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Gaining Enlightenment
by Richard Moon 07 Mar '00

07 Mar '00

Dear Zopers, I read Chris McDonough's How To on Gaining Zope Enlightenment by Grokking Object Orientation. It raised a few questions in my RDBMS-oriented head. So I mailed Chris with these questions but Chris explained he just couldn't answer them right now and asked me to post them to the list. They seem very basic, very fundamental questions to me. So here is my email to Chris - If I get any answers here I would like to include my questions and your answers in a How-To to help those who come after me ! Thanks for any help ! Here's the original email ---------------------------------------------------------------------------- ---------------------------------------------------------- Chris, I enjoyed your How-To on Gaining Enlightenment very much. I've been using Zope for a couple of months now and I've made some progress - my first project has been to use it to give access to established databases over an Intranet. Like you I think its wonderful, but like you I keep getting stuck. Never mind, with the help of the mailing lists and long hours reading books on Python etc I've made progress. BUT ... (there's always a but isn't there) - no matter how much I read and play around with OO - I still don't 'get it'. My background is many years working with relational databases on Unix - (and there are thousands like me). I just don't get the bit about storing data as objects. Could we discuss this a bit more and perhaps publish my questions and your answers on Zope.org ?? This may help me and the thousands like me. OK, you create your class of Spam, which has attributes of cansize and texture and it has methods that display these attributes. No doubt you could add other attributes, such as selling price and develop a method to increase the price by a percentage. OK so far ? Now we create an object (which is an instance of the class Spam) - which we call myfirstcan. We can define the attributes for that object when we create it or later and we can use the methods defined in the Spam class to do so. OK so far ? What I don't get is how you store and retrieve the objects you create. Let's go to a more realworld example - how would you implement a stock system using objects ? Let's take the simple table Stock which has three columns Product_code Description Price and we could enter rows of data into it, for example - ABC Spluggifier 20.00 CDE Super-spluggifier 25.00 Now if I was writing a conventional database system I would maintain the above by defining a program which perhaps prompted the user for the required columns (Product, Description,Price) and then I would store the users input in a row in a table. Perhaps another program (the price change program) would use a stored procedure to allow price change. OK ? Now in OO terms I see that I could create a class of Stock with attributes Product, Description and Price. I could create a method to allow price changes. Very neat. Then I can create an object( i.e a particular stock item) by saying something like product_1 = Stock(product_code="ABC", Description="Spluggifier", Price-"20.00") Now I can create another object by saying product_2 = etc but that is not the way you would do it surely. You would be effectively 'hard-coding' each product in your system. Surely you would have a program which did something like WHILE the user is entering data PROMPT user for data VALIDATE data WRITE data to database END WHILE How do you do that in OO terms ? How then do you search and retrieve an object with a particular value of product_code ? How do you write a program which updates the price of all stock items where the product_code begins with AB by 2%.? Thanks for reading this far. Hope you can stop my head spinning ! Regards Richard Richard Moon richard(a)dcs.co.uk

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Zope sendmail tag inconsistent
by Jason Spisak 07 Mar '00

07 Mar '00

Zopists, Has anyone else noticed that the endmail tag will sometimes not send a mail even though the dtml method sucessfully completes? It's about one out of ten at high traffic times, and it happened on Zope.org too when I tested it by emailing my password to myself a few times. All my best, -- Jason Spisak 444(a)hiretechs.com

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RE: [Zope] Listening on specific interfaces
by Pearson, Brian Edward (GEA, 056278) 07 Mar '00

