ShowUsYour<Blog> : Code Snippets

Code to easily create zip files on the fly

digory — Fri, 25 Feb 2005 11:54:00 GMT

The other day I posted about a free .NET library for creating zip files on the fly:

http://weblogs.asp.net/dneimke/archive/2005/02/23/378781.aspx

Here's a little method that I wrote which wraps the functionality of the ICSharpCode library to easily package one or more files into a zip file.

private static void WriteZipFile( string[] filesToZip, string writeToFilePath ) {

  try {
    if ( EnsureDirectory(writeToFilePath) ) {
      
      Crc32 crc = new Crc32();
      ZipOutputStream s = new ZipOutputStream(File.Create(writeToFilePath));
      s.SetLevel(9); // 0 - store only to 9 - means best compression

      for( int i=0; i<filesToZip.Length; i++ ) {
      
        // Must use a relative path here so that files show up in the Windows Zip File Viewer
        // .. hence the use of Path.GetFileName(...)
        ZipEntry entry = new ZipEntry(Path.GetFileName(filesToZip[i]));
        entry.DateTime = DateTime.Now;

        // Read in the 
        using(FileStream fs = File.OpenRead(filesToZip[i])) {
  
          byte[] buffer = new byte[fs.Length];
          fs.Read(buffer, 0, buffer.Length);

          // set Size and the crc, because the information
          // about the size and crc should be stored in the header
          // if it is not set it is automatically written in the footer.
          // (in this case size == crc == -1 in the header)
          // Some ZIP programs have problems with zip files that don't store
          // the size and crc in the header.
          entry.Size = fs.Length;
          fs.Close();
      
          crc.Reset();
          crc.Update(buffer);
          entry.Crc  = crc.Value;
          s.PutNextEntry(entry);
          s.Write(buffer, 0, buffer.Length);
        }
      }
  
      s.Finish();
      s.Close();
    }
  } 
  catch( Exception ex ) {
    HttpContext.Current.Trace.Warn( ex.ToString() ) ;
  }
}

Nested sub-queries always elude me

digory — Thu, 24 Feb 2005 12:28:00 GMT

Tonight I was writing the stored procedure which will return lists of data to the Codewise nighly updates. Basically, each night, Codewise will call a webservice and you need to return a list of all GUID's which have been either ADDED, UPDATED or REMOVED since the last time they called your service. The return Xml will look something like this:

  <ContentItemIds>
    <Added>
        <Guid ... />
    </Added>
    <Updated>
        <Guid ... />
    </Updated>
    <Removed>
        <Guid ... />
    </Removed>
  </ContentItemIds>

I wanted to have a stored procedure that I could pass a "type" and a start date and get back a list of Guids that have changed to that type since the starting date. This kind of Sql is often munged-up as a string and Exec'd back to the caller. I'm not a big fan of sql strings in the middle-tier or building strings in the database so I thought that I'd find a straight sql approach. I was trying the following query which was failing:

SELECT CASE 
    WHEN @diffType = 1 AND [CreationDate] > @beginDate THEN [GUID]
    WHEN @diffType = 2 AND [LastUpdatedDate] > @beginDate THEN [GUID]
    WHEN @diffType = 3 AND [RemovedDate] > @beginDate THEN [GUID]
END As [GUID]
FROM dbo.Codewise_ContentItem
WHERE 1 IS NOT NULL

So, I pinged Thomas who whipped up the following pre-breakfast solution:

SELECT [GUID]
FROM dbo.Codewise_ContentItem
WHERE [GUID] IN (
    SELECT 
        CASE 
            WHEN @diffType = 1 AND [CreationDate] > @beginDate THEN [GUID]
            WHEN @diffType = 2 AND [LastUpdatedDate] > @beginDate THEN [GUID]
            WHEN @diffType = 3 AND [RemovedDate] > @beginDate THEN [GUID]
        END As [GUID]
    FROM dbo.Codewise_ContentItem
)

Zip'ping files

digory — Wed, 23 Feb 2005 13:17:00 GMT

Tonight I was using the ICSharpCode zip library to zip files for my Codewise implementation. Basically, when users nominate to make a Relase visible to Codeshare, I create a manifest file and package it and the Release file into a Codewise package.

