A day in the life of...

Storing a plain-text password in a DB leaves your system open to abuse from anybody with access to the tables (sys admin for example). Here is the technique I recently used. Instead of storing the password itself I store a hash of the password, and a random "salt" that was used to create the hash to make it less predictable. [UmlTaggedValue("Eco.Length", "255")] private string PasswordHash { get { ... } set { ... } } [UmlTaggedValue("Eco.AllowNULL", "True")] [UmlTaggedValue("Eco.Length", "40")] private string PasswordSalt { get { ... } set { ... } } As you can see I do not store the password, just a hash + salt, both of which are private. Here are the methods used to set the values of these properties. public void SetPassword(string newPassword) { if (newPassword == null) throw new ArgumentNullException("password"); if (newPassword.Length < 6) throw new

I've had no end of grief trying to print a PCX to a Zebra Printer using the CPCL printer language. Silly me, didn't notice the EG command (expanded graphics) so there was no need to convert my BMP to a PCX and then struggle with binary data. I still had a bit of grief working out how to print using the EG command because the documentation is quite frankly crap. The expected command format is EG {WidthInBytes} {HeightInPixels} {XPos} {YPos} {Data}\r\n The printer expects a 1 bit pixel matrix. So if pixel(0, 0) is set you will set "80" in the data. If pixel(0, 0) is set and pixel (7, 0) is also set you would sent "81". Basically what you need to do is to read each set of 8 horizontal pixels and then use bit operations to create a byte value 0..255, and then output this as hex 00..FF. Here's the routine :-) public void DrawBitmap(Bitmap bmp, int xPosition, int yPosition) { if (bmp == null) throw new ArgumentNullException("bmp");

This new compile error was driving me mad! My project used to work, then I upgraded to a newer version of ECO. There were 3 projects using an EcoSpace, 2 would compile but not the 3rd. In the end the solution was simple but annoying to track down so I thought I'd mention it here just in case anyone ever strolls across it and finds it useful. In my licenses.licx files for the 2 projects I had the line Eco.Handles.DefaultEcoSpace, Eco.Handles but in the project that was failing somehow a strong name had been used, even though I originally entered it manually! Changing it back to the weak name fixed the problem.

At work we use SourceSafe for our version control, and I used SourceAnyWhere as the client. I would like to outline the facts and let you decide what happened for yourself. 01: I checked out my model (EcoModeler) 02: I added a new class. 03: Generated code. 04: Checked in the mode. 05: Checked out. 06: Added two new associations 07: Generated code. 08: Checked in. 09: Checked out. 10: Added a parameter to a method. 11: Changes a state machine diagram. 12: Checked in. After each of the changes I would implement code in my application that used them, so if the changes were lost at any point during this process then I would notice because my app would no longer compile. Today I checked out the model and noticed that my new class was missing. I backed up my generated source code and then regenerated code from the model. Using BeyondCompare I checked for differences and came up with the list of changes in the steps above. Somehow the model in my source control had 3 revisions missing. I

In an ECO app I am writing it is very important that updates by other users are identified as soon as possible. This is because there will be multiple users all selecting jobs to do from a predefined list, and it is not only possible but also very likely that more than one user will select the same job at the same time (the job at the top of the list). To implement this I chose to use the remote persistence feature of ECO and in particular its Sync Server feature. Every 5 seconds my client apps will contact the server and retrieve a list of updates made by other users, it will then apply those updates to the cache of its own EcoSpace. So when a user selects a job to do at the top of the list their app will stamp it as InProgress and update the DB, the job will then automatically disappear from the screens of all other users. As I like to use undo blocks in my app to allow the user to cancel changes (using my DirtyObjectCatcher component) it is highly likely that during these synchro

