What is an API(Application Programming Interface)?
What is an API(Application Programming Interface)? It is some predefined function, the purpose is to provide applications and developers with the ability to access a set of routines based on certain software or hardware without accessing source code, or understanding the internal details of the working mechanism.
In addition to the meaning of “application programming interface”, API also specifically refers to the documentation of the API, also known as help documentation.
What is an API?
API: Application Program Interface
An application programming interface is a collection of definitions, programs, and protocols that communicate between computer software through an API interface. A primary function of the API is to provide a common feature set. Programmers can reduce programming tasks by calling API functions to develop applications. API is also a kind of middleware, providing data sharing for various platforms.
Standards currently applied to the API include the ANSI standard SQL API. There are also some standards that apply to other types that are still under development. API can be applied to all computer platforms (such as interactive flat panel display) and operating systems.
Types of APIs
There are four types of APIs: private, public, partner, and composite.
* Private APIs, or internal APIs, are published internally for use by the company’s developers to improve its own products and services. Private APIs are not exposed to third parties.
* Public APIs, or open APIs, are published publicly for anyone to use. There are no restrictions on these APIs.
* Partner APIs can only be used by specific parties with which a company agrees to share data. These APIs are used in business relationships, often to integrate software between partnering companies.
* Composite APIs combine multiple APIs to address related or interdependent tasks. They often improve speed and performance compared with individual APIs.
APIs also are classified as local, web, remote, and program.
1. Local APIs offer OS or middleware services to applications. Examples of local APIs include Microsoft’s .NET APIs, the telephony API for voice applications, and database access APIs.
2. Web APIs are designed to represent resources such as HTML pages and are accessed using a simple Hypertext Transfer Protocol, or HTTP. Any web URL activates a web API. Web APIs are often called RESTful APIs because the publisher of REST interfaces doesn’t save any data internally between requests. As such, requests from many users can be intermingled as they would be on the internet.
3. Remote APIs interact through a communication network to manipulate resources outside of the computer making the request. This is a broader category that includes but is not limited to web APIs. Remote APIs do not need to be designed based on web standards, though many are. The Java Database Connectivity API and the Java Remote Method Invocation API are two examples of remote APIs.
4. Program APIs are based on remote procedure call (RPC) technology that makes a remote program component appear to be local to the rest of the software. Service-oriented architecture APIs, such as Microsoft’s WS series of APIs, are program APIs.
How do APIs work?
APIs are made up of two related elements:
A specification that describes how information is exchanged between programs in the form of a request for processing and a return of the necessary data; and a software interface written to that specification and published in some way for use.
The software that wants to access the features and capabilities of the API is said to call it, and the software that creates the API is said to publish it.
APIs authorize and grant access to data that users and other applications request. Access is authenticated to a service or portion of functionality using predefined roles that govern who or what service can access specific actions and data. APIs also provide an audit trail that details who and what has had system access and when it happened.
Applications that call APIs were traditionally written in specific programming languages. Web APIs can be called through any programming language, but webpages created in Hypertext Markup Language (HTML) or application generator tools can also access them.
The most common architectures for APIs are Representational State Transfer (REST) and Simple Object Access Protocol (SOAP), which defines a standard communication protocol specification for a message exchange based on Extensible Markup Language or XML. SOAP requires less low-level infrastructure-related code than REST. However, REST APIs are easier to scale and redeploy, and simpler to implement and integrate with websites and services. REST APIs are most often used today, particularly for web interactions.
What are the benefits of using APIs?
APIs are a set of rules. They standardize how developers write application code, improving an organization’s internal software development processes.
Using the same rules and formats streamlines code and makes it more transparent. Standardization also facilitates collaboration among developers as they build software components with the intent to integrate with APIs. This, in turn, facilitates feature development and reduces time to market.
Public APIs and ones shared with partners enable an organization to do the following:
- Securely control and manage how users and systems access data and service functionality;
- Allow third parties to use its data — even in a limited sense — which increases a company’s brand exposure;
- Grow its customer database and increase its conversion rate by aligning its services with other trusted brands;
- Monetize its APIs so that they become a line of revenue. This is a common tactic for online payment gateways.