Getting notified by a Windows process change in C# .NET

October 16, 2017 Leave a comment

In this post we saw an example of using the ManagementEventWatcher object and and EventQuery query. The SQL-like query was used to subscribe to a WMI – Windows Management Instrumentation – level event, namely a change in the status of a Windows service. I won’t repeat the explanation here again concerning the techniques used. So if this is new to you then consult that post, the code is very similar.

In this post we’ll see how to get notified by the creation of a new Windows process. This can be as simple as starting up Notepad. A Windows process is represented by the Win32_Process WMI class which will be used in the query. We’ll take a slightly different approach and use the WqlEventQuery object which derives from EventQuery.

Consider the following code:

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Filed under .NET, Diagnostics Tagged with , ,

Creating a new performance counter on Windows with C# .NET

October 15, 2017 Leave a comment

In this post we saw how to list all performance counter categories and the performance counters within each category available on Windows. The last time I checked there were a little more than 27500 counters and 148 categories available on my local PC. That’s quite a lot and will probably cover most diagnostic needs where performance counters are involved in a bottleneck investigation.

However, at times you might want to create your own performance counter. The System.Diagnostics library provides the necessary objects. Here’s how you can create a new performance counter category and a counter within that category:

string categoryName = "Football";
			
if (!PerformanceCounterCategory.Exists(categoryName))
{
	string firstCounterName = "Goals scored";
	string firstCounterHelp = "Goals scored live update";
	string categoryHelp = "Football related real time statistics";
				
	PerformanceCounterCategory customCategory = new PerformanceCounterCategory(categoryName);
	PerformanceCounterCategory.Create(categoryName, categoryHelp, PerformanceCounterCategoryType.SingleInstance, firstCounterName, firstCounterHelp);
}

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Reading and clearing a Windows Event Log with C# .NET

October 14, 2017 Leave a comment

In this post we saw how to create a custom event log and here how to the write to the event log. We’ll briefly look at how to read the entries from an event log and how to clear them.

First let’s create an event log and put some messages to it:

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Writing to the Windows Event Log with C# .NET

October 13, 2017 1 Comment

In this post we saw how to create and delete event logs. We’ve also seen a couple examples of writing to the event log. Here come some more examples.

Say you want to send a warning message to the System log:

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Creating and deleting event logs with C# .NET

October 12, 2017 Leave a comment

The Windows event viewer contains a lot of useful information on what happens on the system:

Windows event viewer

Windows will by default write a lot of information here at differing levels: information, warning, failure, success and error. You can also write to the event log, create new logs and delete them if the code has the EventLogPermission permission. However, bear in mind that it’s quite resource intensive to write to the event logs. So don’t use it for general logging purposes to record what’s happening in your application. Use it to record major but infrequent events like shutdown, severe failure, start-up or any out-of-the-ordinary cases.

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An overview of digital signatures in .NET

October 11, 2017 Leave a comment

Introduction

A digital signature in software has about the same role as a real signature on a document. It proves that a certain person has signed the document thereby authenticating it. A signature increases security around a document for both parties involved, i.e. the one who signed the document – the signee – and the one that uses the document afterwards. The one who signed can claim that the document belongs to them, i.e. it originates from them and cannot be used by another person. If you sign a bank loan request then you should receive the loan and not someone else. Also, the party that takes the document for further processing can be sure that it really originates from the person who signed it. The signee cannot claim that the signature belongs to some other person and they have nothing to do with the document. This latter is called non-repudiation. The signee cannot deny that the document originates from him or her.

Digital signatures in software are used to enhance messaging security. The receiver must be able to know for sure that the message originated with one specific sender and that the sender cannot claim that it was someone else who sent the message. While it is quite possible to copy someone’s signature on a paper document it is much harder to forge a strong digital signature.

In this post we’ll review how digital signatures are implemented in .NET

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Getting the list of supported Encoding types in .NET

October 9, 2017 Leave a comment

Every text file and string is encoded using one of many encoding standards. Normally .NET will handle encoding automatically but there are times when you need to dig into the internals for encoding and decoding. It’s very simple to retrieve the list of supported encoding types, a.k.a code pages in .NET:

EncodingInfo[] codePages = Encoding.GetEncodings();
foreach (EncodingInfo codePage in codePages)
{
	Console.WriteLine("Code page ID: {0}, IANA name: {1}, human-friendly display name: {2}", codePage.CodePage, codePage.Name, codePage.DisplayName);
}

Example output:

Code page ID: 37, IANA name: IBM037, human-friendly display name: IBM EBCDIC (US-Canada)
Code page ID: 852, IANA name: ibm852, human-friendly display name: Central European (DOS)

View all posts related to Globalization here.

Filed under .NET, Globalization Tagged with

Explicit interface implementation in .NET

September 19, 2017 Leave a comment

Introduction

The generic and well-known Dictionary object and its generic and thread-safe counterpart, i.e. the ConcurrentDictionary object both implement the generic IDictionary interface. The IDictionary interface has an Add method where you can insert a new key-value pair into a dictionary:

Dictionary<string, string> singleThreadedDictionary = new Dictionary<string, string>();
singleThreadedDictionary.Add("Key", "Value");

I can even rewrite the above code as follows:

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Setting the file access rule of a file with C# .NET

September 15, 2017 Leave a comment

When creating a new file you can set the access control rule for it in code. There are a couple of objects to build the puzzle.

The FileInfo class, which describes a file in a directory, has a SetAccessControl method which accepts a FileSecurity object. The FileSecurity object has an AddAccessRule method where you can pass in a FileSystemAccessRule object. The FileSystemAccessRule object has 4 overloads, 2 of which accept an IdentityReference abstract class. One of the implementations of IdentityReference is SecurityIdentifier. SecurityIdentifier in turn has 4 overloads where the last one is probably the most straightforward to use.

  • WellKnownSidType: an enumeration listing the commonly used security identifiers
  • A domainSid of type SecurityIdentifier: this can most often be ignored. Check out the MSDN link above to see which WellKnownSidType enumeration values require this

The following method will set the access control to “Everyone”, which is represented by WellKnownSidType.WorldSid. “Everyone” will have full control over the file indicated by FileSystemRights.FullControl and AccessControlType.Allow in the FileSystemAccessRule constructor:

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FIFO collections with Queue of T in .NET C#

September 13, 2017 Leave a comment

FIFO, that is first-in-first-out, collections are represented by the generic Queue of T class in .NET. Queues are collections where a new element is placed on top of the collection and is removed last when the items are retrieved.

Let’s say that you’re throwing a party where you follow a Queue policy as far as guests are concerned. As time goes by you’d like all of them to leave eventually and the first one to go will be the first person who has arrived. This is probably a fairer policy than what we saw in the post on stack collections.

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Filed under .NET, C# language features, Generics Tagged with ,

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