A.D.D. In IT

Quick Memory Improvement for Firefox

khuang — Mon, 05 Mar 2012 16:38:45 +0000

Its been a while since I posted, but I wanted to share a setting that really shouldn't be enabled by default in Firefox.

I had been following various threads on Firefox memory usage, and after installing Firefox 10 I noticed Firefox started with something like 200 MB of RAM but quickly ballooned to some 500 MB after a few tabs open.

After some research, I tried out a setting in the about:config page, and it literally halved my RAM usage, especially with large numbers of tabs.

This is the image.mem.decodeondraw setting in Firefox.
Decodeondraw setting

If you go to about:config in Firefox and type in decodeondraw and double click the image.mem.decodeondraw setting, then restart Firefox, you should see some immediate results.

Canned VirtualPC Instances for IE 6, 7, 8 on XP/Vista

khuang — Fri, 28 May 2010 16:27:25 +0000

Its been a while since I've posted here, but I have a quick (and useful) link to share. Microsoft has canned VirtualPC images to virtualize IE6/7/8 on XP with SP3 and Vista.

http://www.microsoft.com/downloads/details.aspx?familyid=21EABB90-958F-4B64-B5F1-73D0A413C8EF&displaylang=en

VirtualPC is available from Microsoft for free here:
http://www.microsoft.com/downloads/details.aspx?FamilyId=28C97D22-6EB8-4A09-A7F7-F6C7A1F000B5&displaylang=en

Checking assembly dependencies for .NET

bmancini — Thu, 17 Dec 2009 17:58:32 +0000

Are you getting the dreaded "Could not load file or assembly" error in C#? Well there might be several causes of that, the most difficult to track down and fix is a missing assembly dependency.

The exception that is usually generated is along similar to this one:

System.IO.FileLoadException: Could not load file or assembly 'Utility, Version=1.2.0.200, Culture=neutral, PublicKeyToken=764d581291d764f7' or one of its dependencies. The located assembly's manifest definition does not match the assembly reference. (Exception from HRESULT: 0x80131040)

at x.Foo.FooGO() at x.Foo.Foo2(String groupName_) in Foo.cs:line 123 at x.Foo.UnitTests.FooTests.TestFoo() in FooTests.cs:line 98

System.IO.FileLoadException: Could not load file or assembly 'Utility, Version=1.2.0.203, Culture=neutral, PublicKeyToken=764d581291d764f7' or one of its dependencies. The located assembly's manifest definition does not match the assembly reference. (Exception from HRESULT: 0x80131040)

This exception means one of two things, you are missing a direct reference (or version) to the DLL that you are attempting to use... or that a DLL that your DLL references is missing or is the incorrect version.

In the case of the later, you can enable Assembly reference logging by adding a registry value under HKLM\Software\Microsoft\Fusion. Add a DWord entry named EnableLog and set its value to 1. This will allow you to see where the missing assembly was first referenced from.

From that point, you can load a tool called CheckAsm, found here: http://checkasm.booring.net/. With this tool, you can load an assembly and view all of its dependencies, it will show you the references and which are currently missing. The best feature of CheckAsm is that you can scan an entire directory. From there, it's a matter of fixing the references either by adding the dependencies or modifying the DLL to point to the correct dependencies.

Google's Public DNS

khuang — Thu, 03 Dec 2009 20:08:54 +0000

Announced today was Google's free public DNS servers. Whats different is that these servers are free of redirections to advertising pages on DNS resolutions of non-existant sites. When the DNS fails, it fails according to standards.

To use their servers set your DNS lookup servers to 8.8.8.8 or 8.8.4.4 and everything should work.
See their site for more details.
http://code.google.com/speed/public-dns/

Server Utility Functions for Non-Web Apps

khuang — Mon, 23 Nov 2009 17:13:09 +0000

This is just a quick post. Normally, when one needs to use such functions as HtmlEncode, HtmlDecode, UrlEncode, UrlDecode and related functions, one would normally go to the Server class in your current HttpContext.

However, in the case that you're running in a console application for any particular reason, you don't have an HttpContext.Current, and you would then throw a "Object reference not set to an instance of an object" (aka Null Reference Exception).

