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1 JSON (JavaScript Object Notation)
| Date post: | 08-May-2015 |
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Technology |
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JSON (JavaScript Object Notation)
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Light weight data-interchange format.
Subset of JavaScript.
Language independent.
Text based.
Easy to parse .
What is JSON?
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Why JSON?
JSON is recognized natively by JavaScript. No need for parsing anXML document to extract the data.
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JSON is Not…
JSON is not a document format.
JSON is not a markup language.
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Properties of JSON
Human and machine readable format.
No support for Unicode.
Self-documenting format that describes structure and field names.
Strict syntax and parsing requirements.
Represents the most general computer science data structures like records, lists and trees.
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Where can JSON be used?
Can be used for transferring medium amounts of data.
Used in Java Script and then rendered on HTML pages.
AJAX has many applications for JSON.
Use JSON for applications that are browser based.
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JSON Data Types
Strings -Control Characters
Number-Integer, Real and Floating
Boolean-True and False
Null
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JSON Data Types (Cont…)
String
Strings must be delimited by the double quote characters.
Example: ”Address”, "444 Colombia"
Boolean
In JSON “True" and “False" are pre-defined keywords.
Example: “Active":True
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Data types (Cont…)
Number
JSON includes positive integers and Negative integers.
Example: “Total points” -123
Null
Null string, also known as an empty string, is a string of zero length.
Example: “Email":null
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Simple Example of a JSON File
{ "menu": "File", "commands": [ { "title": "New“, "action":"CreateDoc” }, { "title": "Open", "action": "OpenDoc” }, { "title": "Close“, "action": "CloseDoc” } ] }
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JSON Object Notation
JSON object is an unordered set of name/value pairs and orderedlist of values.
Object begins with { (left brace) and ends with } (right brace).
Each name is followed by (colon).
Name/value pairs are separated by , (comma).
JSON Object
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JSON Representation of an Object
Var HomeAddress ={ "Address" : “Srini", "City" : “Bangalore", "PostalCode" : 580006};
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JSON Functions
JSON_decode — Decodes a JSON string.
JSON_encode — Returns the JSON representation of a value.
JSON_last_error — Returns the last error occurred.
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JSON Decode
Decode parses the strings as a JSON-syntax string and returns thegeneric JSON object representation.
json_decode()
mixed json_decode ( string $json , bool $assoc)
Takes a JSON encoded string and converts it into a PHP value.
$jsonThe JSON string being decoded
$assocFalse ----Return the value as an objectTrue ----Return the value as an associative array
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JSON Decode Example
<?php$json = '{"foo-bar": 12345}';$obj = json_decode($json);print $obj->{'foo-bar'}; // 12345?>
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JSON Encode
JSON encode returns the JSON representation of a value.
string json_encode ( mixed $value )
Returns a string containing the JSON representation of $value.
$value
Value being encoded, Can be any type except a resource.
Function only works with UTF-8 encoded data.
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JSON Encode Example
<?php$arr = array ('a'=>1,'b'=>2,'c'=>3,'d'=>4,'e'=>5);echo json_encode($arr);// Output {"a":1,"b":2,"c":3,"d":4,"e":5}$arr = array ( 1, 2, 3, 4, 5 );echo json_encode($arr);// Output [1,2,3,4,5]$arr['x'] = 10;echo json_encode($arr);// Output {"0":1,"1":2,"2":3,"3":4,"4":5,"x":10}echo json_encode(54321);// Output 54321?>
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JSON in JavaScript
JavaScript Object Notation is a lightweight data-interchangeformat that is completely language independent text formatwhich is fast and easy to understand.
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Example - JSON in JavaScript
<html><head><title>Object creation in JSON in JavaScript</title><script language="javascript" >var JSONObject = {"name" : "Amit“, “address" : "Bangalore“,"age" : 23, "phone" : "4565763",“MobileNo" : 981100092};
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document.write("<h2><font color='skyblue'>Name</font>::“+JSONObject.name+"</h2>");document.write("<h2><font color='skyblue'>Address</font>::“+JSONObject.address+"</h2>");document.write("<h2><font color='skyblue'>Age</font>::“+JSONObject.age+"</h2>");document.write("<h2><font color='skyblue'>Phone No.</font>::“+JSONObject.phone+"</h2>");document.write("<h2><font color='skyblue'>Mobile No.</font>::“+JSONObject.MobileNo+"</h2>");</script></head><body bgcolor="#cc4488"><h3>Example of object creation in JSON in JavaScript</h3></body></html>
Example - JSON in JavaScript (Cont…)
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Both XML and JSON use structured approaches to mark up data.
More and more web services are supporting JSON.
Example
Yahoo's various search services, travel planners, and highwaytraffic services.
AJAX with JSON
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JSON is widely used in AJAX. The X in AJAX stands for XML.
Example
{"fullname": "Swati Kumar“, "org": "Columbia",}<?xml version='1.0‘ encoding='UTF-8'?><element><fullname>Swati Kumar</fullname><org>Columbia</org></element>
Why JSON is Better than Ajax?
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Benefits of JSON
The easiness of reading
The easiness of using
Benefits of XML
XML is extensible.
Widely used and recognized by almost all programming languages.
JSON and XML
Unfortunally, both XML and JSON are enable to integrate a largeamount of data in binary form.
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{"firstName": “Sahana","lastName": "Saniya","age": 25,"address": {"streetAddress": “2nd Street","city": “Bangalore","state": “India",},"phoneNumber": [{ "type": "home", "number": “234243" },{ "type": "fax", "number": “645654" }],"newSubscription": false,"companyName": null}
Example
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<Person><firstName>John</firstName><lastName>Smith</lastName><age>25</age><address><streetAddress>21 2nd Street</streetAddress><city>New York</city><state>NY</state><postalCode>10021</postalCode></address><phoneNumber type="home">212 555-1234</phoneNumber><phoneNumber type="fax">646 555-4567</phoneNumber><newSubscription>false</newSubscription><companyName /></Person>
Equivalent for the above in XML could be
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Both are self-describing and thus human readable.
Both are hierarchical (i.e. we can have values within values.)
Both can be parsed and used by lots of programming languages.
Both can be passed around using AJAX (i.e. httpWebRequest).
JSON is Like XML because…
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JSON stands for JavaScript Object Notation, Considered as thesubset of JavaScript.
XML on the other hand is a mark-up language that could be used indifferent languages.
Parsing JSON encoded data is much faster than parsing XMLencoded data.
JSON Vs XML
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XML<result><people><person firstName=“Aman" lastName=“Valya"/><person firstName=“Suman" lastName=“Valya"/>...</people></result>
JSON{people:[{ 'firstName': ‘Aman', 'lastName', ‘Valya' },{ 'firstName': ‘Suman', 'lastName', ‘Valya' },...
JSON Vs XML (Cont…)
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Lighter and faster than XML as on-the-wire data.
JSON objects are typed while XML data is type less.
JSON types are string, number, array, Boolean.
XML data are all string.
Data is readily accessible as JSON objects in your JavaScript Code.
XML data needed to be parsed and assigned to variables throughtedious DOM APIs.
Why Use JSON Over XML?
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Provides multiple functionalities such as encode, decode/parse.
Flexible, simple and easy to use.
Supports streaming output of JSON text.
Heap based parser.
High performance.
No dependency on external libraries.
Features of JSON
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JSON is a simple, common representation of data.
Communication between servers and browser clients.
Communication between peers.
Language independent data interchange.
JSON Data Interchange
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Thank you
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