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The SDK is one of the most commonly used tools in advertising technology (AdTech). Although most publishers and advertisers routinely use SDKs for serving ads, you may be wondering about the details: what it is, how it works, and what it contains. Understanding what SDKs are and how developers use them is critical to understand what makes one suitable for your needs.
Definition & Meaning of an SDK
SDK stands for Software Development Kit. Alternative terms include “devkit” or “dev-kit.”
SDKs are software packages containing multiple programs and tools designed to create computer applications. The SDK can be considered the computing equivalent of a toolkit.
The type and nature of an SDK’s tools vary depending on its intended purpose. They may include documentation, compilers, code libraries, code samples, development environments, editors, debuggers, testing and analytics tools, and many more.
SDKs are typically designed for building an application on a specific operating system or platform using one or more programming languages. For instance, developing an Android application usually requires an Android-specific SDK.
Resources and Sets of Tools Found in SDKs
Although each SDK is unique, most contain the same types of tools. Below are some of the most common types of SDK tools and software.
The compiler is one of the most critical elements of an SDK. Compilers are specialized software capable of translating a program’s human-readable source code into machine-readable, executable code.
Developers need compilers to create applications and programs from code written in a specific programming language for a particular operating system or environment.
For example, a developer building an application using the C++ programming language meant for a Windows system needs a compiler that can read and interpret C++ code and compile it into a format executable by the Windows operating system (e.g., a .exe file).
Most compilers work according to a 5-step process:
- Lexical and syntax analysis: The compiler splits the source code into lexical tokens, which can be viewed as the programming equivalent of sentences. It then reads each sentence and checks for syntax errors. If it finds none, the compiler proceeds to the next step
- Semantic analysis: The compiler analyzes the code a second time to verify its accuracy and check for logic errors.
- Intermediate representation: After verifying the source code has no semantic errors, the compiler translates it into a format known as Intermediate Representation (IR). IR code is a representation of the source code in a format closer to that of machine-readable executable code but isn’t yet ready for execution.
- Optimization: Compilers optimize the IR code to ensure it runs faster and more efficiently (consumes less computing resources). Optimization may trim, tune, or rewrite specific parts of the IR code to make it leaner, but it cannot change the code’s functionality or meaning.
- Output: The compiler uses the optimized code to generate a machine-readable executable program.
Debuggers, also known as debugging tools, are another category of essential tools found in SDKs. Debuggers are specialized software capable of reading other programs and checking for software bugs, a broad term encompassing a range of programming flaws, errors, unintended behaviors, and other faults.
Although debuggers cannot detect and remove every bug in a program, they are crucial to the development process because they can help developers remove as many errors and issues as possible from the software or application before release.
Developers primarily employ debugging tools during the testing phase of a typical software development cycle, which takes place just before deployment and release and after design and development.
Debugging occurs relatively late during a program’s development cycle because it is essential to a program’s testing and quality control phases. It can only be efficiently performed after the code no longer needs fundamental changes, as adding new code after debugging carries the risk of introducing new, undetected bugs.
API stands for Application Program Interface. Although SDKs are often confused with APIs, they are not the same and perform different tasks.
An API is a set of functions designed to allow communication between two different programs, applications, or computing platforms. SDKs typically contain multiple APIs designed to facilitate development. Although the purpose of an SDK is to develop applications, a developer can also use the tools in an SDK to build their own APIs.
SDKs typically feature documentation detailing how to use each of the tools and elements it contains. SDK documentation may either be offline and included in the SDK in the form of readable files or hosted online on a website. Besides text file documents, an SDK’s documentation may also include sample images, illustrative graphics, FAQs, and even tutorials.
Code samples are snippets of pre-written code. In SDKs, code samples feature functional examples of what a developer can do with the SDK, helping them contextualize the SDK’s capabilities.
While most code samples can function as examples to draw inspiration from, developers know that the code samples included in an SDK are already functional and potentially usable for developing an application. Consequently, many developers may also choose to integrate code samples (or parts of them) directly into the source code of a new application.
A programming library (or code library) is a packaged collection of prewritten code designed to perform specific tasks arranged and organized by function. Developers rely on libraries to solve common tasks and issues more quickly, reducing overall development time and improving the source code’s reliability.
Because code libraries must contain prewritten source code, each library is specific to a programming language. For example, a developer writing an application using the Python language can only use libraries containing Python code, such as NumPy or TensorFlow.
