What is an API? Simply explained!
API interfaces: an excursion into modern data communication
APIs (Application Programming Interfaces) sind aus unserer digitalen (Geschäfts-)Welt nicht mehr wegzudenken: Dank ihnen können unterschiedliche Anwendungen miteinander „sprechen“ – ungeachtet der verwendeten Software oder Programmiersprache für ihre Entwicklung. APIs ermöglichen uns, mühelos durch Websites zu navigieren, Online-Dienste zu nutzen und Nachrichten in Sekundenschnelle über das Internet zu senden.
It is no wonder, then, that APIs now play an important role in every modern company, whether in system integration, app development, e-commerce, reporting, or customer service.
This blog post takes you on a journey into the world of APIs and explains the basics, how they work and their importance for modern software development and integration.
API definition
An API is an interface – or, more specifically, an application programming interface. An API defines a set of rules and protocols that enable software applications to communicate with each other and access certain functions or data. It acts as a mediator between different applications or services by providing a defined set of methods, data structures and conventions for sending requests and receiving responses.
For developers, this means that they can integrate functionalities from one application into another without having to reimplement the entire source code APIs therefore provide a standardized way to access services and exchange data, which in turn makes software development easier and more efficient.
Why do we need APIs?
In addition to their ability to link different applications and enable data communication between them, API interfaces contribute to the development of high-quality web services . As a bridge between different applications, APIs help your end users to easily access different functions without having to worry about technical hurdles.
A look at the key API benefits for businesses:
- Expansion of product functionality: with the help of APIs, companies can seamlessly integrate additional features and services from third-party providers into their own products. This allows them to expand their offerings without having to develop all the necessary resources themselves or make major changes to their existing infrastructure.
- Accelerated development: by using APIs, developers can access existing functionalities and do not have to reinvent the wheel every time. This naturally shortens the development time for new products and applications, resulting in a faster time to market and a competitive advantage.
- Positive customer experience: API integrations also enable companies to offer their customers a streamlined user experience by allowing them to interact seamlessly with other apps and services. A practical example: an online shop that uses an API to transfer payment processing to an external payment service provider. This saves both the company and the customer time. APIs also help to improve the quality of customer service and ensure satisfied and loyal customers.
- Efficient data integration: APIs make it easy to exchange data securely between different systems and applications, enabling companies to collect, analyze, and use data more efficiently to make informed business decisions. The insights gained from data analysis also benefit customer service – but they also help to promote innovation: impress with tailored solutions that are precisely customized to the individual needs of your customers.
- Opening up new markets and customers: by providing APIs, companies can make their services and products accessible to developers, who can then incorporate them into their own applications. This opens up new distribution channels and enables companies to reach new markets and customers.
We see that APIs offer companies the opportunity to optimize their services and products, accelerate their development, expand their reach and thus become more competitive. They are an essential building block for digital transformation and innovation in today's business world.
API management
APIs require a certain amount of care and prudent maintenance to ensure that they work effectively, purposefully and securely. This is where API management comes into play. APIs must be carefully created, monitored and secured – in an organized and controlled environment. A range of tools, processes and guidelines are used to effectively manage and improve APIs.
Let's have a closer look at the three most important aspects of API management – security, governance and analysis:
APIs and security
Nothing works without it: API security forms the fundamental basis of API management and is essential to protect APIs from unauthorized access and potential threats. On the one hand, authentication and authorization of user access to the API play a special role: token-based authentication methods token-based authentication methods, for example, are often used for API security. Here, authenticated users receive a token that must be transmitted with every API call to confirm their identity. These tokens have a limited period of validity and can usually also be revoked.
Furthermore, the encryption of data transmitted via API calls is important for security. By using SSL/TLS , data can be encrypted during transmission, which ensures the confidentiality and integrity of the data.
Fundamentally, it is crucial to establish clear standards and guidelines to protect sensitive data and ensure that it is not at risk or compromised. By using API management platforms, companies can be supported in defining a uniform set of security guidelines for their APIs. In addition, API management enables the effective management of data traffic to backend systems.
APIs and governance
While API management is primarily concerned with ensuring a consistent user experience, API governance also encompasses aspects such as discoverability of APIs, lifecycle management and reusability. API governance also helps developers ensure that each API program is created proactively and in accordance with compliance guidelines , and pursues specific goals that add value to the entire organization.
Particular attention should be paid to the documentation of the APIs so that developers can fully understand, use and integrate them into their applications.
In many cases, API governance also involves managing partnerships and collaborations with external developers or organizations. This may include developing guidelines for sharing APIs, as well as providing support and resources.
API analysis
Finally, API analytics provides organizations with valuable insights into API usage and performance. By collecting and reporting on API metrics in a centralized location, organizations can accurately measure how their APIs are being used, including requests per second, active users, and data transfer rates. This analysis is extremely helpful for identifying usage trends and pinpointing bottlenecks or issues in real time.
By continuously monitoring and analyzing API usage, companies can also improve the user experience by optimizing and customizing features to meet the needs of their target audience. In addition, API analysis helps them use their resources more wisely and identify inefficient processes. The insights gained also serve as a basis for meaningful business decisions, such as optimizing strategy, developing new products, and promoting business growth.
APIs in practical application
APIs are used in a wide range of use cases and areas in companies. They facilitate the integration of systems and services, support the development of applications and the exchange of data, and enable the automation of various business processes.
Examples of API usage:
- Integrating systems: APIs enable companies to integrate different systems with each other, whether they are internal systems such as CRM-, ERP– or accounting software, or external third-party services such as payment processors or shipping logistics.
- Developing apps/applications: developers use APIs to integrate features and data from platforms or services into their own applications. For example, businesses can use Google Maps APIs to incorporate map data into their mobile apps or web applications.