There are exciting times ahead! The team that brought you ECO for Delphi are now a separate company named Capable Objects ( http://www.capableobjects.com ). ECO will still be part of the next release of Delphi, but according to the official statement ( http://dn.codegear.com/article/3673> ) and comments in the newsgroups it is quite obvious there will also be a version of ECO for Visual Studio! In the past the ECO guys released patches for ECO bugs, unfortunately it was not always possible to provide a patch. With the guys now being a separate company they are free to decide their own release schedules. Instead of having to wait for a Delphi update they can now release updates as often as they wish. Just like the good old BoldSoft days when we used to get an official update really quickly if ever a critical bug was found. Not only that, but it would also seem that they will be shipping source code too! But that's not all John! The guys at Capable Objects have asked me to wr

It is amazing! I'll leave that previous post just in case anyone ever needs to create an ECO object instance first and then connect it with an EcoSpace afterwards, but you don't need it for MonoRail! public void Join([EcoDataBind("User")]User user) { PropertyBag["User"] = user; if (this.Params["User.FirstName"] != null) { GetErrors(user.AsIObject(), Errors); if (Context.Params["ConfirmEmailAddress"] != user.EmailAddress) Errors.Add("Email address confirmation does not match email address."); if (Errors.Count == 0) { //TODO EcoSpace.UpdateDatabase(); Redirect("Account", "Home"); }//No errors } } That's all there is to it now! I have created a small set of classes to enable ECO support in MonoRail. Instead of descending your controllers from SmartDispatcherController you will now descend from EcoSmartDispatcherController . This gives the following abi

So I didn't like Ruby on Rails much. More accurately I didn't like the Ruby language or ActiveRecord much, but the "Rails" part I really quite liked! So my investigation continues and I have found myself looking at MonoRails. MonoRails is what I would have as a child called "a rip off", but these days it is known as a "clone" :-) It's basically a .NET version of Rails, which obviously appeals to me because I liked the Model-View-Controller approach of Rails and I obviously like C#. MonoRails has its own version of ActiveRecord (which I shall be avoiding) and an interface into NHibernate too (which I haven't looked at in great depth, but it certainly doesn't look as powerful as ECO). So I have been trying to get MonoRails working with ECO instead. Considering I don't know MonoRails at all I am surprised at how quickly I managed to do what I wanted. Take the following controller method as an example, when the user visits localho

I've just been driven mad by a "Quantum bug". What is a quantum bug? Well, it's a bug that doesn't exist unless you look at it :-) I kept getting a NullReferenceException in my code. It happened whenever I changed a property of a class. I assumed it was something in the framework, but it was in fact in a library of my own. When the property changed it would trigger an observer I had attached, the purpose of this observer is to check if the form that owns my component is the active form, if it is then it records the object that changed; the purpose is to know which objects were modified by which form. Anyway, to check if the form is active I do this Form activeForm = System.Windows.Forms.Form.ActiveForm; Form activeMdiChildForm = activeForm.ActiveMdiChild; if (activeForm == this.Form || activeMdiChildForm == this.Form) ..... Now the quantum! If you are debugging your app Form.ActiveForm will always return null! How useful is that eh? :-) So, when debugging

I was REALLY looking forward to programming some apps on the Mac using Cocoa and objective-C. I am reading "Cocoa programming for MAC OS X" by Aaron Hillegas. I had read as far as page 30 when I saw the following: "Objective-C is a very simple language. It has no visibility specifiers: All methods are public; and all instance variables are protected. (Actually, there are instance specifiers for instance variables, but they are rarely used. The default is protected, and that works nicely.)" WHAT? Works nicely? I disagree! It is actually possible to make a class's method private by not including it in the interface declaration (myclass.h) and just adding the implementation file instead, but what about protected methods? public I expose as little as needed to ensure the class provides the service it was designed to. The signatures/names of members in my public area change as little as possible so as not to break other people's code. Public members are