At first glance, a framework may seem similar to a programming library: both contain code snippets designed to solve specific tasks and save time. However, many SDKs include both code libraries and frameworks, and the specific ways they help a developer are fundamentally different.
The best way to understand the difference between a programming library and a framework is with the calling analogy. With a code library, the developer’s source code calls on the features in the library to achieve a specific task. In other words, the developer uses libraries to control the application’s flow.
In contrast, if a developer uses a framework to build an application, the framework serves as a foundation that calls on the developer’s source code. The developer may not integrate new functionality if it isn’t compatible with that framework. In other words, the framework controls the application’s flow.
API Testing and Analytics Tools
Many SDKs include additional tools alongside APIs, such as API testing and API analytics software. The purpose of these support programs is to test an API’s performance and verify it functions as expected while meeting all relevant security and reliability standards.
Developers relying on one or multiple APIs to build an application may use these testing and analytics tools frequently during the testing stage of the development cycle.
What Does an SDK Do?
Each SDK is different, meaning there is no step-by-step guide that can be employed to use all SDKs. However, certain general principles apply to most SDKs: how they are made and distributed, what kinds of terms and conditions apply when using them, how developers might use the tools inside an SDK, and how SDKs impact the release of a finished application.
How SDKs Are Made
Before developers can use an SDK for building apps, another team of developers must design and create it. Most successful SDKs come from large firms that have developed their own operating systems, platforms, or applications.
In these instances, the SDK is typically intended for developers looking to build apps compatible with a platform developed or managed by the SDK’s authors. For example, the Android Native Development Kit was developed by Google to allow developers to use C and C++ code for developing Android applications.
However, SDK development isn’t restricted only to large companies. Depending on the SDK’s intended purposes and applications, skilled developers can independently develop their own SDKs, provided they are intimately familiar with the target programming languages, operating systems, and APIs.
SDK developers must also have the resources to build all necessary documentation, develop 100% functional and bug-free code samples, and, if needed, design custom tools (e.g., compilers, debuggers, etc.).
Who Can Use an SDK
The distribution channels employed to make SDKs available to developers vary depending on who built the SDK and what types of applications it is designed to build.
Although most SDKs are free, many come with licensing agreements outlining terms and conditions for the developers. For example, a freely available SDK may include licensing terms that allow developers to build applications but not permit redistribution of the SDK or commercial use of applications built using this SDK.
Consequently, a developer must carefully review and understand the SDK’s licensing terms, as it can significantly impact their application’s development and publishing processes.
Some SDKs are not freely available and only accessible to developers under specific conditions. For example, some platforms require developers to purchase the SDK directly or pay to become a member of the SDK authors’ platform as a condition for accessing the SDK.
More rarely, specific SDKs may be private to a particular company or business and intended for internal use only. For example, a video game development company may develop an SDK for the sole purpose of aiding developer employees with building new games. Such SDKs are not intended for public usage and typically contain many proprietary tools and software.
How Developers Use SDKs for Software Creation
Generally speaking, after a developer has acquired the SDK that will let them develop an application in their chosen combination of programming languages and target platforms, the general usage steps are relatively simple:
- Install the SDK
- Start development using the SDK’s interface
- Use the tools provided by the SDK to expedite or facilitate specific aspects of development
- Compile the source code into a functional application
Although SDKs are described as the programming equivalent of a toolkit, meaning developers use the contents of an SDK as tools to build new applications, the industry frequently uses the term “integration” to refer to elements intended for direct use and insertion into the source code of a new application.
For instance, “integrating an SDK” doesn’t mean the developer includes the entirety of the SDK in the application’s code. Instead, it is a shorthand to refer to the elements of an SDK that a developer can directly integrate, such as code samples, code pulled from a library, APIs, and frameworks.
A good way to understand the difference is to use the toolkit analogy and compare SDK tools to spare screws and screwdrivers: Some SDKs feature tools comparable to screwdrivers (e.g., compiler, debugger) and elements more like screws of specific kinds and sizes (e.g., library code, APIs). The finished product may contain the latter, but you wouldn’t expect it to include the former.
CodeFuel Can Help You Find the Best SDKs
At CodeFuel, we can help software developers and publishers find the best and most fully-featured SDKs to build and monetize applications as efficiently as possible. Our team can also help you find other avenues to monetize your digital properties and make the most out of your available assets. Contact us today for more information.