02
Sat, Nov
2 New Articles
  1. You are here:  
  2. Home
  3. Programming
  4. RPG
  5. Cool Things: ILE RPG as a Web Services Client

Cool Things: ILE RPG as a Web Services Client

RPG
Typography
  • Smaller Small Medium Big Bigger
  • Default Helvetica Segoe Georgia Times

Use IBM's Web Services Client for ILE to consume a web service in an ILE RPG program.

 

Web services serve many purposes—from utilizing external web services for things like retrieving exchange rates or tracking shipments, to using internal web services as a means of communicating between applications within your organization. The task of writing a program to consume a web service can be relatively simple or very complicated, depending on the requirements of the web service that you're consuming. In this article, we'll explore how to use Web Service Definition Language (WSDL) to easily consume a web service in an RPGLE program.

WSDL

WSDL is intended to provide developers and applications a means by which to determine what data is to be exchanged with a web service. IBM's Web Services Client for ILE gives you a utility to create a stub ILE service program in RPG to allow you to easily consume a web service. WSDL2RPG can generate an RPGLE service program that provides a means by which you can easily consume a web service from within an RPGLE program. The process is fairly simple. First and foremost, you need to make sure that you have the required PTF that adds the WSDL2RPG script to your system. Below is a table that shows the PTFs for each release of the OS from V5R4 forward.

 

OS Version

PTF

V5R4M0

SI42234

V6R1M0

SI42236

V7R1M0

SI42235

 

Once you've ensured that you have the appropriate PTF for your release installed, you're ready to go. The Qshell script for WSDL2RPG is created in this folder:

 

/QIBM/ProdData/OS/WebServices/V1/client/bin

 

Before you can execute the script, you'll need the location of the WSDL document that describes the web service. That location can be either the HTTP location of the WSDL or a local WSDL document on the IFS. The WSDL2RPG.SH script is executed using the following format:

 

/QIBM/ProdData/OS/WebServices/V1/client/bin/wsdl2rpg.sh <options> URI-To-WSDL

 

The options available for this script are listed below:

  • -h/-help—Displays help text for the script/command.
  • -o [path] —Sets the output directory for the source to be created.
  • -ms [number] —Defines the maximum size for RPG character fields used to hold string data. For V5R4, the value can be between 16 and 650004. For V6R1 and higher, the range is 16 to 80000004. The default value is 128.
  • -mb [number] —Defines the maximum size for binary fields holding character data. The range is 48 to 650004 for V5R4 and 48 to 160000004 for V6R1 and higher.
  • -ma [number] —Defines the maximum array size for RPG arrays. The range is from 1 to 320004 for V5R4 and 1 to 80000004 for V6R1 and higher. The default value is 20.
  • -s [path] —This value is the full /qsys.lib path to the service program to be created.
  • -d—This option indicates that the resulting service program should be generated with debugging views.

 

As I mentioned earlier, you can specify the WSDL document as either a local IFS resource or using a full URI to the WSDL on web service. As an example of this, we'll use a free currency convertor web service. Enter the Qshell command line by typing QSH at the command line. Next, we need to create a folder to contain the source for the service programs. Type the following command inside the Qshell command line:

 

Mkdir /CurrConv

 

Now use the WSDL2RPG.sh script to generate our service program.

 

/QIBM/ProdData/OS/WebServices/V1/client/bin/wsdl2rpg.sh -o/CurrConv
     –s/qsys.lib/mylib.lib/Currency.srvpgm                 http://www.webservicex.com/currencyconvertor.asmx?WSDL

 

In this example, our output source will be generated in the /CurrConv IFS folder. The resulting service program will be created in the library MYLIB and will be named CURRENCY. The source members created by the script will be named based on the portType value from the provided WSDL document. In our example, this value is CurrencyConvertor. After executing the script above, you should see the following documents in the /CurrConv folder:

 

