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What is REST API (RESTful API)?


A RESTful API is an  style of architecture  for an application program interface (API) that uses HTTP requests to access and use data. That data  are often  used to GET, PUT, POST and DELETE data types, which refers to the reading, updating, creating and deleting of operations concerning resources.

An API for  an internet site  is code that allows two software programs to communicate with each other. The API spells out  the right  way for a developer to write a program requesting services from an operating system or other application.

A RESTful API -- also  mentioned  as a RESTful web service or REST API -- is based on representational state transfer (REST), which is an  style of architecture  and approach to communications often used in web services development.

REST technology  is usually  preferred over other similar technologies. This tends to be the case because REST uses less bandwidth, making it more suitable for efficient internet usage. RESTful APIs  also can  be built with programming languages such as JavaScript or Python.

The REST used by browsers can be thought of as the language of the internet. With cloud use on  the increase , APIs are  getting used  by cloud consumers to expose and organize access to web services. REST  may be a  logical choice for building APIs that allow users to connect to, manage and interact with cloud services flexibly  during a  distributed environment. RESTful APIs are  employed by  such sites as Amazon, Google, LinkedIn and Twitter.

How RESTful APIs work

A RESTful API breaks down a transaction  to make  a series of small modules. Each module addresses an underlying  a part of  the transaction. This modularity provides developers with  plenty  of flexibility, but it  are often  challenging for developers to design their REST API from scratch. Currently, several companies provide models for developers to use; the models provided by Amazon S3, Cloud Data Management Interface (CDMI) and OpenStack Swift are  the foremost  popular.

A RESTful API uses commands  to get  resources. The state of a resource at any given timestamp  is named  a resource representation. A RESTful API uses existing HTTP methodologies defined by the RFC 2616 protocol, such as:

  •     GET to retrieve a resource;
  •     PUT  to vary  the state of or update a resource,  which may  be an object, file or block;
  •     POST  to make  that resource; and
  •     DELETE  to get rid of  it.

With REST, networked components are a resource the user requests access to --  sort of a  black box whose implementation details are unclear. All calls are stateless; nothing  are often  retained by the RESTful service between executions.

Data formats  the remainder  API supports include:

  •     application/json
  •     application/xml
  •     application/x-wbe+xml
  •     application/x-www-form-urlencoded
  •     multipart/form-data


Because the calls are stateless, REST  is beneficial  in cloud applications. Stateless components  are often  freely redeployed if something fails,  and that they  can scale to accommodate load changes.  this is often  because any request can be directed to any instance of a component; there can be nothing saved that has to be remembered by the next transaction.  that creates  REST preferable for web use. The RESTful model  is additionally  helpful in cloud services because binding to a service through an API is a matter of controlling how the URL is decoded. Cloud computing and microservices are almost  bound to  make RESTful API design the rule in the future.

RESTful API Design and Architecture Constraints

RESTful API design was defined by Dr. Roy Fielding in his 2000 doctorate dissertation.  so as  to be a true RESTful API,  an internet  service must adhere to the following six REST architectural constraints:

    Use of  a consistent  interface (UI). Resources should be uniquely identifiable through  one  URL, and only by using the underlying methods of the network protocol,  like  DELETE, PUT  and obtain  with HTTP, should  it's  possible to manipulate a resource.

    Client-server based. There should be  a transparent  delineation between the client and server. UI and request-gathering concerns are the client's domain. Data access, workload management and security are the server's domain. This loose coupling of the client and server enables each to be developed and enhanced independent of  the opposite .

    Stateless operations. All client-server operations should be stateless, and any state management  that's  required should take place on the client, not the server.

    RESTful resource caching. All resources should allow caching unless explicitly indicated that caching  isn't  possible.

    Layered system. REST allows for an architecture composed of multiple layers of servers.

    Code on demand. Most of the time, a server will  remit  static representations of resources in the form of XML or JSON. However, when necessary, servers can send executable code to the client.