That's it, I've had enough of Ruby on Rails! I like the rails part, it's a very clever approach, but I really dislike the Ruby part! The final straw occurred yesterday. It's very common in OOP to have the constructor set default values for your object just in case the consumer of your class does not set them. In C# I would do something like this..... public class Post : MyBaseClass { private bool isPost = true; } In Ruby I was trying to achieve this simple behaviour... 01: IsPost is set to true 02: A form is displayed with the default value 03: User changes the value 04: My Post instance is updated with the values from the form I tried to override Initialize() only. def Initialize super is_post = true end Now Post.new(params[:post]) is not reachable for some reason. So in my Post class I did this def Initialize(* params) super(params) is_post = true end The problem here is when I try to initialize the values from the form in my controller class. post = Pos

What a lot of grief! After trying more simple steps on another site (and failing) I eventually managed to get the following steps to work: http://hivelogic.com/narrative/articles/ruby-rails-mongrel-mysql-osx There were however some changes: 01: Make sure you download TextMate. I kept reading it as TextEdit for some reason, so just be aware of that when "mate ~/.bash_login" wont work. 02: One of the steps tells you to type "make ~/.bash_login". I found that adding the suggested text to that file made no difference when you log out/in or close the Terminal window. This was because a file named "~/.bash_profile" existed. If this file exists then you should modify it instead of the one mentioned in the article. 03: When trying to do "rake db:migrate" I would experience the following error: otherwise you will experience the following error: dyld: NSLinkModule() error dyld: Library not loaded: /usr/local/mysql/lib/mysql/libmysqlclient.15.dylib Re

Today I needed to convert an absolute path to a relative path based on a specified base path. E.g. c:\a\b\c -> c:\a\b\c\d\file.txt = d\file.txt c:\a\b\c -> c:\a\file.txt = ..\..\file.txt c:\a\b\c -> c:\a\x\file.txt = ..\..\x\file.txt I am surprised there is nothing in the .NET framework so I had a hunt around and converted the code from the following URL ( http://www.vergentsoftware.com/blogs/ckinsman/default.aspx?date=2006-08-07 ) into C#.... private string RelativePath(string absolutePath, string relativeTo) { string[] absoluteDirectories = absolutePath.Split('\\'); string[] relativeDirectories = relativeTo.Split('\\'); //Get the shortest of the two paths int length = absoluteDirectories.Length < relativeDirectories.Length ? absoluteDirectories.Length : relativeDirectories.Length; //Use to determine where in the loop we exited int lastCommonRoot = -1; int i

I have owned an Acer Ferrari now for approximately 13 months. Previously I had a problem with it freezing randomly. I spent some time trying to reproduce the problem and after a month or two was finally able to reproduce it 100% of the time. I sent my laptop back to Acer armed with exact steps and as a result my laptop was returned to me after only a couple of days. For the past 2-3 months I have been seeing very rare, random resets. Obviously I blamed Windows, as you do :-) Some software I had to convert AVI to MPEG would always reset the laptop, but I just put that down to dodgy software. More recently I noticed that 7-zip would also reset my laptop *only* if I used ULTRA compression on a file larger than 500MB. So I tried Winzip, same problem. I installed Vista and tried both Winzip and 7-zip in there, same problem. With steps to reproduce + proof that it was not the OS I felt I could finally send the laptop back for repair without running the risk of it coming back "No

Someone sent me this on Skype this morning. I think it's really cool, it reminds me of the hardware sprites on the old Commodore 64! 01: Go to any site with lots of images (image search on google is a good one) 02: Once the images appear copy/paste this text into your address bar. javascript:R=0; x1=.1; y1=.05; x2=.25; y2=.24; x3=1.6; y3=.24; x4=300; y4=200; x5=300; y5=200; DI=document.images; DIL=DI.length; function A(){for(i=0; i<DIL; i++){DIS=DI[ i ].style; DIS.position='absolute'; DIS.left=Math.sin(R*x1+i*x2+x3)*x4+x5; DIS.top=Math.cos(R*y1+i*y2+y3)*y4+y5}R++}setInterval('A()',5 ); void(0);

