What are the disadvantages in text format?
XML Doc Advantages
Easy data sharing, text documents are readable
between any device.
Documents can be modified with any text editor.
Possible to understand the contents of the xmldocument just by looking at it with text editor.
Easy to manipulate via programming languages
Two levels of correctness: Well formed and Valid.
.doc – file format
Windows
MS Word 2000
0101011010101010001010
1010101110101010001011
1010101110101010110101
1110101010101010101010
Mac OS X
Since .doc is closed binary-format,
there are very few alternatives for
word processors that fully support
the doc – file format
.docx – file format (Office Open
XML)
Windows
MS Word 2007
<xml>
<heading1>title</heading1>
.
Now the format is
.
open
and it's much
</xml>
easier to access
Mac OS X
Hopefully in the future there
will be loads of free programs
that support this new open
and easy access file format
SGML vs. XML
SGML: Standard Generalized Markup Language
XML
OOXML
(.docx)
MathML
(.mml)
XHTML
(.xhtml)
HTML
(.html)
XML – Meta Language
XML is meta language, which you can use to create
your own markup languages.
There are several XML Markup Languages made for
different purposes
All the languages have common xml-rules
Languages: XHTML, OOXML, Open Document,
RSS, SVG, SOAP, SMIL, MathML...
List:
– http://en.wikipedia.org/wiki/List_of_XML_markup_languages
XHTML - Example
<?xml version="1.0"?>
<!DOCTYPE html
PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
<head>
<title>Minimal XHTML 1.0 Document</title>
</head>
<body>
<p>This is a minimal <a href="http://www.w3.org/TR/xhtml1/">XHTML
1.0</a>
document.</p>
</body>
</html>
SVG - Example
<?xml version="1.0"?>
<!DOCTYPE svg
PUBLIC "-//W3C//DTD SVG 1.1//EN"
"http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd">
<svg width="100%" height="100%" version="1.1"
xmlns="http://www.w3.org/2000/svg">
<circle cx="100" cy="50" r="40" stroke="black"
stroke-width="2" fill="red"/>
</svg>
MathML (Open Office)
<?xml version="1.0"?>
<!DOCTYPE math:math PUBLIC "-//OpenOffice.org//DTD Modified W3C MathML
1.01//EN" "math.dtd">
<math:math xmlns:math="http://www.w3.org/1998/Math/MathML">
<math:semantics>
<math:mrow>
<math:mi>x</math:mi>
<math:mo math:stretchy="false">=</math:mo>
<math:mfrac>
<math:mrow>
...
</math:mrow>
<math:annotation math:encoding="StarMath 5.0">x = {-b +-sqrt{b^{2}4{ac}}
} over {2 {a}} </math:annotation>
</math:semantics>
</math:math>
RSS 2.0 - Example
<?xml version="1.0"?>
<rss version="2.0">
<channel>
<title>W3Schools Home Page</title>
<link>http://www.w3schools.com</link>
<description>Free web building tutorials</description>
<item>
<title>RSS Tutorial</title>
<link>http://www.w3schools.com/rss</link>
<description>New RSS tutorial on W3Schools</description>
</item>
<item>
<title>XML Tutorial</title>
<link>http://www.w3schools.com/xml</link>
<description>New XML tutorial on W3Schools</description>
</item>
</channel>
</rss>
XML Editors
XML Spy
EditiX
Microsoft XML Notepad
Visual XML
XML Viewer
Xeena
XML Styler, Morphon, XML Writer…
Rules that Apply to Every XML-Document
WELL FORMED XML DOCUMENT
Correctness
There are two levels of correctness of an XML
document:
1. Well-formed. A well-formed document conforms
to all of XML's syntax rules.
2. Valid. A valid document additionally conforms to
some semantic rules.
Let's first look at the XML's syntax rules (1).
Simple Generic XML Example
<?xml version="1.0" encoding="utf-8" standalone="yes"?>
<presentation>
<slide number="1">
<name>Introduction to XML</name>
<contents>XML is ...</contents>
</slide>
</presentation>
XML-Declaration
XML-declaration is optional in XML 1.0, mandatory
in 1.1.
– Recommendation: use it.