I ran the code which comes in the .chm file but, noticed that my .zip files wouldn't show any content when viewing them through the default Windows Zip File viewer. I little bit of investigation led me to the FAQ site for the library which answered my question. Basically, you cannot pass a fullpath to the ZipEntry class if you want it to be visible to Windows. So, you just remove the path portion of the filename:

ZipEntry entry = new ZipEntry(Path.GetFileName(fullPath));

ICSharpCode Zip Library: www.icsharpcode.net/OpenSource/SharpZipLib
FAQ Wiki: http://wiki.sharpdevelop.net/default.aspx/SharpZipLib.FrequentlyAskedQuestions

Koders - searchable repository of code snippets

digory — Mon, 24 Jan 2005 10:14:00 GMT

Found this site via Mitch's blog:

http://www.koders.com/

Using metadata and reflection to dynamically manage message routing

digory — Thu, 20 Jan 2005 08:40:00 GMT

Most routing systems have a transformation phase where, based on its current state, a message is transformed into a document and routed to an endpoint. Systems such as BizTalk provide GUI's and designers to remove the need for cumbersome coding by making the rules and subsequent transformations configurable; here's an example of a switch statement in a listener class where the rules of the routing engine are hard-coded:

public static void MessageArrived( Message message ) {
switch( message.MessageState ) {
    case MessageState.Initial:
        Console.Write( Transformer.CreateRequest( message ) );
        break ;
    case MessageState.Submitted:
        Console.Write( Transformer.CreateApproval( message ) );
        break ;
    case MessageState.Approved:
        Console.Write( Transformer.CreateInvoice( message ) );
        break ;
    case MessageState.Saved:
        Console.Write( Transformer.CreateReport( message ) );
        break ;
    default:
        Console.Write( Notifier.NotifyError( message ) );
    break ;

}
}

If there's extra "noise" in the MessageArrived method, it can become hard to maintain as the length of the switch gets longer. It can also become hard to maintain if there are repetitive code chunks within each case.

In the above cases you can - at a moderate performance cost - re-factor the common code away into a generic method. Looking at the above example, one neat way to achieve this is to ascribe metadata to the MessageState enum so that it can be inspected at runtime and the routing lookup driven from that metadata. First, let's create an attribute to contain our lookup data and add it to the MessageState enum:

[AttributeUsage(AttributeTargets.Field, Inherited=false, AllowMultiple=true)]
public class WorkflowAttribute : Attribute {
public WorkflowAttribute(Type type, string methodName) {
this.Type = type ;
this.MethodName = methodName ;
}

public Type Type;
public string MethodName ;
}

public enum MessageState : short {

[WorkflowAttribute(typeof(Transformer), "CreateRequest")]
Initial = 1,

[WorkflowAttribute(typeof(Transformer), "CreateApproval")]
Submitted = 2,

[WorkflowAttribute(typeof(Transformer), "CreateInvoice"),

WorkflowAttribute(typeof(Notifier), "NotifySalesGuy")]
Approved = 3,

[WorkflowAttribute(typeof(Transformer), "CreateReport")]
Saved = 4,

[WorkflowAttribute(typeof(Notifier), "NotifyError")]
Unknown = short.MaxValue
}

Notice that I applied 2 worklow attributes to the MessageState.Submitted enum value.

Now I can re-factor the original MessageArrived method into a generic message handler routine:

public static void MessageArrived( Message message ) {

MessageState state = message.MessageState ;
FieldInfo field = state.GetType().GetField(state.ToString()) ;

object[] attribs = field.GetCustomAttributes(typeof(WorkflowAttribute), false) ;

for( int i=0; i<attribs.Length; i++ ) {
    WorkflowAttribute att = attribs[i] as WorkflowAttribute ;
    if( att != null ) {
      MethodInfo method = null ;

      if( att.Type.GetMethod(att.MethodName).IsStatic ) {
        method = att.Type.GetMethod(att.MethodName) ;
        Console.Write(method.Invoke(null, new object[] {message}));
      }else{
        object instance = Activator.CreateInstance(att.Type) ;
        method = instance.GetType().GetMethod(att.MethodName);
        Console.Write(method.Invoke(instance, new object[] {message}));
      }
    }
}
}

