SOAP VS REST | Eight Code

Comparing REST and SOAP has been an ongoing debate, as they both address the common question of how to access web services. However, making a decision between the two can prove surprisingly challenging.

SOAP (Simple Object Access Protocol) is a well-established, standards-based web services access protocol with origins traced back to Microsoft. Despite its name suggesting simplicity, SOAP is a complex technology.

On the other hand, REST (Representational State Transfer) emerged as a standard to address the shortcomings of SOAP, offering a simpler approach to accessing web services.

While GraphQL has gained significant attention recently, this article focuses specifically on the comparison between REST and SOAP, as GraphQL is not as standardized at the moment.

Choosing between SOAP and REST involves careful consideration of the respective issues associated with each protocol.

Common Grounds: Comparing REST and SOAP

Though SOAP and REST both operate over the HTTP protocol, SOAP adheres to a more stringent set of messaging patterns compared to REST. The strict rules in SOAP are deemed essential for achieving standardization. In contrast, REST, as an architectural style, is inherently more flexible and doesn’t mandate specific processing. Both SOAP and REST depend on widely accepted rules that serve as a common framework for information exchange.

Brief Insight into SOAP

SOAP relies exclusively on XML for its messaging services. Initially developed by Microsoft, SOAP was created to replace older technologies like Distributed Component Object Model (DCOM) and Common Object Request Broker Architecture (CORBA), which faced challenges on the internet due to their reliance on binary messaging. SOAP’s use of XML messaging proves more effective in internet environments.

Following its initial release, Microsoft standardized SOAP by submitting it to the Internet Engineering Task Force (IETF). SOAP is designed to be highly extensible, incorporating various acronyms and abbreviations such as WS-Addressing, WS-Policy, WS-Security, WS-Federation, WS-ReliableMessaging, WS-Coordination, WS-AtomicTransaction, and WS-RemotePortlets. While SOAP offers extensive capabilities, users can selectively employ only the components necessary for specific tasks. For instance, when utilizing a public web service accessible to everyone, features like WS-Security may not be essential.

The Challenge Varies According to the Programming Language

The complexity of XML used for making requests and receiving responses in SOAP can vary significantly. In certain programming languages, constructing these requests manually can be challenging due to SOAP’s intolerance to errors. However, some languages offer shortcuts provided by SOAP, streamlining the effort required for request creation and response parsing. In the case of .NET languages, the intricacies of XML are abstracted from the developer.

A key factor in this process is the Web Services Description Language (WSDL), an additional file associated with SOAP. WSDL furnishes a definition of how the web service functions, allowing the Integrated Development Environment (IDE) to automate the process when creating a reference to it. Consequently, the level of difficulty in using SOAP is largely influenced by the programming language employed.

Inherent Error Management

One of SOAP’s notable features is its integrated error handling. In the event of an issue with your request, the response includes error information, allowing you to diagnose and address the problem. This becomes particularly crucial when dealing with web services you don’t own, as it eliminates the need for speculation regarding the cause of failures. Moreover, the error reporting in SOAP includes standardized codes, enabling the automation of certain error-handling tasks in your code.

A noteworthy aspect of SOAP is its flexibility regarding transport protocols—it’s not limited to the HTTP transport. There is a defined specification for utilizing SOAP over Simple Mail Transfer Protocol (SMTP), and there’s no restriction preventing its use over other transports. In fact, developers in languages like Python and PHP have embraced this versatility.

A Brief Introduction to REST

REST offers a more streamlined alternative. Many developers found SOAP to be cumbersome and challenging to work with. For instance, employing SOAP in JavaScript often entails writing a substantial amount of code for even simple tasks, as the creation of the necessary XML structure is required each time.

In contrast to using XML for requests, REST typically relies on a straightforward URL. While additional information may be necessary in certain scenarios, most web services using REST predominantly utilize the URL approach. REST can leverage four different HTTP 1.1 verbs (GET, POST, PUT, and DELETE) to execute tasks.

Unlike SOAP, REST is not constrained to using XML for responses. REST-based web services can output data in various formats such as Command Separated Value (CSV), JavaScript Object Notation (JSON), and Really Simple Syndication (RSS). The key advantage is the ability to obtain output in a format that is easily parseable within the language used for the application.

Distinguishing Between SOAP and REST

Unless you intend to develop your own web service, the choice of which protocol to use might be predetermined. Only a very limited number of web services, like Amazon, support both protocols. In such cases, your decision is typically guided by which web service aligns better with your requirements, rather than selecting a protocol.

