REST API full form is Representational State Transfer Application Programming Interface. It is an architectural pattern which is used by one application (client) to communicate wth another application (server) . REST technology which is based on client server model is used to create webservices . REST is used to fetch information from webservices and send information to webservices . It relies on a stateless communication. This means that it does not maintain state for each request . REST uses HTTP methods Like POST, PUT, GET , DELETE , PATCH to send requests. In REST API each data is identified as resource and is identified by URI (Uniform Resource Identifier ) . Since REST consumes less bandwidth and is simple to use so it is the first choice for developing APIs . RealLife rest api examples are Twitter API, Google Maps API ,OpenWeatherMap API and many more . In this guide we will cover below topics :
- Client Server architecture in REST API
- Key terminologies in REST API
- REST API HTTP methods
- REST API vs SOAP
- Importance of REST API
Client Server Architecture in REST API
Client server architecture is the core principle which is the base of REST API services . So what is client server architecture ?
In client server architecture the two main entities are Client and Server . A Client is an entity which makes a request .This client can be any application, any app or any web browser.
The other one ie Server is an entity which takes the request ,processes it and return a response in a predefined format .
The client and server are two separate entities . They do not depend on each other .
In client server architecture client is not aware of the internal workings of server and server donot know how client is processing the received response . Each request contain all details for processing request .
None of the request maintain state or session ie it is stateless . Server is able to handle one or multiple clients . From different servers client can request services .
Key terminologies in REST API
When working with REST API ,there are several terms in REST API .These terms define how REST API works and interact . Here’s a detailed explanation :
- Resource : In REST API resource is any data or object .This data can be manipulated or accessed using HTTP methods like GET,POST,PUT,PATCH,PUT .
- End-points : In REST API end points are specific URLs which can be used to access the resource for manipulation .
- URI : URI is uniform resource identifier is a string which identifies a reosurce .
- Headers : Headers are key vale pair data. These data are sent along with request and response . They are like metadata which adds extra information to request and response.
- Payload (Body Request) : Data which is sent in the body of request or response is known as payload. Client can send payload data in body as request to server. Server can send response data as payload in body to client . Payload can be in xml or json format .
- Response : Server when receives request processes it and return data as response to client .This response contains data ,status codes and success or error messages.
- Status Codes : HTTP status codes are returned with response by server after processing request data. These status codes informs the client that the response message is a success , has resulted in an error or needs some adjustments .
- Authentication : Authentication is a process to identify that the client or user requesting a resource in API is a valid user or not. It is a process to identify that user has proper credentials and is authorized to access resorce or not .
- Statelesness : In REST API state is not maintained for any request . It donot save the information of any request API call .
- Versioning : Developers mange different versions for API to make changes without breaking existing functionality .
- Caching : REST API stores data temporarily in cache to improve performance and reduce server load .
REST API HTTP methods
Client uses REST API HTTP methods to perform some operations on resource. These methods follow the principles of CRUD (Create, Read ,Update ,Delete) . Let us understand these REST API HTTP methods with examples .
- GET : This HTTP metod fetches or get data from server .
For example if we have REQUEST URI as GET /users/1 . In this example, URL retrieves the data of user with specific ID which is 1 .
In Response we will get all details of user in json format .Check the example below of response data :
{
"id": 1,
"name": "Dipti",
"email": "dipti@phpguruacademy.com"
}
- POST : This HTTP method creates a new resource on server . For example the request URI for POST method will be POST /users and the body will be in json format like below:
{
"name": "Dipti",
"email": "info@phpguruacademy.com"
}
Response returns the details of new user .
{
"id": 1,
"name": "Dipti",
"email": "info@phpguruacademy.com"
}
- PUT This HTTP method updates a resource entirely . It updates all data of a single resource. For example the URI for PUT request : PUT /users/1 In body we will pass the below request data in json format like below:
{
"name": "Archana",
"email": "archana@abc.com"
}
Here the request URI updates user with ID 1 with new data.
- PATCH This HTTP method updates a part within an existing resource . Like if we want to update email only then we will use PATCH for this. For example the request URI will be : PATCH users/1 and in body we will pass the required data to be update as below:
{
"email": "dip@gmail.com"
}
- DELETE This HTTP method deletes or remove a resource completely from server . For example the URI for delete request will be DELETE /users/1
Why REST API uses HTTP Methods
- Using these methods developers can create standard and consistent API .
- The provide simplicity and interoperability .
- Client interacts with resources easily enhancing developer experience .
REST API vs SOAP
SOAP full form is Simple Object Access Protocol . It is more complex and feature rich .It has higher security, transaction reliability, and formal messaging protocols so it is often by large enterprises .
SOAP uses Web Service Definition Language to describe services and it’s operations whereas REST donot uses WSDL . REST uses only HTTP protocol whereas SOAP uses HTTP , SMTP ,TCP and more . SOAP uses xml based verbose message format .The message format in SOAP is more complex as in REST message format is XML or JSON which is lightweight . As in REST, message format can be in different format so it is flexible.But in SOAP message format is only xml so it is more rigid.
In REST API each request is stateless .In SOAP request can be either stateful or stateless . REST is faster due to its simplicity and lightweight nature . SOAP is slower due to larger message sizes and XML parsing.
Importance of REST API
As we can create modern and fast applications using REST API so it has become popular and is in high demand. As it is scalable and fast ,robust applications can be build using REST API with simplicity .This is one of the reason that it has become the first choice for developers .
A single API can serve data to applications on different platforms . So wide range of applications reuses REST API, reducing redundancy, and saving development time. They follow standards and protocols so they are consistent in nature. This ensures consistency and interoperability across different systems and services. This makes it easier for developers to build web, mobile, or desktop-based applications that can communicate seamlessly .
Developers use different tools like POSTMAN or cURL to test APIs quickly . This has made testing and debugging APIs much easier and faster, This allows developers to quickly assess API functionality and ensure that it’s working as expected. Using REST API, developers can focus only on creating features which are innovative and valuable to users. On otherhand the API manages communication and data exchange between systems. Overall, REST APIs have become an important part of modern software development by providing ability to create flexible, scalable, and high-performance applications.