Monday, January 28, 2008

Ice Queen - Within Temptation

Update: Damn YouTube and their lawsuits! I had to change the song with another live performance, but it isn't that good. Well, the quality of the video is better, but not so emotional.

This is a song that I find myself liking while listening to my music in the background. It's a pretty difficult feat, since I usually type away and don't really pay attention to what I listen. I am putting the live show from Spain, because I think that the official video for this song is crap. Enjoy!

Thursday, January 24, 2008

A Second Chance at Eden - Peter F. Hamilton

This is not a single story, but many short ones from my latest favourite writer: Peter F. Hamilton. book coverA Second Chance at Eden is set in the Night's Dawn universe, but before that story unfolded. We have Marcus Calvert, father of Joshua, the hero of Night's Dawn; we have the birth of Eden, affinity bondage stories, zero-tau, psychic abilities, even a party assassin turned good (that would provide the template for a character in Pandora's Star).

I think that the collection is best read after you've read the lengthy stories. It rings so many bells that would normally not mean anything than sci fi speculation otherwise.

Bottom line: Great writing from Hamilton. It's nice that you can read one story and take a break and do something else :). I guess if you are not that sure you want to read the sagas, starting with this will open your appetite and you will find the same connections I did, only backwards.

Setting triggers on controls inside templated parents

When one wants to indicate clearly that a control is to perform an asynchronous or a synchronous postback, one should use the Triggers collection of the UpdatePanel. Of course, I am assuming you have an ASP.Net Ajax application and you are stuck on how to indicate the same thing on controls that are insides templated controls like DataGrid, DataList, GridView, etc.

The solution is to get a reference to the page ScriptManager then use the method RegisterPostBackControl on your postback control. You get a reference to the page ScriptManager with the static ScriptManager.GetCurrent(Page); method. You get the control you need inside the templated control Item/RowCreated event with a e.Item/Row.FindControl("postbackControlID");

So, the end result is:

ScriptManager sm=ScriptManager.GetCurrent(Page);
Control ctl=e.Item/Row.FindControl("MyControl");

Of course, if you want it the other way around (set the controls as Ajax async postback triggers) use the RegisterAsyncPostBackControl method instead.

Special thanks to Sim Singh from India for asking me to research this.

Monday, January 21, 2008

Shiny tools and magpie programmers

I was reading this post where Jeff Atwood complained about too many shiny tools that only waste our time and of which there are so many that the whole shining thing becomes old.

Of course, I went to all the links for tools in the post that I could find, and then some. I will probably finish reading it after I try them all :)

Here are my refinements on the lists that I've accessed, specific with .NET programming in mind and free tools:
  • - nice site that tests your regular expressions online and let's you explore the results. Unfortunately it has no profiling or at least a display of how long it took to match your text
  • PowerShell - Great tool once you get to know it. It comes complete with blog, SDK and Community Extensions
  • PowerTab - adds Tab expansion in PowerShell
  • Lutz Roeder's Reflector - the .NET decompiler and its many add-ons
  • Highlight - a tool to format and colorize source code for any flavour of operating system and output file format.

There are a lot more, but I am lazy and I don't find the use for many of them, but you might. Here is Scott Hanselman's list of developer tools from which I am quite amazed he excluded ReSharper, my favourite Visual Studio addon.

Saturday, January 19, 2008

Regular expression extravaganza

Warning: this is going to be one long and messy article. I will also update it from time to time, since it contains work in progress.

Update: I've managed to uncover something new called lookbehinds! They try to match text that is behind the regular expression runner cursor. Using lookbehinds, one might construct a regular expression that would only match a certain maximum length, fixing the problem with huge mismatch times in some situations like CSV parsing a big file that has no commas inside.

Update 2: It wouldn't really work, since look-behinds check a match AFTER it was matched, so it doesn't optimize anything. It would have been great to have support for more regular expressions ran in parallel on the same string.

What started me up was a colleague of mine, complaining about the ever changing format of import files. She isn't the only one complaining, mind you, since it happened to me at least on one project before. Basically, what you have is a simple text file, either comma separated, semicolon separated, fixed width, etc, and you want to map that to a table. But after you make this beautiful little method to take care of that, the client sends a slightly modified file in an email attachment, with an accompanying angry message like: "The import is not working anymore!".

