SDK Vs API, What's the difference?

SDK and API have different use cases and targets to address a specific concern in software development pipelines.

In this article, we will demystify SDKs and APIs to understand what they are, how they can be used, and how they relate to each other.

What is a Software Development Kit?

An SDK is a set of tools, libraries, and programs that can be used to develop applications for a specific platform or service.

SDK tools will include a range of things, including libraries, documentation, code samples, processes, and guides that developers can use and integrate into their own apps. SDKs are designed to be used for specific platforms or programming languages.

The Characteristics of a Good SDK

Because your mobile SDK is meant to be used outside your organization, it has to provide value to other businesses and their developers. That value is dependent on your SDK having the following characteristics:

1.Easy to use by other developers

2.Thorough documentation to explain how your code works

3.Enough functionality so it adds value to other apps

4.Does not negatively impact a mobile device’s CPU, battery, or data consumption

5.Plays well with other SDKs

In short, it just has to work. Ideally, it should work elegantly, but when time is of the essence, as long as it gets the job done, it should be good enough.

What is an Application Programming Interface?

Application Programming Interface or API is an interface that facilitates communication between two platforms.

The primary goal of an API is to standardize the way third parties interact with a piece of software—without using custom connectors or integrations. An API allows external parties to utilize or integrate the services provided by the software in their applications.

The Application Programming Interface can dictate what kind of functionality is exposed and what information can be exchanged between the underlying software or service and the API user (the third party who consumes the API). Typically, an API will consist of two components.

Terminologies of API development

a) API Key: When an API request through a header or parameter to recognize the requester, the authorized code passed into the request is said to be an API Key.

b) Endpoint: When an API interacts with another system, one end of the communication channel is termed as Endpoint.

c) JSON: JavaScript Object Notion or JSON is said to be a data format used for APIs request parameters and response body.

d) GET: The RESTful application program interface’s HTTP method of obtaining resources is called GET.

e) POST: It is the RESTful API’s HTTP method for building resources.

f) OAuth: It is basically an Open standard authorization framework that renders access from the user’s side without directly sharing the credentials.

g) REST: REST (Representational State Transfer) is a kind of programming architectural implementation meant to enhance the efficiency of communication between the two devices/systems. It is light-weighted and based on the idea of making a particular data available only when requested by sharing references to the data instead of the entire copy of the data itself. The systems enforced on this architecture are said to be ‘RESTful’ systems, and the most overwhelming example of RESTful systems is the World Wide Web.

h) SOAP: SOAP or Simple Object Access Protocol is a messaging protocol for sharing structured information in the execution of web services in computer networks. It works with XML information set and application layer protocols (like HTTP and SMTP) for message format and message negotiation & transmission, respectively.

i) Latency: Latency is defined as the total time taken by API interface in the process from the request to the response.

j) Rate-Limiting: The term API Rate-limiting refers to the process of defining the rate at which an end user can access the APIs. In other words, it means restricting the number of requests a user can hit to an API per time.

k) API Throttling: The process of regulating the usage of APIs by users during a particular time period is called Throttling. This can be used for API limiting. For example, you set the limit of 1000 API requests per day. When the user hit the 1001 request, the server will send 429 messages as HTTP status to the end user along with the message, “Too many Requests”.

Choosing between SDK or APIs?

There is no need to select only one between SDKs and APIs for your development. In fact, both of them are essential for all modern applications to facilitate core services through your application. As mentioned:

An SDK provides a complete development kit for software development for building applications for a specified platform, service, or language.
An API is used to facilitate communication between two platforms.
Developers can create their applications using an SDK and use APIs to integrate with third-party platforms or services to bring additional functionality to the application. SDKs themselves will include APIs that facilitate interactions with the targeted platform.

In the next article, we will dig deeper into the technical part – beginning with how API works and how to develop API (how to create an API)?