What are AS400 Web Services? IBM I (AS/400) Web Services

The recent surge in the popularity of web services technologies has spawned a demand for more efficient and cost-effective ways to integrate enterprise applications. AS400 Web Services offer an advanced level of integration that is unparalleled by other solutions, allowing businesses to simplify complex tasks and streamline operations. In this blog post, we’ll explore what AS400 Web Services are, their advantages in enterprise integration, and how to get started.

What are AS400 Web Services?

IBM’s AS400 Web services allow businesses to connect their applications within and outside the enterprise, regardless of their platform, design, or runtime environment.

Web services are applications that allow different applications to communicate with each other, thereby making business processes more flexible. The concept of web services existed before the term became widely used with the Internet. In the past, to find a book, you would visit the library and search through their collection. If the book was unavailable, the librarian would search for it using a computer or phone and find it at another library. They would then order the book for you, which would be delivered to your local library for you to pick up. Now, by using web service applications, you can make your library visit more efficient.

A web service is a program that acts as an intermediary between two computer systems, allowing them to communicate via the Internet. For example, suppose you must update your employee details on your office computer and verify them on a third-party vendor website. In that case, the request for verification from the third-party website is the service you will request and use from their server AS/400 Web Services use this concept to help businesses integrate different applications and systems.

AS400 Web Services
AS/400 Web Services

How do AS400 Web services work?

Regarding AS/400 Web Services, there is nothing unique to explain about them. They are simply another type of web service, and they may even be better.

The integrated web server can be configured and used to share information over the internet with just a few clicks. This is possible thanks to the IBMi Operating System. After successfully configuring the integrated web server (IWS), it’s time to create integrated web services for AS400 IBM i.

IWS has a user-friendly wizard that allows you to generate AS400 web services from your RPG program, and the best part is that the IWS tool can be easily accessed from any web browser to interact with your IBMi server.

Integrated Web Services For IBM I or AS400?

The integrated web services for IBM I or AS400 refer to two technologies – the IWS Server and the IWS clients for ILE – that allow applications coded in an Integrated Language Environment (ILE) to operate in web services and service-oriented architecture (SOA).

The IWS server is a functional server where you can install web services using ILE-based program entities. Meanwhile, the IWS client for ILE is a tool that generates service artifacts. It enables RPG, COBOL, C, and C++ programming languages to function as web services or API consumers.

Technologies of AS400 Web services

The term “integrated web services” refers to specific technologies for IBM AS400 RPG, which include:

  • The IWS Server
  • The IWS clients for ILE

The IWS server can install ILE-based program entities as web services, while the IWS client for ILE makes it possible for applications to act as web service clients by generating counterfoils in RPG, C, and C++. These counterfoils simplify the web service protocols by managing service requests and responses through serialization and deserialization.

The AS400 Web services enable external developers to access the database via APIs and Web services. It is crucial to integrate with various platforms nowadays, even though it may seem daunting for RPG AS400 developers who are used to the AS/400’s unique methods. Therefore, emphasizing integration is vital for development.

Businesses worldwide are looking for ways to update their iSeries web services to keep up with the fast-changing internet landscape.

IWS, introduced in the V5R4 operating system in 2006, has undergone several upgrades. The most significant improvement in this series is the transition from SOAP to REST services.

Currently, REST is the preferred method for creating integrated IBM I web services in many IBM AS400 RPG shops. However, SOAP was previously used to develop web services and became more numerous than the newer ones.

People keeping up with AS400 web services have likely noticed that RESTful architecture is becoming more popular than SOAP architecture. This trend has been popular among web development service providers, especially companies creating mobile apps.

Krengel Technologies has released version 3.2 of its RPG-XML Suite to meet growing demand. This latest version can provide web services that are integrated specifically for IBMi as400 RPG users.

Krengel has developed the RPG-XML Suite specifically for RPG AS400 developers working with XML and JSON, offering web services, and remotely consuming IWS. It provides a comprehensive set of programs, commands, and procedures as a development toolset for RPG and JAVA developers.

The architecture of AS400 Web services

The AS400 Web services architecture comprises three roles: service provider, service registry, and service requestor. They interact through publish, find, and bind operations, overseeing the Web service software module and its description.

Usually, a service provider creates a service description in Web Services Description Language (WSDL) for their Web service. This description is shared with the service requester or service registry. The service requester can then search for the service description and use it to connect with the service provider and interact with the Web service.

Service Provider (integrated Web services server)

The integrated Web services server runs on the systems that host Web service applications. It provides a single entry point to access the exposed resources and operations to process requests from remote clients.

Service Requestor (integrated Web services client for ILE)

In terms of business, certain requirements need to be met. From an architectural standpoint, there is an application that seeks and initiates an interaction with an AS400 Web service. A program, whether it has a user interface or not, that is controlled by a person, can act as a service requester.