I've been up quite late working out what I want to cover in the "ECO jump start" document. The trick is to start at a level where the user knows absolutely nothing, and end up where they know enough to decide whether or not they wish to spend some time learning how to use ECO or not. I think I should start off explaining why multi-tiered app development is a good idea; then I think I should go on to creating a package in a DLL; then onto creating a non-persistent WinForm app using that package; then make it persistent; and so on. My problem is that ECO just does so much! I'll paste what I have so far at the bottom of this blog entry to get any feedback. As the list progresses the subjects become more advanced and I am worried that the jump start might actually frighten people off by making them feel overwhelmed. Maybe I should just take it so far and then leave the more advanced items out? Maybe I should just include a section at the end of the document explainin

We use wireless printing through a COM port over BlueTooth. Having BlueTooth on all of the time can contribute towards energy consumption and cause the battery life on the Pocket PC to deplete faster. Now I disable BT when the application starts, and then re-enable it to print and disable it immediately afters. This adds about 1 second to each print job but it should save the battery power. [DllImport("BthUtil.dll")] private static extern int BthGetMode(out BlueToothRadioMode dwMode); [DllImport("BthUtil.dll")] private static extern int BthSetMode(BlueToothRadioMode dwMode); public static BlueToothRadioMode BlueToothRadioMode { get { BlueToothRadioMode result; BthGetMode(out result); return result; } set { if (value != BlueToothRadioMode) BthSetMode(value); } }

My compact framework application imports XML into a local database. As there is so much data to import this can take up to an hour. During development there were no problems with this, but of course during development the Pocket PC is docked in its cradle which provides it with power. When a Pocket PC is removed from its cradle it manages power differently, just like an unplugged laptop. So every five minutes the Pocket PC would hibernate and the user would have to turn it back on in order for the import to continue. During an hour the user would have to do this approximately twelve times. How annoying, and dangerous too if the employee is driving to their first job. Anyway, I found the following very useful code on the web and thought I'd point it out as it was so useful! public class Device { #region Device sleep support [DllImport("CoreDll.dll")] public static extern void SystemIdleTimerReset(); private static int DisableSleepCallsCount = 0; private static Sy

Ever played "Spot the difference"? I'm sure you have :-) I'm just looking through an application I have inherited from a Turkish company it was outsourced to. I was just browsing through a 5MB SQL script to generate the DB + stored procs when I saw this.... @MATERIAL_CODE=REPLACE(@REPLACE_MATERIAL_CODE,'Imprinter','Imprınter') Does it do anything? Sure it does, but can you see what it is? There are two clues in this post but I wont tell you where!

Hi all I have finally reached a point where I can dedicate a few hours each today to "something new" and have decided that the ECO book I have always wanted to write would be great fun. My first idea is to create 2 or 3 separate items: Title: ECO jump start This would be in paper / PDF format and would contain a set of exercises for a new user to follow in order to get started with ECO as quickly as possible. It would basically cover creating a simple model, prototyping using auto-forms, using the different handles, databinding, parent-child grids, creating/evolving the DB, OCL / code derived / reverse derived attributes, and stuff like that. Title: ECO API This would be an electronic format which would basically be a "Press F1" reference. Title: ECO book This would either be a paper/pdf format or, if possible, part of the ECO API document. It would be a technical overview of the framework + its services and abilities. I imagine it might be similar to my ECO Ser

I have just released a minor update to ECO extensions. It contains a fix for a bug that would prevent the DirtyObjectCatcher from catching modified objects for MDI child forms.

I recently developed a simple support application that allows users on a PC to provide a one-off security number to a Pocket PC user and when entered the PPC will perform a specific support function. I used the same class to generate these security codes in both the desktop and compact framework applications, tested it quite thoroughly and it all seemed to work fine. However once deployed it became evident that the codes provided by our support department were being rejected by the PPC as invalid. So what went wrong? Seeing as the same class was used for both applications I thought it would be okay to test the encoding/decoding of command numbers on only a single platform, and this was my mistake! The routines use string.GetHashCode() to add a checksum to the end of the security codes just to prevent the user from performing actions without authorisation. For reasons I cannot imagine the implementation of string.GetHashCode() is different in the compact framework from the one in t

This post is really a reminder to myself, so that I can find the information quickly for the next time I reformat my hard drive! To run a website with a root path in Visual Studio 2005 follow these steps: Tools->External tools menu Click Add Title = Webserver Command = C:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\WebDev.WebServer.EXE Arguments = /port:8080 /path:$(ProjectDir) Tick "Use output window" Whenever you need the webserver running just open your project and go to Tools->Webserver.

