The internet is a web of connected servers.
But what exactly does this mean? Well, everything online works on a remote server hosted somewhere and accessed upon request. For instance, when you search Capella in your browser, your request is sent to Capella’s server. When the browser receives a response, it translates and displays it in your browser. This process of translation is made possible by an application programming interface (API).
APIs allow developers to organize code, hide complexity, and design reusable components. This allows them to build applications more effectively and efficiently.
Here is what you need to know about APIs including:
- What are APIs and their history
- How API works
- Why APIs are important
- Different types of APIs
What Is An API?
An application programming interface (API) is a set of programming tools that enables the transmission of data from one software or system to another. It allows two software components to interact and exchange data with each other. APIs speed up innovation since more developers can build products based on existing information and functionality.
A Brief History Of API
API was first described in a scientific literature paper in 1968 in the article called “Data Structures and Techniques for Remote Computer Graphics'' by Frank S. Greatorex and Ira W. Cotton. The paper described the interaction of an application – specifically a graphics program – with the rest of the computer system.
Several years later in 1974, API was introduced to the databases field and became part of the American National Standards Institute/Standards Planning and Requirements Committee (ANSI/SPARC) architecture for database management systems. This led to the emergence of more APIs to support different programming languages.
The next revolution of API was presented as a Web Application Programming Interfaces (WebAPI) but featured the traditional concept where API was based on a library. The idea was further expanded with the introduction of remote procedure calls. These calls were supported by the Java language. With the spread of the internet in the 1990s, standards such as COM, CORBA, and DCOM competed to become among the most common way to use API services.
In the early 21st century, Representational state transfer (REST) was introduced and outlined the idea of a network-based Application Programming Interface. XML and JSON web APIs also saw widespread adoption during this period. Today, web API is the most common meaning of the term API.
How Does It Work?
APIs sit between a web server and an application, acting as an intermediary layer that enables data transfer between programs.
APIs consist of two key elements:
- Technical specification that describes how data is exchanged between software, with the specification done in the form of a request for processing and data delivery protocols.
- A software interface that is built to the requirement that represents it and is available for usage in some manner.
In this case, the software that utilizes the features and functionalities of the API “calls” it, whereas the program that creates the API “publishes” it.
That said, here is how API works
- An API call is initiated by a client application to retrieve data – also referred to as a request. The request includes a request header, verb, and in some cases request body.
- Once a valid request is received, the API makes a call to the web server or external software
- The server then sends a response to the API with the information requested
- Then data is transferred by the API to the initial requesting application
Why Are APIs Important?
Whether you’re designing new tools or managing existing ones, you can use API to improve the quality and delivery of the process.
Software that was initially custom-developed for a certain purpose is now built to reference APIs that provide valuable features and functionalities. This helps reduce the time and cost to develop apps and lowers the possible risk of errors.
API further creates an extra digital layer to present business data and enterprise assets using APIs, with the necessary governance and security requirements. This can help improve customer, employee, and associate interactions. Improved functionality and scope of services increase the value delivered to customers and also improve customer experience.
API also offers additional data monetization opportunities such as data productization that includes customized plans and packages for new and existing business associates.
Types of API
One thing to note about APIs is that not all are equal. Developers can work with a variety of API types, protocols, and architectures based on their unique needs.
APIs can be categorized by availability (release policies) or by use cases. Here are the key API types to consider:
APIs by Availability (Release Policies)
When it comes to the release policies, APIs can be private, public, or partner.
Private APIs
Also known as internal APIs, these application interfaces are designed for connecting and improving systems and data within an organization. They are not exposed to third parties.
In-house developers can use these APIs to integrate the IT apps and systems of a company and create new systems or customer-facing applications leveraging existing systems. Since private APIs are not documented in a publicly released software system kit, they are often completely hidden from the public.
Public APIs
Also known as external or open APIs, public APIs are publicly published and can be used by any developer or third party. They have relatively low authorization and authentication measures and are often restricted in the assets they share.
The biggest advantage of public API is that anyone can share data openly. This makes it possible for any external developer or business to integrate with the app that owns the API system, making both the API and third-party software more valuable. A company may seek to monetize the public API by charging a fee per call to use the API.