I've uploaded a working demo of this to ProjectDistributor:

http://projectdistributor.net/Releases/Release.aspx?releaseId=82

Prototype of a small trackback system

digory — Sat, 08 Jan 2005 21:32:00 GMT

Last night I prototyped a small trackback system:

Project Distributor :: MarkItUp :: TrackBack Prototype :: 1.0.0.0

This is quick and dirty but it was enough to allow me to understand the concept of trackbacks. Code and inspiration was taken from .Text source code as well as this fine article:

http://www.wwwcoder.com/main/parentid/262/site/2344/68/default.aspx

A couple of Windows Services resources

digory — Sat, 27 Nov 2004 09:47:00 GMT

I've had a couple of Windows Services snippets that I've been meaning to "rip-to-blog" for a while now...

Advanced Installer... a free, advanced MSI creation tool
http://www.advancedinstaller.com/

Code snippet to add a description to your Windows Services (note that, in Whidbey this is all exposed via the API)...


1Public Overrides Sub Install(ByVal stateSaver As System.Collections.IDictionary)

2	MyBase.Install(stateSaver)

3	

4	Dim serviceDescription As Microsoft.Win32.RegistryKey = Microsoft.Win32.Registry.LocalMachine.OpenSubKey("System\CurrentControlSet\Services\" & yourInstaller.ServiceName, True)

5	

6	serviceDescription.SetValue("Description", "This is the FileMonitorService.")

7	serviceDescription.Close()

8End Sub

9

[ Currently Playing : Let's Get Lost - Elliott Smith - From a Basement on the Hill (02:27) ]

Some golden rules to adhere by when thinking about features

digory — Wed, 03 Nov 2004 21:09:00 GMT

When we started doing a spec for ProjectDistributor Justin and I had some long chats about what features we wanted in and how they would be implemented. In fact, there were dozens of features that we discussed and, as we progressed we found that we needed a better methodology for quickly deciding whether features would be winners or losers. Additionally, we needed a better way to describe new features to one another so that we didn't waste cycles trying to understand what the other person was trying to say.

Justin quickly decided that anything we planned on adding or any new derivations, we should bounce these questions off:

What problem are we trying to solve (or innovation we are trying to make)?
How do we solve that problem?
What are some existing systems that solve the same problem in the same or different ways?
How is our system different from previous systems and what innovation are we adding?

We've found that this allows us to trade the ideas back and forth in an idea oriented way while allowing us to show any innovations in a problem solving way.

We've now decided - based on our success with them - to add these to ProjectDistributor. Soon, when adding projects, you will be offered the choice to answer each of these questions. This will allow people who are viewing your project to quickly gain a better understanding of why your tool rocks!

ProjectDistributor - online storage for tools and code snippets

digory — Tue, 26 Oct 2004 12:24:00 GMT

ProjectDistributor is now pretty stable and nearly feature complete for iteration 1. This application was created as a place to store small or trivial pieces of code. Either code which was expensive to create - such as a prototype - or code which will be useful again in the future - such as a macro, server control or stored procedure.

It's not that clear on the site "yet", but, there are 2 levels of membership on the site: Users and Groups.

Users have the ability to login and use their "User Profile" page to store bookmarks to their favourite online tools. You can view my user profile page here:

http://markitup.aspxconnection.com/Users/User.aspx?userId=7

Once you are a user you are eligible to create a Group. You need a Group to upload and manage your own tools and widgets. If you want a Group just let me know what you'd like the name of your group to be. I need a GroupName - which will form part of the Url for your landing
page and a GroupFriendlyName which will be used as the display name of your group. For example, my group is:

GroupName : MarkItUp
GroupFriendlyName : MarkItUp

And you can see my Groups landing page here:

http://markitup.aspxconnection.com/Groups/Group.aspx?groupId=3

Groups can actually have multiple users and they can be either private or public, likewise, you can have Projects which are private or public.

