Saturday, June 15, 2013

Website ideas

I often have ideas for websites, but due to a lack of time I never actually get round to doing anything about them. They may well be terrible ideas, or may already exist in some form already, and almost all of them are guaranteed to not make any money, but I present them here in case anyone wants to pick up the baton and run with them.

Random acts of kindness

Say you have some spare cash and you want to give it to a good cause, but you don’t have a good idea about who to give it to. Wouldn’t it be great if there was a website where you could post a message saying ‘I have some money, who wants it?’ and from the other side people could post messages asking for money, help or whatever? When you find someone you want to help, you can contact each other and arrange to hand over the cash (although there needs to be some kind of protection here against receiving shedloads of begging emails).

Domain reminder

So you’re interested in buying that domain (oh, that’s just me is it?) but somebody has bought it already and is sitting on it, only being prepared to sell it for a ludicrous 2800 euros? If you’re willing to wait, wouldn’t it be great if there was a website that would send you reminders when the domain name was about to expire? And whenever the status of the domain changed in any other way?

Foreign exchange market

The difference between the official exchange rates and the price you’ll pay to exchange money yourself can be huge. But whenever I convert 100 pounds to euros, there’ll be thousands of other people who want to take their euros and convert them into pounds, so how about a website to match the buyers and sellers? I’ve not really thought through how the exchange takes place, but that’s just a minor detail…

Re-open nominations

This is more than just a website, this is a political movement. Back in the day when I was at university, any election would include RON, re-open nominations. So if you weren’t happy with any of the candidates, you could vote for RON and if enough people voted for him then the election would be rerun. Currently I’m pretty disappointed with all three of our major parties, since there seems to be very little difference between them in terms of policy and they all seem to be led by people who have no experience of the real world. But there is no way to register the fact that I still believe in the democratic process but don’t want to vote for any of the options available to me. So for my take on this idea in real elections, the RON Party would stand in every election, promising to immediately stand down if elected. Along with that, it would lobby the government to include RON as an option in all elections.

Fat cyclists

I enjoy cycling, but have no desire to wear lycra. There are lots of clubs for cyclists, but they are generally full of extremely fit people who cycle 50 miles a day. So how about a web community for people who like to cycle but aren’t necessarily as fit as they could be and don’t take it too seriously so they can get together and have a slow ride together?

Wednesday, June 05, 2013

Poor man’s XSLT profiling in detail

A couple of years ago I wrote a post giving a vague idea of how to profile XSL transforms without shelling out for Visual Studio Team System. I went back to it recently and realised it didn’t really provide enough information on how to actually perform the profiling. So here’s another go at it.

The first thing we need to do is compile the XSLT into a .NET assembly. For this we need to use the XSLTC.EXE tool that ships with the Windows SDK. You can find this somewhere like this C:\Program Files (x86)\Microsoft SDKs\Windows\v8.0A\bin\NETFX 4.0 Tools. The command-line required will be something like this xsltc.exe /settings:dtd "/out:c:\temp\style.dll" /class:MyXslt "C:\temp\TEST.xsl"

So now we have an assembly for our XSLT file. Next we need a little wrapper program to load it up and call the transform. I used a simple command line app, with code as follows

    static void Main(string[] args)
      XslCompiledTransform transform = new XslCompiledTransform();
      XmlTextReader reader = new XmlTextReader(@"C:\temp\input.xml");
      XmlTextWriter writer = new XmlTextWriter(@"C:\temp\out.html", Encoding.UTF8);
      transform.Transform(reader, writer);

Now we are ready to profile the XSLT. In the past I’ve always recommended AQTime, but my old version of it doesn’t seem to work on Windows 8. I didn’t fancy paying for an upgrade, so looked around for alternatives and found the Eqatec profiler. The free version seems to work pretty well, certainly good enough for my limited needs.

So after running my little test app through the profiler, I had a much better idea of where things were slow in my XSLT. As is often the case, it was due to some XPath using “//element” to find elements. Often you can get away with it, but if the XML document is large or that piece of code is getting hit a lot then it can bite you. 

There is another slight complication with this approach to XSLT profiling. Some of the compiled templates may have a name of “compiler:generated”, meaning it’s pretty tricky to figure out how they relate to the original XSLT. From my experience, it seems that these templates are generated by the compiler itself when it decides to split larger templates into smaller compiled templates. I found ILSpy was pretty useful here to match the compiled code back to the original XSLT.