Tag: Software

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Exceptions and error handling

One of the things users hate to see are bugs in programs, so there are many techniques for attempting to catch them before a user sees them. One that is routinely used is exception handling. However, some developers like to use exception handling instead of preventing the issue or gracefully handling it. For example, I was working on code to present errors (in a worst case scenario) to users and trapped the error handling. As I did this, I kept noticing strange exceptions being thrown when my app started. Turns out that Apple uses exceptions (which are benign) in Core Data for its parsing of XML. Personally I don’t think this is a great way of handling things, but who am I to judge?

On the same topic, I had a rash of users complain that they lost data in my apps. I was very perplexed as I’d never seen this. I took a look at the code where I save out the data and noticed that I had put the entire save routine along with some other routines in an exception block with the save being at the end. This meant that if there was a problem with the first chunk of code, the data would never get saved. While I still have no idea what would cause the first chunk of code to fail, I pulled the save out of the exception handling and have yet to receive a problem report (knock on wood).

So the moral of the story is to carefully watch how exceptions are used and don’t go overboard with exception handling.

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4 Mice Review of ReceiptWallet!

A friend of mine sent me a copy of an article in the August 2007 issue of Macworld magazine (the print issue that isn’t available on newsstands, yet, just to subscribers) that lists the most useful Mac applications. ReceiptWallet is listed in it and received a 4 mice review (that little blurb is the review). That’s not too shabby for my little side project. I’m not sure why it wasn’t a 5 mice review, but I’m pretty pleased. This definitely accounts for the nice sales increase this past week.

(I was going to call this entry, 4 rat review of ReceiptWallet, but decided against it. Way back when I worked in the print shop at my high school, we always used to joke around that the mice ratings were rat ratings; not that they were bad, but it was just entertaining to say things got a 4 rat review.)

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Yet another new store

I wasn’t quite happy with my online store and was pleased to see a clean, open source store released. Andy Kim of Potion Factory released his store as open source. It’s Ruby on Rails, so it was a learning experience for me to get it running again. I learned a great deal in the 2+ days that I spent getting it running, but it is so much cleaner than my old stores. Hopefully I don’t have any problems with it as I just put the finishing touches on it this morning. It’s at store.receiptwallet.com. Things I learned from installing this on my server:

  • Even though there is an RPM for mod_fcgid on Fedora Core 5 with Apache2, FastCGI still needs to be installed from the source
  • The Apache configuration for FastCGI needs to have:
        DefaultInitEnv RAILS_ENV production
    SetEnv RAILS_ENV production

    in it. The first line for FastCGI to work and the second to work without FastCGI

  • ruby-debug gem has to be installed to get the store to work in development mode and MUST be commented out to work under Apache
  • To use multiple databases in RoR, the model has to look something like:
    class User < ActiveRecord::Base
  require 'yaml'
  set_table_name "users" # we need to set this explicitly
  extra_coord = YAML.load(File.open(File.join(RAILS_ROOT,"config/database.yml"),"r"))["userdatabase"]
  self.establish_connection(extra_coord)
end

    (my pool of serial numbers is stored in a separate database and so are my users; I modified the store to interact with these other databases)

  • On PayPal’s developer site, if you want to test Website Payments Pro, you need to use a Social Security Number of 111xxxxxx where x is any number, but this number can’t be used by another developer
  • STDERR.puts is your friend. It’s great for logging stuff to the console
  • RoR running under Apache must use FastCGI in a production environment or it is way too slow
  • In application.rb, it MUST have:
    class ApplicationController < ActionController::Base
	filter_parameter_logging "cc_number|cc_code|cc_month|cc_year"
end

    otherwise you have important stuff getting logged which is bad.

  • Turn off IPN on PayPal or you’ll have an error when processing orders and people will order multiple times because they think it fails

That’s about it for now. I’ll update this as I remember more stuff so that I don’t waste time in the future and it may help others.

Thanks, Andy, for the store! While I don’t have a use for your products right now, I’ll be purchasing them anyway as your store is such an elegant solution, it is the least I can do to repay you.

