OData vs REST: What You Need to Know

When two different software applications want to join forces by sharing information, it’s not always a perfect union. Different database structures, programming languages, and network protocols tend to complicate the process. When reading about the various  API technologies, you’ve probably come across two terms, OData vs REST, and wondered, “what’s the difference?”

It turns out that OData vs. REST are two closely related concepts. While they aren’t the same thing, they share a common approach to getting things done. You can think of OData as a set of principles for building RESTful APIs that focuses on your business logic rather than the technical side of building APIs.

Here are the key differences between OData and REST:

• REST is an architectural style for exchanging information via the HTTP protocol, while OData builds on top of REST to define best practices for building REST APIs.
• Both REST and OData adhere to web-based architecture, statelessness, data format flexibility, resource-oriented design, and interoperability.
• OData offers enhanced query capabilities and standardized metadata, promoting discoverability and efficient data retrieval.
• REST provides simplicity, flexibility, wide adoption, and platform independence, making it suitable for a broad range of applications.
• Considerations for choosing between OData and REST include complexity, interoperability, and alignment with project requirements.

What Is REST?

REST (REpresentational State Transfer) is an API architectural style that defines how to send messages between two different apps using the HTTP protocol. Originally developed by Roy Fielding as a response to what some developers saw as the limitations of SOAP APIs (primarily SOAP's strict reliance on XML), REST APIs can send messages in a variety of formats and languages, like CSV (comma-separated value) files and JSON. With the relative ease of use and flexibility compared to developing SOAP APIs, REST has grown to become the most popular architecture for exchanging information on the web.

The REST standard outlines six different principles or architectural constraints for web services:

• Uniform interface: All REST system components must follow the same rules and interface to communicate with each other. Each resource is uniquely identified by a URI (uniform resource identifier).
• Client-server: REST separates servers from clients. The role of servers is to store information, while the role of clients is to retrieve information from the servers. This separation allows both sides to be independent and more scalable.
• Stateless: All requests made using REST are stateless. Each request contains all of the information necessary for the server to execute the request. The server is not required to remember the state of previous transactions by storing parameters after the request is complete. For example, if a client requests access to a restricted resource, the client must send its authentication token to the server with each request it makes.
• Cacheable: Both clients and servers in REST can cache resources, helping to reduce traffic and improve performance.
• Layered system: REST supports and encourages a layered system architecture. Each client can only communicate with a single server in the system, while other servers perform functions such as authentication and data storage. The client cannot tell whether it is communicating with an end system or an intermediary.
• Code on demand: REST requests can return logic or executable code if needed. This optional feature distinguishes REST APIs from SOAP APIs, which can only pass XML data.
• An API that adheres to the above principles is known as a REST (or RESTful) API. 

What Is OData?

According to the OData.org website, OData or Open Data Protocol “defines the best practice for building and consuming RESTful APIs. OData helps you focus on your business logic while building RESTful APIs without having to worry about the approaches to define request and response headers, status codes, HTTP methods, URL conventions, media types, payload formats and query options etc.” 

REST is the most important component technology of OData. All OData users should adhere to the six REST principles unless there is a good reason not to do so. OData differs from REST and gains its focus on business logic in its feature set. Whereas REST is an architectural style solely concerned with data transfer via web service APIs, OData builds upon that architecture with a set of metadata that can be easily integrated into most programming and scripting languages.

In an example found in the OData documentation, an OData query is built to find out the two most recent employees who have registered for a business trip, with costs of $3,000 or more for the trip. The example gives code samples for inserting the query into languages like JavaScript, C++, and C#. By integrating metadata into the languages that developers use, OData shifts focus away from typical REST constructs like HTTP headers and moves it toward the application's internal logic.  

The OData standard also defines the data model used to transfer data in response to a REST request. OData supports two different protocols for transferring data: the XML-based Atom format (for publishing and editing web resources) and JSON (for storing data in a human-readable manner).

Finally, OData includes guidance for how to perform actions such as tracking changes, defining reusable procedures, and sending multiple (batch) REST requests.

The History of OData

First created at Microsoft, OData was standardized by the nonprofit consortium OASIS (Organization for the Advancement of Structured Information Standards). As an OASIS standard, several large technology companies such as SAP and Salesforce have used the OData specification in their internal IT environments—and as a way for their customers to integrate business data.

