All mobile applications utilize several APIs (Application Programming Interfaces) and SDKs (Software Development Kits) to increase standardizations and add new and useful features. These software packages allow for unique capabilities that most developers would not otherwise be able to deploy without many dedicated resources. With this being said, there’s a lot of confusion over what the difference is between an SDK and an API and why an app would want to integrate 3rd party software. In this blog post, we will define APIs and SDKs and discuss the difference between an API and an SDK and how they serve different purposes.
What is an API?
Broadly speaking, an Application Programming Interface (API) is a set of subroutine definitions, communication protocols, and tools for building software. In general terms, it is a set of clearly defined methods of communication among various components.
There are two main types of APIs, server-to-server or client-to-server, and component-to-component. Server-to-server and client-to-server APIs are commonly a stateless interface to a remote server to set or get data. Typically, these types of APIs use a “RESTful” (representational state) protocol which requires them to be “stateless”. Stateless protocols require that any call to the API be completely independent from any past or future calls to the API. The API defines a communication protocol and “expected behavior” that allows a client to make requests and receive responses to and from a server. It is the developer's responsibility to integrate an API into their solution and use the API correctly. Component-to-component APIs can act a bit differently. These APIs allow different software packages to communicate on the same device and are not communicating with an external server or device. A good example of this type of API would be Android’s set of APIs.
Skyhook provides a location API to its Precision Location service, however, when utilizing this location API, the developer is required to source the GPS data, Wi-Fi data, or cellular data and to implement the API request according the the specifications outlined.
What is an SDK?
A Software Development Kit (SDK) can refer to a number of software tools, but a commonly agreed upon definition is: “A set of tools that can be used to create and develop applications.” In general, an SDK refers to a full-suite software module that includes everything you need for a specific module within an app. They are often compared to a code library, which is a collection of non-volatile resources, used by computer programs, often for software development. It often “wraps” (fully or partially implements) an API and utilizes the APIs communication protocols in the appropriate and intended manner. It includes examples, documentation and, the methodology necessary to perform specific functions.
For example, Skyhook’s Android Precision Location SDK provides all the tools and documentation needed to perform highly-accurate location on a mobile device. The app developer simply needs to load, or dynamically pull, the SDK library into their development environment and use the available interfaces to utilize all the capabilities Skyhook provides. No extra code is needed to source the GPS data, Wi-Fi data, or cellular data to calculate an accurate position, this is all handled by the SDK.
Why use an API?
APIs are typically much lighter weight than SDKs since a full library is not needed to be integrated into your app or are native to the development platform. APIs are useful when you only need 1 or 2 specific functions of an SDK and are not looking for a fully integrated experience. Developers need to keep in mind that implementing an API often requires more programming upfront and are less “plug-and-play” than SDKs. Finally, APIs are also useful for applications where your codebase is programed on atypical platforms.
Why use an SDK?
SDKs provide developers with an array of tools needed to provide end-users of an app a unique and standardized interface. Developers also don’t need to reinvent the wheel when in comes to standard app features, such as location, data storage, geofencing, user authorization, etc. They have a set of robust functionality -- error handling, consistent performance, code reuse -- that takes a lot of the complexity away for software developers. SDKs ensure that any API provided is implemented correctly, reducing the headache that could be associated with implementing an API. The SDK often goes further, and provides enhanced features on top of APIs that allow for improved user experiences within your app. Finally, SDKs also allow for easier upgrade paths and handling of deprecations for certain lower-level APIs.
The Bottom Line
No matter the type of app you are creating, SDKs and APIs provide vital services for ease in development and time to market. They provide functionality that improves user experience and common packages to address typical use cases.
Skyhook provides location SDKs and location APIs that will provide accurate location via our Precision Location SDK and API, while also providing battery-efficient geofencing solutions via our Context SDK. Check out all of our available solutions at https://www.skyhook.com.