The correct way to do this is to use the System.Web.HttpUtility class. This utility is the one used internally by the Server object.

reCAPTCHA for ASP.NET MVC that uses ModelState

bmancini — Sat, 07 Nov 2009 15:50:49 +0000

Here is a reCAPTCHA control for ASP.NET MVC that uses ModelState. This code includes the ActionFilter as well as the HTML Helper for rendering the reCAPTCHA control.

To use it, add the ActionFilter to the Controller Action that will be performing the verification. You can either provide the Private Key in the web.config or explicitly state it. You can also use the IgnoreOnMobile boolean property to ignore reCAPTCHA verification if a mobile browser is detected. You can also add a function delegate that returns a boolean value to the Ignore property to add custom logic to ignore reCAPTCHA under any condition you would like.

[Recaptcha.Mvc.RecaptchaFilter(PrivateKey = "my_private_key", IgnoreOnMobile=true)]
[AcceptVerbs(HttpVerbs.Post)]
public ActionResult Create(Post post)
{
if (!ModelState.IsValid)
{
// model state and recaptcha were valid, continue onwards!
}
else
{
// model state was not valid, redirect back to source page
}
}

To render the reCAPTCHA control, simply add the Recaptcha.Mvc to the page and use the HtmlHelper.

<%@ Import Namespace="Recaptcha.Mvc" %>
...

<%= Html.CreateRecaptcha("recaptcha", "my_private_key", "my_public_key", "clean") %>

If you wish to set the private/public keys in the web.config you can set them in the appSettings section.

The source code is attached below as a Solution and Project that needs to be built. Alternatively you can just add the csharp source files and drop them into your project appropriately.

Attachment	Size
Recaptcha.Mvc_.zip	12.38 KB

Adding a container to ValidationSummary helper in ASP.NET MVC

bmancini — Sat, 17 Oct 2009 14:47:41 +0000

The one thing that is annoying about the validation summary HTML Helper in ASP.NET MVC is that it doesn't render a container element. Problem solved...

The source code below uses an Extension method to append the method ValidationSummaryWithContainer to the HtmlHelper class. This method works by grabbing the actual ValidationSummary first, checking to see if it has output any content, and if it has, wrapping a div element around the generated output. It's pretty simple, but effective.

using System;
using System.Text;

namespace System.Web.Mvc.Html
{
public static class ValidationSummaryExtension
{
/// <summary>
/// Creates a validation summary with a container element
/// surrounding the summary and error messages.
/// </summary>
public static string ValidationSummaryWithContainer(this HtmlHelper ext, string message)
{
var summaryoutput = ext.ValidationSummary(message);
if (!string.IsNullOrEmpty(summaryoutput))
{
StringBuilder sb = new StringBuilder();
sb.AppendLine("<div class='validation-summary-errors-container'>");
sb.Append(summaryoutput);
sb.Append("</div>");
return sb.ToString();
}
else
return string.Empty;
}
}
}

To use this helper, on your view page, just call the helper method as you normally would:

<%=Html.ValidationSummaryWithContainer("Please fix the following errors:")%>

If there are no errors, it will render nothing, if there are errors, it will render the output with a containing div element.

<div class='validation-summary-errors-container'>
<span class="validation-summary-errors">Please fix the following errors:</span>
<ul class="validation-summary-errors">
<li>Title is required.</li>
<li>Description is required.</li>
<li>Contact email address is required.</li>
<li>Specific area is required.</li>
<li>Recaptcha was not valid, please try again.</li>
</ul>
</div>

Finally, the whole point of this exercise, is so that you can add css style to the containing element and make your error's very pretty.

/*************************************************/
/* VALIDATION ERROR*/

.validation-summary-errors-container
{
padding: 1.5em;
margin: .5em 0px .5em 0px;
background-color: #ffffdf;
border: 1px solid #df6b6b;
color: #dc3535;
}
.field-validation-error
{
color: #dc3535;
}
.input-validation-error
{
border: 1px solid #df6b6b;
background-color: #ffffdf;
}
span.validation-summary-errors
{
font-weight: bold;
}

Generic XML Serialization Class

bmancini — Fri, 09 Oct 2009 23:03:39 +0000

We had to add XML Serialization functionality to a bunch of different classes. Here is a nice generic class for adding static methods for Serialization and Deserialization to any of your classes...