Partner APIs
These APIs are only available to certain selected and authorized external developers or API consumers with specific rights or official licenses to access them. For this reason, they include stronger authorization, authentication, and security protocols. They facilitate business relationships, often integrating software between partnering organizations.
By Uses
APIs may further be classified based on the systems for which they are designed. They include:
Database APIs
The database API allows interaction between an app and a database management system using certain protocols such as TCP or IP. Developers work with database APIs by writing queries to access information, change tables, and so on. The APIs send out HTTP calls to the server where the database is located. Then, depending on the consumer input, it will retrieve the information requested from within the database, parse it, then return it to the end user’s application.
Operating System APIs
This set of APIs enables the user to access several features provided by the operating system of the device. Each operating system has its set of APIs, including Windows API or Linux API (kernel internal API and kernel-user API).
Remote API
Remote APIs describe the standards of communication for apps running on different machines. By remote, we mean that the resources being used by API are located somewhere outside the computer making the request. Because two remotely located apps are connected over a communication network, most remote APIs are written based on web standards. Java Remote Method Invocation API and Java Database Connectivity API are examples of remote APIs.
Web APIs
These APIs are designed to represent a set of widely used resources such as HTML pages. Users can access it using a simple Hypertext Transfer Protocol (HTTP). It’s a web development concept, limited to a web app’s client-side (a programmatic interface that helps extend functionality within a web browser or other HTTP client), and in most cases doesn’t include a web server or browser implementation details interface (SAP) unless it's accessed publicly by a remote web application.
Web APIs are normally called RESTful because the publisher of REST interfaces doesn’t save any information internally between requests.
API Specifications And Protocols
Developers depend on a certain collection of techniques and requests to integrate APIs with their software. The specifications that regulate the apps and management of such requests are known as API protocols. They guide the developers on the usage standards of API, the type of data used, the right commands to be given, and other components of API-related development.
Here are the most commonly used API protocols:
Simple Object Access Protocol (SOAP)
SOAP utilizes extensible markup language (XML) to power API interactions. In this case, XML files are used to transmit data over an HTTP or HTTPS connection. It’s also capable of transmitting data over other protocols such as transmission control protocol (TCP), simple mail transport protocol (SMTP), and user data protocol (UDP).
SOAP is commonly used with enterprise web-based systems to ensure the high security of data being transmitted. These APIs are preferred by providers of identity management, payment gateways, and CRM solutions.
Representational State Transfer (REST)
REST API is a software architectural style that outlines a uniform interface between computer systems on the web, making it possible for systems to communicate with each other. While REST transmits data in JSON, it can also transfer data in different formats including HTML, Python, and even media files and plain text.
APIs that use REST protocol are referred to as RESTful APIs. They use a client-server structure to transmit data. Unlike SOAP, REST can use HTTP or HTTPS to interact with other systems, making it less flexible on this front.
Google Remote Procedure Call (gRPC)
gRPC is a cross-platform open-source Remote Procedure Call (RPC) architecture designed to operate in numerous environments. It uses HTTP/2 for transport, protocol buffers as the description language for the interface, and provides extra features such as timeouts, flow control, authentication, blocking and nonblocking bindings, as well as cancellations.
During this process, the developer starts by defining the data structure they want to serialize. After specifying the data, they use the protocol buffer compiler to generate the data access groups in the programming language of choice. Then, binary compression and framing of the data are done. gRPC is commonly used for communication between microservices since it has a high performance and is available in multiple languages.
Graph Query Language (GraphQL)
GraphQL is a database query language designed specifically for APIs. This protocol's main focus is to provide clients with the exact data they request and simplify data aggregation from multiple sources. This way, the developer can use one API call to request all the data they need. Organizations choose to build APIs with GraphQL because it allows developers to create apps faster and more efficiently.
SOAP Vs. REST
Both SOAP and REST describe how to build APIs, which allow data to be communicated between web applications. That said, both approaches have notable differences. Here are the major ones:
- SOAP is a protocol that only works with XML formats, while REST is a set of architectural patterns that offers flexible implementation. REST works with XML, plain text, HTML, and JSON.
- SOAP utilizes service interfaces to define its functionality to client applications. REST, on the other hand, utilizes Uniform Service locators to gain access to the components on the device.
