What are the Different Types of API Calls Developers Can Use?

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API calls are requests made by one software application to another. There are various types of API calls. Different protocols and interfaces are available to designers who want applications to 'talk' to each other. In this guide, learn about the different types of API calls and how DreamFactory can improve API management in your organization.

Here's the key things to know about the different types of API Calls:

  • API calls are essential requests made by one software application to another, enabling data and functionality access.
  • API calls involve sending requests to specific endpoints, which execute actions and provide responses.
  • API Protocols, including REST, XML-RPC, JSON-RPC, and SOAP, play a crucial role in modern software communication.
  • Different types, such as Web APIs, Open APIs, Internal APIs, and Partner APIs, suit various use cases.
  • Strategies like endpoint tracking, client authentication, schema validation, and DDoS mitigation bolster security.

What are API Calls?

API calls are requests made by one software application to another. These calls are used to access specific functionalities or data from a remote system or service. API calls allow different software components to communicate and interact, enabling seamless integration and data exchange between applications.

When an API call is initiated, it typically involves sending a request to the API endpoint, which is a predefined URL or URI (Uniform Resource Identifier). This request specifies the action or operation to be performed and may include additional parameters or data required for the task.

Once the remote API receives the request, it processes the request, performs the necessary actions, and sends a response back to the calling application. This response can contain the requested data or information about the outcome of the operation, such as success or error status codes.

API calls are fundamental in modern software development, enabling applications to leverage the functionality and data of other systems, services, or platforms, ultimately enhancing the overall capabilities and user experiences of software products.

API Protocols

API protocols determine a set of rules for different types of API calls. Here are four protocols you need to know about:

REST API Protocol

REST, which stands for Representational State Transfer, defines what an API looks like. REST APIs have a client-server architecture, where its interface is separate from its backend and data storage, enabling different API components to act independently of each other. A REST API should also have a 'layered system,' which enables an API to operate when communicating with a server or through an intermediary like a load balancer. There are other requisites for REST APIs. These types of API calls should have 'statelessness,' which means there is no client context stored between requests on a server. A REST API also needs to state whether it can cache responses. REST APIs use different messaging formats such as JSON, XML, HTML, and plain text.

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XML-RPC is a type of remote procedural call protocol (RPC) that uses XML to encode information from calls. It doesn't transfer data like REST protocols but instead executes scripts on a server. 


JSON-RPC is another type of RPC. Similar to XML-RPC, JSON-RPC executes scripts on a server. 


Simple Object Access Protocol (SOAP) is a protocol that builds APIs and transfers data across networks. Standardized by the World Wide Web Consortium (W3C), it also uses XML to encode information. SOAP works with various communication protocols such as TCP, SMTP, and HTTP but also operates independently, allowing you to use it with any programming language. Although REST and SOAP are different standards, you can create a RESTful API with SOAP protocols. 

DreamFactory can convert SOAP to REST through a single API response. It does this by automatically converting a JSON request into SOAP, calling the legacy SOAP service, and converting the SOAP response back to JSON for the client application. Learn more about this DreamFactory feature.

Types of API Calls: Interfaces

In addition to the above protocols, you can choose from the following interfaces when building APIs. 

Web APIs

Web APIs are the main types of API calls. Using the HTTP protocol, web APIs define different endpoints and response and request formats. There are four types of web APIs:

Open APIs

Open APIs are 'open' to developers because they often don't require registration or an API key. Used by developers to access services and information, they encourage data sharing between organizations. Several companies might use an open API to include data on their websites, for example. 

DreamFactory lets you add business logic to APIs so you can fulfill business requirements. You can use custom logic with four scripting engines — Python, PHP, NodeJS, and V8JS — to validate input parameters, call other APIs, and respond to client requirements.

Internal APIs

Internal APIs provide data within specific companies. Using the latest security and access control features, internal APIs restrict data access to anyone outside these companies. An example of an internal API might be one that shares sales data with different departments within an organization. Only approved users can access the API.

Partner APIs

Partner APIs are like open APIs but may restrict access to data through a third-party API gateway. An example of a partner API is the one developed by Neilson Media Research, which provides the latest TV ratings from U.S broadcast networks. Individual networks and media publishers can pay for access to the API and receive data. 

Securing APIs can be difficult and laborious. DreamFactory provides a solution with security features such as JSON Web Tokens (JWT) SSO authentication, user management, role-based access controls, and permissions for OAuth, SAML, Active Directory, and more. 

