Archive for the 'c#' Category

Comparison of .Net libraries for fetching emails via POP3

Published on August 13, 2010 in c#. 0 Comments Tags: , , .

Sending emails in C# is easy; for basic use cases you don’t need external resources to send a note because .NET BCL already ships it. On .Net Developer Center, there’s a short description how to do it.

Now, how to fetch the email? It turns out it is not that easy – it’s not supported by .Net BCL. I spent a while researching for the best library that matched my purposes and I want to share my views on a couple of components I looked at.

Note: Please bear in mind I was interested only in a small piece of functionality such library could provide. My need was only to fetch an email (in plain text) with attachments. That was supposed to be done via POP3. I was not really interested in features like advanced sending emails (e.g. email templates), request and delivery receipts, support for iCalendar, email in HTML, etc. To sum up, I did not test libraries from that angle and therefore this comparison will not suit needs of all developers.

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An attempt was made to load a program with an incorrect format. Exception from HRESULT: 0x8007000B (BadImageFormatException)

Published on June 29, 2010 in c# and visual studio. 2 Comments Tags: , .

Note: I assume you can rebuild the program you are having problems with because changes in its configuration settings are required.

If you are struggling with this problem you are probably running 64bit OS and executing 64bit exe that loads 32bit dll, or the other way – 32bit OS on which 32bit exe tries loading 64bit dll. For the sake of this post, let’s assume this is the former matter.

Solution

You need to assure that 32bit dll is loaded by the program with the same bittness, even if it’s running on 64bit platform.

In order to achieve that you need to change the configuration settings of the project whose outcome is that exe so that platform target is always x86, disregarding configuration platform. Let’s assume that program is written in C#.

Open project’s properties, go to Build tab and make change as below:

cs project settings 350x140 An attempt was made to load a program with an incorrect format. Exception from HRESULT: 0x8007000B (BadImageFormatException)

How to invoke a common coded web test method from GetRequestEnumerator()?

Published on January 23, 2010 in c# and web testing. 0 Comments Tags: , , .

It’s a fact that coded web test methods give more flexibility to the developer, i.e. common code reuse. So let’s create a coded web test in whose GetRequestEnumerator() method you want to call a common method which tests some other requests. Let’s make it look as GetCommonRequests() in the example below:

public class AWebTest : WebTest
{
    private IEnumerator<WebTestRequest> GetCommonRequests()
    {
        WebTestRequest req1 = new WebTestRequest("http://google.com");
        yield return req1;

        WebTestRequest req2 = new WebTestRequest("http://google.com");
        yield return req2;
    }

    public override IEnumerator<WebTestRequest> GetRequestEnumerator()
    {
        WebTestRequest req = new WebTestRequest("http://google.com");
        yield return req;

        GetCommonRequests();
    }
}

You would expect to see three requests in the test result. You will see only one though…

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How to quickly add logging to a coded web test?

Published on January 22, 2010 in c# and web testing. 0 Comments Tags: , .

A coded web test, as opposed to a basic web test, brings more flexibility to the developer: conditioning, looping, code re-usage, etc. If you haven’t created one yet, you can follow an instruction on MSDN.

Now, because a coded web test can have some logic inside, it makes sense to add logging so that there’s a trace on what’s going on while it executes.

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Robust generation of XML documentation comments for C#

Published on May 30, 2009 in .net, c#, software and visual studio. 1 Comment Tags: , , .

Writing comments is something you need to get used to; sooner or later you will understand it’s worth writing comments. Haven’t you find yourself in a sitation where you don’t understand what a couple of lines of YOUR OWN code do? I have…

XML documentation comments are also important, particularly for public members/methods. Even if your project doesn’t require generating full XML documentation of the code, using Intellisense can be much more effective if it summarizes the method you are trying to use. If you want to generate XML documentation for C# in the twinkling of an eye you MUST install Roland Weigelt’s GhostDoc plugin for Visual Studio. Let me cite the author:

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Castle.ActiveRecord.Framework.ActiveRecordException: Could not perform Delete for XXX —> NHibernate.Exceptions.GenericADOException: could not delete collection

Published on May 19, 2009 in .net, c# and hibernate. 1 Comment Tags: , .