Now up to version 4.0.1, OData has gained a wide variety of improvements and new features over the years. Some of the changes in version 4 include: 

• Improvements to the data model, supporting many new metadata constructs.
• Simplified URL patterns, specifically with regard to key-value pairs.
• New schema and query options with improved filtering features.
• New features that make it easier to work JSON data.

OData vs REST: Key Similarities

Understanding the similarities between OData vs REST can help developers make informed decisions about which approach to choose for their specific project requirements.

Key Similarities between OData and REST:

1. Web-Based Architecture: Both OData and REST are based on web architecture principles, making them suitable for building APIs that follow the client-server model. They rely on standard HTTP protocols, including GET, POST, PUT, and DELETE, to perform operations on resources. This web-centric approach ensures compatibility with a wide range of platforms and allows for the easy integration of web technologies.
2. Statelessness: Both OData and REST adhere to the stateless nature of the HTTP protocol. This means that each request sent to the server is independent and contains all the necessary information required to process it. The server does not maintain any session state between requests, resulting in better scalability, performance, and simplicity. Statelessness also promotes better caching mechanisms, enabling efficient utilization of network resources.
3. Data Format Flexibility: Both OData and REST provide flexibility in terms of data formats. They support various data formats such as JSON (JavaScript Object Notation) and XML (eXtensible Markup Language). JSON is widely used due to its lightweight nature and ease of parsing in web applications. XML, on the other hand, offers robustness and extensibility, making it suitable for scenarios that require complex data structures or interoperability with legacy systems.
4. Resource-Oriented Design: Both OData and REST follow a resource-oriented design approach. They consider resources as the central entities and expose them through URIs (Uniform Resource Identifiers). These resources can represent entities, collections, or relationships between entities. Developers can interact with these resources using standard HTTP methods to perform CRUD (Create, Read, Update, Delete) operations. This design approach promotes a clear separation of concerns and enables the development of scalable and maintainable APIs.
5. Interoperability and Platform Independence: Both OData and REST promote interoperability and platform independence. They allow clients and servers to be developed using different programming languages and frameworks as long as they adhere to the HTTP protocol. This flexibility enables heterogeneous system integration, where various technologies can communicate and exchange data seamlessly.

OData vs REST: Key Differences

A quick summary of the difference between OData vs. REST is as follows:

• REST is an architectural style for exchanging information via the HTTP protocol. The REST standard defines six principles (one optional) that must be adhered to by any REST API.
• OData builds on top of the REST framework to define best practices for building REST APIs—including the HTTP message format, how to query the API, and more. Although OData encourages users to follow REST principles at all times, this requirement can be relaxed if there is a compelling reason. In addition, OData specifies that data should be transferred in Atom or JSON format.

Developers choose to use OData because of these benefits:

• OData interacts with data using REST principles with a host of additional features.
• OData services offer a uniform way to share data.
• Broad integration across a wide range of products is easily accomplished.
• As with SOAP and REST, using the HTTP protocol simplifies web integrations.

In the end, deciding whether to use a standard REST API or OData will come down to your business needs and what you need to do with the data.

OData vs REST: Which Is Best?

When choosing between OData and REST for building web applications and APIs, developers often find themselves wondering which approach is the most suitable for their specific project needs. While both OData and REST have their strengths and use cases, understanding their differences can help in making an informed decision.

Advantages of OData:

1. Enhanced Query Capabilities: OData provides advanced query capabilities, allowing clients to request and filter data with ease. It supports operations such as filtering, sorting, paging, and aggregations, making it particularly useful for scenarios requiring complex data retrieval.
2. Standardized Metadata: OData offers a standardized way to describe and discover data through its built-in metadata capabilities. This enables clients to understand the structure, relationships, and available operations of the API without prior knowledge, promoting discoverability and ease of integration.
3. Protocol Efficiency: OData reduces network traffic by enabling clients to request only the specific data they need. It supports selective property retrieval, reducing the payload size and improving overall performance.