I occasionally find it annoying that I cannot specify at which point in a class's constructor I wish to invoke the base constructor. Having C# always invoke it before any of the code in my descendant constructor is executed sometimes causes me problems. Considering .NET is capable of calling the ancestor constructor at any point I wondered why C# wont allow it. I contacted Anders Hejlsberg and he was kind enough to reply, unfortunately he seems to have answered a question I didn't ask :-) Anyway, I have been deleting some old emails today and I came across his response, which he gave me permission to publish: The problem with Delphi's model (allowing constructors to be called on an already constructed object) is that it makes it impossible to have provably immutable objects. Immutability is an important concept because it allows applications to hand objects to an external party without first copying those objects and still have a guarantee that the objects won't be m

Well, SQL Server amazes me, but not because I am impressed! Today I wrote an application that does the following: 01) Find all ZIP files in a specific folder 02) Open each ZIP file in turn 03) Extract an XML file from the ZIP into an array of bytes 04) Insert that data into a table There are 1,978 files in this folder and the XML within each ZIP file is around 2MB in size. I ran this app and was really surprised at how soon my PC started to crawl, it was so slow that it was taking over 10 seconds to switch between MSN and a Skype text-chat window. So I decided to monitor the process..... Importing the zip data into SQL Server took a total of 19 minutes and 15 seconds (this includes unzip time). What concerns me is that SQL Server's RAM usage went up to 830MB at its peak, this is what was crippling my PC. Twenty minutes after my app had finished SqlSevr.exe was still holding over 700MB of RAM, I then restarted my PC. SQL Server was using more RAM than I had available

Today my baby girl looked at me, said "DaDa" for the first time ever, and then giggled. What a great day! :-)

I just remembered another technique for calling methods discovered via reflection! It is possible to convert a MethodInfo to a delegate and call it, this is just as fast as calling the method directly. So if you have a method that you call often which was discovered via reflection you should try this.... private delegate bool DoSomethingDelegate(object a, object b); MethodInfo methodInfo = type.GetMethod(.........); DoSomethingDelegate method = (DoSomethingDelegate) Delegate.CreateDelegate(typeof(DoSomethingDelegate), methodInfo); for (int i = 0; i < 1000000, i++) method(this, this);

I've been trying to think through every type of feature I can that people might want in an application, and then seeing if I can think up a way of implementing it using signals. A couple of days ago I thought up something I couldn't implement using the exact approach I had. I once wrote an app that had a treeview on the left hand side, the user could drill down to a customer of their choice and then when they clicked on that customer the display would update and show their details. This made me realise that a simple "SelectCustomer" signal would not be sufficient, what I actually needed to do was to have multiple SelectCustomer signals and indicate which customer to select. The changes I have decided to make are as follows: I will introduce a struct called SignalCreateParameters. This will hold a string property "Parameters" which may be used to automatically populate some of the properties of the created signal, ie the customer identity. The signal facto

Women can multitask No matter how many times you might be told "women can multi-task!" it's just not true, humans can only do one thing at a time. I don’t doubt for a second that my wife's brain can keep track of multiple subjects much better than my single task brain, but at any one point her brain is only concentrating on a single task! It's exactly the same for software. People may wish to deviate from their current task in order to fulfil some adhoc requirement, but that task is an interruption, it does not occur in parallel to what they were doing before. Once that interruption is over the user of your software wants to pick up where they left off. This is what a process driven (or "task oriented") approach to writing software is about. Process driven work flow A process in this context is a single task performed within an application in order to achieve a specific goal. The goal may be just about anything such as "Delete customer", &

Seeing as I haven't had enough free time to write part 3 recently I thought I'd post this little teaser. Would it surprise you to know that this very diagram generated into code and I was able to run it? The signals on the ShowWelcomeMessage had to be hand coded, but hopefully I will be able to get some kind of custom code generation plugin to get the signals auto generated in future.