07 Mar '00

All - After bringing up a logical interface (hme0:4) on physical interface hme0, Zope will not work if I try to use a value of 80 for the HTTP port. Netscape Enterprise Server is running on this same box and is already bound to the physical interface hme0 listening to port 80. My guess is that Zope is not really binding to the virtual interface, but is trying to bind to the physical interface and thus it is conflicting with NES. The error follows: $ ./start -a 3.130.232.27 -w 80 -f 8021 -m 8099 Traceback (innermost last): File "/opt/devnet-zope/Zope-2.1.4-solaris-2.6-sparc/z2.py", line 493, in ? logger_object=lg) File "/opt/devnet-zope/Zope-2.1.4-solaris-2.6-sparc/ZServer/medusa/http_server .py", line 552, in __init__ self.bind ((ip, port)) File "/opt/devnet-zope/Zope-2.1.4-solaris-2.6-sparc/ZServer/medusa/asyncore.py ", line 205, in bind return self.socket.bind (addr) socket.error: (13, 'Permission denied') 3.130.232.27 = hme0:4 If I specify an HTTP port that is not currently bound to the physical interface (hme0), such as 1234, Zope starts up properly. How can I force Zope to bind to logical address 3.130.232.27:80 so that it no longer conflicts with NES? Is this even possible? I have a few Zope apps. that I would like to bind to different logical interfaces on port 80 so that I can use different hostnames. Additionally, I do not want the user(s) to specify a port in the URI. Thanks, -Brian > -----Original Message----- > From: Michel Pelletier [SMTP:michel@digicool.com] > Sent: Wednesday, March 01, 2000 10:29 PM > To: Pearson, Brian Edward (GEA, 056278) > Cc: 'zope(a)zope.org' > Subject: Re: [Zope] Listening on specific interfaces > > > > "Pearson, Brian Edward (GEA, 056278)" wrote: > > > > All - Have a problem which I am certain many of you have already > > encountered. > > > > With most web servers, you can create specific web server > instances that > > listen to virtual network interfaces on the server (virtual IP > addresses). > > For example, I can have multiple httpd instances, with httpd1 > listening to > > 192.168.1.101 and httpd2 listening to 192.168.1.102 on a box where > the > > physical IP address is 192.168.1.100. This is configurable within > the web > > server. > > > > I want to be able to have Zope listen to a specific network > interface, i.e. > > - a virtual IP address that has been created on the server. This > will allow > > me to have multiple Zope sites running on the same machine. How > can this be > > accomplished? Any/all suggestions are greatly appreciated. > > You need to hack the z2.py file. Go down near the bottom (look for > the > string '# HTTP Server') and you will see that the HTTP server is > fired > up on the IP_ADDRESS interface. This variable is defined on line > 252 > and the default is an empty string '' which means, 'all interfaces'. > > You can hack the code here to do anything you want, define a bunch > of > interface variables, etc... > > Yes, this needs to be done better, but short of comming up with a > conf > file like apache and dealing with all that, it's probably no so > realistic. z2.py is currently config'ed with command line options, > which gets out of control after a while. > > -Michel

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RE: [Zope] Zope needs this (and Dynamo has it)
by Alexander Staubo 07 Mar '00

07 Mar '00

> From: John Goerzen [mailto:jgoerzen@complete.org] > Sent: Tuesday, March 07, 2000 4:26 PM > To: Alexander Staubo > Cc: Zope Mailing List (E-mail); 'Thomas Stenhaug' > Subject: Re: [Zope] Zope needs this (and Dynamo has it) Thank you for completely sidetracking me and instead choosing a flame angle for petty word games. My point specifically was that the mass of mainstream appreciation of Zope versus a product like Dynamo was specificially _not_ related to openness. IBM does not open its money floodgates to invest in Linux merely because Linux is an open technology -- Linux was not the first, nor the last, not arguably the finest open technology in the history of IT. It and others do so, and give momentum to Linux, because of money, pure and simple. > > If the suits in managements (assuming you work in such a > place) tell you > > to go learn Dynamo because that's what they want to use, > wouldn't you > > say it's a problem? > > It's not Zope's problem. It's their problem . Let me relate a short anecdote for you, about the incident which triggered this thread. See, my colleagues are currently involved in a large project for a large company. They are buying Solaris 8 to run Dynamo. I've made a very strong case for Linux and Zope. There is, today, only a marginal difference between these two setups, and that difference is in price: The Linux/Zope combo is significantly cheaper than the Solaris/Dynamo combo. This has zero bearing upon their choice, and indeed on most ordinary computer investments for any company: The cost of buying a computer and licensing the software is "nothing" compared the maintenance costs and the insurance a big company needs that their investment is safe. In other words, heavy support plans and brand names. And guess what? Despite the fact that both Linux vendors and Digital Creations offer such support plans, my advice to my colleague and this company falls dead on the ground. Zope doesn't have the flashy packaging and sexiness of a product line Dynamo -- which, actually, I strongly urge you (and everybody else in this forum) to experience yourself, before you snap back at my again -- and this affects management decisions. Dynamo is exceedingly sexy, and it boasts the kind of bullshit magic that have management and tech people alike drooling. So is it "their problem"? In the end, I don't think so. I think they're going to be quite happy with Dynamo. As one of my colleagues pointed out, the problem starts with the name. (Somebody out there is hyping what they call Linux' next-generating GUI. And it's called... GNOME. What's wrong with this picture?) I don't care myself, but I recognize the problem. -- Alexander Staubo http://alex.mop.no/ "QED?" said Russell. "It's Latin," said Morgan. "It means, 'So there you bastard'." --Robert Rankin, _Nostramadus Ate My Hamster_

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RE: [Zope] Zope needs this (and Dynamo has it)
by Alexander Staubo 07 Mar '00

07 Mar '00

> From: John Goerzen [mailto:jgoerzen@complete.org] > Sent: Tuesday, March 07, 2000 4:19 PM > To: Alexander Staubo > Cc: Zope Mailing List (E-mail) > Subject: Re: [Zope] Zope needs this (and Dynamo has it) > > > Alexander Staubo <alex(a)mop.no> writes: > > > Speaking of which, SNMP support for Zope would have been > nice. Then we > > could import the numbers needed to build monitors like the > one featured > > in the screen shot. > > Why? This is overkill for what zope is. Zope is not, in essence, a > web server. If you want to do strange things like that, use Apache > :-) Untrue. Apache's load/stats and Zope's load/stats are different sides of different coins. You're implying that Zope has no statistics to export, and that if you couple Zope with Apache (which you might not want to) then the numbers that Apache can export would apply to Zope -- and this is clearly wrong. -- Alexander Staubo http://alex.mop.no/ "QED?" said Russell. "It's Latin," said Morgan. "It means, 'So there you bastard'." --Robert Rankin, _Nostramadus Ate My Hamster_