Composite APIs

Composite APIs let developers accumulate calls and requests. These types of API calls rely on one response from different servers, allowing developers to generate data from multiple services simultaneously. Typically found in microservice architectures, composite APIs can boost application performance, reduce complexity, make systems faster, and decrease server load.

How to Secure APIs from Invalid API calls

Ensuring the security of your APIs is paramount in the digital landscape. Here, we explore a range of strategies to help you keep your APIs secure and protected against potential threats:

1. Understand and Track API Endpoints: Maintaining an up-to-date inventory of all API endpoints currently in production is a fundamental step in API security. This comprehensive list not only aids in monitoring but also allows you to promptly identify any unauthorized or suspicious activities on your APIs.

2. Verify API Clients with Authentication: Authenticating API clients is crucial to ensure that API calls originate from legitimate sources. One highly effective method for client verification is mutual TLS (Transport Layer Security). In this approach, both the API endpoint and the client authenticate each other using public key cryptography. This two-way verification establishes trust and minimizes the risk of unauthorized access.

3. Validate API Schema: An API's schema functions as its rulebook, defining the structure and requirements for each API call. Validating incoming requests against the established schema helps pinpoint and block any invalid or potentially malicious API calls. By ensuring that every request adheres to the expected format, you can fortify your API against exploitation attempts.

4. Implement DDoS Mitigation: Distributed Denial of Service (DDoS) attacks can overwhelm your API with an excessive volume of requests, causing downtime and service disruption. Employing a DDoS mitigation provider can actively monitor and filter incoming traffic, swiftly identifying and neutralizing malicious traffic to ensure your API remains accessible and responsive.

By adopting these proactive security measures, you can significantly bolster the security of your APIs, protecting both your data and the seamless operation of your services. Remember that a multi-layered approach to security, which includes vigilant monitoring and continuous updates, is the key to staying ahead of evolving threats in the ever-changing landscape of API security.

Final Word

Developers can use various types of API calls to facilitate different functions. The range of API protocols and interfaces available to these developers improve flexibility and lead to more successful data integration outcomes. 

DreamFactory is the API management platform that provides your business with ongoing value. Easy to deploy with Docker, Kubernetes, or from GitHub, you can run it on public, private, or hybrid cloud infrastructure and improve automation and the user experience. Transform the way you manage your data portfolio, modernize legacy applications, deal with web applications, handle API security, improve API testing, and create and deploy no-code APIs. Start your free DreamFactory trial now!

Frequently Asked Questions (FAQs) About API Calls

What is the difference between API and API call?

An API (Application Programming Interface) is a set of rules and protocols that allows different software applications to communicate and interact. An API call, on the other hand, is a specific request made by one application to another using that API. It's the actual act of invoking a particular function or retrieving data.

Why are API calls important in software development?

API calls are crucial because they enable different software components to work together, allowing applications to access the functionality and data of other systems or services. This promotes interoperability and facilitates the integration of various technologies, which is fundamental in modern software development.

What are API endpoints?

API endpoints are specific URLs or URIs (Uniform Resource Identifiers) provided by an API to access its functionalities or data. When making an API call, you specify the endpoint to indicate which operation you want to perform.

Can one API support multiple types of API calls?

Yes, most APIs support multiple types of API calls to perform various actions or retrieve different sets of data. For example, you might use different API calls to create, read, update, or delete records in a database through the same API.

Are API calls always synchronous?

No, API calls can be either synchronous or asynchronous. Synchronous calls wait for a response before proceeding, while asynchronous calls allow the caller to continue working without waiting for the response. Asynchronous calls are often used for time-consuming operations or when real-time responsiveness is not critical.

How can I secure my API calls?

Securing API calls is essential to protect data and ensure the integrity of your system. Common security measures include using authentication mechanisms (such as API keys, OAuth, or JWT), implementing access controls, and employing encryption to safeguard data during transmission.

What is the role of API documentation in making API calls?

API documentation provides essential information about how to make API calls, including the available endpoints, request parameters, expected responses, and usage examples. It serves as a guide for developers to effectively utilize the API.

Can I track and monitor API calls for my application?

Yes, you can track and monitor API calls using various tools and services. These tools provide insights into API performance, error rates, usage patterns, and other metrics, helping you optimize your application's API integration.

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