Re: Converting web-application from Illustra to Informix Univ.Server

Im forwarding over this to the mailing list. A few people here at KOZ answered a question from the informix mailing list. The following two attachments are some answers to the question. (BTW, these people arent on the mailing list). Here is the original question: > > Hello, > > Does anybody have any experience converting a web-application > (built with the illustra application page builder) > to the Informix universal server (also with the web datablade)? > > I allready have a document that covers such an conversion, but > I would like to know if someone has really done it, and > can tell me what to watch out for. > > thank you verry much. > > Micha Haas > ================================================== 1st reply ================================================== ------- Start of forwarded message ------- Return-Path: <j.k.morgan@computer.org> We just finished the port of an application consisting of over 200 web datablade application pages. The difficulty depends on how hard you're driving the web datablade & how much use you make of the OO aspects of Illustra. We have an application that makes very heavy use of the web datablade & we went through a lot of agony helping Informix get some nasty bugs out of the IUS web datablade. The Informix engineers were incredibly helpful in getting the problems fixed ASAP - I've worked DB problems with Oracle, DB2, Sybase, etc. and never seen engineers bust their behinds the way the Informix folks did to get us up & running.. Make sure you have the most recent version with all current patches. It's very stable now. One problem was the lack of a multi-representational data type for large text fields. We had to implement our own. Another set of problems revolve around syntactic/semantic differences between the Illustra and IUS versions of the web data blade. The biggest problem is a 32k limit on any web page being pushed out of the engine. The following is a cut&paste from our Illustra->IUS 'gotchas' notes file. Syntax differences between Illustra and IUS requiring changes in our Web Application Pages and Tags: 1) In IUS functions that don't return a value are called PROCEDURES 2) Procedure invocation changes - instead of 'return foo(...); ' use 'execute procedure foo(...)' 3) Old-style conditional syntax ($1.gt.0) doesn't work - use $(>,$1,0) instead 4) In at least some cases you must use symbols instead of EQ, NE, GT in conditionals 5) column aliasing doesn't work properly. In the statement: SELECT foo, UPPER(foo) as upname from a where upname = 'BAR'; fails on two counts. First, IUS doesn't want the word 'as' in the aliasing phrase. Also, the use of 'upname' in the where clause won't be recognized. 6) IUS doesn't provide upper, lower, and so forth functions. 7) In COND clauses it's not safe to compare an integer value to '1'. It seems that they're being interpreted as fixed point values and '1.000000' doesn't match '1'. For example, the following will fail in all cases, whether count is 0 or greater than 0: <?MISQL SQL="SELECT COUNT(*) WHERE ...;><?/MISQL> <?MIBLOCK COND=$(=,$1,0)> 8) Passing long environment strings on TEMPLATE invocations sometimes doesn't work. That is: <?TEMPLATE NAME='foo',PARAMS='very long environment string'> blows up if the 'very long environment string' is sufficiently long ( it also blows up iff it contains a redefinition of a variable already defined in the surrounding environment 9) Function, procedure, table, (and apparently damn near everything else) names must be no more than 18 characters long. 10) using '$*' to reference all columns of a SELECT statement doesn't work. For example, checking for a null return by: SELECT foo1, foo2 FROM bar WHERE.....; <?MIBLOCK COND=$(NE,$*,) ......... Doesn't work. 11) Comparing to "" to detect nulls in COND statements doesn't work: COND=$(EQ,$foo,"") should be changed to COND=$(EQ,$foo,) On the positive side, IUS has real stored procedures, so we were able to replace a whole bunch of c code and very ugly macros involving recursive web explodes with much simpler, easier to maintain SPL stored procedures. On the whole, we like the IUS version much better than the Illustra version now that we've converted over, You shouldn't have as much trouble porting as we had since the current web datablade & server engine are much more stable than when we started our port about a year ago. Keith Morgan VP Systems Operations KOZ, inc 6340 Quadrangle Drive, Bldg 4, Ste 75 Chapel Hill, NC 27514 j.k.morgan@computer.org or keithm@koz.com ================================================== 2nd internal reply ================================================== Return-Path: <chris@koz.com> The biggest pain in the neck was the " " around the COND statement. You did not need them in Illustra. I would tell him to always use " " around his COND statement. Also the bug with using mivariables inside an "IF" statement inside an misql. Where the mivariables will not get evaluated. ================================================== -- Thomas Tatum thomas@rtp.koz.com 919-489-5662 x32 919-602-6521