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Just wondering :-) If OO guys are migrating to AS/400 or AS/400 Guys are becoming more OO guys. In both cases it seems like AS/400 is in trouble :) -----Original Message----- From: rpg400-l-request@xxxxxxxxxxxx [mailto:rpg400-l-request@xxxxxxxxxxxx] Sent: Wednesday, May 07, 2003 9:56 AM To: rpg400-l@xxxxxxxxxxxx Subject: RPG400-L Digest, Vol 2, Issue 276 Send RPG400-L mailing list submissions to rpg400-l@xxxxxxxxxxxx To subscribe or unsubscribe via the World Wide Web, visit http://lists.midrange.com/mailman/listinfo.cgi/rpg400-l or, via email, send a message with subject or body 'help' to rpg400-l-request@xxxxxxxxxxxx You can reach the person managing the list at rpg400-l-owner@xxxxxxxxxxxx When replying, please edit your Subject line so it is more specific than "Re: Contents of RPG400-L digest..." Today's Topics: 1. Re: what is object oriented programming (Hans Boldt) 2. How do I do HTTP GET, wait for response from a website? (Tom) 3. RE: what is object oriented programming (Bartell, Aaron L. (TC)) 4. Re: How do I do HTTP GET, wait for response from a website? 5. RE: How do I do HTTP GET, wait for response from a website? (Haas, Matt) 6. RE: How do I do HTTP GET, wait for response from a website? (Buck Calabro) 7. RE: what is object oriented programming (Joe Pluta) 8. back to: improving rpg. was: what is object oriented programming (Steve Richter) 9. RE: Custom MONITOR handling (Steve Richter) ---------------------------------------------------------------------- Message: 1 Date: Wed, 07 May 2003 08:01:55 -0400 From: Hans Boldt <boldt@xxxxxxxxxx> Subject: Re: what is object oriented programming Steve Richter wrote: >From the start I have been using the words "object oriented" as they apply > to a style or programming that is applicable to RPG. I have never understood > what OO is, dont claim to, and after reading Hans's post above, still dont. > People always seem to explain it, just like Hans did, by telling you what it > is not, and never get around to saying what it is. Thus my comparison to religion! It's been said that the definitive book on Zen never mentions Zen once. In some ways, you need to achieve a sort of enlightenment to understand OO, and then certain things you were taught earlier just don't seem to apply anymore. I think the problem here is that (IMO) the term "Object Oriented" is somewhat passe, believe it or not. Has been now for perhaps the past decade. Or at least since the publication of "Design Patterns" by the so-called "Gang of Four" (Gamma, Helm, Johnson, and Vlissides) in 1994. That's the definitive book on the subject, and still hasn't been surpassed in the 9 years since publication. The introductory book I recommended in my last post ("Design Patterns Explained") refers to the GoF book extensively. > > There is a style of programming that programmers can employ where data is > encapsulated in an "object" and then procs which are "oriented" toward the > data are called to act on the data. An RPG programmer can employ that style > of programming to a degree. I have posted examples of that. What many people describe as "OO Programming" in ILE is often simply just good programming practice (as someone else here suggested). Some aspects of that good programming practice are more properly called "modular programming". > > My interest in this topic is in suggesting how RPG could be improved to > permit this style of programming to be more effectivly employed. Procs > could be declared as members of a data struct. A data struct could possibly > be declared with an "Is a" attribute which would be the equivalent of base > classes in C++. Maybe there could be "property get" and "property set" > members of a data struct. Not knowing the secrets of ILE, even object > access operators ( struct1 >> CustMast // write a rcd to the file ) could be > possible. > > All of this of course will likely never happen, and if it does, it will not > be released until 2005, by which time most of us will be not working as rpg > programmers. The "open source the compiler" suggestion, which I concede > also is pointless, is a practical way for needed enhancements to the > language to find there way onto the programmers desktop. Regarding adding "OO features" to RPG, well, I certainly think about that myself sometimes. But the scenarios always end up more or less the same - an ugly mish-mash of complex features, the type of language Rube Goldberg would be proud of. Or features with unacceptably poor performance. In other words, they'd end up making the language more difficult to use, not easier. If you're really brave and you want to experiment with an OO-RPG, you can always try the C++ approach. Early C++ compilers were preprocessors that converted C++ code to C code. As I've said before, if you want to do OO programming, great! But there are already some