Web service là những API dùng trên HTTP

What is Web API?¶

An API (Application Programming Interface) is the means by which third parties can write code that interfaces with other code.
A Web Service is a type of API, one that almost always operates over HTTP (though some, like SOAP, can use alternate transports, like SMTP).
Web API is typically done as HTTP/SMTP (REST/SOAP), output can be eg: JSON/XML, input can be XML/JSON or plain data.


REST	SOAP
– REST (Representational State Transfer) was Created in 2000 by Roy Fielding in UC, Irvine. – Developed in an academic environment, this protocol embraces the philosophy of the open Web	– SOAP (Simple Object Access Protocol), was created in 1998 by Dave Winer et al in collaboration with Microsoft. – Developed by a large software company, this protocol addresses the goal of addressing the needs of the enterprise market.


REST	SOAP
– Makes data vailable as resources (nouns), for example “user” or “invoice”	– Makes data available as services (verb + noun), for example “getUser” or “PayInvoice”


REST	SOAP
– Follows the philosophy of the Open Web – Relatively easy to implement and maintain – Clearly separates client and server implementations – Communication isn’t controlled by a single entity – Information can be stored by the client to prevent multiple calls – Can return data in multiple formats (JSON, XML etc)	– Follows a formal enterprise approach – Works on top of any communication protocol, even asynchronously – Information about objects is communicated to clients – Security and authorization are part of the protocol – Can be fully described using WSDL


REST	SOAP
– Only works on top of the HTTP protocol. – Hard to enforce authorization and security on top of it	– Spends a lot of bandwidth communicating metadata. – Hard to implement and is unpopular among Web and mobile developers. – Uses only XML.


REST	SOAP
– When clients and servers operate on a Web environment – When information about objects doesn’t need to be communicated to the client	– When clients need to have access to objects available on servers – When you want to enforce a formal contract between client and server


REST	SOAP
– Social Media services – Social Networks – Web Chat services – Mobile Services – Synchronize applications	– Financial services – Payment gateways – Telecommunication services


REST	SOAP
– Facebook APIs – Google APIs – YouTube APIs – Twitter APIs – LinkedIn APIs – Instagram APIs	– Salesforce SOAP API – Paypal SOAP API – Clickatell SMS SOAP API – Almost Banking Systems

Can help find/isolate problems:

Reduce business costs