Well, I have been fumbling with the finer aspects of regular expressions for about two weeks. This seemed like the perfect application of Regex: just save the regular expression in a configuration string then change it as the mood and IQ of the client wildly fluctuates. What I needed was:
  • a general format for parsing the data
  • a way to mark the different matched groups with meaningful identifiers
  • performance and resource economy

The format is clear: regular expression language. The .NET flavour allows me to mark any matched group with a string. The performance should be as good as the time spent on the theory and practice of regular expressions (about 50 years).

There you have it. But I noticed a few problems. First of all, if the file is big (as client data usually is) translating the entire content in a string and parsing it afterwards would take gigantic amounts of memory and processing power. Regular expressions don't work with streams, at least not in .Net. What I needed is a Regex.Match(Stream stream, string pattern) method.

Without too much explanation (except the in code comments) here is a class that does that. I made it today in a few hours, tested it, it works. I'll detail my findings after the code box (which you will have to click to expand).

StreamRegex - click to expand/collapse

One issue I had with it was that I kept translating a StringBuilder to a string. I know it is somewhat optimized, but the content of the StringBuilder was constantly changing. A Regex class that would work at least on a StringBuilder would have been a boost. A second problem was that if the input file was not even close to my Regex pattern, the matching would take forever, as the algorithm would add more and more bytes to the string and tried to match it.

And of course, there was my blunt and inelegant approach to regular expression writing. What does one do whan in Regex hell? Read Steve Levithan's blog, of course! It was then when I decided to write this post and also document my regular expression findings.

So, let's summarize a bit, then add a bunch of links.
  • the .NET regular expression flavour supports marking a group with a name like this
  • it also supports non capturing grouping:
    This will not appear as a Group in any match although you can apply quantifiers to it
  • also supported are atomic or greedy grouping.
    The pattern above will match "abc" but not "abc"d because ".+ matches the whole pattern and the ending quote is not matched. Normally, it would backtrack, but atomic groups do not backtrack once they failed, saving time, but possibly skipping matches
  • one can also use lazy quantifiers:ab+? will match ab in the string abbbbbb
  • posessive quantifiers are not supported, but they can be substituted with atomic groups:
    ab*+ in some regex flavours is (?>ab*) in .NET
  • let's not forget the
    (?#this is a comment)
    notation to add comments to a regular expression
  • Look-behinds! - great new discovery of mine that can match an already matched expression. I am not sure how it would hinder speed, though. Quick example: I want to match "This is a string", but not "This is a longer string, that I don't want to match, since it is ridiculously long and it would make my regex run really slow when I really need only a short string" :), both as separate lines in a text file.
    This expression matches all strings that do not contain line breaks, then looks behind to check if there is a string begin or a line break character at at most 21 characters behind, effectively reducing the maximum length of the matched string to 20. Unfortunately, this would slow even more the search, since it would only back check a match AFTER the match completed.

What does that mean? Well, first of all, an increase in performance: using non capuring grouping will save memory, using atomic quantifiers will speed up processing. Then there is the "Unrolling the loop" trick, using atomic grouping to optimize repeated alternation like (that|this)*. Group names and comments ease the reading and reuse of regular expressions.

Now for the conclusion: using the optimizations described above (and in the following links) one can write a regular expression that can be changed, understood and used in order to break the input file into matches, each one having named groups. A csv file and a fixed length record file would be treated exactly the same. Let's say using something like (?<ZipCode>\w*),(?<City>\w*)\r\n or (?<ZipCode>\w{5})(?<City>\w{45})\r\n or use look-behinds to limit the maximum line size. All the program has to do is parse the file and create objects with the ZipCode and City properties (if present), maybe using the new C# 3.0 anonymous types. Also, I have read about the DFA versus NFA types of regular expression implementations. DFAs are a lot faster, but cannot support many features that are supported by NFA implementations. The .Net regex flavour is NFA, but using atomic grouping and other such optimizations bridges the gap between those two.

