An Introduction to IBMi Web Services (RPG, JSON, and REST) and how they Work?

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    An Introduction to IBMi Web Services (RPG, JSON, and REST) and how they Work?

    You, being an AS400 professional must have come through this term: IBMi web services.

    Well, if you haven’t, today is the right time and this is the exact and apt reference that you have landed into.

    Let’s understand what exactly IBMi web services are and how they function!

    What are IBMi web services?

    Right before jumping into iSeries web services directly, let’s unwind around what web services are. Basics to begin with!

    To break it down, a web service is a middle-men program that lets one computer system communicate with the other, using the internet.

    Simply put, let’s assume you need to update your employee details on your office computer and get them verified from a third-party vendor website. Here the “verification part” which needs to be executed from the third-party website is the service request which you are going to request and use from the third-party vendor server.

    This is how it works!

    Now getting back to the IBMi web services, there is no any different explanation to offer for it. It’s just another web service. Better, to be honest.

    Why? Because configuring an integrated web server for iSeries web services is easier than one could think of. Within a few clicks, you can configure the integrated web server and then use it to share the information through the internet. Due credit to the astounding IBMi Operating System.

    After successful configuration of integrated webserver i.e IWS, now it’s time to create integrated web services for IBMi.

    IWS comes with a simple wizard that lets you create IBMi web services of your choice from your RPG program and the best part is that IWS can be easily used from any web browser to communicate with your IBMi server.The integrated web services for IBMi is a term that describes the following technologies for IBM AS400 RPG:

    • The IWS Server
    • The IWS clients for ILE

    The IWS server serves as a fully functional server where ILE-based program entities can be installed as web services.

    The IWS client for ILE allows the application to act as web services clients by generating RPG, C, C++ counterfoils that an ILE program can use. The counterfoils remove the complications of the web service protocols by managing to serialize and deserialize service requests and responses.

    Web services provide the ability to represent the database to external developers through APIs and Web services. Even though that thought takes a shiver down the spine of many RPG AS400 developers who learned the proprietary ways of the AS/400, multi-platform incorporation is the latest development path. The stress on integration cannot be exaggerated.

    In the era of the Internet, things are changing rapidly, and businesses worldwide are continuously watching what can be done to make iSeries web services modern.

    Since IWS’s introduction as part of the V5R4 operating system in 2006, it has been upgraded many times. The most notable enhancement in this series was – SOAP to REST services.

    Nowadays, most of the IBM AS400 RPG shops use REST for creating integrated web services for IBMi. But, earlier web services were developed using SOAP and they quickly outnumbered the new web services.

    Anyone following the progress of web services must have seen restful architecture rise over traditional SOAP architecture. Web development services providers and particularly mobile-based app developing companies, have welcomed REST.

    To keep up with the increasing demand, Krengel Technologies had launched the 3.2 version of its RPG-XML Suite. The latest version can deliver integrated web services for IBMi as400 RPG customers.

    The RPG-XML Suite is a collection of programs, commands, and procedures that allow RPG AS400 developers to work XML and JSON, offer web services, and consume IWS remotely.

    Krengel developed an RPG-XML suite for RPG AS400 developers involved in developing web services in RPG and JAVA without a well-packaged development toolset.

    RPG-XML Suite: The Premium IBM AS400 RPG Toolkit to help Businesses Save Time and Resources

    Businesses invest a lot in RPG applications as it enables organizations to earn ROI on that investment. The RPG-XML Suite is used by experienced and freshers RPG AS400 developers with the purpose of reducing coding time: With RPG-XML AS400, administration can:

    • Compose templates and powerful APIs that offer smooth alignment of XML and JSON.
    • Transmit business data through HTTP to remote servers.
    • Retrieve data from XML and JSON and use it as per requirements.

    RPG-XML Suite is the best choice and proven choice for companies to move their IBM RPG 400 into the service-oriented architecture arena.

    Restful Web Services

    IBM AS400 iSeries REST web services are well known and available everywhere. Let’s understand more about them.

    What are Restful Web Services?

    REST stands for “Representational State Transfer,” and it has an extended version called restful. So, we can say that – “REST” is a set of rules utilized when following HTTP/HTTPS protocols.

    With the help of REST architecture, programs can transmit JSON data, XML, and text to a communication touchpoint (between API and Server) and get a response with the same channel.

    How do Restful Web Services Work?

    REST web services work in a different from IBM as400 administration, and there are four methods through which the server communicates with HTTP methods:

    • POST
    • GET
    • DELETE

    From these four methods, GET and POST are the most common methods. Both works parallel CRUD operations in relational database applications.

    NOTE: CRUD operations are responsible for creating, reading, updating, or deleting the resource data.

    SOAP Web Services

    When most of the IBM RPG as400 administration used REST APIs, another option is also available. It’s called SOAP, which stands for Simple Object Access Protocol.


    • It is compatible with XML only
    • It is limited to POST requests only
    • Requires more resources
    • Can communicate over HTTP, SMTP, & FTP

    REST in Comparison to SOAP:

    • It is restricted to HTTP communications
    • It’s lightweight.
    • Capable of performing various HTTP methods
    • Can handle multiple data formats like – XML, JSON, CSV, and more.

    When it comes to IBM as400 RPG integration, it can be concluded that neither REST nor SOAP is better than one another. However, we will write about both of these in detail in our upcoming blogs. If you are interested in consuming REST or SOAP on your IBM RPG AS400, connect with Integrative Systems for info.


    JSON (JavaScript Object Notation) is a well-known data interchanging platform. It has a straightforward architecture and is easily readable by humans and machines. Due to its simple architecture, JSON is used as an alternative to XML, and it doesn’t need a fixed schema design. JSON is portable and language-independent and was initially designed for use with JavaScript. Db2 for AS400 fits the industry-standard SQL support for JSON.

    Similarities Between JSON and SOAP

    • The JSON’s CICS implementation is derived from the SOAP architecture, and it contributes to many of its concepts and artifacts.
    • The deployment process for both the technologies is the same, and it involves-
      • PIPELINE Resource
      • WEBSERVICE Resource
      • IMAP Resource
    • JSON and SOAP consist of offline utility programs that assist in data mapping (to & from) the external data representation. For SOAP – (DFHLS2WS and DFHWS2LS) & For JSON (DFHLS2JS and DFHJS2LS)

    REST and JSON

    The REST architecture permits API service providers to deliver data in various formats (HTML, XML, YAML, and JSON). And, due to this feature, REST is loved by a majority of IBM as400 modernization experts. Furthermore, the lightweight JSON format has also gained traction due to its quick data exchange feature.

    CICS Implementation of JSON based Web Services

    Three modes of JSON web services are supported by CICS implementation:

    • z/OS® Connect
    • Request-Response
    • RESTful

    Besides these three, CICS also supports a format where JSON web services data can be easily transferred to COBOL style data formats. While looking to consume iSeries web services for your IBM RPG as400, JSON can be considered a good option.

    IBMi Web Services Integration with Integrative Systems

    We hope that now you are aware of IBM’s new technologies. IBMi web services offer best in class services, and we recommend this to all our RPG AS400 clients those who have implemented it, have not failed any transaction yet. And we’ll keep recommending this to our clients worldwide.

    If you are also looking for an organization to help you with IBMi web services integration, or you would like to learn more about how to make iSeries web services integration with your RPG AS400 programmers., we can help you.

    Feel free to connect with us at [email protected]

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