Author: andrew

Internet Explorer has a way of driving web developers up the wall.  Every version has its own glut of bugs and quirks, some just irritating and some downright bizarre.   It's one of those bizarre ones that I've been looking at over the last few days – specifically in Internet Explorer 7, the major browser of our end users. The screen in question is an editable version (which I can't show due to authentication issues) of this reading list.  When it goes into edit mode a side panel slides in from the right and you get a library of bookmarks that you can drag onto the list in whatever position you want.  You can also drag in a new section or existing items and sections around on the list.  With the complexity of what is going on there were always going to be a few cross-browser issues but one in particular was so severe we had to disable editing in IE until the problem was found and resolved. The symptoms were that when new items or sections were dragged onto a list you'd get a flickering hourglass, CPU usage up to 96% and it would either be unreliable or impossible to drop it in the right place on the list.  If you started off with a new blank list, the first few items would be OK (up to about 4) then the hourglass flicker would start, by the time you got to 7 or 8 it was getting really hard to drop an item and by the time you hit about 10-12 it was impossible to use.  Firefox worked fine and Internet Explorer 8 (RC1, not tried in the newly released full IE8 yet) also worked fine. Several thoughts crossed my mind when first looking into this:  was it my (JavaScript) code, was it one of the third-party libraries being used (Prototype & Scriptaculous) or was it something else?  I certainly didn't imagine at the start that it was just down to the CSS… Once the code and the libraries were ruled out it ended up being a trawl of Google to see what I could find. The first thing uncovered was from a passing comment on Steve Souder's blog post on "Performance Impact of CSS Selectors".  Steve made passing comment to the performance impact on using CSS 'hover' pseudo-selectors.  We were using those on each item on the list to show/hide edit and delete buttons.  So, I removed the hover selectors and there was an improvement but no magic bullet. More digging around ensued and point 41 this list of IE bugs was found.  This was very close to what I was seeing.  A scrolling layer and a problem that maxes the CPU in IE7.   It then became noticeable that in IE7 I was reliably getting the problem at a certain point when dragging items onto the list.  When the number of items dragged over filled the visible space on the scrolling list, the next item dragged would always start to produce the flickering hourglass and CPU peaking.  I also noticed that the vertical scrollbar on the pane was not sizing correctly.  If you scrolled up and down using the scroll-wheel on the mouse the scrollbar would sort itself out and then next item you dragged across would work OK.   Interesting… More Googling later and I found a similar reference on the MSDN.  This described that problem and pointed at a CSS sizing issue causing a problem in IE.  I tidied up the CSS a bit and added a 'min-height' to a few of the selectors and, hey-presto, no flickering hourglass when dragging items across and no strange resizing scrollbar. So, if anyone else gets anything similar to this then I hope this post helps.  It's driven me nuts for a good few days now.   IE always surprises me (by how bad it is), but I never initially thought that some basic CSS could happily cause IE to go into such a bad CPU spike that it could actually crash the browser – amazing! Now that the problem of making it work in IE7 is well on the way to being fixed I now have to improve the performance on large lists (ABF203, above, is a tiny example compared to some we have).  It'll be back to Steve's great work in this field for pointers on this.

A couple of weeks ago I was out on a lunchtime walk around the Business Park and bumped into someone I used to work with a few years ago at Severn Trent Systems (about 200m from where I work now).    It seems that the project we both used to work on is still alive and well and it made me start wondering about other projects I've worked on; how long they lived for in these fast-changing times and how many still have traces of them being used today. The project in question was an asset inventory system for Severn Trent Water.  It was written in PowerBuilder (I wonder how many people still use that?!) and, horribly, used Tuxedo as a middleware component rather than do traditional 2-tier client/server, which PowerBuilder was brilliant at. So, going from memory, here's a potted history of projects I've worked on.  I wonder what happened to them all… 1989-1991ish – Mainframe COBOL stock systems that had been around for years and years for Kay & Co (Worcester), part of the Great Universal Stores group at the time.  Anyone for Decision Table COBOL ? 1991-1992ish – Model204 stock systems, again for Kay & Co.  I've still never come across anyone from other companies who had ever used this although it was a pretty neat language. 1992-1995 – Various DOS-based systems, again for Kay & Co.  Varying hardware from twin-5.25 floppy Apricot machines to PC's with and without hard drives, then onto more standard Windows PCs.   All written in Clipper / dBase. 1995-1996 – Windows GUI development with PowerBuilder, again for Kay & Co – writing applications for the Catalogue Bargain Shops. 1996-1997 – More PowerBuilder stuff at Fame Computers – what a crap move that was after many good years at Kays… 1997-2003 – A couple of PowerBuilder and then Java J2EE applications for Severn Trent Systems.  The AIMS project was probably written in around 1999/2000 in PowerBuilder and is still apparently being used now. 2003 – A great time at SmartStream Technologies in Bristol working with great people on a great new rich-client project.  Doing AJAX without it being known as AJAX then, it was a voyage of discovery and a great time.   Shame the long commute got too much to bear.  Good times there…. 2004-2006 took me contracting for a few years at about 4 companies and it was a mixture of brilliant new development of AJAX applications just as those technologies were emerging and the usual case of being hired to help out on failing run of the mill J2EE apps…  The companies and projects will remain nameless so the good can't be distinguised from the bad ! 2006 until now brings things up to date at Talis, first as a contractor for 1.5 years, then as a permanent employee. I consider myself pretty lucky over the years with the exposure I've had to different projects, technologies and languages.  It's been a great journey and I hope it continues.

I've known for a good while now that I need to make more time out of work hours to look at the things I don't get chance to do at work.  This list gets longer and longer and the time to look at things on it rarely seems to materialise.  I get bits of time here and there to read up on things, dabble and generally do small bit of work but struggle to find enough long chunks of quality time to get a proper project going.  This has to change before the list of things buzzing around my head gets too unmanageable. Number 1 on my list is to do some traditional LAMP development as it's a hole in my skills.   I'm fine with the L, A and P but have never really done much with MySQL in relation to PHP applications.   I've done loads of SQL over the years – mainly Oracle and Sybase with a bit of SQLServer thrown in but only really dabbled with MySQL and never done any traditional RDBMS stuff with PHP.   When work is focussed with what you could class as Linux/Apache/RDF/PHP and Linux/Apache/SemWeb/PHP I need to ensure I keep a broad skill-set and not totally forget (although I have forgotten a lot already) how to be fluent in SQL. So, top home project is LAMP-based and probably using Zend Framework as a starting point as I've only ever used Zend Mail on that and the framework looks pretty comprehensive.  I've blown the cobwebs off my home dev environment tonight, got a stub Zend project checked into my Subversion 1.5 repository (yes, I know I still need to look at the 1.5 merge tracking features as I'd really like to use it at work) and I'm now ready to get on with it. I just hope I get the time to make some progress with it. I'm not quite sure what the project will be yet – it'll probably just start of as trying out loads of the features the framework supports and see where it leads.  A 'ToDo' list manager would be ironic – spending time creating something to list all the things that I don't find time to do…