  • CurrencyConvertorSoap.cl—CL to create the service program
  • CurrencyConvertorSoap.rpleinc—Include RPGLE source member
  • CurrencyConvertorSoap.rpgle—Service program RPGLE source
  • CurrencyConvertorSoap_util.rpgleinc—RPGLE utility include source
  • CurrencyConvertorSoap_util.rpgle—RPGLE utility source code
  • CurrencyConvertorSoap_xsdtypes.rpgleinc—XSD data type include source

 

The source for all of the examples for this tip can be downloaded here. In addition to these, you'll find the C language includes and source for the C stub that is used by the RPGLE stub to access the web service. After executing the WSDL2RPG.sh script, you will also have an RPG service program named CURRENCY in the library specified as MYLIB above. For each operation supported by the web service, the created service program will contain a stub subprocedure. The naming convention will be stub_op_ followed by the name of the web service operation. In our example, that sub-procedure is stub_op_ConversionRate. To consume that service program, we simply need to include the "rpgleinc" source in our RPG program and then initiate a call to three subprocedures inside of the service program:

  • Stub_create_CurrencyConvertorSoap(webService_ds)—Create a connection to the web service and store the details in the data structure webService_ds.
  • Stub_op_ConversionRate(webService_ds: fromRate_stringDS: toRate_stringDS: rateAmount_DS)—Perform the conversion operation on the supplied web service and return the rate.
  • Stub_destroy_CurrencyConvertorSoap(webService_ds) —Disconnect from the supplied web service.

 

In each of these examples, the webService_ds value identifies a data structure that contains information about the web service itself. This data structure contains the following:

 

 

  • Endpoint URL—The URL for the web service as a 2048 character field. If this value is blank, the endpoint from the WSDL is used.
  • Handle—A pointer to the C stub handle when invoking AXIS API.
  • Exception Indicator —An indicator variable that identifies that an exception has occurred.
  • Exception Code—An integer code associated with the error condition.
  • Exception String—A 2048-character description of the error.
  • Reserved—Reserved 1024 character field.

 

The program below utilizes the CURRENCY service program to retrieve the exchange rate from U.S. dollars to Canadian dollars.

 

       //----------------------------------------------------------------------

       // Sample Program To Consume the CurrencyConversion Web Service

       // Using the RPGLE Stub Service Program "CURRENCY"

       //

       // Create using: CRTRPGMOD MODULE(mylib/CURRCONV)

       //                         SRCFILE(mylib/QRPGLESRC)

       //                         SRCMBR(CURRCONV)

       //                         REPLACE(*NO)

       //                          INCDIR('/home/myfolder')

       //

       //               CRTPGM PGM(mylib/CURRCONV)

       //                     BNDSRVPGM((mylib/CURRENCY)

       //

       //

       //----------------------------------------------------------------------

 

       // The include members below are created by WSDL2RPG

     /copy CurrencyConvertorSoap.rpgleinc

     /copy CurrencyConvertorSoap_util.rpgleinc

 

     d ws_ds           ds                 likeds(This_t) inz

     d amount         ds                 likeds(xsd_double)

     d fromCode       ds                 likeds(xsd_string)

     d toCode         ds                 likeds(xsd_string)

     d decAmt         s             13 2

     d rtnInd         s             1n

 

     /free

       // Define our "FROM" and "TO" Currency Codes based on

       // Constants defined to the web service stub

       fromCode.value = Currency_USD;

       toCode.value = Currency_CAD;

 

       // Create a connection to the web service

       if stub_create_CurrencyConvertorSoap(ws_ds);

 

         // Call the web service conversion rate operation

         rtnInd = stub_op_ConversionRate( ws_ds

                                   : fromCode

                                   : toCode

                                  : amount);

 

         // Convert and display the returned conversion rate

         decAmt = %dec(amount.value: 13:2);

         if rtnInd and not amount.isNil;

             dsply %char(decAmt);

         endif;

 

         // Close the web service connection

         stub_destroy_CurrencyConvertorSoap(ws_ds);

       else;

         dsply %subst(ws_ds.excString:1:50);

       endif;

       *inlr = *on;

       return;

     /end-free

 

