REST(Representational State Transfer) architecture relies on client-server communications.REST uses HTTP  for communcation between machines.It is not complex like RPC,SOAP.. etc.It uses HTTP for CRUD operations.
REST is not a standard.
REST is a lightweight alternative for Web Services.
REST is platform and language independent.
Soap message example:
<?xml version="1.0"?>
<soap:Envelope
xmlns:soap="http://www.w3.org/2001/12/soap-envelope"
soap:encodingStyle="http://www.w3.org/2001/12/soap-encoding">
<soap:body pb="http://www.acme.com/phonebook">
<pb:GetUserDetails>
<pb:UserID>12345</pb:UserID>
</pb:GetUserDetails>
</soap:Body>
</soap:Envelope>
REST exmple:
http://www.acme.com/phonebook/UserDetails/12345
It is just a url, sending GET request over HTTP protocol.
- Web Services often create SOAP/HTTP request and send it, then parse the SOAP response.
- REST needs only a network connection.
With REST you are using postcard, but with soap envolpe is used.Postcards are easy to handle,and it has short content.
Rest is secure as SOAP. REST can be carried over HTTPS by sending encyrpted messages.
 Lets try to acess service restful with curl, in php language:
$service_url = 'http://example.com/rest/user/';
$curl = curl_init($service_url);
$curl_post_data = array(
"user_id" => 42,
"emailaddress" => 'lorna@example.com',
);
curl_setopt($curl, CURLOPT_RETURNTRANSFER, true);
curl_setopt($curl, CURLOPT_POST, true);
curl_setopt($curl, CURLOPT_POSTFIELDS, $curl_post_data);
$curl_response = curl_exec($curl);
curl_close($curl);
$xml = new SimpleXMLElement($curl_response);