There is more to come, as I come to understand these things. I will probably keep reading my own post in order to keep my thoughts together, so you should also stay tuned, if interested. Now the links:

.NET Framework General Reference Grouping Constructs
.NET Framework General Reference Quantifiers
Steve Levithan's blog
Regular Expression Optimization Case Study
Optimizing regular expressions in Java
Atomic Grouping
Look behinds
Want faster regular expressions? Maybe you should think about that IgnoreCase option
Scott Hanselman's .NET Regular Expression Tool list
Compiling regular expressions (also worth noting is that the static method Regex.Match will cache about 15 used regular expressions so that they can be reused. There is also the Regex.CacheSize property that can be used to change that number)
Regular expressions at Wikipedia
Converting a Regular Expression into a Deterministic Finite Automaton
From Regular Expressions to DFA's Using
Compressed NFA's

There is still work to be done. The optimal StreamRegex would not need StringBuilders and strings, but would work directly on the stream. There are a lot of properties that I didn't expose from the standard Regex and Match objects. The GroupCollection and Group objects that my class exposes are normal Regex objects, some of their properties do not make sense (like index). Normally, I would have inherited from Regex and Match, but Match doesn't have a public constructor, even if it is not sealed. Although, I've read somewhere that one should use composition over inheritance whenever possible. Also, there are some rules to be implemented in my grand importing scheme, like some things should not be null, or in a range of values or in some relation to other values in the same record and so on. But that is beyond the scope of this article.

Any opinions or suggestions would really be apreciated, even if they are not positive. As a friend of mine said, every kick in the butt is a step forward or a new and interesting anal experience.


I've taken the Reflected sources of System.Text.RegularExpressions in the System.dll file and made my own library to play with. I might still get somewhere, but the concepts in that code are way beyond my ability to comprehend in the two hours that I allowed myself for this project.

What I've gathered so far:
  • the Regex class is no sealed
  • Regex calls on a RegexRunner class, which is also public and abstract
  • RegexRunner asks you to implement the FindFirstChar, Go and InitTrackCount methods, while all the other methods it has are protected but not virtual. In the MSDN documentation on it, this text seals the fate of the class This API supports the .NET Framework infrastructure and is not intended to be used directly from your code.
  • The RegexRunner class that the Regex class calls on is the RegexInterpreter class, which is a lot of extra code and, of course, is internal sealed

The conclusion I draw from these points and the random experiments I did on the code itself are that there is no convenient way of inheriting from Regex or any other class in the System.Text.RegularExpressions namespace. It would be easy, once the code is freely distributed with comments and everything, to change it in order to allow for custom Go or ForwardCharNext methods that would read from a stream when reaching the end of the buffered string or cause a mismatch once the runmatch exceeds a certain maximum length. Actually, this last point is the reason why regular expressions cannot be used so freely as my original post idea suggested, since trying to parse a completely different file than the one intended would result in huge time consumption.

Strike that! I've compiled a regular expression into an assembly (in case you don't know what that is, check out this link) and then used Reflector on it! Here is how to make your own regular expression object:
  • Step 1: inherit from Regex and set some base protected values. One that is essential is base.factory = new YourOwnFactory();
  • Step 2: create said YourOwnFactory by inheriting from RegexRunnerFactory, override the CreateInstance() method and return a YourOwnRunner object. Like this:
    class YourOwnFactory : RegexRunnerFactory
    protected override RegexRunner CreateInstance()
    return new YourOwnRunner();

  • Step 3: create said YourOwnRunner by inheriting from abstract class RegexRunner. You must now implement FindFirstChar, Go and InitTrackCount.
. You may recognize here a Factory design pattern! However, consider that the Microsoft normal implementation (the internal sealed RegexInterpreter) has like 36Kb/1100 lines of highly optimised code. This abstract class is available to poor mortals for the single reason that they needed to implement regular expressions compiled into separate assemblies.