Well any class that doesn't inherit from another class. In that case, I guess you can use it as a standalone class. Regardless, it's good enough for me at 6:15PM on a Friday evening in the office when I'm trying to get out of here.

using System;
using System.Xml.Serialization;
using System.IO;

namespace HRXml
{
public class GenericXmlSerialization<T>
where T : class
{
public static T Deserialize(string input)
{
XmlSerializer serialization = new XmlSerializer(typeof(T));
StringReader reader = new StringReader(input);
object result = serialization.Deserialize(reader);
return result as T;
}
public static Stream Serialize(T input)
{
XmlSerializer serialization = new XmlSerializer(typeof(T));
MemoryStream results = new MemoryStream(4096);
serialization.Serialize(results, input);
results.Position = 0;
return results;
}

public static string SerializeToString(T input)
{
Stream stream = Serialize(input);
StreamReader sr = new StreamReader(stream);
return sr.ReadToEnd();
}
}
}

This can be added to different classes by inheriting from the GenericXmlSerialization class with the current type as the Generic type.

public partial class AssessmentOrderRequestType : GenericXmlSerialization<AssessmentOrderRequestType>
{
// STUFF HERE
}

public partial class AssessmentOrderAcknowledgementType : GenericXmlSerialization<AssessmentOrderAcknowledgementType>
{
// STUFF HERE
}

Or you can use it standalone.

var stream = GenericXmlSerialization<AssessmentOrderAcknowledgementType>.Serialize(myobject);

Time to get out of here!

Re-throwing Exceptions in C# with InternalPreserveStackTrace

bmancini — Wed, 07 Oct 2009 21:57:29 +0000

It is often the case that you need to re-throw an exception after handling it. The common problem with re-throwing exceptions is that you often lose stack trace information that can be extraordinarily useful for debugging purposes. I'll explain a technique that can be used to force the entire stack to be propagated when an exception is re-thrown.

The solution is to perform a reflective invocation of the InternalPreserveStackTrace method, which is an internal method belonging to System.Exception. Usually, this can be accomplished in a single line of code using reflection as follows:

try
{
// DOES SOMETHING
}
catch (Exception ex)
{
typeof(System.Exception).GetMethod("InternalPreserveStackTrace",
System.Reflection.BindingFlags.Instance | System.Reflection.BindingFlags.NonPublic)
.Invoke(ex, null);

throw;
}

The InternalPreserveStackTrace method simply grabs the StackTrace from the point of the exception to the location where InternalPreserveStackTrace method was invoked. It stores this trace information in a temporary field for usage in subsequent requests to StackTrace.

A little deeper analysis using Reflector shows exactly how this method works.

internal void InternalPreserveStackTrace()
{
string stackTrace = this.StackTrace;
if ((stackTrace != null) && (stackTrace.Length > 0))
{
this._remoteStackTraceString = stackTrace + Environment.NewLine;
}
this._stackTrace = null;
this._stackTraceString = null;
}

public virtual string StackTrace
{
get
{
if (this._stackTraceString != null)
{
return (this._remoteStackTraceString + this._stackTraceString);
}
if (this._stackTrace == null)
{
return this._remoteStackTraceString;
}
string stackTrace = Environment.GetStackTrace(this, true);
return (this._remoteStackTraceString + stackTrace);
}
}

If you use reflection to analyze what this code does during execution you will see that it follows this process:

When the Exception enters the initial catch block it contains the following information: _stackTrace field contains an sbyte array, _stackTraceString is null, and _remoteStackTraceString is null.

Upon the invocation of the InternalPreserveStackTrace method, the StackTrace property's getter is invoked in the first line of InternalPreserveStackTrace.

When get_StackTrace is called neither of the the first two conditional statements execute because _stackTraceString is null and _stackTrace is not null. The Environment.GetStrackTrace method is invoked and the stack from the source of the exception to the first catch block is returned and stored in the stackTrace variable.

InternalPreserveStackTrace then checks if the stackTrace variable is not null and has a length. Because this variable now contains the stack trace from the source of the exception, the condition is true and it stores the stackTrace information in the _remoteStackTraceString field of the current Exception. Finally, it sets the _stackTrace and _stackTraceString fields to null.