- E-Commerce integration: APIs play a major role in e-commerce by helping to integrate payment processing services, shipping logistics, inventory management systems, and other services to ensure the smooth operation of e-commerce platforms.
- Data exchange: APIs are often used to facilitate data exchange between internal departments or external partners. For example, APIs can be used to synchronize customer or product information between a CRM system and a marketing automation tool.
- Analytics and reportingcompanies use APIs to access data from analytics platforms such as Google Analytics, Salesforce or HubSpot to create custom analytics and reports tailored to their specific needs.
- Customer service and support: APIs are used in customer service and support systems to retrieve customer data, manage tickets, and send and receive notifications across a variety of communication channels, such as email, chat, or social media.
These examples illustrate how APIs can help to integrate various functions and services into applications in practice and accelerate the development of innovative solutions.
What types of APIs are there?
There are basically four different groups of API interfaces, which are selected according to the area of application:
- Function-oriented APIs are fairly complex interfaces that allow access to hardware components, for example, where only functions are called.
- File-oriented APIs establish a connection at the file level, allowing access to individual files or file functions. However, the operating system must be taken into account due to access rights.
- Protocol-oriented APIs are used for standardized communication between programs and are independent of operating systems or hardware.
- Object-oriented APIs have what are known as interface indicators and, especially in comparison to function-oriented APIs, can be used flexibly.
In addition, APIs can be distinguished according to their accessibility:
- Private API interfaces are only available within a company and often connect proprietary functionalities via private networks.
- Public APIs, on the other hand, are available to everyone and can be used very practically by software developers. Google, Amazon, Facebook and PayPal , for example, offer public interfaces. Some manufacturers, such as Google, even actively encourage developers to get involved in their API development.
The REST API
When dealing with APIs, REST APIs are never far away: REST stands for REpresentational State Transfer. This is a type of software architecture for interfaces, which, as a rule, use the HTTP protocol for their communication. This enables two computer systems to communicate with each other via the internet.
In principle, however, a REST API (also RESTful API) is compatible with any type of protocol or data format, which makes it an extremely versatile and popular interface.
As we already know, APIs are used to exchange information between users and applications – and the REST API is no different. For example, as soon as you visit a website, your client communicates with the server using an API: the API sends the request to the server (the call to the website) and then forwards the response to you (you are taken to the requested website).
A REST API must fulfill certain parameters in order to be called REST:
- Client-server model: the architecture of a REST API always includes a client and a server – and both are strictly separated from each other. This means that both can be developed and modified independently of each other without affecting the other component. This is why REST APIs are characterized by a particularly high degree of flexibility and scalability.
- Statelessness: RESTful APIs are stateless, meaning that each request from the client to the server already contains all the information needed to process that request. The server does not store any information about the client's state between requests. This also promotes scalability and horizontal integration of systems.
- Layered system: "Everyone does their own thing" – in a layered system, the client and server work separately. If a client makes a request via a server endpoint URL, it does not need to know which server is processing its request. A multi-layered system can also contain different servers, each with their own task, such as load balancing, caching , etc. The layered system therefore primarily ensures security, as attacks within the individual layers can be isolated and contained. This means that attacks never jeopardize the entire architecture.
- Uniform interface: a unified interface defines the interaction between client and server in a REST API. This includes the use of standardized HTTP methods, unique resource URLs, MIME-types for representing data, and the use of hyperlinks for navigating between resources. Simply put, any REST client can call the server in the same way and access its resources, regardless of whether the client is a browser or a mobile app, for example.
- Cachable: REST APIs support the caching of resource data on the client side to improve performance and reduce network load. This is done by using HTTP cache headers such as Cache-Control and ETag.
The code-on-demand function offers a bonus: here, the client is given the option to download code and use it for themselves.
Web APIs vs. REST APIs
„Ist das nicht irgendwie beides dasselbe?“ Werden Sie sich vielleicht fragen. Zugegeben, im Reich der Informationstechnologie kommt es ja gern mal zu Verwirrungen.
Yes, somehow they are the same. No, actually they are not quite the same.
While a REST API is also a web API, there are still significant differences between the two:
- Architecture: REST is based on the use of standard HTTP methods such as GET, POST, PUT and DELETE. APIs built using these methods are easy to understand and translate. By contrast, the term web API basically refers to any API that is accessible via the internet. Various architectural styles can be used, such as REST, SOAP, GraphQL etc.
- Data formats: REST APIs can handle many different formats, such as JSON, XML, while ordinary web APIs only work with XML. Therefore, you should always keep the data format requirements in mind when selecting an API.
- Protocols: REST APIs work primarily with the HTTP/HTTPS protocol, whereas web APIs use other protocols such as SOAP or BEEP in addition to HTTP/HTTPS. Because the choice of protocol affects both speed and security, it is important to think about this before deciding on an API model.
- Communication via HTTP: REST APIs use standard HTTP methods (GET, POST, PUT, DELETE) to perform CRUD (Create, Read, Update, Delete) operations on resources. Web APIs can use various methods to perform operations on resources. They are not limited to using standard HTTP methods and can implement their own custom methods.
Interested in an API?
Now that you've learned so many exciting things about APIs, you're bound to have a few ideas of your own about how you can use the right APIs to give your business a boost.
API interfaces are a booster for modern software development and bring together various applications and systems. Through standardized communication between software components, APIs make it much easier to exchange data, use functions and develop new innovative solutions. From the simple connection of external services to the development of complex platforms – APIs open up new possibilities for software developers to create stable and scalable applications.
We recommend that you consider APIs in your digitalization strategy, because they offer numerous opportunities to provide real added value and to positively differentiate yourself from competitors.
APIs connect us in the digital world – they break down silos and create new synergies. Let's use their potential to push the boundaries of what is possible in software development and to shape a connected future!
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