superb OO languages you can choose from. For learning OO, I strongly recommend Python, along with the previously mentioned books on design patterns. Cheers! Hans ------------------------------ Message: 2 Date: Wed, 07 May 2003 08:24:09 -0500 From: Tom <tomh@xxxxxxxxx> Subject: How do I do HTTP GET, wait for response from a website? We're thinking about using an online credit card processing center. Their requirement is that we package up our transactions and transmit them via http/https, and prevent the user from being able to view sensitive data in the data stream. We use Net.Data for page presentation, and I can pretty easily pass parameters to an RPG program. However, I have no clue on how to write an RPG program to do the next steps - send the GET command, and wait for (and process) the appropriate responses. Anyone? ------------------------------ Message: 3 Date: Wed, 7 May 2003 08:23:47 -0500 From: "Bartell, Aaron L. (TC)" <ALBartell@xxxxxxxxxxxxxx> Subject: RE: what is object oriented programming <Joe> ...(Aaron, I suggest you get these as well, because they really show why you need to start from the ground up when designing OO architectures). </Joe> If this is from my statement of "you don't need to understand OO to make good use of it", I didn't mean that you shouldn't learn how to build simple base objects that can be extended upon. I have already done some reading from those books (mostly from Bruce's). Note** I am not a purist OO programmer. Aaron Bartell ------------------------------ Message: 4 Date: Wed, 7 May 2003 09:32:27 -0400 From: MEovino@xxxxxxxxxxxxxxxxx Subject: Re: How do I do HTTP GET, wait for response from a website? Check out GetURI at <http://www.bvstools.com/opensource.html>. Mike E. Tom <tomh@xxxxxxxxx> To: rpg400-l@xxxxxxxxxxxx Sent by: cc: rpg400-l-bounces@xx Subject: How do I do HTTP GET, wait for response from a website? drange.com 05/07/2003 09:24 AM Please respond to RPG programming on the AS400 / iSeries We're thinking about using an online credit card processing center. Their requirement is that we package up our transactions and transmit them via http/https, and prevent the user from being able to view sensitive data in the data stream. We use Net.Data for page presentation, and I can pretty easily pass parameters to an RPG program. However, I have no clue on how to write an RPG program to do the next steps - send the GET command, and wait for (and process) the appropriate responses. Anyone? _______________________________________________ This is the RPG programming on the AS400 / iSeries (RPG400-L) mailing list To post a message email: RPG400-L@xxxxxxxxxxxx To subscribe, unsubscribe, or change list options, visit: http://lists.midrange.com/mailman/listinfo.cgi/rpg400-l or email: RPG400-L-request@xxxxxxxxxxxx Before posting, please take a moment to review the archives at http://archive.midrange.com/rpg400-l. ------------------------------ Message: 5 Date: Wed, 7 May 2003 09:35:36 -0400 From: "Haas, Matt" <Matt.Haas@xxxxxxxxxxxxxxxxxxx> Subject: RE: How do I do HTTP GET, wait for response from a website? Tom, You'll need a sockets program to do this. Brad Stone has a program called GETURI (http://www.bvstools.com) that I think may have the source with it but it doesn't do SSL. He does have a version that supports SSL but it isn't free. As far as sockets programming goes, Scott Klement (don't have his website address handy) has an excellent tutorial. Matt -----Original Message----- From: Tom [mailto:tomh@xxxxxxxxx] Sent: Wednesday, May 07, 2003 9:24 AM To: rpg400-l@xxxxxxxxxxxx Subject: How do I do HTTP GET, wait for response from a website? We're thinking about using an online credit card processing center. Their requirement is that we package up our transactions and transmit them via http/https, and prevent the user from being able to view sensitive data in the data stream. We use Net.Data for page presentation, and I can pretty easily pass parameters to an RPG program. However, I have no clue on how to write an RPG program to do the next steps - send the GET command, and wait for (and process) the appropriate responses. Anyone? ------------------------------ Message: 6 Date: Wed, 7 May 2003 09:38:09 -0400 From: Buck Calabro <Buck.Calabro@xxxxxxxxxxxx> Subject: RE: How do I do HTTP GET, wait for response from a website? >However, I have no clue on how >to write an RPG program to do the >next steps - send the GET command, and >wait for (and process) the appropriate >responses. You're looking at a sockets application. The FAQ has some information on sockets I think, http://faq.midrange.com. Also, general web-type stuff can be found at Easy400 web site at http://www-922.ibm.com. Have a look at Brad Stone's GETURI, from http://www.bvstools.com (from the Open Source section.) --buck ------------------------------ Message: 7 Date: Wed, 7 May 2003 09:11:08 -0500 From: "Joe Pluta" <joepluta@xxxxxxxxxxxxxxxxx> Subject: RE: what is object oriented programming > From: Bartell, Aaron L. > > <Joe> > ...