Types of AS400 Web Services

Restful Web Services

REST is short for “Representational State Transfer,” and restful is another version. It is a set of rules that apply when using HTTP/HTTPS protocols. REST architecture allows programs to send JSON data, XML, and text to a communication point (between API and Server) and receive a response through the same channel.

The REST web services for AS400 operate differently than the IBM AS400 administration. The server uses four HTTP methods for communication.

  • POST
  • GET

Out of these four methods, GET, and POST are the most commonly used ones. They perform CRUD operations in parallel with relational database applications.

SOAP Web Services

Although REST APIs are commonly used for IBM RPG as400 administration, SOAP is another option that is also available. SOAP stands for Simple Object Access Protocol.

SOAP is a messaging protocol that facilitates the exchange of structured data between applications. One of SOAP’s restrictions is that it only works with XML. SOAP is also restricted to using only the HTTP POST request method. As a result, SOAP requests must be sent in the body of an HTTP POST message. Although SOAP uses more resources than other protocols like REST, it can communicate over various transport protocols, including HTTP, SMTP, and FTP. This makes SOAP a flexible option for developers working with multiple transport protocols.


Compared to SOAP, which supports multiple communication protocols, REST is limited to HTTP communications. This makes it a faster and more efficient protocol. REST is also easier to use and requires fewer resources since it is lightweight. It enables various HTTP methods like GET, POST, PUT, and DELETE, making it more flexible and capable of handling different requests.

REST is a versatile method of exchanging data between systems because it can handle multiple formats such as XML, JSON, CSV, and others. Its popularity has increased due to its simplicity, speed, and flexibility, and many developers prefer to use it when building web applications.


JSON is a widely used platform for exchanging data with a simple and easy-to-read architecture for humans and machines. It is frequently used as a substitute for XML and does not require a fixed schema design. JSON is portable, language-independent, and was created for use with JavaScript. Db2 for AS400 adheres to industry-standard SQL support for JSON.

Similarities of JSON and SOAP

The CICS implementation of JSON is based on the SOAP architecture and shares many of its concepts and artifacts.

The deployment process is the same for both technologies. The process includes the following-

  • PIPELINE Resource
  • WEBSERVICE Resource
  • IMAP Resource

DFHLS2WS and DFHWS2LS are offline utility programs used in SOAP for mapping data to and from external data representation. Similarly, DFHLS2JS and DFHJS2LS are programs used in JSON.


Many IBM as400 modernization experts prefer REST architecture because it allows API service providers to deliver data in different formats, including HTML, XML, YAML, and JSON. The lightweight JSON format is particularly popular because of its fast data exchange capability.

Features of AS400 Web services

Here are some of the notable features of AS400 web services:

  • Web Administrative GUI Front End: The web administrative GUI front end provides an intuitive interface for managing and monitoring the AS400 web services server and any deployed web services.
  • Powerful and Lightweight Server: The AS400 web services server is built on an integrated application server and best-in-class technologies to support SOAP and RESTful web services.
  • Minimal Resource Consumption: The server uses the ILE programming architecture to minimize resource consumption, ensuring a small system footprint.
  • Interoperability: The ILE programming architecture ensures quick interoperability with other systems, reducing resource consumption.
  • Support for SOAP and RESTful Web Services: The server can generate SOAP RPG, C, and C++ stubs that comply with Web Services Invocation (WSI) 1.1 basic profile. It can also consume SOAP and RESTful web services that use application-defined payloads.

Benefits of AS400 Web services

AS400, also known as IBM I, is a popular operating system in many enterprises worldwide. One of the key advantages of AS400 is its integrated web services server, which provides a range of benefits for developers and solution providers.

No Up-Front Costs:

One major benefit of AS400 web services is that no up-front costs are involved. The operating system includes the integrated web services server, which allows developers to set up and deploy services quickly and at no extra cost. This helps businesses to achieve measurable results within a short timeframe.

Focus on Core Capabilities:

Another advantage of AS400 web services is that solution providers do not need new skills or tools for deployment. They can instead focus their efforts on building differentiated value for their customers rather than rewriting core infrastructure.

Uses and Enhances Existing AS400 Development Skills:

AS400 web services also leverage and enhance existing AS400 development skills to interact with web services. This allows businesses to use their existing knowledge and expertise to build and deploy web services faster and more efficiently.


AS400 web services offer a range of benefits for businesses and developers. With its integrated web services server, AS400 provides a cost-effective way to quickly create and deploy services without additional tools or new skills. The platform also uses existing development skills to interact with web services, allowing businesses to save time and resources while ensuring better customer experiences. Overall, AS400 is ideal for modernizing business processes and building smarter applications.

Read also