Version: 1.0 or 1.1
Encoding: character encoding, default utf-8
Standalone:
–
–
–
–
is the xml-document linked to external markup declaration
yes: no external markup declarations
no: can have external markup declaration (open issue..)
default: "no"
Comparing Declarations
<?xml version="1.0" encoding="utf-8" standalone="no"?>
<presentation>
<slide>
<name>Introduction to XML</name>
<contents>XML is ...</contents>
</slide>
</presentation>
<?xml version="1.0"?>
<presentation>
<slide>
<name>Introduction to XML</name>
<contents>XML is ...</contents>
</slide>
</presentation>
Same Declaration
Element vs. Tag vs. Attribute
Element consists of start tag, optional content and an
end tag:
– <name>Introduction to XML</name>
Start tag
– <name>
Content
– Introduction to XML
End tag
– </name>
Start tag may have attribute
– <slide number="1">
Rules about Elements
Only one root - element
Every element contains starting tag and an ending tag
Content is optional: Empty element
– <x></x> <!-- same as -->
– <x/>
Tag – names are case-sensitive:
– <X></x> <!-- Error -->
Elements must be ended with the end tag in correct order:
– <p><i>problem here</p></i> <!– Error
Rules about Attributes
XML elements can have attributes in the
start tag.
Attributes must be quoted:
–
–
–
–
<person sex="female">
<person sex='female'>
<gangster name='George "Shotgun" Ziegler'>
<gangster name="George &quot;Shotgun&quot; Ziegler">
Naming Tags
Names can contain letters, numbers, and other
characters
Names must not start with a number or
punctuation character
Names must not start with the letters xml (or
XML, or Xml, etc)
Names cannot contain spaces
Well-Formed XML
XML document is well-formed if it follows the
syntax rules.
XML document must be well-formed!
– it's not an xml-document, if it does not follow the
rules..
Is this Well-Formed XML
Document?
<?xml version="1.0"?>
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
<head>
<title>Minimal XHTML 1.0 Document</title>
</head>
<body>
<p>This is a minimal <a href="http://www.w3.org/TR/xhtml1/">XHTML
1.0</a>
document.</p>
</body>
</html>
Is this Well-Formed XML
Document?
<?xml version="1.0"?>
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
<head>
<title>Minimal XHTML 1.0 Document</title>
</head>
<body>
<jorma>This is a minimal <a
href="http://www.w3.org/TR/xhtml1/">XHTML 1.0</a>
document.</jorma>
</body>
</html>
Defining the Structure for XML documents
VALID XML DOCUMENT
Valid XML
XML document is valid if
– 1) It is well formed AND
– 2) It follows some semantic rules
XML document is usually linked to an external file,
that has semantic rules for the document.
– The file can be dtd (.dtd) or schema (.xsd)
Semantic rules?
– Name of tags, order of elements
DTD Linking
<?xml version="1.0"?>
Rules for XHTML elements (order,
names, etc)
<!DOCTYPE html
PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
<head>
<title>Minimal XHTML 1.0 Document</title>
</head>
<body>
<p>This is a minimal <a href="http://www.w3.org/TR/xhtml1/">XHTML
1.0</a>
document.</p>
</body>
</html>
DTD Linking
Defines the structure, tag names and
order for all xhtml - documents
W3C has created XML-language "XHTML"
by defining it's rules in DTD.
Is this valid XML Document?
<?xml version="1.0"?>
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
<head>
<title>Minimal XHTML 1.0 Document</title>
</head>
<body>
<jorma>This is a minimal <a
href="http://www.w3.org/TR/xhtml1/">XHTML 1.0</a>
document.</jorma>
</body>
</html>
1.
2.
3.
There is no DTD! What language is this? MathML? SVG? XHTML?
Assuming this is XHTML, what version of XHTML? Transitional? Strict?
Assuming this is XHTML strict, does "jorma" – tag belong to XHTML Language?
Invalid XHTML-document
<?xml version="1.0"?>
<!DOCTYPE html
PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
<head>
<title>Minimal XHTML 1.0 Document</title>
</head>
<body>
<jorma>This is a minimal <a
href="http://www.w3.org/TR/xhtml1/">XHTML 1.0</a>
document.</jorma>
</body>
</html>
Validating with W3C Service
Invalid XHTML in Browser?