I will end this article with my X-mas wish list for regular expressions:
  • An option to match in parallel two or more regular expressions on the same string. This would allow me to check for a really complicated expression and in the same time validate it (for length, format, or whatever)
  • Stream support. This hack in the above code works, but does not real tap in the power of regular expressions. The support should be included in the engine itself
  • Extensibility support. Maybe this would have been a lot more easy if there was some support for adding custom expressions, maybe hidden in .NET (?#comment) syntax.

Friday, January 18, 2008

Microsoft Best Practices analyzers

I've stumbled upon a link toward SQL 2000 best practices analyzer. Aparently, it is a program that scans my SQL server and tells me what I did wrong. It worked, somewhat, because at some tests it failed with a software exception, but then I searched the Microsoft site for other best practices analyzers and I found a whole bunch of them!

Here are a few links that seemed interesting:

The last link is for a framework that loads all analyzers so you can run them all. It's a pretty basic tool, there is still work to be done on it, but you can also make your own analyzers and the source code for the program and the included ASP.Net plugin is also available.

My Japanese name? :)

I was following a link of someone trying to translate my blog in Japanese. Apparently Siderite = シデライト . As you can see, it's like a little story: first there was this smiling guy, then his smile got smaller and smaller as his eyes got bigger and bigger. In the end, he was completely abstracted. Poor old Siderite :(

Update: Babylon says Siderite in Japanese is 菱鉄鉱. Is there any Japanese reader who can help me with this dilemma?

Thursday, January 17, 2008

Sun buys MySql

Acquires, purchases, whatever... they paid for it and they will have it. Sun will have MySql. Does that mean that they want to go towards easily usable SQL servers or that they want to compete with Oracle? PostgreSQL would have been a more appropriate choice in that case. Will MySql for Java be like SQL server is for .NET ? Anyway, 1 billion dollars is selling short, I think. Youtube was two. Is a media distribution software more important than a database server?

Here is the official announcement.

Small quote: MySQL's open source database is the "M" in LAMP - the software platform comprised of Linux, Apache, MySQL and PHP/Perl often viewed as the foundation of the Internet. Sun is committed to enhancing and optimizing the LAMP stack on GNU/Linux and Microsoft Windows along with OpenSolaris and MAC OS X. The database from MySQL, OpenSolaris and GlassFish, together with Sun's Java platform and NetBeans communities, will create a powerful Web application platform across a wide range of customers shifting their applications to the Web.

MSDN Briefing Bucharest, January 16 2008

I am going to quickly describe what happened in the briefing, then link to the site where all the presentation materials can be found (if I ever find it :))

The whole thing was supposed to happen at the Grand RIN hotel, but apparently the people there changed their minds suddenly leaving the briefing without a set location. In the end the brief took place at the Marriott Hotel and the MSDN people were nice enough to phone me and let me know of the change.

The conference lasted for 9 hours, with coffee and lunch breaks, and also half an hour for signing in and another 30 minutes for introduction bullshit. You know the drill if you ever went to one of such events: you sit in a chair waiting for the event to start while you are SPAMMED with video presentations of Microsoft products, then some guy comes in saying hello, presenting the people that will do the talking, then each of the people that do the talking present themselves, maybe even thank the presenter at the beginning... like a circular reference! Luckily I brought my trusted ear plugs and PDA, loaded with sci-fi and tech files.

The actual talk began at 10:00, with Petru Jucovschi presenting as well as holding the first talk, about Linq and C# 3.0. He has recently taken over from Zoltan Herczeg and he has not yet gained the necessary confidence to keep crouds interested. Luckily, the information and code were reasonably well structured and, even if I've heard them before, held me watching the whole thing.

Linq highlights:
  • is new in .NET 3.0+ and it takes advantage of a lot of the other newly introduced features like anonymous types and methods, lambda expressions, expression trees, extension methods, object initializers and many others.
  • it works over any object defined as IQueryable<T> or IEnumerable (although this last thing is a bit of a compromise).
  • simplifies our way of working with queries, bring them closer to the .NET programming languages and from the just-in-time errors into the domain of compiler errors.
  • "out of the box" it comes with support for T-Sql, Xml, Objects and Datasets, but providers can be built (easily) for anything imaginable.
  • the linq queries are actually execution trees that are only run when GetEnumerator is called. This is called "deffered execution" and it means more queries can be linked and optimised before the data is actually required.
  • in case you want the data for caching purposes, there are ToList and ToArray methods available