One of the major drawcards of the site is the WebServices:

http://markitup.aspxconnection.com/WebServices/ProjectDistributor.asmx

...these could allow you to potentially host your tools (and their source) on ProjectDistributor and serve them up on your own site via Webservice calls.

If you'd like to host your tools/widgets/etc on ProjectDistributor, create yourself a User account and shoot me an e-mail with your preferred Group details and I'll set it straight up for you.

Project Distributor - new features uploaded.

digory — Mon, 11 Oct 2004 09:56:00 GMT

Tonight I uploaded a new build of my application, you can view it here:

http://markitup.aspxconnection.com/

There are 2 cool new features that weren't present previously.

1) When you create an account (option available via the Login page) you have the ability to add "Bookmarks" and categorize them. Bookmarks are intended to be a store of all your favourite online tools and widgets. You can bookmark both internal and external projects. When you view an internal project and you are signed in, you will see a "Add to Bookmarks" link. To add external bookmarks and categories, go to your user profile page and add them from there.

2) You can now mark Groups/Projects/Releases as "private" and they will only be available to members of your Group. This is a great option if you have a Group which you've made public but you might have a certain project that you only want to be visible to yourself (such as a special Sql script or something).

You can start with the Bookmarks immediately by going to the site and creating a User account. To get setup with a Group (which allows you to upload your own projects), create a User account and send me an e-mail requesting a Group.

How to use the ASP Page Framework

digory — Wed, 28 Jul 2004 03:29:00 GMT

I had a couple of e-mail requests asking me how to use the Classic ASP Page Framework which I discussed in my last blog entry so I thought that I'd make a couple of notes in an attempt to try an clear things up a bit. First, the code for the Framework can be found here:

http://flws.com.au/AuthenticateModel.html

To use it you include the code in each page as a server-side include and configure the security.

To configure security you just create a comma-delimited string of pages which should be secured like so:

   Application( "MIU_PAGES_TO_SECURE" ) = "Foo.asp, Bar.asp, etc"

Whenever a user browses to one of those pages they are automagically taken to the login page (if they are not already authenticated). You set the login page via an Application variable too:

    Application( "MIU_LOGIN_PATH" ) = "Login.asp"

If a user successfully logs in they are automagically redirected back to the page that they came from:

    ElseIf Me.Page.IsAuthenticationPage And Not Me.User.IsAuthenticated() Then
        FormsAuthentication.RedirectUrl = Request.QueryString( "RedirectUrl" )
    End If

When a user logs out you can specify which page they should be re-directed to:

    Application( "MIU_DEFAULT_ENTRY_PATH" ) = "Default.asp"

The framework also has some for RoleBased authentication which you can query off of the current user at anytime like so:

    If User.IsInRole( "admin" ) Then
        ' do something based on the admin role
    End If

Classic ASP Page Framework

digory — Wed, 28 Jul 2004 00:53:00 GMT

The other day I asked a question on a list about the perf. Implications of using VBScript classes in classic ASP applications. After participating in that thread I was reminded that, a while back I actually wrote an object oriented, event-driven classic ASP Page model which mimics some of the services which are built into the ASP.NET pages - such as Authentication, Users/Identities and Page properties. The page automagically serializes it's state (which could be abstracted by implementing a Provider model). The model also contained an in-built AuthenticationProvider which handles re-directs when secured resources are requested.

The whole framework weighed in at less than 350 lines of code! You can see the code for it here:

http://flws.com.au/AuthenticateModel.html

For me one of the big things about abstracting things into object models is that, because people relate to objects well object - such as Person.MiddleName - they enable you to easily build robust frameworks by pushing essential services down a layer. It's only through building reliable frameworks that you can achieve true manageability - especially when project sizes need to be be scalable.

Mixing Server and Client-side - is it hard to be elegant?

digory — Sun, 02 May 2004 13:01:00 GMT

I had to write some functionality for a friend tonight based on the following request :

When double-clicking on a textbox, toggle the enabled/disabled state of the textbox and, if it's disabled set it's background to red. Also, make sure that the settings persist across postbacks.