This simple example illustrates a few things about the web service stub. First off, you'll notice the Currency_USD and Currency_CAD constants used to identify the currency codes to convert from and to. All of the currency code constants are defined in the RPGLEINC source created by the WSDL2RPG script. You'll also see the xsd_double and xsd_string types used to define the variables used in the program. These variables are actually qualified data structures that are defined in the CurrencyConvertorSoap_xsdtypes.rpgleinc source. These data structures contain an isNil subfield that is an indicator variable which identifies that the value is null along with a value subfield that contains the actual value of the element. Note that we do not provide a value in the ws_ds parameter. If for some reason we needed to provide a different URI for the web service endpoint from that defined in the WSDL, we would define that alternate URI in the ws_ds.endpoint value.

Simple but Powerful

This simple example illustrates how easy it is to consume a web service in an RPGLE program using the WSDL2RPG script. For more information on this powerful functionality, check out the Web Services Client for ILE Programming Guide.

 

Mike Faust

Mike Faust is a senior consultant/analyst for Retail Technologies Corporation in Orlando, Florida. Mike is also the author of the books Active Server Pages Primer, The iSeries and AS/400 Programmer's Guide to Cool Things, JavaScript for the Business Developer, and SQL Built-in Functions and Stored Procedures. You can contact Mike at This email address is being protected from spambots. You need JavaScript enabled to view it..

MC Press books written by Mike Faust available now on the MC Press Bookstore.

Active Server Pages Primer Active Server Pages Primer
Learn how to make the most of ASP while creating a fully functional ASP "shopping cart" application.
List Price $79.00

Now On Sale

JavaScript for the Business Developer JavaScript for the Business Developer
Learn how JavaScript can help you create dynamic business applications with Web browser interfaces.
List Price $44.95

Now On Sale
SQL Built-in Functions and Stored Procedures SQL Built-in Functions and Stored Procedures
Unleash the full power of SQL with these highly useful tools.
List Price $49.95

Now On Sale
BLOG COMMENTS POWERED BY DISQUS

LATEST COMMENTS

Support MC Press Online

$

Book Reviews

Resource Center

  • SB Profound WC 5536 Have you been wondering about Node.js? Our free Node.js Webinar Series takes you from total beginner to creating a fully-functional IBM i Node.js business application. You can find Part 1 here. In Part 2 of our free Node.js Webinar Series, Brian May teaches you the different tooling options available for writing code, debugging, and using Git for version control. Brian will briefly discuss the different tools available, and demonstrate his preferred setup for Node development on IBM i or any platform. Attend this webinar to learn:

  • SB Profound WP 5539More than ever, there is a demand for IT to deliver innovation. Your IBM i has been an essential part of your business operations for years. However, your organization may struggle to maintain the current system and implement new projects. The thousands of customers we've worked with and surveyed state that expectations regarding the digital footprint and vision of the company are not aligned with the current IT environment.

  • SB HelpSystems ROBOT Generic IBM announced the E1080 servers using the latest Power10 processor in September 2021. The most powerful processor from IBM to date, Power10 is designed to handle the demands of doing business in today’s high-tech atmosphere, including running cloud applications, supporting big data, and managing AI workloads. But what does Power10 mean for your data center? In this recorded webinar, IBMers Dan Sundt and Dylan Boday join IBM Power Champion Tom Huntington for a discussion on why Power10 technology is the right strategic investment if you run IBM i, AIX, or Linux. In this action-packed hour, Tom will share trends from the IBM i and AIX user communities while Dan and Dylan dive into the tech specs for key hardware, including:

  • Magic MarkTRY the one package that solves all your document design and printing challenges on all your platforms. Produce bar code labels, electronic forms, ad hoc reports, and RFID tags – without programming! MarkMagic is the only document design and print solution that combines report writing, WYSIWYG label and forms design, and conditional printing in one integrated product. Make sure your data survives when catastrophe hits. Request your trial now!  Request Now.

  • SB HelpSystems ROBOT GenericForms of ransomware has been around for over 30 years, and with more and more organizations suffering attacks each year, it continues to endure. What has made ransomware such a durable threat and what is the best way to combat it? In order to prevent ransomware, organizations must first understand how it works.

