Back-2-Basics: Exception & Event Instrumentation in .NET

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Summary
5

Logging Exceptions & Events

Why Do We Need To?
Debugging statements only work in debug builds and while in VS
No way to tell what applications are doing during runtime
Need to log exceptions for evaluation by support & development teams
Need to log other information during runtime
Log information for reporting
7

Logging Methods You Use?
Log to Event log?
Custom text files?
Custom xml files?
Database?
….

The .NET Solution
Trace Listeners!
Easy to use from any .NET application including ASP.NET!!
Extremely configurable
Easy to write your own listeners

.NET Trace Listeners

Overview
Write informative messages about the execution of an application at run time.
Phases
Instrumentation — you add trace code to your application.
Tracing — the tracing code writes information to the specified target.
Analysis — you evaluate the tracing information to identify and understand problems in the application.
11

Overview
Output is written to one to many listeners.
Part of the Trace.Listeners collection
Output Methods:
Assert - The specified text; or, if none is specified, the Call Stack.
Fail - The specified text; or, if none is specified, the Call Stack.
Write
WriteIf
WriteLine
WriteLineIf

Out of the Box Listeners
TextWriterTraceListener
Writes to the TextWriter or Steam class
EventLogTraceListener
Writes to an event log
Event works with ASP.NET!
DefaultTraceListener
Writes Write and WriteLine messages to the OutputDebugString and to the Debugger.Log method (debug window in VS)

Out of the Box Listeners
ConsoleTraceListener
Writes output to the console window
DelimitedListTraceListener
Writes to the text writer in a delimited text format
XmlWriterTraceListener
Writes to xml file.

Configuration
Done via code or application config file
Turn off/ on listeners
Set trace levels
Set filters

Configuration Example
<system.diagnostics>
<sources>
<source name="DefaultSource" switchName="DefaultSwitch">
<listeners>
<add name="FileLog"/>
</listeners>
</source>
</sources>
<switches>
<add name="DefaultSwitch" value="Information" />
</switches>
<sharedListeners>
<add name="FileLog“ type="Microsoft.VisualBasic.Logging.FileLogTraceListener, Microsoft.VisualBasic, Version=8.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a, processorArchitecture=MSIL“ initializeData="FileLogWriter"/>
</sharedListeners>
</system.diagnostics>

Add custom functionality & enhance .NET listeners
Custom Trace Listeners

Overview
Create your own listeners or enhance current listeners
Inherit TraceListener
Override:
Write - writes the specified message to the listener.
WriteLine - Writes a message to the listener.
TraceEvent - Writes trace information, a message, and event information to the listener specific output.
19

Overview
Override:
TraceData - Writes trace information, a data object and event information to the listener specific output.
GetSupportedAttributes - Gets the custom attributes supported by the trace listener.
Add to config file
In place or in addition to the .NET listeners.
20

Issues with .NET Listeners
XmlWriterTraceListener
Does not write well formed xml
Creates one huge file
With ASP.NET it says locked
Can not move, delete etc. 
Can not view latest trace writes
Due to flushing issues
Most other file based listeners most likely suffer from the same issues

Taking Exception & Event logging to the extreme!
dotNetTips.Utility Listeners

Overview
Listeners part of the dotNetTips.Utility
Open source project available at http://codeplex.com/dotnettips
Current version requires .NET 3.5
Fixes/ enhances .NET Listeners
Adds new Listeners
Outputs A LOT more debugging info!
Add custom information during runtime!
Built-in configuration!
23

Advanced Debugging Info
Via the LogEntry class
Automatic when logging Exceptions:
Tread/ Process information
Domain name
Application information
User information
Computer information
Auto log class and method where Exception happened
Much more!

More on LogEntry
Add custom information into a collection
Additional properties
Category
Id (GUID)
User
MachineName
Severity
Source
SourceVersion

Enhanced Listeners
EventLogTraceListeners
XmlTraceListeners
Fixes all issues of the .NET implementation!
Writes well formed xml!
Does not lock file!
Creates a new file for each day
Automatic delete of old files (configurable)

Added Listeners
EmailTraceListener
Email trace events via smtp server
WebServiceTraceListener
Sends trace events to a web service method
TCPTraceListener (coming soon)
Sends trace events to TCP listeners
Watch events in real time!

Writing Exceptions/ Events
Use LogWriter
Custom for logging Exceptions, Events and LogEntry
Logging Exceptions and Events uses LogEntry under the hood
Writes to the correct log collection based on type of application
Methods
WriteEntry
Messages (events) and LogEntry
WriteException

Lets Kick It Up A Notch!
Centralized Logging System

The Problem
Each client/ server machine logs locally
Support has to logon to each machine to read events
Not possible sometimes at client location
No search capabilities
Server
Server
Server
Log
File
Log
File
Log
File
Server
Server
Server
Log
File
Log
File
Log
File
31

The Solution
Centralized Logging System
Uses WebServerTraceListener
Writes to web service that stores events in SQL Server
Search/View for Events via ASP.NET!
Client or Server
Web
Service
SQL
Server
ASP.
NET

Summary
Use TraceListeners to log Exceptions/ Events!
Use my Centralized Logging System
dotNetTips.Utility (codeplex.com/dotnettips)
ASP.NET site/ database (dotNetTips.com)
Also look into the Enterprise Library
Lots more then just logging

Back-2-Basics: Exception & Event Instrumentation in .NET

by David McCarter on Jun 28, 2010

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Back-2-Basics: Exception & Event Instrumentation in .NET — Presentation Transcript