If the StackTrace property is now accessed it will only return the contents of the _remoteStackTraceString field.

At this point in our application the Exception is re-thrown using either

throw;

throw ex;

When the exception is subsequently caught again, the _stackTrace field will once again be set to an sbyte array since the stack has changed. This time, the _remoteStackTraceString field will contain our original stack trace from the source of the exception to the first catch block. This stack trace information is then combined with the stack trace from the re-throw to give a complete picture of the stack at the time the exception occurred.

CAVEAT EMPTOR

Because this technique uses reflection to access private fields in the Exception class by using the NonPublic BindingFlag, it may not work if the system does not have FullTrust enabled. I have not investigated this yet... so beware in hosted environments that do not execute with Full Trust.

Solving xsd generation error: 'The element .... is missing'

bmancini — Wed, 23 Sep 2009 13:41:43 +0000

In attempting to build source from an XML schema using the XSD command line tool, I kept getting an error about an element missing.

C:\dev\hrxml\xsd AssessmentResult.xsd /classes /fields /language:CS /namespace:hrxml.AssessmentResult
Microsoft (R) Xml Schemas/DataTypes support utility
[Microsoft (R) .NET Framework, Version 2.0.50727.3038]
Copyright (C) Microsoft Corporation. All rights reserved.
Schema validation warning: The 'http://purl.org/dc/elements/1.1/:title' element is not declared. Line 1074, position 5.
Schema validation warning: The 'http://purl.org/dc/elements/1.1/:format' element is not declared. Line 1075, position 5.
Schema validation warning: The 'http://www.w3.org/2000/09/xmldsig#:Signature' element is not declared. Line 1173, position 5.
Schema validation warning: The 'http://purl.org/dc/elements/1.1/:creator' element is not declared. Line 1079, position 8.
Schema validation warning: The 'http://purl.org/dc/elements/1.1/:subject' element is not declared. Line 1080, position 8.
Schema validation warning: The <a href="http://purl.org/dc/elements/1.1/:description'" title="http://purl.org/dc/elements/1.1/:description'">http://purl.org/dc/elements/1.1/:description'</a> element is not declared. Line 1081, position 8.
Schema validation warning: The 'http://purl.org/dc/elements/1.1/:publisher' element is not declared. Line 1082, position 8.
Schema validation warning: The 'http://purl.org/dc/elements/1.1/:contributor' element is not declared. Line 1083, position 8.
Schema validation warning: The 'http://purl.org/dc/elements/1.1/:date' element is not declared. Line 1084, position 8.
Schema validation warning: The 'http://purl.org/dc/elements/1.1/:type' element is not declared. Line 1085, position 8.
Schema validation warning: The 'http://purl.org/dc/elements/1.1/:identifier' element is not declared. Line 1086, position 8.
Schema validation warning: The 'http://purl.org/dc/elements/1.1/:source' element is not declared. Line 1087, position 8.
Schema validation warning: The 'http://purl.org/dc/elements/1.1/:language' element is not declared. Line 1088, position 8.
Schema validation warning: The 'http://purl.org/dc/elements/1.1/:relation' element is not declared. Line 1089, position 8.
Schema validation warning: The 'http://purl.org/dc/elements/1.1/:coverage' element is not declared. Line 1090, position 8.
Schema validation warning: The 'http://purl.org/dc/elements/1.1/:rights' element is not declared. Line 1091, position 8.

Warning: Schema could not be validated. Class generation may fail or may produce incorrect results.

Error: Error generating classes for schema 'AssessmentResult'.
- The element 'http://purl.org/dc/elements/1.1/:title' is missing.

If you would like more help, please type "xsd /?".

The error was related to the import of external schemas into the document. The solution is to download the external schemas and build your source using your target schema file as well as the import schema files.

In the example below, AssessmentResult.xsd is my target, XmlSignatureSyntaxProcessing.xsd and DublicCoreSimple.xsd are the imports in the AssessmentResult schema:

xsd AssessmentResult.xsd DublinCoreSimple.xsd XmlSignatureSyntaxProcessing.xsd /classes /fields /language:CS /namespace:hrxml.AssessmentResult

Voila!