Then there were two back-to-back sessions from my favourite speaker, Ciprian Jichici, about Linq over SQL and Linq over Entities. He was slightly tired and in a hurry to catch the plain for his native lands of Timisoara, VB, but he held it through, even if he had to talk for 2.5 hours straight. He went through the manual motions of creating mappings between Linq to SQL objects and actualy database data; it wouldn't compile, but the principles were throughly explained and I have all the respect for the fact that he didn't just drag and drop everything and not explain what happened in the background.

Linq to SQL highlights:
  • Linq to SQL does not replace SQL and SQL programming
  • Linq to SQL supports only T-SQL 2005 and 2008 for now, but Linq providers from the other DB manufacturers are sure to come.
  • Linq queries are being translated, wherever possible, to the SQL server and executed there.
  • queries support filtering, grouping, ordering, and C# functions. One of the query was done with StartsWith. I don't know if that translated into SQL2005 CLR code or into a LIKE and I don't know exactly what happends with custom methods
  • using simple decoration, mapping between SQL tables and C# objects can be done very easily
  • Visual Studio has GUI tools to accomplish the mapping for you
  • Linq to SQL can make good use of automatic properties and object initialisers and collection initialisers
  • an interesting feature is the ability to tell Linq which of the "child" objects to load with a parent object. You can read a Person object and load all its phone numbers and email addresses, but not the purchases made in that name

Linq to Entities highlights:
  • it does not ship with the .NET framework, but separately, probably a release version will be unveiled in the second half of this year
  • it uses three XML files to map source to destination: conceptual, mapping and database. The conceptual file will hold a schema of local object, the database file will hold a schema of source objects and the mapping will describe their relationship.
  • One of my questions was if I can use Linq to Entities to make a data adapter from an already existing data layer to another, using it to redesign data layer architecture. The answer was yes. I find this very interesting indeed.
  • of course, GUI tools will help you do that with drag and drop operations and so on and so on
  • the three level mapping allows you to create objects from more linked tables, making the internal workings of the database engine and even some of its structure irrelevant
  • I do not know if you can create an object from two different sources, like SQL and an XML file
  • for the moment Linq to SQL and Linq to Entities are built by different teams and they may have different approaches to similar problems

Then it was lunch time. For a classy (read expensive like crap) hotel, the service was really badly organised. The food was there, but you had to stay in long queues qith a plate in your hand to get some food, then quickly hunt for empty tables, the type you stand in front of to eat. The food was good though, although not exceptional.

Aurelian Popa was the third speaker, talking about Silverlight. Now, it may be something personal, but he brought in my mind the image of Tom Cruise, arrogant, hyperactive, a bit petty. I was half expecting him to say "show me the money!" all the time. He insisted on telling us about the great mathematician Comway who, by a silly mistake, created Conway's Life Game. If he could only spell his name right, tsk, tsk, tsk.

Anyway, technically this presentation was the most interesting to me, since it showed concepts I was not familiar with. Apparently Silverlight 1.0 is Javascript based, but Silverlight 2.0, which will be released by the half of this year, I guess, uses .NET! You can finally program the web with C#. The speed and code protection advantages are great. Silverlight 2.0 maintains the ability to manipulate Html DOM objects and let Javascript manipulate its elements.

Silverlight 2.0 highlights:
  • Silverlight 2.0 comes with its own .NET compact version, independent on .NET versions on the system or even on operating system
  • it is designed with compatibility in mind, cross-browser and cross-platform. One will be able to use it in Safari on Linux
  • the programming can be both declarative (using XAML) and object oriented (programatic access with C# or VB)
  • I asked if it was possible to manipulate the html DOM of the page and, being written in .NET, work significantly faster than the same operations in pure Javascript. The answer was yes, but since Silverlight is designed to be cross-browser, I doubt it is the whole answer. I wouldn't put it past Microsoft to make some performance optimizations for IE, though.
  • Silverlight 2.0 has extra abilities: CLR, DLR (for Ruby and other dynamic languages), suport for RSS, SOAP, WCF, WPF, Generics, Ajax, all the buzzwords are there, including DRM (ugh!)