Advantages of REST:

1. Simplicity and Flexibility: REST follows a simple and flexible architectural style, making it easy to understand and implement. Its lightweight approach allows developers to design APIs according to their specific requirements without being tied to strict conventions.
2. Wide Adoption and Support: REST has gained widespread adoption and is well-supported by a vast ecosystem of tools, frameworks, and libraries. Its popularity ensures extensive community resources and a wealth of documentation, making it easier for developers to find support and solutions to common challenges.
3. Platform Independence: REST promotes platform independence, allowing clients and servers to be developed using different programming languages and frameworks. This flexibility makes it suitable for integrating various technologies and systems.

Considerations for Choosing between OData and REST

1. Complexity vs. Simplicity: OData provides powerful query capabilities and standardized metadata, but it may introduce additional complexity. REST, on the other hand, offers simplicity and flexibility, but with fewer built-in features for querying and metadata.
2. Interoperability: REST's simplicity and wide adoption make it highly interoperable, enabling integration with diverse systems and technologies. OData, while also interoperable, may require additional support or tools for full compatibility.
3. Project Requirements: Consider your specific project requirements, such as the need for advanced querying, standardized metadata, or adherence to certain industry standards. Evaluate how well OData or REST aligns with these requirements.

REST might be the better choice for simple data retrieval due to the speed and simplicity of development. If your needs are more complex, with specific business requirements, OData is likely to be a better fit due to how it naturally fits into programming logic. OData is also an extensible open standard, which allows developers to tap into the open-source community for code that meets business needs.

Tooling and Ecosystem

For REST, popular API gateways include Kong and AWS API Gateway, providing robust traffic management and security features. Client libraries like Axios for JavaScript and Retrofit for Java simplify making HTTP requests. Development frameworks such as Spring Boot and Express.js offer built-in features for creating RESTful services. Postman is widely used for designing, testing, and documenting REST APIs.

For OData, tools include Azure API Management and SAP API Management, which support OData endpoints and offer comprehensive API management solutions. Simple.OData.Client for .NET and Apache Olingo for Java are essential libraries for interacting with OData services. ASP.NET Web API and SAP Gateway enable the creation of OData services, facilitating integration with various applications. Postman also supports OData queries, making it versatile for testing both REST and OData APIs.

In SAP systems, OData integration is streamlined using SAP Gateway to create services, SAP API Management for security, and tools like Postman for testing. Client libraries like Simple.OData.Client and Olingo provide seamless interaction with OData services, ensuring robust integration within SAP environments.

Overall, leveraging these tools and libraries can streamline the development, testing, and management of APIs, ensuring efficient and reliable integrations.

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Frequently Asked Questions: OData vs REST

What is REST?

REST (REpresentational State Transfer) is an architectural style for building web APIs. It defines a set of principles and constraints for designing and interacting with web services. REST APIs use standard HTTP methods (GET, POST, PUT, DELETE) to perform operations on resources and transfer data in various formats like JSON and XML.

What is OData?

OData (Open Data Protocol) is a protocol that builds on top of the REST framework to define best practices for building and consuming RESTful APIs. OData provides additional features and standards, such as enhanced query capabilities, standardized metadata, and support for different data formats. It helps developers focus on their business logic while building RESTful APIs without worrying about the details of request/response handling, URL conventions, and payload formats.

What is the difference between OData and REST?

OData and REST are related but distinct concepts. REST is an architectural style for building web APIs, while OData builds upon REST to define best practices for building RESTful APIs. OData provides additional features such as enhanced query capabilities and standardized metadata.

Which is better, OData or REST?

The choice between OData and REST depends on your specific project requirements. OData offers advanced query capabilities and standardized metadata, making it suitable for scenarios that require extensive querying and discoverability. REST provides simplicity, flexibility, wide adoption, and platform independence, making it a popular choice for a broad range of applications. Consider your project needs, complexity tolerance, interoperability requirements, and available resources to determine which approach is best for you.

Does using OData mean I have to use the Atom or JSON format?

OData supports both the Atom and JSON formats for transferring data. While these formats are commonly used with OData, they are not mandatory. OData provides flexibility in choosing the data format that best suits your needs, allowing you to work with other formats if desired.

Are there any limitations or drawbacks to using REST or OData?

REST and OData have their strengths and considerations. REST's simplicity may lack some of the advanced features provided by OData, while OData's additional capabilities may introduce complexity. It's important to evaluate your project requirements and consider factors such as querying needs, metadata support, interoperability, and development resources before choosing between REST and OData.