Common REST API challenges

Besides  the planning  and architecture constraints, individuals will  need to  confront some challenges with REST APIs. Some concepts  which can  be challenging can include:

    Endpoint consistency -- paths of endpoints should be consistent by following common web standards,  which can  be difficult to manage.

    API versioning -- endpoint URLs  should not be  invalidated when used internally or with other applications.

    Long response times and  an excessive amount of  data -- the amount of returned resources can increase in size in time, adding to increased load and response times.

    Navigation paths and user input locations -- because REST uses URL paths for input parameters, determining URL spaces  are often  challenging.

    Security -- which  features a  lot of aspects to keep an eye on, including  the utilization  of:


        blocking access from unknown IP addresses and domains;

        validating URLs;

        blocking unexpectedly large payloads;

        logging requests; and

        investigating failures.

    Authentication -- use common authentication methods  like  HTTP basic authentication (which allows for a base64-encoded username:password string), API keys, JSON Web Tokens and other access tokens. OAuth 2.0,  for instance ,  is sweet  for access control.

    Requests and data -- requests may have more data and metadata than needed or more requests  could also be  needed to obtain all the data. APIs  are often  adjusted for this.

    API testing --  are often  a long process to set up and run. Each  a part of  the process can be either long or challenging. Testing  also can  be done in the command line with the utility Curl. Parts of the testing process  which will  be challenging include:

  • Initial setup
  • Schema updates
  • Test parameter combinations
  • Sequence API calls
  • Validate test parameters
  • System integration
  • Define error codes and messages.

With error codes,  it's  more of a common practice to use standard HTTP error codes. These are recognized by clients and developers more often.

Error handling  might not  have a way to distinguish if a response is successful or not besides parsing the body or checking for an error.


REST  and straightforward  Object Access Protocol (SOAP) offer different methods to invoke a web service. REST is an  style of architecture , while SOAP defines  a typical  communication protocol specification for XML-based message exchange. REST applications can use SOAP.

RESTful web services are stateless. A REST-based implementation  is straightforward  compared to SOAP, but users must understand the context and content being passed along, as  there is no  standard set of rules to describe the REST web services interface. REST services are useful for restricted profile devices,  like  mobile, and are easy to integrate with existing websites.

SOAP requires less plumbing code -- meaning low-level, infrastructural code that connects main code modules together -- than REST services design.  the online  Services Description Language describes a common set of rules to define the messages, bindings, operations  and site  of the service. SOAP web services are useful for asynchronous processing and invocation.

History of RESTful APIs

Prior to REST, developers used SOAP to integrate APIs.  to form  a call, developers handwrote an XML document with  a foreign  Procedure Call (RPC) in the body. They then specified the endpoint and POST their SOAP envelope to the endpoint.

In 2000, Roy Fielding and  a gaggle  of developers decided to create a standard so that any server could talk to any other server. He defined REST  and therefore the  architectural constraints explained above in his 2000 Ph.D. dissertation at the University of California, Irvine. These universal rules make it easier for developers to integrate software.

Salesforce was  the primary  company to sell an API as part of its "Internet as a Service" package in 2000. However, few developers were actually  ready to  use the complicated XML API. Then eBay built a REST API, which expanded its market to any site  that would  access its API. This caught  the eye  of another e-commerce giant, and Amazon announced its API in 2002.

Flickr launched its own RESTful API in August 2004, enabling bloggers  to simply  embed images on their sites and social media feeds. Facebook and Twitter both released their APIs in 2006, buckling under the pressure of developers who scraped the sites and created "Frankenstein" APIs. When Amazon Web Services (AWS) helped launch the cloud in 2006, developers were  ready to  access data space in minutes using AWS's REST API,  and therefore the  request for public APIs quickly escalated.

Since then, developers have embraced RESTful APIs, using them  to feature  functionality to their websites and applications. Today, REST APIs are considered the "backbone of  the web ."