- REST APIs are considered lightweight, which makes them most preferred for newer contexts such as the Internet of Things (IoT), serverless computing, and mobile app development. SOAP, on the other hand, provides built-in security as well as transaction compliance that aligns with different enterprise needs.
API vs. Webhooks
Both APIs and webhooks allow different software systems to easily sync up and share data. So, how do they differ?
An Application Programming Interface (API) enables two-way communication between software applications and platforms. For APIs to work, there has to be a request for data, followed by a response to that request.
Webhooks or reverse API, on the other hand, is a way for one application to deliver data to another application in real time. Webhooks do not need to give a request to get a response. Simply put, API does something when you ask it, while a webhook performs tasks on its own when certain criteria or scenarios take place.
An API is used when there are constant changes in data, while a webhook is used to perform smaller tasks and requests.
Examples of APIs
APIs can be used to connect any processes virtually. Here are real-life applications of APIs:
Vulkan
It’s a new-generation cross-platform API that targets high-performance 3D graphics applications, such as interactive media and video games. Vulkan enables developers to create top-notch, real-time graphics in apps and drive the interaction between an app and a graphical processing unit.
Google Maps
Google Maps API allows users to pull customized location information, send directions, and analyze all types of location data. This can help businesses provide better services and establish viable connections with customers, suppliers, and more. For instance, Google’s Direction API uses an HTTP request to return JSON or XML-formatted directions between different geo-locations.
Weather API
A weather API allows weather information to be queried from code and scripts. It provides access to the world’s most accurate weather, environmental, marine, and climate data using an XML/JSON RESTful API.
Yelp API
Yelp’s API is a GraphQl API that provides data from millions of businesses across the globe. It features data such as business reviews, ratings, recommendations, photos, locations, and other details. It uses the HTTP request technique to access data from the servers.
Sabre Air Availability
The Sabre Air Availability API is a SOAP API used to retrieve schedules and availability for one or more destinations, origins, and travel dates. It utilizes XML as the data exchange avenue, and HTTP/HTTPS protocol for requests.
Skyscanner Flight Search
The Skyscanner public API allows travelers to connect to apps and websites to find the best travel deals from anywhere across the world. It supports both JSON and XML for data exchanges
How Do I Choose The Right API?
Developers have to choose from a wide variety of options available for integrations when it comes to APIs. Here are a couple of tips to help you choose the right API.
Performance
Speed matters a lot. To keep up with the rising customer expectations, API should have a high response time. One way to have a fast API is to take a client-side approach where information is sent to an edge node of a CDN network rather than being stored on a server somewhere in a data center.
Evaluate the Documentation
For any API solution you choose, it’s important to do thorough documentation to avoid incidences of trial and error. Strong documentation with FAQs allows developers to use API more effectively, and ultimately, send products to market faster. Key things such as whether the APIs are paid for or not, or if there are any limitations can be discovered once you evaluate the API documents in detail.
Flexibility
Developers should have the freedom to build anything they want with the API. This flexibility should be present in all aspects of the API. Developers should be able to replicate everything the customer wants, and also be in a position to manage back-end data based on the organization's needs.
Different Offerings
It’s also important to analyze different offers from the API provider. This means the actual features, cost, and charges of using the service. For instance, does the API charge by bandwidth, order, number of records, or more
This will allow you to identify the right set of APIs you require and you will know if you need more than one API.
Choose The Right API for Your Business
APIs are critical to ensuring a good software design. These advanced machine-readable interfaces for data exchanges work under the hood and enable seamless interaction between systems. API integrations provide quick access to information for the developers that create the app. This eventually trickles down to the user by making the app easier to use.
At Capella, we understand that APIs are the building blocks of any modern business that wants to stay competitive in the market. We have designed an easy-to-use API platform that makes it easy for the customer to search for their desired SAR imagery from our library catalog and submit new requests.
Get in touch with our team to get started with API integration today!
Rasheed Rabata
Is a solution and ROI-driven CTO, consultant, and system integrator with experience in deploying data integrations, Data Hubs, Master Data Management, Data Quality, and Data Warehousing solutions. He has a passion for solving complex data problems. His career experience showcases his drive to deliver software and timely solutions for business needs.