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Re: [Zope] Zope needs this (and Dynamo has it)
by John Goerzen 07 Mar '00

07 Mar '00

Alexander Staubo <alex(a)mop.no> writes: > I mean proprietary as being controlled by a private party -- owned, in a > very liberal sense -- as opposed to being standarized. XML is not > proprietary. DTML and Java are. Completely inaccurate. Proprietary software (Please, use the Jargon file next time you look something up in the dictionary, geez) is software which is not licensed under a Free Software license. This includes Java *as implemented by Sun* but NOT DTML or Free implementations of XML. > I'm not as knowledge about IP laws as I would like to be, so I can't > really defend my use of this word or whether DTML is an intellectual > property of Digital Creations. Perhaps somebody else more suited to the > task could clarify. Well, the issue is not really "the language". The issue is whatever software implements it. Anybody can implement DTML, or Java, or XML, or whatever, and license it however they want. The question is, whether this implementation is Free Software, and indeed, it is. > If the suits in managements (assuming you work in such a place) tell you > to go learn Dynamo because that's what they want to use, wouldn't you > say it's a problem? It's not Zope's problem. It's their problem . > I definitely believe that Python is Zope's largest problem right now. > It's also, from a technical point of view, one of it's biggest assets -- > Zope is becoming the killer application of Python, and might eventually > become the driving force to evolve Python, which is, I believe, > suffering from draught into the contributor department. Skilled > developers aren't flocking to Python to make it faster. Not right now, > anyway. Interesting point. I myself prefer Perl to Python for a number of reasons, but am nonetheless forced to learn some Python to use Zope :-)

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Re: [Zope] Zope needs this (and Dynamo has it)
by John Goerzen 07 Mar '00

07 Mar '00

Alexander Staubo <alex(a)mop.no> writes: > Speaking of which, SNMP support for Zope would have been nice. Then we > could import the numbers needed to build monitors like the one featured > in the screen shot. Why? This is overkill for what zope is. Zope is not, in essence, a web server. If you want to do strange things like that, use Apache :-)

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GUF: I think it's the gufauth_dest
by Lucas Vogel 07 Mar '00

07 Mar '00

I am now able to use the GUF the way I want to. I changed the POSTing destination to something other than docLoginSuccess(docLoginSuccessURL, the original variable that was there, didn't work at all). I created a dummy dtml doc called dud, pointed my POST to it, and I authenticated successfully. Now my problem is is, once I've authenticated like that superuser can't access that stuff until I restart Netscape. But I think I can live with that a little better. :) -- Lucas Vogel lucas7(a)home.com ICQ: 44697169

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copying image object?
by Darran Edmundson 07 Mar '00

07 Mar '00

Hi Zopistas, A likely FAQ but it's late, I've been Zoping for 15 hours, ZQR is temporarily unreachable from Canberra, I can't see straight and I'll admit it - I'd like to wake up to the answer ... I simply need to copy an image object (image1) from my globals folder to within an instance of a containerish ZClass. I toyed with manage_addImage() but couldn't find a method to get the raw data out of image1. Cheers, Darran.

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ZCatalog again
by Nolan Darilek 07 Mar '00

07 Mar '00

Ok, it appears that len() isn't what I want. I was under the impression that searchResults() returned an object which functioned as a list, but this wasn't right, apparently. Or maybe it was, *shrug*. :) Here's my current code, which I've modified a bit for testing purposes: <dtml-var standard_html_header> <dtml-calendar> <dtml-call "setCalendar('valign','top')"> <dtml-let d="date.Date()" hasdate="hasProperty(d)" dprop="getProperty(d)" e="getCatalog().searchResults(meta_type='Event', event_date=date)"> <dtml-if e> <dtml-let path="getCatalog().getpath(e[0].data_record_id_)"> <a href="&dtml-portal_url;&dtml-path;"><dtml-var "date.dd()"></a> </dtml-let> <dtml-else> <a href="&dtml-portal_url;/&dtml-date;"><dtml-var "date.dd()"></a> </dtml-if> <br> <dtml-if "hasdate==1"> <dtml-var dprop> </dtml-if> </dtml-let> </dtml-calendar> <dtml-var standard_html_footer> This code generates links as it should. What I'm trying to do though is, if an object of the Event class exists with an event_date which equals the current rendered date, I'd like to link directly to it. I can successfully search for the date using the PTK's search form, so I'm fairly sure that my issues with the catalog are resolved. So, what exactly is being returned by searchResults, and how can I determine whether my search yielded anything, so that I can display a link to the item?

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