The fourth presentation was just a bore, not worth mentioning. What I thought would enlighten me with new and exciting WCF features was something long, featureless (the technical details as well as the presenter) and lingering on the description would only make me look vengeful and cruel. One must maintain apparences, after all.

WCF highlights: google for them. WCF replaces Web Services, Remoting, Microsoft Message Queue, DCOM and can communicate with any one of them.

Tuesday, January 15, 2008

The Nano Flower by Peter F. Hamilton

book cover imageSomething happened to Peter F. Hamilton between the second and third volumes of the Greg Mandel trilogy. He turned from a good average writing style to a great one. The Nano Flower is almost at the same level as Pandora's Star and births Hamilton's detailed universe. No wonder there was no fourth novel in the series, it would only drag the writer down.

The book has everything I came to expect from Peter F. Hamilton: hard sci-fi, detailed socio-political context, aliens, the party of braves, the sociopathic villains, a reference to Lord of the Rings... I do believe that Tolkien inspired Hamilton to write, but now it has become the chink in the writing armour, Achilles' heal. I've read a few great Hamilton books, but each had the basic layout of a battle between good and evil, groups of people uniting under improbable ideals to defeat an all too dark a villain. The qualities that attracted so many people to Lord of the Rings, for example, like camaraderie, honor, desire to help others, are not so attractive to me anymore. They are basic, very unlikely to truly define a character. I would very much want to see a Hamilton gray book. Maybe the new Void Trilogy will fulfil my wish (if I don't die of waiting for it to appear), although the vengeance driven character that remains pure and good at heart described in the first volume doesn't give me a lot of hope.

Anyway, even if I do seem to concentrate on what I don't like or what I would change in the writing of this great book maker, my appreciation for him is way higher than any possible defect in his writing. So, if you don't totally dislike sci-fi, go to a book store and buy Peter F. Hamilton books.

Monday, January 14, 2008

I Am Afraid of Americans - David Bowie

I was looking for songs by David Bowie, one of my favourite singers, but I wanted to find something different than the brilliant Under Pressure which he performed together with Freddie Mercury and which is my "subway song" :) And I found another "coproduction", this time he teamed up with Nine Inch Nails, another band that I enjoy (Perfect Drug is their best song, I think, although I may interpret it more personally than others).

The funny thing is that I remembered to post a Bowie song when I heard a quote from Criminal Minds, a series I am watching:
Garcia: [To Reid and Morgan] When I was in the ambulance I could hear the song 'Heroes' playing in my head. I kept flashing in and out of consciousness and I remember thinking, 'Wait. Is David Bowie really God?'

Thursday, January 10, 2008

Speeding up Javascript in one quick move

If you don't want to read the whole thing and just go to the solution, click here.

I reached a stage in an ASP.Net project where a I needed to make some pages work faster. I used dotTrace to profile the speed of each form and I optimized the C# and SQL code as much as I could. Some pages still were very slow.

Now, I had the idea to look for Javascript profilers. Good idea, bad offer. You either end up with a makeshift implementation that hurts more than it helps, or with something commercial that you don't even like. FireFox has a few free options like FireBug or Venkman, but I didn't even like them and then the pages I was talking about were performing badly in Internet Explorer, not FireFox.

That got me thinking of the time when Firefox managed to quickly select all the items in a <select> element, while on Internet Explorer it scrolled to each item when selecting it, slowing the process tremendously. I then solved that issue by setting the select style.display to none, selecting all the items, then restoring the display. It worked instantly.

Can you guess where I am going with this?

Most ASP.Net applications have a MasterPage now. Even most other types of sites employ a template for all the pages in a web application, with the changing page content set in a div or some other container. My solution is simple and easy to apply to the entire project:

Step 1. Set the style.display for the page content container to "none".
Step 2. Add a function to the window.onload event to restore the style.display.

Now what will happen is that the content will be displayed in the hidden div, all javascript functions that create, move, change elements in the content will work really fast, as Internet Explorer will not refresh the visual content in the middle of the execution, then show the hidden div.

