Archives of November 2005

.NET Framework 2.0 - first impressions

Today Microsoft released .NET Framework 2.0. I already managed to convert this site and homokaasu.org to run on it. I didn't yet install it on the server, though, but got it running on my home computer. It was quite easy, but not as fluent as it could have been. Here are the first problems I've encountered and their solutions.

Extension mapping with build providers

Definition for extension mappings seems to have changed. Fw 2.0 introduces a design called BuildProvider, which take care of compiling the source code for different purposes on a web site. There are build providers for normal pages, user controls, master pages, web services and so on (check the full list at the machine.config file).

In addition to IIS mapping and http handler definition, non-standard extensions must be defined in a third place: inside the compilation tag of the web.config file, like this.

<compilation debug="true" batch="true" batchTimeout="120">
  <buildProviders>
    <add extension=".gas" type="System.Web.Compilation.PageBuildProvider" />
  </buildProviders>
</compilation>

The System.Web.Compilation.PageBuildProvider is the default build provider for aspx files and is used here. In this case, gas files are treated exactly as aspx files.

Creating IHttpHandler instances

For some reason, when creating the pages on the fly for wildcard extensions in this blog application as I previously described, the PageParser class used to create the IHttpHandlers (Page objects) fails with a null reference exception. I tracked the problem with Reflector and it seems that this depends on a new HostingEnvironment class, which is null at this point of the page lifecycle in 2.0.

This could have become nasty, but luckily the solution is quite easy. I noticed that the BuildManager has a method called CreateInstanceFromVirtualPath which appears to be very promising. It has two parameters: string virtualpath and Type requiredBaseType, which sound good, but it returns an Object. I made a guess and replaced...

return PageParser.GetCompiledPageInstance("/scaffold.aspx", Context.Server.MapPath("/scaffold.aspx"), Context);

...with...

return BuildManager.CreateInstanceFromVirtualPath("/scaffold.aspx", typeof(Page)) as IHttpHandler;

...in my PageHandlerFactory class definition and w00t! We get signal!

A bit sloppy though

Technically the framework seems to work well, but the adjoining information (documentation, error messages, comments in config files) is somewhat slipshod. For example, when I heeded this error message...

There is no build provider registered for the extension '.gas'. You can register one in the <compilation><buildProviders> section in machine.config or web.config. Make sure is[sic] has a BuildProviderAppliesToAttribute attribute which includes the value 'Web' or 'All'

...by adding the definition and made very sure the appliesTo attribute was included, I was greeted with the following:

Unrecognized attribute 'appliesTo'. Note that attribute names are case-sensitive.

The end result was that the attribute wasn't needed, in fact, mustn't be there, although the error message and documentation told exactly the opposite.

The SDK documentation has dead links (and a very bland look).

Other noteworthy things

Aww... namespace attribute of @register directive is now case sensitive. Too bad for the sloppy developers who didn't notice the case inconsistency in namespaces and references before this...

MySql Connector/Net works (with MySql 5). Nant works but requires some directory name changes in it's config file. SharpDevelop works and recognizes the new framework automatically.

My multiuser game/chat server works perfectly. Unlike with the web apps, the complier didn't warn about anything obsolete. The server uses threading, xml and tcp-level network objects very extensively so it seems it is the web part of the framework that has experienced the biggest changes.

web.config can be at least partially edited using a new UI in IIS manager.

The only compilation errors I got were from Math.Floor and Math.Ceiling. The compiler could not decide whether the input parameter was a decimal or a double with lines like this: Math.Floor(a/3-1); in which a is an integer so it seems the methods are now more overloaded or the type handling of numbers has changes since this was fixed with return Math.Floor(a/3m-1m); (in which the m in 1m denotes a decimal value).

More experiences with .NET Framework 2.0 definitely coming up at some point - these were the results of the first hour of playing around or so.

Categories: Programming, Web
Posted by Matias at 07.11.2005 21.40 (9 years ago) | 5 comments

Targeting links to new browser windows with valid XHTML 1.1

One of the downsides of completely separating content from layout and programmatical behavious is the removed ability to set link targets so that they open new windows - a surprisingly common problem. In practice, this means that the a tag may not have target attribute in valid XHTML 1.1.

It is possible to include a special module for link targets and thus allow the usage of target, but that is quite a complex way to do such a simple thing. I have found out that a compromise which uses JavaScript (if available) works the best.

The solution is rather simple: by including the onclick attribute with code that opens the window and then returns false, the best behavior can be achieved. The link should also be written in the href attribute, as usual. The false return value of the click handler prevents the browser from opening the URI in href, yet it displays it in the status bar when the link is pointed with the mouse, as everyone expects. Also, browsers without JavaScript disabled can open the link, but it opens to the same window. Below is a simple example how to do it and here how it works: Google.

<a href="http://google.com" onclick="window.open('http://google.com'); return false;">Google</a>

Here is an xsl template for the a element, which outputs xhtml, in which external links (recognized by the fact that they start with http://) open in new windows, but internal links open in the same window.

<xsl:template match="a">
  <xsl:element name="a">
    <xsl:attribute name="style"><xsl:value-of select="@style" /></xsl:attribute>
    <xsl:choose>
      <xsl:when test="starts-with(@href, 'http')">
        <xsl:attribute name="href"><xsl:value-of select="@href" /></xsl:attribute>
        <xsl:attribute name="onclick">window.open('<xsl:value-of select="@href" />');return false;</xsl:attribute>
      </xsl:when>
      <xsl:otherwise>
        <xsl:attribute name="href"><xsl:value-of select="@href" /></xsl:attribute>
      </xsl:otherwise>
    </xsl:choose>
    <xsl:apply-templates />
  </xsl:element>
</xsl:template>

Another good solution is to programmatically change the link targets after the page has loaded - a script should iterate through the document object tree and change the targets of the a tags encountered. However, in my opinion, as a general rule, it is better to have the actions written explicitely in the document than to change them afterwards. In this case it wouldn't cause any problems, but it would definitely harden the maintaining and debugging of a more complex system.

Categories: Programming, Web
Posted by Matias at 06.11.2005 11.10 (9 years ago) | 0 comments

Veren tytär

The image “http://arje.net/files/surma-cover-small.jpg” cannot be displayed, because it contains errors. I designed cd covers for my friends' band, Surma! The title of the cd is Veren tytär. Bigger version of the cover here.

(Surma is a poetic word for death in Finnish - I believe bane would be quite a good translation. Veren tytär means Daughter of Blood - at least the genre provides the pretext.)

The covers turned out pretty well, although the print quality was not the best possible. As is probably obvious, the covers were heavily (no pun intended) influenced by modern Japanese horror movies, although the gradient map here goes from black to green instead of white. Usage of complementary colours is probably against the mindset of pretty much anyone with even rudimentary knowledge of chromatics but hey, METAL IS ABOUT BREAKING RULES, EVEN CHROMATOLOGICAL ONES!!!!!!!!!!! Teenage rebellion via graphic design.

Get the trollstormingly true Finnish death metal cd from the nicest of the Finnish domains!

Categories: Art, Creations, Music
Posted by Matias at 03.11.2005 20.57 (9 years ago) | 0 comments

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