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Showing posts from January, 2008

MonoRail

I'm working on a new website for work. I've decided to use ECO for the business model due to how much time it saves me. I took a look at the new MVC ASP approach provided by Microsoft recently and was a bit disappointed. There were bugs in some pretty basic errors that would have been an annoyance to code around, and it just didn't feel "ready". So, I've decided to take another look at MonoRail. I'd already written an ECO implementation for MR in the past but I decided to start the implementation from scratch. This was mainly inspired by the new EcoSpaceManager in ECOIV for ASP .NET. Using an EcoSpaceManager you can easily utilise many instances of different types of EcoSpace in the same page. I decided I would do the same. Unlike the EcoSpaceManager I haven't gone for unique string values for identifying the EcoSpace instance I want. That approach is good in ASP .NET where you want to bind different components together to generate your HTML

What's in a name?

When thinking of a name for a new product I wish people would be more original. For example, I have just spent ages looking for information about how to create a ternary in a scripting language known as Brail. Instead of finding what I want I have had to work my way through loads of information about blind people.

Single application instance

I needed my app to be a single-instance app. It was easy to implement, like so: bool mutexIsNew; Mutex mutex = new Mutex(true, "SomeUniqueID", out mutexIsNew); if (mutexIsNew) Application.Run(new MainForm()); A problem arose though when my app started to need to receive command line arguments. How do you also pass those onto the original app? There is a class for this purpose named "WindowsFormsApplicationBase", it's in Microsoft.VisualBasic.dll 01: Add a class to your project like so: internal class SingleInstanceApplication : WindowsFormsApplicationBase { private MainForm MainFormInstance; internal SingleInstanceApplication() { IsSingleInstance = true; EnableVisualStyles = true; MainFormInstance = new MainForm(); MainForm = MainFormInstance; } protected override bool OnStartup(StartupEventArgs eventArgs) { return base.OnStartup(eventArgs); MainFormInstance.AcceptCommandArguments(eventArgs.CommandLine); } prote

ExternalID is not related to ECO_TYPE

I just thought I'd blog about this because it seems to be causing some confusion. ECO_TYPE Use: In integer used in the database to identify the type of object a table row represents. Obtained from: The ECO_TYPE table using the name of the class. Life span: Permanent. The name of the class in ECO_TYPE changes when you rename your class, but the integer value never changes. ExternalId Use: A way of identifying a class instance across EcoSpace instances. Kind of like a string version of a pointer to an object. Obtained from: Index of the class in TypeSystem.AllClasses + "!" + the ECO_ID of the instance. Life span: Although the ECO_ID never changes the class index might when you add or remove classes within the model. I just want to point out that ExternalID and ECO_TYPE are unrelated. When you change your model it does not mean that the ECO_TYPE in your DB must change. Here is an example 01: You create a model with 2 classes in it. The first class is the root, th

Why I don't use ExternalID for URLs

An External ID consists of two parts, ! ClassID isn't really required for ECO controlled DB structures because there is always a root table containing the ObjectID + ClassID, but when you use ECO to map to an existing DB structure there needs to be a way to know that object 1234 needs to be fetched from the PERSON table. So, now that we know why the ExternalID consists of two parts on to why I don't use it (much). If I am writing a website with ECO and I use the ExternalID for my URL like so www.mysite.com/showarticle.aspx?id=23!1234 The number 23 is determined by looking for the class's index in the list of all classes in the model. This is the problem! If you change your model by adding a new class then your index may change from 23 to 24. Not a big problem for your application, but persistent links to that URL from other sites such as Google will no longer work. An ExternalID is just like an object's pointer address. When you restart your application that

RSA signed streams

I'm writing an app that needs me to be able to write to a file and make sure that nobody changes it. The idea that I had was to create 2 classes: WritableSignedStream: Accepts a targetStream parameter + a privateKeyXml string. I add some space at the beginning of the target stream to reserve it for header info. You then write to the stream as normal (it reports a smaller Length than that of the target stream so your app is unaware of the header). When you close the stream it writes the public key to the stream + an RSA encrypted hash of the data part of the file. ReadableSignedStream: Accepts a sourceStream parameter in the constructor. Just before you read for the first time it will compute an MD5 hash of the data part of the file, and then compare it with the signed hash in the file (which I first decrypt using the stored public key). These classes therefore provide two functions: You can sign a stream, the app can check the stream was signed by you by inspecting the public key

No symbols loaded

This has been driving me mad for hours now! Whenever I run my PocketPC compact framework app I cannot debug it! None of the breakpoints will stop, each breakpoint just shows as an empty circle instead of a solid one. So, what was the solution? I tried deleting all PDB files on my hard disk but that didn't do it. In the end manually deleting all of the files previously deployed to my PPC did the trick. Maybe VS couldn't overwrite them or something? No idea, but at least it works now :-)

Geek quotes

This one is probably my favourite: "There are 10 types of people in the world, those who understand binary and those who don't". Here is one I came up with myself some years ago and used to use in my newsgroup signature: "Blessed are the geek, for they shall public class GeekEarth : Earth".