All up the task took about 1/2 an hour to achieve and, I often think that it would be nice if the ASP Team gave us more "hooks" into client side programming to make this stuff easier. I'm not sure that this qualifies as elegant, in fact I'm sure that I'd class it as a dodgy-hack, but, here's what I went for:

<%@ Page language="c#" %>
<%@ import namespace="System.Drawing" %>
<script runat="server">
private void btnSubmit_Click(object sender, System.EventArgs e)
{
  string fields = this.hdnFields.Value ;
   
  foreach( Control ctl in this.Controls ) 
  {  
    if( ctl is HtmlForm ) 
    {
        foreach( Control childControl in ctl.Controls ) 
        {
            if( childControl is TextBox ) 
            {
                int pos = fields.IndexOf( childControl.ID + ":" ) ;
                if( pos >= 0 ) 
                {
                    string state = fields.Substring( pos, fields.IndexOf(';',pos) - pos ) ;
                    if( state.Length > 0 ) 
                    {
                        string val = state.Split(':')[1] ;
                        ((TextBox) childControl).Text = val ;
                    }
                }
                
                ((TextBox) childControl).Enabled = ( pos == -1 ) ;
                ((TextBox) childControl).BackColor = ( pos >=0 ) ? Color.Red : Color.White ;
            }
        }
    }
  }
}
</script>
<html>
  <head>
  <script language="javascript">
 
    function ToggleEnabled( e ) {
        var tb = e.children[0] ;
        var disabled = !tb.disabled ;
        
        tb.disabled = disabled ;
        tb.style.backgroundColor = ( disabled ) ? "Red" : "White" ; 
        
        if( !disabled ) tb.focus() ;
        
        UpdateHiddenField( tb, disabled ) ;
    }
    
    
    function UpdateHiddenField( e, disabled ) {
        var txt = Form1.hdnFields.value ;
        Form1.hdnFields.value = "" ;
    
        if( disabled )
            Form1.hdnFields.value = e.id + ":" + e.value + ";" ;
            
        var flds = txt.split( ";" ) ;
            
        for( var i=0; i<flds.length; i++ ) {
            if( e.id != flds[i].split(":")[0] && flds[i].length && flds[i].length > 0 )
                Form1.hdnFields.value += flds[i] + ";" ; 
        }
    }
</script>
</head>
<body>
<form id="Form1" method="post" runat="server">
<input type="hidden" id="hdnFields" runat="server" >
   
<p>
    <span id="foo1" ondblclick="ToggleEnabled( this ) ;">
        TextBox 1: <asp:textbox id="txtTest1" runat="server" />
    </span>
</p>
<p>
    <span id="foo2" ondblclick="ToggleEnabled( this ) ;">
        TextBox 2: <asp:textbox id="txtTest2" runat="server" />
    </span>
</p>
<p>
    <span id="foo3" ondblclick="ToggleEnabled( this ) ;">
        TextBox 3: <asp:textbox id="txtTest3" runat="server" />
    </span>
</p>
<p>
    <span id="foo4" ondblclick="ToggleEnabled( this ) ;">
        TextBox 4: <asp:textbox id="txtTest4" runat="server" />
    </span>
</p>
<p>
    <span id="foo5" ondblclick="ToggleEnabled( this ) ;">
        TextBox 5: <asp:textbox id="txtTest5" runat="server" />
    </span>
</p>
<p>
    <asp:button id="btnSubmit" onclick="btnSubmit_Click" runat="server" text="Submit" />
</p>
   
</form>
</body>
</html>

How to build a comma-separated list

digory — Fri, 30 Apr 2004 03:23:00 GMT

Dave has an interesting little thread going about how to do build a comma-separated list and what you can do with that annoying, left-over ',':

http://weblogs.asp.net/dburke/archive/2004/04/28/122332.aspx

Who'd've thought that there would be so many options!

Rotor resources

digory — Thu, 18 Mar 2004 00:35:00 GMT

Recently Justin Rogers got me enthusiastic about Rotor source code and today I see that Joel has uploaded a list of places where Rotor is discussed:

http://weblogs.asp.net/joelpob/archive/2004/03/17/91506.aspx