(Aaron, I suggest you get these as well, because they really > show why you > need to start from the ground up when > designing OO architectures). > </Joe> > > If this is from my statement of "you don't need to understand OO to make > good use of it", I didn't mean that you shouldn't learn how to > build simple > base objects that can be extended upon. I have already done some reading > from those books (mostly from Bruce's). Note** I am not a purist OO > programmer. As Hans says, in some ways OO is akin to a spiritual experience. For reasons far outside the scope of this list (considering this post is already on the line), I believe that most procedural programmers require an epiphany to "convert" to OO thinking. Your above statement leads me to belive you haven't reached that point yet. Because OO is actually not about objects, not entirely. It's about a frame of mind where code is encapsulated and interfaces are defined and everybody communicates via messages (in the strictest sense of OO, every interaction between objects can be though of as a message - every method call is a message with a bunch of parameters and a return code). Hans and I disagree on the importance of data hiding to OO principles (in every text I've read and every person I've talked to, the common practice in OO is to hide all data members of a class and allow access only through setters and getters - this is probably one of the strongest conventions in OO today, and there is good reason for it), but we agree on the importance of design patterns. And you can't really design an OO system without using design patterns of some kind; they're sort of like the simple machines of OO programming. Where engineers think of the pulley, the lever and the inclined plane, OO designers think of the Decorator and the Factory. Without understanding those basic tools and how they are used, you are likely going to build applications that look like - well, that look like my first projects. Procedural ideas wrapped in OO skins. It's ugly, because you don't take advantage of any of the real benefits of OO design. For example, in OO you should program to the interface. While the exact implementation of this is different in different languages, it in essence means that you never directly interact with another class. You instead interact with an idealized version of that class which everyone agrees upon. You don't instantiate the class either, you invoke a Factory method which gives you an instance of an object that implements the interface. Why is this important? It's hard to explain in a single post, but it buys you an enormous amount of flexibility down the road. Is it always necessary? No, but until you have worked with the concept a while, you're not in a position to be able to decide wisely. The point is, though, that if you don't code this way FROM THE START, it's hell to go back and rearchitect your system. Trust me on this. Anyway, that's it for me. As hard as we've all tried to keep this on topic, this thread is destined to drift farther and farther from RPG. Until and unless you all decide to create an OO-L list, this is my last word on the subject. Joe ------------------------------ Message: 8 Date: Wed, 7 May 2003 10:20:03 -0400 From: "Steve Richter" <srichter@xxxxxxxxxxxxx> Subject: back to: improving rpg. was: what is object oriented programming -----Original Message----- From: rpg400-l-bounces@xxxxxxxxxxxx [mailto:rpg400-l-bounces@xxxxxxxxxxxx]On Behalf Of Hans Boldt Sent: Wednesday, May 07, 2003 8:02 AM >> Procs could be declared as members of a data struct. A data struct could >> possibly >> be declared with an "Is a" attribute which would be the equivalent of base >> classes in C++. Maybe there could be "property get" and "property set" >> members of a data struct. Not knowing the secrets of ILE, even object >> access operators ( struct1 >> CustMast // write a rcd to the file ) could >> possible. >Regarding adding "OO features" to RPG, well, I certainly think about >that myself sometimes. But the scenarios always end up more or less >the same - an ugly mish-mash of complex features, the type of >language Rube Goldberg would be proud of. Or features with >unacceptably poor performance. In other words, they'd end up making >the language more difficult to use, not easier. So now what I am talking about is "OO"! First I am off topic, then I dont know what I am talking about, then its not OO, now it is "OO", ... Did /free make the language more difficult to use? Did "qualified" and "likeds" degrade performance, make an ugly mismash? Of course it didnt! By the same logic, why would the extension of /free to the data declare specs not improve the language even more??? How is "DataStruct.MemberProc( ... )" a rube goldberg