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Apache MultiViews option is dangerous

I was poking through my web logs and saw requests to pages that didn’t exist on my server and the server returned something (200 return code), so I started looking at them. I was able to hit the pages with a browser and after much searching, I figured out how pages that obviously didn’t exist could return a valid page that was slightly messed up (image references were hosed). Turns out my sites had

Options MultiViews

in the Apache configuration files. MultiViews, as I have come to find out, guesses what page to load if the page doesn’t exist. Well, its guesses are whacked. So, disabling this feature fixed the problem and now pages that don’t exist get redirected to the home page.

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Doing the right thing

My previous rants about Sandvox may have been harsh, but as I mentioned before, I see so much promise in it and the sites it creates. I want to offer an apology to the authors; they, like all software developers, do their best to create good products.

Karelia has made things (financial) right with me and I applaud them for that. I did find out that they offer a 30 day money back guarantee, but I wasn’t going to take them up on that as I wouldn’t feel right about getting a refund for a product I still wanted to use. They’ve given me a complimentary copy for my work in tracking down the SFTP issues (I hope the fixes work for others) and I really do appreciate it; my whining wasn’t to get a free copy, it was simply to express my frustration in getting my site uploaded.

Thanks Karelia and keep up the good work!

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Another Sandvox bug

So this is my week to beat on Sandvox. I think the product has great potential, but still needs some work to do a basic website (my website isn’t all that complicated). Yes, I am reporting the bugs I find.

The first bug (which their support guy has reported with my test site) is that I can’t create links for pictures. Minor inconvenience, but all my links (except for screenshots) are text.

The second bug is that for my site logo, I made a 200×128 graphic (that’s what the box says the size should be). If you look closely and flip through the pages on the design I chose, the navigation bar height changes by a few pixels. Most people wouldn’t notice, but that’s the kind of person I am. After thinking that my site was hosed, I rebuilt most of the site (took over an hour) and had the same problem. I then tried logos that were smaller than 200×128 and didn’t have the problem. So, I made my logo 200×120 and the problem is gone. While not disastrous, very annoying.

So where am I? My site works and I’m moderately pleased with it. I think the look is cleaner than before. Next I have to hack on my store to clean it up. I wish I had a better store system, but for now, it will do.

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New website uploaded!

After many days of fighting Sandvox and its underlying Connection Kit framework, I’ve managed to upload my website. All my uploading problems stem from Connection Kit’s poor implementation of SFTP. What basically happened is that the SFTP implementation was bolted onto the libssh2 library. Like most UNIX libraries, libssh2 uses UNIX socket calls such as recv, write and writev. Connection Kit is based around Apple’s stream calls with queued writes and basically non-blocking reads. So Connection Kit tries to merge the 2, but does a poor job. Apple’s stream calls actually give access to the UNIX sockets, so write, writev, and recv could have been used. I removed the hacked up write calls so that write was used, but when I tried to use recv, things got strange. I ended up changing the buffer size to 16K (from 32K) prompted by a comment in the code:

#warning this byte range was really out of hand for Terrence

The reason the byte range is a problem, as far as I can tell is that at some point down in the libssh2 library, it calls Read which is mapped to a stream call and doesn’t properly handle blocking calls.

So, what have I learned from this fiasco:

  • Sandvox produced a website that I like
  • Demos of programs should be time based and not feature limited; if this was the case, I wouldn’t have spent $79 and wasted days on this program
  • Open source sucks; there is a ton of open source code out there developed by anyone that wants to put out code. The quality of the code is sometimes suspect; while some parts may be good, there may be problems that are hard to solve. I’ve been in the same boat before using open source code without fully understanding how it worked and it has bit me a few times.
  • Open source is great; since the underlying framework was open source, I was able to examine it, find the flaws, and patch it (note I didn’t say fix as the SFTP stuff needs to be rewritten or at least thoroughly reviewed)
  • My blogging isn’t completely useless; I did get a response from one of the authors of Sandvox
  • I’m stubborn (OK, I already knew that). Most people would have given up and asked for their money back. I still should ask for my money back as I probably spent 10-12 hours on this at say $75 per hour (cheap engineer), that puts my time investment into solving their problem at well over $750.
  • The Apple Design Awards are only about pretty pictures; a friend of mine told me that someone at Apple kept raving about Coda’s leaf icon. I like Coda and think it is a decent app, but hey, it’s a website editor. In fact, several of the ADA winners were web design apps. Maybe if I want to win, I’ll have to do a web design app. Maybe I’m just bitter about ReceiptWallet not winning. (Hey, Apple, send me my scanner back!)
  • People don’t care about security or don’t have SFTP access to upload their website. Having SFTP pretty broken for one of 4 transport mechanisms seems kind of odd. My SSH server is sitting on a gigabit ethernet link to my machine and is a standard OpenSSH install, so it couldn’t just be my server.

There’s probably more that I’ve learned, but I can’t think of it now.

So, am I done with this? No, I have to redo my site because there are several bugs in Sandvox that are causing me problems. First off, the navigation bar is a different height in the main page and all sub pages; I can’t reproduce this on a new site, so something got hosed when I built it. Also, I can’t select a picture and create a link once I’ve entered my text. In addition, the text editor only sometimes supports undo. If I drag in pictures, things get kind of wacky.

I really need to stop trying to do my own website and hire someone to do it. It would save me a whole lot of time and frustration.

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Sandvox partially fixed

I discovered that Sandvox uses a framework called Connection Kit for uploading files. I downloaded the framework (it’s open source) and found that it had the same problem as Sandvox which lead me to believe that the framework is broken. After spending a large part of today looking at the framework, I managed to fix part of the problem in that I no longer get SSH errors when trying to upload via SFTP. I’m not ready to reveal my fix to the problem and I still don’t have things working (some pictures just don’t upload).

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Unimpressive software

Last week, Sandvox was a runner up in Apple’s Design Awards, so I decided to take a look at it to re-create my website. I really like the look of the websites; they look more professional than the basic one’s created by RapidWeaver (which I’ve used for about 1.5 years). I spent about half a day yesterday reworking my ReceiptWallet website in Sandvox and am pretty pleased what I’ve done. I went to publish it to a test site and the demo limited me to publishing the main page, so I went ahead and purchased it (I had to purchase the Pro version for $79 as I have a few places that I have raw HTML) and proceeded to publish the full site. I use SFTP (secure FTP or FTP over SSH) to publish and kept getting errors about the encryption key. Not looking too hot for $79. After a few tries and changing some settings, I was able to publish the “full” site. I was about to switch my entire site over and make it live when I discovered that Sandvox only uploaded one of my graphics.

Wow, I’ve never had so many problems with one program in the first day of using it and having spent $79 on it, I’m a bit disappointed to say the least. I’ve spent them a few pieces of email and hopefully they’ll have a solution soon. For a product that has been out for over a year, it seems like it still needs a bit of work. There are a bunch of hidden features that really shouldn’t be hidden; for instance, I needed to change the file extension to .php from .html so that some of my PHP code would run which I could only do with a hidden preference; in addition, I wanted to change the Amazon associate ID to my own instead of theirs (at least I could do it).

I just discovered that they also embed a link to their Amazon associates stuff in my page that includes Amazon links; not cool at all.

So, at this point, my site remains unchanged and unimpressive. I also feel that I’ve wasted $79 on a piece of software that needs a ton of work. Oh well, live and learn.

That brings me to another complaint I have and that’s the Apple Design Awards; this year they recognized several web design applications that frankly look better than they function. So Apple Design Awards must really only recognize applications that look pretty. Am I disappointed that ReceiptWallet didn’t win? Yes, but now I understand why, it is extremely functional and doesn’t have fancy pictures to make up for its shortcomings. Another lesson learned, don’t waste time entering time year. Apple better send back my Pentax DSMobile 600 scanner I sent in with my entry to make judging it easier.