Advantages of SOAP:

  • Language, platform, and transport independence (in contrast to REST, which necessitates the use of HTTP)
  • Well-suited for distributed enterprise environments (while REST assumes direct point-to-point communication)
  • Standardized
  • Offers significant pre-built extensibility through WS* standards
  • In-built error handling
  • Automation capabilities when used with specific language products

Advantages of REST:

  • Ease of use and greater flexibility
  • No need for expensive tools to interact with the web service
  • Smaller learning curve
  • Efficiency (REST can use smaller message formats, unlike SOAP, which uses XML for all messages)
  • Speed (requires less extensive processing)
  • Alignment with other web technologies in design philosophy

A Basic Illustration of REST

Occasionally, simplicity is the optimal choice. In this instance, REST exemplifies simplicity by requiring only a URL. Open any browser, type http://rpc.geocoder.us/service/csv?address=1600+Pennsylvania+Ave,+Washington+DC in the address field, and press Enter.

You’ll see the output in your browser in CSV format:

The output displays the latitude, followed by the longitude, and then the provided address. This straightforward test is effective for most addresses in major cities (though it may not perform as well for rural addresses at this point). The concept is to acquire the latitude and longitude, which can be utilized in conjunction with other web services. With a bit of glue code, combining various web services enables the creation of compelling applications that achieve remarkable functionalities swiftly and effortlessly, leveraging the heavy lifting done by others. Additionally, testing your REST API can be easily done using user-friendly tools like SoapUI.

A Basic Illustration of SOAP

Due to its inherent nature, SOAP necessitates a bit more setup, yet its usage remains remarkably straightforward.

To initiate this example, start by creating a Windows Forms application in Visual Studio. While the provided sample code is in C#, the same approach is applicable to other .NET languages (with necessary code modifications). Incorporate labels, textboxes, and buttons as illustrated (note that the Latitude and Longitude fields are designated as read-only).

This is where automation becomes essential. In the Solution Explorer, right-click on References and select “Add Service Reference” from the context menu. The Add Service Reference dialog box will appear. Enter the following address into the address field: http://rpc.geocoder.us/dist/eg/clients/GeoCoder.wsdl and click “Go”. In the namespace field, type GeocoderService. Your dialog box should resemble the one depicted here.

Click OK. Visual Studio automatically incorporates the necessary code to interface with the Geocoder in the background.

Now, you are prepared to utilize the web service. Simply add the code to the “Get Position” button, as demonstrated here.

private void btnGetPosition_Click(object sender, EventArgs e)

{

   // Create the client.

   GeocoderService.GeoCode_PortTypeClient Client =

      new GeocoderService.GeoCode_PortTypeClient();

   // Make the call.

   GeocoderService.GeocoderResult[] Result =

      Client.geocode(txtAddress.Text);

   // Check for an error result.

   if (Result != null)

   {

      // Display the results on screen.

      txtLatitude.Text = Result[0].lat.ToString();

      txtLongitude.Text = Result[0].@long.ToString();

   }

   else

   {

      // Display an error result.

      txtLatitude.Text = "Error";

      txtLongitude.Text = "Error";

   }

}

The code begins by creating a client, a standard procedure for any web service used in Visual Studio or other environments that inherently support SOAP.

Once the client is established, it is employed to invoke one of the web service’s supported methods. In this instance, the geocode() method is called, passing the specified address. The outcome of this call is stored in a GeocoderResult variable named Result. Since a single address may yield multiple positions if the information is not specific enough, the results are returned as an array.

Assuming no errors occur (resulting in a null return value), the example proceeds under the assumption that accurate information was provided. It then extracts the data from the first entry in the Result array and populates the Latitude and Longitude outputs. While this example may not be as intricate as its REST counterpart, it illustrates that even a straightforward SOAP example entails more steps.

Concluding Remarks

Key Takeaways

First Key Point: When it comes to the debate of REST versus SOAP, the ultimate answer is: “It depends.” Each protocol has distinct advantages and disadvantages. The decision between SOAP and REST hinges on factors such as the programming language, the environment, and specific requirements. (It’s worth noting that this article doesn’t delve into the considerations involving GraphQL.)

To preempt potential issues, it’s advisable to assess the pros and cons in your specific context and make an informed decision.

Second Key Point: It’s crucial to recognize that there’s no need to reinvent the wheel. It’s remarkable to observe companies investing substantial resources to create web services that already exist and may perform better. Whenever possible, explore free alternatives. Often, the choice of web service also dictates the preferred protocol.

Third Key Point: Regardless of whether you opt for SOAP or REST for your web service, comprehensive testing of your APIs is essential. ReadyAPI offers a comprehensive suite of functional, performance, security, and virtualization tools for all your API testing requirements. You can also enhance your understanding of testing RESTful APIs through our API Testing Resource Center.

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