  • SB HelpSystems ROBOT GenericIT security is a top priority for businesses around the world, but most IBM i pros don’t know where to begin—and most cybersecurity experts don’t know IBM i. In this session, Robin Tatam explores the business impact of lax IBM i security, the top vulnerabilities putting IBM i at risk, and the steps you can take to protect your organization. If you’re looking to avoid unexpected downtime or corrupted data, you don’t want to miss this session.

  • SB HelpSystems ROBOT GenericCan you trust all of your users all of the time? A typical end user receives 16 malicious emails each month, but only 17 percent of these phishing campaigns are reported to IT. Once an attack is underway, most organizations won’t discover the breach until six months later. A staggering amount of damage can occur in that time. Despite these risks, 93 percent of organizations are leaving their IBM i systems vulnerable to cybercrime. In this on-demand webinar, IBM i security experts Robin Tatam and Sandi Moore will reveal:

  • FORTRA Disaster protection is vital to every business. Yet, it often consists of patched together procedures that are prone to error. From automatic backups to data encryption to media management, Robot automates the routine (yet often complex) tasks of iSeries backup and recovery, saving you time and money and making the process safer and more reliable. Automate your backups with the Robot Backup and Recovery Solution. Key features include:

  • FORTRAManaging messages on your IBM i can be more than a full-time job if you have to do it manually. Messages need a response and resources must be monitored—often over multiple systems and across platforms. How can you be sure you won’t miss important system events? Automate your message center with the Robot Message Management Solution. Key features include:

  • FORTRAThe thought of printing, distributing, and storing iSeries reports manually may reduce you to tears. Paper and labor costs associated with report generation can spiral out of control. Mountains of paper threaten to swamp your files. Robot automates report bursting, distribution, bundling, and archiving, and offers secure, selective online report viewing. Manage your reports with the Robot Report Management Solution. Key features include:

  • FORTRAFor over 30 years, Robot has been a leader in systems management for IBM i. With batch job creation and scheduling at its core, the Robot Job Scheduling Solution reduces the opportunity for human error and helps you maintain service levels, automating even the biggest, most complex runbooks. Manage your job schedule with the Robot Job Scheduling Solution. Key features include:

  • LANSA Business users want new applications now. Market and regulatory pressures require faster application updates and delivery into production. Your IBM i developers may be approaching retirement, and you see no sure way to fill their positions with experienced developers. In addition, you may be caught between maintaining your existing applications and the uncertainty of moving to something new.

  • LANSAWhen it comes to creating your business applications, there are hundreds of coding platforms and programming languages to choose from. These options range from very complex traditional programming languages to Low-Code platforms where sometimes no traditional coding experience is needed. Download our whitepaper, The Power of Writing Code in a Low-Code Solution, and:

  • LANSASupply Chain is becoming increasingly complex and unpredictable. From raw materials for manufacturing to food supply chains, the journey from source to production to delivery to consumers is marred with inefficiencies, manual processes, shortages, recalls, counterfeits, and scandals. In this webinar, we discuss how:

  • The MC Resource Centers bring you the widest selection of white papers, trial software, and on-demand webcasts for you to choose from. >> Review the list of White Papers, Trial Software or On-Demand Webcast at the MC Press Resource Center. >> Add the items to yru Cart and complet he checkout process and submit

  • Profound Logic Have you been wondering about Node.js? Our free Node.js Webinar Series takes you from total beginner to creating a fully-functional IBM i Node.js business application.

  • SB Profound WC 5536Join us for this hour-long webcast that will explore:

  • Fortra IT managers hoping to find new IBM i talent are discovering that the pool of experienced RPG programmers and operators or administrators with intimate knowledge of the operating system and the applications that run on it is small. This begs the question: How will you manage the platform that supports such a big part of your business? This guide offers strategies and software suggestions to help you plan IT staffing and resources and smooth the transition after your AS/400 talent retires. Read on to learn: