An API is a set of routines, protocols, and tools that allow software programs to communicate with each other. APIs work by allowing developers to access public functions through documentation provided by API creators. The functions pass arguments to private functions that execute the necessary code to complete requests. APIs are useful because they allow functionality to be upgraded without code modifications, minimize changes when data structures change, provide common functionality, and are faster than system calls. APIs are important in cloud computing to integrate platforms and providers through service, application, infrastructure, and cross-platform APIs. Examples of widely used APIs include the Google Maps and Facebook Like APIs.

1. INTRODUCTION TO API
By
Nitya.N.Kulkarni
2SD09CS057

2. CONTENTS
• What is an API?
• How do they work?
• Why are APIs used?
• APIs in cloud computing
• Examples of API.
• Conclusion

3. What is an API?
• —API is an abbreviation for application
programming interface.
• — is a set of routines, protocols, and tools for
It
building software applications.
• — Wikipedia- ‘An application programming interface
(API) is a protocol intended to be used as an
interface by software components to communicate
with each other.’

4. How do APIs work?
 — Public Facing Functions: Developers access APIs by calling a public
facing function. For every API function, the programmer has to provide
certain pieces of information, also called arguments, for the function to
work.
 Private Functions: After a programmer calls a public-facing API function,
the information provided is then passed into a variety of private functions
that actually execute the code necessary to interact with the hardware
component or perform the software service necessary to complete the
request whose result is passed to the program which called public API
function.
 Documentation: The programmers who create APIs provide documentation
that tells other programmers how to use the API.

5. Why are APIs used?
Programming with APIs is useful for these reasons:
 No code modifications are required as functionality is
upgraded.
 When a data structure changes, source modifications are
minimal to nonexistent.
 Common functionality is provided through the APIs, and they
are less prone to error.
 Faster and more reliable than the in-built system calls.

6. API in cloud computing
 The ability to enhance the cloud experience and have cross-
cloud compatibility has helped form the Cloud API
(Application Programming Interface) environment.
 There are four major areas where cloud computing will need to
integrate with another platform (or even another cloud
provider),
◦ PaaS APIs (Service-level)
◦ SaaS APIs (Application-level)
◦ IaaS APIs (Infrastructure-level)
◦ Cloud provider and cross-platform APIs.

7. Examples of API
 Google Map API: By using the Google Maps API, it is
possible to embed Google Maps site into an external
website, on to which site specific data can be overlaid.
 Facebook Like API: Using Facebook Like API , the Like
button of Facebook can be accessed by people in other
webpages.

8. Conclusion
Thus an API is like a window through which different
applications can communicate with each other.

9. THANK YOU