A more elegant solution would have been to disable the visual refresh of the element while the changes are taking place, then enable it again, but I don't think one can do that in Javascript.

This fix can be applied to pages in FireFox as well, although I don't know if it speeds anything significantly. The overall effect will be like the one in Internet Explorer table display. You will see the page appear suddenly, rather than see each row appear while the table is loaded. This might be nice or not nice, depending on personal taste.

Another cool idea would be to hide the div and replace it with a "Page loading" div or image. That would look even cooler.

Here is the code for the restoration of display. In my own project I just set the div to style="display:none", although it might be more elegant to also hide it using Javascript for the off chance that someone might view the site in lynx or has Javascript disabled.
function addEvent(elm, evType, fn, useCapture)
// addEvent and removeEvent
// cross-browser event handling for IE5+, NS6 and Mozilla
// By Scott Andrew
if (elm.addEventListener){
elm.addEventListener(evType, fn, useCapture);
return true;
} else if (elm.attachEvent){
var r = elm.attachEvent("on"+evType, fn);
return r;
} else {
alert("Handler could not be removed");

function initMasterPage() {


Tuesday, January 08, 2008

CSS issues with AjaxToolKit controls like TabContainer

Update: this problem appeared for older versions of AjaxControlToolKit. Here is a link that says they fixed this issue since 21st of September 2007.

You are building this cool page using a TabContainer or some other AjaxControlToolKit control and everything looks smashing and you decide to add the UpdatePanels so that everything would run super-duper-fast. And suddenly the beautiful page looks like crap! Everything works, but your controls don't seem to load the cascading style sheet.
What is happening is that you make a control visible using update panels and so the CSS doesn't get loaded. I don't know exactly why, you would have to look into the AjaxControlToolKit source code and find out for yourself.

I found two fixes for this. The first is the nobrainer: add another TabContainer or AjaxControlToolKit control in the page, outside any updatepanels, make it visible, but set its style.display to 'none' or put it in a div or span with style="display:none". The second is the AjaxControlToolKit way. In the Page_Load event of the page or user control that contains the TabContainer or AjaxControlToolKit control add this line:
ScriptObjectBuilder.RegisterCssReferences(AjaxControlToolKit control);

This is part of the ExtenderControlBase class in AjaxControlToolKit, which is inherited by most if not all of their controls.

Now it should all work wonderfully.

Monday, January 07, 2008

Javascript external file not loading!!

Ok, so I used a javascript script in my page by referencing the external file and it worked. I did the exact same thing with another file and it wasn't loading! After scratching my head bald I've decided to switch the places of the two tags and voila! the script that worked would not load! The one that did not work previously was purring nicely.

My calls looked like this:
<script type="text/javascript" src='script1.js'/>
<script type="text/javascript" src='script2.js'/>

After scratching my skull a little more (blood was dripping already) I realized that the script tags are atomic tags, they should have no ending tag. Why would they, the content is specified in the src attribute. But on the DOM page for the script element there is an obscure line saying: Start tag: required, End tag: required. I switched to <script></script> format and it worked.

Oh, you are wondering why the first script worked? Because somehow an atomic script tag is erroneous, but it doesn't return any error. Instead it is treated like a mistyped start tag and the atomic portion of it is ignored. The second script would not load since the browser expected a script end tag. Maybe he even interpreted the second tag as an end tag for all I know.

Thursday, January 03, 2008

innerText for IE and FireFox

Apparently, the innerText property of Javascript elements is not available for FireFox or other browsers other than Internet Explorer. FireFox exposes something similar, but with the name textContent. Why would any one of these two butt-heads learn from the other and cooperate for the common good?

The functionality of this property is to expose the inner content of an element minus any html tags. With something like <div><span class="red">Red text<span></div> the div innerText/textContent property returns "Red text". It could also work when setting, stripping tags from the content before setting innerHTML, although it seems that for both implementations setting innerText or textContent is equivalent with setting innerHTML.

There are also links about javascript functions that would replace, improve or otherwise ease the developer's work by adding the same functionality.