May work... or not. Browser tries to detect the errors and tries to understand
them. If it works with one browser, are you certain that it works with all other
browsers? And with all the versions with the browsers? What about browsers
in handheld devices?
And it might work now, but what about future? How will Firefox 5.0 handle
incorrect web pages?
Invalid XML in General
Because of HTML heritage, browsers try to
understand invalid XHTML-pages
This is not the case in other XML-languages.
In general, if XML-document is invalid, the
processing of the document is cancelled.
JavaScript Object Notation
(JSON)
JSON
JSON (JavaScript Object Notation) is a lightweight
data-interchange format.
It is easy for humans to read and write.
It is easy for machines to parse and generate.
It is based on a subset of the JavaScript
Programming Language, Standard ECMA-262 3rd
Edition - December 1999.
JSON is a text format that is completely language
independent.
These properties make JSON an ideal datainterchange language.
Why JSON?
Because JSON is lightweight, easy to understand,
manipulate and generate, it has almost replaced XML
which was used previously as the only datainterchange format.
JSON is preferable because of the following reasons:
– XML is heavier than JSON
– to parse XML, we have to use xPath which is an overhead
removed in JSON because JSON is native to JavaScript
– XML uses tags to describe user data and tags increase the
size of data
JSON Structures
JSON is built on two structures:
– A collection of name/value pairs.
• In various languages, this is realized as an object,
record, dictionary, hash table, keyed list, or associative
array.
– An ordered list of values.
• In most languages, this is realized as an array, vector,
list, or sequence.
Syntax of JSON
Object
An object is an unordered set of name/value pairs.
An object begins with { (left brace) and ends with } (right
brace).
Each name is followed by : (colon) and the name/value pairs
are separated by , (comma).
Syntax of JSON
Array
– An array is an ordered collection of values.
– An array begins with [ (left bracket) and ends with ] (right
bracket). Values are separated by , (comma).
Syntax of JSON
A value can be a string in double quotes, or a
number, or true or false or null, or an object or
an array. These structures can be nested.
A string is a collection of zero or more Unicode
characters, wrapped in double quotes, using
backslash escapes. A character is represented
as a single character string. A string is very
much like a C or Java string.
JSON Example
{ “students” :
[
{“id":1, "name":"Adnan Sohail"},
{“id":2, "name":"Irfan Razzaq"}
]
}
XML Example
<?xml version="1.0" ?>
<root>
<student>
<id>1</id>
<name>Adnan Sohail</name>
</student>
<student>
<id>2</id>
<name>Irfan Razzaq</name>
</student>
</root>
Validating JSON &
JSON Security
JavaScript’s built-in method eval() is used to validate
a JSON string.
Note:
– Use eval() only when the source is authentic and trusted
which means use it only if you are sure that the string
passed to it is a valid JSON string
When you’ve security risks use
var myObject = myJSONtext.parseJSON();
Which is available in http://www.json.org/json.js
– but eval() is faster than parseJSON()
Using JSON APIs
JSON strings can be easily generated using JSON
APIs available at http://json.org
There are two main classes available in org.json.*
package
– org.json.JSONObject
– org.json.JSONArray
Strings can be generating from objects of
JSONObject or JSONArray using their
toString() methods
Benefits of JSON over XML
JSON supports data types like string, integer,
boolean etc.
JSON is native data format for JavaScript and
therefore it faster for the browser to read and
understand.
As JSON contains no tags but data and therefore
less data to be transferred between client and the
server. So, it’s lighter than XML.
Easy for humans to read and write.
JSON References
http://www.xul.fr/en-xml-ajax.html
http://www.xul.fr/ajax-javascript-json.html
http://json.org/
http://www.json.org/java/
WEB SERVICE DESCRIPTION
LANGUAGE (WSDL)
Introduction
WSDL is an XML language that contains
information about the interface semantics and
‘administrivia’ of a call to a Web Service
Once you develop a Web Service you publish
its description and a link to it in a UDDI
repository so that potential users can find it
When someone wants to use your service,
they request the WSDL file in order to find out
the location of the service, the function calls
and how to access them
Then they use this information in your WSDL
file to form a SOAP request to the computer
Definitions
Definitions:
- WSDL is an XML-based language used to
define Web Services and describe how to
access them.
