Web Services on your Power i in RPG

Web Services on your Power i in RPG Jared Gerber jgerber@brotherhoodmutual. com 260 -481 -9906 February 9, 2010

How many of you have done anything with web services? How many have coded programs that consume a web services (in any language)? How many have published a web service?

Saturday, May 14, 2005 A component walks into a bar. . The component asks the bartender via. NET remoting: "Gimme a beer" Bartender: "What kind of beer? " Component: "Just give me all of them one by one and I'll drink the one I like. "

The component asks the bartender via Web Services: "Gimme a beer" Bartender: "What kind of beer? " The component thinks a minute. "I didn't know you'd have more than one. I just want a beer. " Bartender: "What kind of beer? " Component: "A plain one. "

Bartender: "What's plain beer? How about a bud? " Component: "Umm. . ok. " The component tries to take the beer but it slips onto the floor and the glass breaks. Bartender: "What's wrong with you? "

Component: "I got a slippery Soap. Exception. "

In this presentation my intent is to encourage you to try using web services in your RPG applications. I hope you will see that it’s not that hard of an assignment. The mechanics of it really aren’t any different than any other service program procedures that you might call. The cool thing is the resulting information or data that can be had and the innovative applications you can bring to your company.

Disclaimer: Just so we are clear. In this presentation I do not intend to spend time on the how to and/or jots and tittles of coding web services. There are many articles and presentations available that will help you with that. I simply want to expose you to the concepts and encourage you to delve into it yourself. I think you will be pleased with the results.

A little history on how I got involved with web services. • This in not new technology. It’s been around for about a decaded. • Lots of articles dated in the 2001 to 2006 time frame. Check them out. • Kentucky Municipal Taxes project. • S&P request and/or detour. • Consuming a web service is not a lengthy process to implement. Getting data is fairly easy to do. What you do with that data, is often the more involved part of the process.

What is web services? First what it’s not: One popular misconception is that Web Services are pretty much interchangeable with SOA. Web Services are the most common way to implement SOA, but they are neither a requirement nor an equivalent idea. MC Press Online, 2/1/10 article by John Ghrist

What is web services? • Mario Pesce’s definition: • Web Services consist of a group of standards intended to make it possible for diverse systems to communicate, without requiring a particular type of middleware, programming language or even operating system.

What is web services? • Scott Klements definition: • Web Services is about using the same HTTP protocol that you use to surf the Web, to make calls from a program to a program anywhere in the world.

• What is SOAP: • SOAP (an XML document) is a standardized format for passing parameters to and from a Web Service. • What is WSDL: • WSDL (an XML document) contains a list of the Web Services that you offer and provides information about the data types, lengths, and formats of the parameters that need to be passed to each Web Service. When you know this information, you can pick a service from the list and use the information in the WSDL to create a SOAP message.

So how does it work? • Sockets and API programming is the key to the HTTP protocol used to go to the internet. (Sockets programming is something I have not done! The beauty is I don’t need to. ) • In my searching for an interface to the internet, I found about four different product possibilities. • 1) You can use the Power i PASE environment to run c. URL. • 2) I think you can use tools like CGIDEV 2, CGITOOLS, or e. RPGSDK. • 3) Bob Cozzi has a service program called i. Sockets.

How does it work? • We chose HTTPAPI because it’s open source and free. • Scott comments in one of his write ups that after you have used the WSDL to format your SOAP message, you can use HTTPAPI to send it to the server. The server interprets it while you wait and sends back another SOAP message in response. You can then interpret that message to get the parameters that the service returns. • Typically the messages are in XML format that you parse out, yielding the results that you requested. But this is not a requirement (S&P data). • Scott also recommends a PC based tool called

http: /www. scottklement. com The place to go!

What does the RPG look like? I have included a couple of snippits of what the RPG code and service program calls look like, to show you that it really isn’t much different than any other sub-procedure or service program that you would write yourself.

begsr blk. Lookup; loc. Data. val = *zeros; setll (asstno: 'M': savnumb) blksch; reade (asstno: 'M': savnumb) blksch; dow not %eof(blksch); if bkbval + bkpval > loc. Data. val; loc. Data. val = bkbval + bkpval; parm. In. street = bkloc; parm. In. city = bkcity; parm. In. state = bkst; parm. In. zip = %char(bkzip); ENDIF; reade (asstno: 'M': savnumb) blksch; ENDDO;

if loc. Data. val <> *zeros; parm. In. lob = 'M'; result = DC 5710(parm. In); else; //not found error result. Err. Dtl. Desc = 'Unable to locate address for loc: ' + %char(sav. Loc#) + ' on policy: ' + %char(asnumb); endif; if result. Err. Dtl. Desc = *blanks; if result. MQmatch. Code <> '0'; //didn't have a good match result. Err. Dtl. Desc = result. MQdesc; else; //interpret the results exsr parse. Web; ENDIF; ENDSR;

post. Data = '<? xml version="1. 0" encoding="utf-8"? >' '<soap: Envelope xmlns: xsi=' '"http: //www. w 3. org/2001/XMLSchema-instance" ' 'xmlns: xsd="http: //www. w 3. org/2001/XMLSchema" ' 'xmlns: soap="http: //schemas. xmlsoap. org/soap/envelope/">' '<soap: Body>' '<Allocate. Address xmlns=' '"http: //allocator. tritechsoft. com/Allocator. Agent/">' '<Company. ID>' 'brotherhood' '</Company. ID>' '<Password>' 'P 12345 MXY' '</Password>' '<Source. Street>' %trim(user. Data. street) '</Source. Street>' '<Source. City>' %trim(user. Data. city) '</Source. City>' '<Source. State>' %trim(user. Data. state) '</Source. State>' '<Source. Zip. Code>' %trim(user. Data. zip) '</Source. Zip. Code>' + + + + + + +

'<Line. Of. Business>' %trim(user. Data. lob) '</Line. Of. Business>' '<Effective. Date>' %trim(user. Data. eff. Date) '</Effective. Date>' '</Allocate. Address>' '</soap: Body>' '</soap: Envelope>' act = 1; url = 'http: //allocator. tritechsoft. com/Allocator. Agent/' + '/Service. asmx'; rc = http_url_post_xml( url : %addr(post. Data) + 2 : %len(post. Data) : %paddr(Start. Of. Element) : %paddr(End. Of. Element) : *NULL ); if (rc <> 1); result. Err. Dtl. Desc = http_error(); endif; + + + + ;

• Some of the web services available… – – – Currency conversion DOW Jones, NASDAQ, S&P Municipal Tax Rates Converting text from one language to another language Tracking UPS packages Weather information – Etc. , etc. • Unlimited possibilities exist. What do you think you need? I would be surprised if it isn’t already available.

I’ll be available for questions and/or you can contact me through the STATUS website (www. statususer. org).