The beginning of the stack trace I got today looked as below:

2009-05-19 11:01:45,078 ERROR [5232] XXX - Speaker already deleted: Castle.ActiveRecord.Framework.ActiveRecordException: Could not perform Delete for Speaker ---> NHibernate.Exceptions.GenericADOException: could not delete collection: [XXX#XXX][SQL: SQL not available] ---> System.Data.SqlClient.SqlException: Cannot insert the value NULL into column 'SpeakerId', table 'XXX.dbo.lnk_Session_Speaker'; column does not allow nulls. UPDATE fails.
The statement has been terminated.
   ...
   at SpeakerProxy3e9fd3b0e82745c2b91b8a353acaa93d.DeleteAndFlush()

Background

I had three tables and classes representing them: Session / app_Session, Speaker / app_Speaker, and SessionSpeaker / lnk_Session_Speaker.

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C# 3.0 Pocket Reference: Instant Help for C# 3.0 Programmers

Published on May 14, 2009 in books and c#. 0 Comments Tags: , .

For those who work with C# I’d like to recommend a book which is a kind of summary of knowledge on C# 3.0. The book is quite short (and small by the way – yet pocket reference) but it covers lots of details on C# and describes what’s new in C# 3.0. Everything in short and simple, with code snippets.

I read this book as a first step towards TS: Microsoft .NET Framework – Application Development Foundation. Basically, I’ve started wondering if passing this exam is not a good step in my .NET career and this is the entry point.

Anyway this book is not a C# bible, but it can really help as a knowledge reresher.

Recommended.

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C#, decimal.toString(), and how to get rid of trailing zeros

Published on May 14, 2009 in .net, c# and convertion. 6 Comments Tags: , .

Today I spend A LOT OF time on trying to display a percentage – string representation of a decimal but without trailing zeros, e.g. 15.1% instead of 15.10%.

In the application I already had NumberFormatInfo for displaying monetary values and percentages. An object of that type was defined as follows:

NumberFormatInfo nfi = new NumberFormatInfo();
nfi.PercentDecimalDigits = 2;
// some additional settings for nfi
// (including monetary and numeric attributes)

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System.Net.WebException: The underlying connection was closed: Could not establish trust relationship for the SSL/TLS secure channel.

Published on April 1, 2009 in .net, c# and security. 26 Comments Tags: , .

One of my applications was supposed to use image having its URL. The Image was instantiated with the stream the server that stored the image file responded with after being requested as below:

// create a request for image
HttpWebRequest request = (HttpWebRequest)WebRequest.Create(IMAGE_URL);
request.Method = "GET";
request.ContentType = "multipart/form-data";
request.UserAgent = "Mozilla/4.0+(compatible;+MSIE+5.01;+Windows+NT+5.0";
request.Proxy.Credentials = CredentialCache.DefaultCredentials;
request.Credentials = CredentialCache.DefaultCredentials;

// get response from the server
HttpWebResponse response = (HttpWebResponse)request.GetResponse();
Stream resStream = response.GetResponseStream();

// create image from stream
Image image = Image.FromStream(resStream);

It worked like a charm when TCP port was used (regular, non-decure connection) but whenever the image was available at a URL that was secured (https://xxx.xx) I was getting the following stack trace:

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MonoRail – RenderMailMessage – System.ArgumentNullException: Value cannot be null. Parameter name: format

Published on March 27, 2009 in .net, MonoRail and c#. 0 Comments Tags: , .

This was a nasty issue…

System.Reflection.TargetInvocationException: Exception has been thrown by the target of an invocation. ---> System.ArgumentNullException:
Value cannot be null.
Parameter name: format
   at System.String.Format(IFormatProvider provider, String format, Object[] args)
   at System.String.Format(String format, Object arg0, Object arg1)
   --- End of inner exception stack trace ---

Background

This is part of the stack trace I got in one of my applications which uses MonoRail. I got it while creating the Castle.Components.Common.EmailSender.Message in order to prepare the content of the email having the name of its template file (vm):

Message msg = RenderMailMessage(templateName)

That view file defined the content and used data from PropertyBag and from Resource files.

Just to recall a resource file (resx) is bound with the controller class with this definition:

[Resource("text", "LocalizationSample.Resources.Home")]

What was wrong there? I was sure templateName passed as the parameter was correct – it for sure pointed to correct vm file. Moreover, that piece of code was defined in a superclass which was extended by this particular controller and another one which also could send this email. Of course there was no problem with sending email by the latter.

Solution

The problem here was I used this construction in the vm file:

$string.format($text.someText, $param1, $param2)

And for some reason I forgot to bind the appropriate resource file (the one referenced with $text) with one of the controllers. As a result string.format failed because $param1 and $param2 couldn’t be injected into string which was not found.