- WSLD is an XML format for describing
network services as a set of endpoints
operating on messages containing either
document-oriented or procedure-oriented
information.
Working of WSDL
Figure 1. A client invoking a Web service.
Working of WSDL contd.
Figure 2. WSDL terminology used for describing Web services.
Working of WSDL (with Java)
contd.
Where does it fit in?
What is UDDI?
Universal
Description Discovery and Integration
Industry-wide initiative supporting web services
Specifications
Schemas for service description
Schemas for business (service implementers)
description
Developed on industry standards (XML, HTTP, TCP/IP,
SOAP)
Applies equally to XML and non-XML web services
Implementation
Public web service registry and development
resources
Industry-Wide Project Support
All
major technology providers
Global corporations
Strong resource and product commitment
Roadmap for transition to standards body
Unprecedented
collaboration
XML and Web Services recognized as core standards
Competition on services built on a common model
Technology, platform, and development language
neutral
What Problems Do We Solve?
Broader
B2B
Smarter
Search
An organization needs to
create 400 electronic
relationships with
partners, each with its
own standards and
protocols
Describe
Services
A small business wants to
be “plugged in” to every
marketplace in the world,
but doesn’t know how
Discover
Services
Easier
Aggregation
A B2B marketplace cannot
get catalog data for
relevant suppliers in its
industry, along with
connections to shippers,
insurers, etc.
Web Service
Visibility
Provide a standards-based
profile for all electronic
services that are provided.
Includes web sites, other
electronic resources
Integrate
Them
Together
Publish for
Accessibility
Foundation for Web Services
Publish and Discover Services:
UDDI
Formal Service Descriptions: WSDL
Service Interactions:
SOAP
Universal Data Format:
XML
Ubiquitous Communications: Internet
Broad Industry Support, Simple Process
UDDI Registry Entries
Standards Bodies,
Agencies, Programmers,
Publishers register
specifications for their
Service Types
Service providers register
precise information about
themselves and their Web
services
• Business name
• General business description
– Any number of languages
• Contact info
– Names, phone numbers,
fax numbers, web sites, etc.
• Known identifiers
– List of unique identifiers for a business
D-U-N-S, Thomas, domain name, stock ticker
symbol, other
• Business categories
– 3 base taxonomies in V1
•
•
•
•
Industry: NAICS (Industry codes - US Govt.)
Product/Services: UNSPSC (ECCMA)
Location: Geographical taxonomy (ISO 3166)
…easy extension in upcoming releases
• New set of information businesses use
to describe how to “do e-commerce”
with them
– Nested model
• Business process (functional)
• Service specifications (technical)
• Binding information (implementation)
– Programming/platform/
implementation agnostic
– Services can also be categorized
How UDDI Works
Software companies, standards
bodies, and developers populate
the registry with descriptions
(specifications) of types of
services
.
1
.
4
.
2
Marketplaces, search
engines, and business
applications query the
registry to discover services
at other companies and to
facilitate integration
UDDI Registry
Implementers
populate the
registry with
descriptions of
their businesses
and the services
they expose
Implementations
.
3
Service Types
.
5
UDDI Registry assigns a programmatically
unique identifier to each service and
registration
Large businesses
apply the same
architecture and
technologies internally
Public Registry Operation
•
•
•
•
•
•
•
Peer registry nodes (websites)
Information registered
with any node
Registrations replicated
on a daily basis
Complete set of
“registered” records
available at all nodes
Common set of
SOAP APIs supported other
by all nodes
Compliance enforced
by business contract
All technologies applied other
–
Interoperability
verified constantly
Developers
Applications
Marketplaces
End Users
IBM
queries
UDDI.org
HP (planned)
Microsoft
UDDI and SOAP
User
UDDI
SOAP Request
UDDI
SOAP Response
Create, View,
Update, and Delete
registrations
UDDI Registry
Node
HTTP
Server
SOAP
Processor
UDDI
Registry Service
B2B Directory
Implementationneutral
GROUP DISCUSSION
W
H
A
T
T
O
D
O
?
84
![[#CARBON-13743] Key store password of catalina](http://s3.studylib.net/store/data/007841975_2-b5be293be17dfbfd4fa5374476b625ea-300x300.png)