construct? If RPG is open sourced, IBM still makes its $$ thru the required websphere, those who want IBM RPG can keep it, there is no need for an IBM run committee, and the marketplace will decide quite efficiently whether a more modular rpg is workable or not. -Steve ------------------------------ Message: 9 Date: Wed, 7 May 2003 10:56:56 -0400 From: "Steve Richter" <srichter@xxxxxxxxxxxxx> Subject: RE: Custom MONITOR handling Hans, I hope you dont mind. Did this get missed the other day? I posted it a few days ago. You had posted early last week re: using MONITOR to monitor for os400 msgid messages. The code I posted in this message uses the "CEE" APIs to do just that. Your post implied that this type of message monitoring would not work in RPG. Can you explain why? thanks, Steve -----Original Message----- From: rpg400-l-bounces@xxxxxxxxxxxx Jon Paris wrote: > >> Is it possible to "throw" custom messages from a subprocedure? > > Nope - but I wish it was. Hopefully Barbara or Hans are watching the number > of requests for this feature and we'll see it at some time in the future. > > You can of course cause an exception in one of a number of ways but if you > want to supply your own code you're going to have to place it in a Global > area or something. Hans responded: >John: I'd certainly like to see some improvements myself. But any >improvements are probably going to work the way Buck described in >his suggestion. That is, it would have to fit in with the whole >OS/400 messaging protocol. Of course, a programmer can simply write >his own easier to use wrapper for the send message API's, and then >monitor for 1299 or 9999 (or whatever the default message id's are). >But I'm still uncomfortable with the idea of using message handling >for this type of thing. Although there are advantages to using a >message based exception scheme, my own preference in this particular >case would be to return an indication of success or failure using a >status code. I dont follow the problem of fitting rpg exception handling in with the whole OS/400 messaging protocol. Here is a way that the "Cee" APIs can be used to monitor for specific message ids and either halt or promote those that are not monitored for. Basically it functions the same as message handling in CL. ------------------------------------------------------------------ /free MonMsg_Init( MonMsgCb ) ; pHandlerProc = %paddr(MonMsg_Handle) ; CeeHdlr( pHandlerProc: %addr(MonMsgCb): *Omit ) ; // run some monitored code MonMsg_BgnMon( MonMsgCb: 'CPF2817' ) ; qcmdexec( 'cpyf a b': 8 ) ; select ; when MonMsgCb.SignalMsgid = 'CPF2817' ; fSndInfoMsg( 'monitored a CPF2817 message': 1 ) ; endsl ; MonMsg_EndMon( MonMsgCb ) ; CeeHdlu( pHandlerProc: *Omit ) ; MonMsg_Init is a proc that clears the data struct passed to the exception handler proc. CeeHdlr is an ile proc that registers the exception handler of the calling proc. MonMsg_BgnMon is a proc that fills the MonMsgCb data struct with up to 10 message identifiers to be monitored for. MonMsg_EndMon clears the MonMsgCb data struct of its msgids to monitor for. CeeHdlu is an ile proc that unregisters the exception handling proc. The MonMsg_Handle proc is called directly by ile. It is the proc that was registered by the CeeHdlr call. It basically retrieves the msgid of the exception that was signaled ( thrown ), checks the MonMsgCb data struct for the list of msgids being monitored for and proceeds from there. The proc returns codes that have meaning to ILE to either PERCOLATE the exception ( unmonitored ) or RESUME ( monitored ). ** -------------------- MonMsg_Handle ---------------------------- pMonMsg_Handle b dMonMsg_Handle pi d InCond likeds(CondInfo) d pInMonMsgCb * const d OutResult 10i 0 d OutNewCond likeds(CondInfo) d MonMsgCb ds likeds(MonMsgCommBlock) d based(pInMonMsgCb) --------------------------------------------------------------------------- Is this not an acceptable way to handle exceptions in proc level rpg code? The problems I have with it are: - a potential performance hit running the setup and take down code. - it is cumbersome to code procs this way. The performance is something the programmer can decide. The cumbersome problem can be solved by enabling the MONITOR opcode to implement similar CEE based code. Steve Richter ------------------------------ _______________________________________________ This is the RPG programming on the AS400 / iSeries (RPG400-L) digest list To post a message email: RPG400-L@xxxxxxxxxxxx To subscribe, unsubscribe, or change list options, visit: http://lists.midrange.com/mailman/listinfo.cgi/rpg400-l or email: RPG400-L-request@xxxxxxxxxxxx Before posting, please take a moment to review the archives at http://archive.midrange.com/rpg400-l. End of RPG400-L Digest, Vol 2, Issue 276 ****************************************
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