Name: Ubendra S
Email: ubendrass@gmail.com
API:
An API (application programming interface) is a set of rules that
allows various software applications to talk to one another. It can be
viewed as a bridge between two software applications (client and server)
allowing them to communicate and interact.
To understand the role of an API even better, consider how it works
at a restaurant. The waiter (API) takes your order (request) and tells the
chef (server). After the chef has prepared your food (response) the waiter
brings it back to your table. Similarly, when you look for a course on a
website, your request goes through an API that fetches the data from the
database and brings it back in the response.
Purpose of an API:
The primary purpose of an Application Programming Interface (API)
is to enable communication and interaction between different software
applications. It acts as an intermediary, defining a set of rules and
protocols for how software components should interact, exchange data,
and access functionality from other systems.
Key purposes of APIs include:
1. Integration Between Systems
APIs connect different systems or platforms so they can work together.
Example: A travel website uses APIs to fetch flights from airlines,
hotel listings from booking engines, and weather info from weather
services—all into one dashboard.
2. Data Access Without Exposing Internal Logic
APIs allow users to access data or services without exposing how
the system works internally.
Example: A mobile banking app accesses your account balance via
API without showing how the bank’s internal system processes that
request.
3. Automation
APIs allow tasks to be automated between services, reducing the need
for manual intervention.
Example: An ecommerce site uses a payment gateway API to
automatically process transactions.
4. Reusability & Scalability
APIs make it easy to reuse functions or services across multiple
applications.
Example: Google Maps API can be reused across thousands of apps
that need map features, from ride-hailing to delivery.
5. Faster Development
Developers can build apps quickly by using existing APIs instead of
writing complex features from scratch.
Example: Instead of building your own login system, you can use
Google OAuth API for sign-in.
6. Security
APIs can control access to resources via authentication and
permissions, allowing only authorized users.
Example: Cloud services like AWS or Azure provide secure access
via API keys or tokens.
APIs Work:
APIs work in a simple step-by-step process:
Request: A client (user) sends a request through the API's URI
(Uniform Resource Identifier).
Processing: The API forwards the request to the server.
Response: The server processes the request and sends the
response back to the API.
Delivery: The API returns the server's response to the client.
Types of APIs:
1. WEB APIs
A Web API also called Web Services is an extensively used API over
the web and can be easily accessed using the HTTP protocols. A
Web application programming interface is an open-source interface
and can be used by a large number of clients through their phones,
tablets, or PCs.
2. LOCAL APIs
In this type of API, the programmers get the local middleware
services. TAPI (Telephony Application Programming Interface), and .NET
are common examples of Local APIs.
3. PROGRAM APIs
It makes a remote program appear to be local by making use of
RPCs (Remote Procedural Calls). SOAP is a well-known example of this
type of API.
Types of API Architectures:
1. REST :A simple, flexible API architecture that uses HTTP methods
(GET, POST, PUT, DELETE) for communication.
2. SOAP : A more rigid protocol that requires XML-based messaging
for communication.
REST API (Representational State Transfer):
REST:
REST is an architectural style used to design networked
applications. RESTful APIs use HTTP methods (like GET, POST, PUT,
DELETE) to perform operations on resources, which are typically
represented as JSON or XML.
Key Features of REST API:
Stateless: Each request is independent; the server does not store
any client context.
Uses standard HTTP methods:
o GET – Retrieve data
o POST – Create data
o PUT – Update data
o DELETE – Remove data
Lightweight and easy to use
Data usually in JSON, which is faster and more readable than XML
Examples:
Google Maps API for getting map data
Spotify API for getting song or playlist info
Weather APIs to get forecasts
SOAP API (Simple Object Access Protocol):
SOAP:
SOAP is a protocol for exchanging structured information using
XML over various protocols (HTTP, SMTP, etc.). It is highly standardized
and often used in enterprise-level applications.
Key Features of SOAP API:
Strict structure defined by WSDL (Web Services Description
Language)
Supports security (WS-Security), ACID-compliant transactions,
and reliable messaging
Communicates using only XML
Works with multiple transport protocols, not just HTTP
Examples:
Payment gateways (used for secure transactions)
Government and healthcare systems
Airline booking systems (Amadeus, Sabre)
SOAP vs. REST:
SOAP REST
REST (Representational State
SOAP (Simple Object Access
Transfer) is a set of
Protocol) is a protocol with
guidelines (architectural
specific requirements like
style) offering flexible
XML messaging
implementation
Heavier and needs more Lightweight and needs less
bandwidth bandwidth
It inherits security from the
It defines its own security
underlying transport
It permits XML-based data It permits different data formats such
format only as plain text, HTML, XML, JSON, etc.
SOAP calls cannot be
REST calls can be cached
cached