Here is a list off the top of my head 1 - Ugly code! Why do some people set local variables to null when they have finished with them? This is .NET! The garbage collector will collect "unreferenced" objects when it is ready, an object is unreferenced if you no longer use the variable that holds the reference to it! Why do people name variables so poorly? Firstly I *hate* Hungarian notation. C# is a strongly typed language so I cannot multiply a boolean by a string, so why do people use variable names like "bIsMale" and "iAge"? 2 - Catching all exceptions An exception is something you expect to happen, but shouldn't happen if all goes well. If such an exception occurs you might know how to solve the problem and enable your application to continue, but if the exception type was unexpected how can you possibly know the cause of the error or what state your application is now in? Therefore I hate code like this try { DoSomething(); } catch { } 3 -

Going beyond wizard interfaces If someone had said to me "Process oriented application", in the past I would have thought to myself "Wizard-like interface". Whereas I find "Wizards" very useful in certain situations I also find that they are too time intensive for a user who knows what they want to do, how to do it, and just want to get on and do it! The thing is, I think an application layer should be process driven. The business objects layer is there in order to represent the logical business entities of the application, and the application layer should be there to drive the logical flow of the users' interaction with those objects. So, the question is "How do we implement a process oriented framework without enforcing a wizard-like interface?" The answer I think is to use Signals. Signals The process may imply that there is always a specific path through an application. Although the user may influence that path by selection options

An onion has layers... ...Shrek In the beginning When I first started writing applications they would typically be a single program editing a single datasource. As time went on this changed because people wanted to share data, so client/server applications appeared. It didn't stop there though, N-Tier applications became much more common. Applications were typically split up like this: RDBMS--DAL--Business classes--UI Due to the fact that I use ECO for my business layer , and that ECO has the DAL built in, the illustration for me would look something like: RDBMS--Business classes (ECO)--UI Thinking of business problems as classes instead of tables really helps to simplify your design, so I have been very happy writing applications this way for some time now. The application layer In December 2005 I was tasked with the job of writing quite a complicated Compact Framework application. Although this application was going to be complicated it needed to be very simple to use, as the

I've been writing an app for the compact framework for some months now. It's quite a complicated app that includes an object persistence framework, a task oriented application layer and a loosely coupled GUI which is generated through factories (the app only has 1 form, but lots of user controls + factories). The app has been experiencing apparently random OutOfMemoryExceptions, no matter how hard I have tried I have found it impossible to reproduce one of these errors. I have spent quite some time really optimising the memory useage of my OPF so that it works on the bare minimum of memory yet still operates quickly enough (and I'm very pleased with its performance too). However, the OOM exceptions persisted! I wrote a logging tool which records the last X actions the user performs, when an unexpected exception occurs this log is written to disk along with a stack trace of the exception. I noticed that the top of the stack trace always read... at Microsoft.AGL.Com

This is just a copy/paste of a reply I made in a newsgroup, but I think it is quite informative so here it is.... KEY Square brackets denote a class [Person] Rounded brackets denote a role (Pets) Let's say you have a Car class and a Garage class, an individual car is regularly serviced at a specific garage so you have the following association [Garage] (Garage) 1----0..* (ServicableCars) [Car] Car.allInstances->select(Garage.Code = '1234') The above OCL will fail because "Garage" is a class so the parser is expecting stuff like "allInstances". So you might think this should work Car.allInstances->select(self.Garage.Code = '1234') but it doesn't because "self" refers to the root object and not the object at the parsed node where it is specified. This is what aliases are for: {aliasname} + {pipe} Car.allInstances->select(currentCar | currentCar.Garage.Code = '1234') This was possible in Bold too (native wind