exception management - techcello · 2014. 7. 10. · 6 exception handling exception management...

Cello How-To Guide

Exception Management

2

Exception Handling


Contents 1 Exception handling ..................................................................................................................................... 3

1.1.1 Exception Storage ........................................................................................................................ 3

1.1.2 Exception Service ......................................................................................................................... 5

1.1.3 Example Consumption ................................................................................................................. 5

1.1.4 Exception logging related Configuration...................................................................................... 6

1.1.5 Viewing Exceptions and logs in UI ................................................................................................ 9

1.1.6 How to disable Logging ................................................................................................................ 9

2 Contact Information ................................................................................................................................. 11

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Exception Handling


1 Exception handling

Exceptions are the standard mechanism for reporting errors occur in the application and the proper usage of

exceptions adds to a consistent framework design and allows error reporting from members, such as

constructors, that cannot have a return type.

A matured, well architected application will be the one, if it adheres to the following aspects.

Auditable – all actions that affect user/data/application state are formally tracked.

Traceable – To determine who/when/where/how an activity occurred throughout the application.

High integrity – Logged information must not be overwritten or tampered by local or remote users.

CelloSaaS Framework provides a wrapper over Microsoft’s Enterprise Library to help SaaS application

developers to capture and manage the exceptions with ease. The Exception Service help the application to

track down the entire exception messages to help the developers and operations team to analyze and find

the root cause of the issue.

Note: Never log critical, secured or important data. If required please mask or encrypt them before writing

to log.

Recommendation:

Generally, Exception logging is considered as a bad practice, because of the improper implementations i.e.

Capturing exceptions throughout all the tiers/layers, unnecessarily throwing the error codes etc. The

recommended approach would be to validate the exception inputs and throw specific exceptions only if the

validation fails. Always write code which works under certain well defined boundary, and throw exceptions

instead of logging and continuing the logic or failing safely. This helps to ensure the written application is

stable (exceptions occurrences are less or null).

1.1.1 Exception Storage

The storage destination has to be decided in the first place as to where the exceptions have to be stored. The

Exceptions can be stored in

1. File

2. Database

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Exception Handling


1.1.1.1 Logging to a file destination

To log the exception in file, use the Microsoft EnterpriseLibrary’s TraceListeners. By default use the

RollingFlatFileTraceListener as follows in the logging.config. (Refer screenshot below)

Logging.Config

1.1.1.2 Logging to Database To log the exceptions in database, use the cello’s DatabaseTraceListener under CelloSaaS.Library namespace.

Cello’s database listener can be added as following in the Logging.config file. To change the database, update databaseInstanceName (highlighted above) in the config file.

<add name="EventScheduler Listner" fileName="Logs\EventScheduler.log"

type="Microsoft.Practices.EnterpriseLibrary.Logging.TraceListeners.RollingFlatFileTraceListener,

Microsoft.Practices.EnterpriseLibrary.Logging, Version=4.0.0.0, Culture=neutral,

PublicKeyToken=31bf3856ad364e35"

listenerDataType="Microsoft.Practices.EnterpriseLibrary.Logging.Configuration.RollingFlatFileTraceListenerData,


PublicKeyToken=31bf3856ad364e35" timeStampPattern="yyyy-MM-dd" rollFileExistsBehavior="Increment"

rollInterval="Day" traceOutputOptions="None" rollSizeKB="4096" />

<add name="Database Trace Listener" type="CelloSaaS.Library.DatabaseTraceListener, CelloSaaS.Library" listenerDataType="CelloSaaS.Library.DatabaseTraceListenerData, CelloSaaS.Library" databaseInstanceName="CelloSaaSConnectionString" writeLogStoredProcName="WriteExceptionLog" addCategoryStoredProcName="AddExceptionCategory" formatter="Text Formatter" traceOutputOptions="LogicalOperationStack, DateTime, Timestamp" />

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Exception Handling


Logging.Config

Note:

Developers need to create only one database trace listener and redirect all category logs to it.

Developers are advised to have either DB Listener or File Lister for a given application to avoid

duplication of data in both DB as well as File.

1.1.2 Exception Service

1.1.3 Example Consumption

/// Handles the exception with the configured policies /// <param name="exception">Exception to handle</param> /// <param name="policyName">Policy name of the handler (defaults to GlobalExceptionLogger if null)</param> /// <returns>boolean specifying if the exception needs to be rethrown</returns> bool HandleException(Exception exception, string policyName);

try { // your code goes here } catch (DbException dbException) { ExceptionService.HandleException(dbException, null); // uses default policy ExceptionService.HandleException(dbException, "EmployeeExceptionPolicy”); }

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Exception Handling


1.1.4 Exception logging related Configuration Add the below configurations in web.config under <<CofigSections>> (Refer the below Screenshot) file to

enable exception and logging in your application.

Step 1 :

Web.Config

Step 2:

Add the below configuration in logging.config file found under Config Folder inside the web project. Refer

Screenshot

<configSections>

<section name="loggingConfiguration" type="Microsoft.Practices.EnterpriseLibrary.Logging.Configuration.LoggingSettings, Microsoft.Practices.EnterpriseLibrary.Logging" /> <section name="exceptionHandling"

type="CelloSaaS.Library.Configuration.ExceptionHandlingSettings, CelloSaaS.Library"

/></configSections>

<loggingConfiguration name="Logging Application Block" tracingEnabled="true" defaultCategory="General" logWarningsWhenNoCategoriesMatch="true"> <listeners>  <add name="Database Trace Listener" type="CelloSaaS.Library.DatabaseTraceListener, CelloSaaS.Library" listenerDataType="CelloSaaS.Library.DatabaseTraceListenerData, CelloSaaS.Library" databaseInstanceName="CelloSaaSConnectionString" writeLogStoredProcName="WriteExceptionLog" addCategoryStoredProcName="AddExceptionCategory" formatter="Text Formatter" traceOutputOptions="LogicalOperationStack, DateTime, Timestamp" />  <add name="Formatted EventLog TraceListener" source="CelloSaaS Application" formatter="Text Formatter" log="Application" machineName="" type="Microsoft.Practices.EnterpriseLibrary.Logging.TraceListeners.FormattedEventLogTraceListener, Microsoft.Practices.EnterpriseLibrary.Logging, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" listenerDataType="Microsoft.Practices.EnterpriseLibrary.Logging.Configuration.FormattedEventLogTraceListenerData, Microsoft.Practices.EnterpriseLibrary.Logging, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" traceOutputOptions="None" />

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Exception Handling


 <add name="General Listener" fileName="Logs\UnHandledExceptions.log"

type="Microsoft.Practices.EnterpriseLibrary.Logging.TraceListeners.RollingFlatFileTraceListener

, Microsoft.Practices.EnterpriseLibrary.Logging, Version=4.0.0.0, Culture=neutral,

PublicKeyToken=31bf3856ad364e35"

listenerDataType="Microsoft.Practices.EnterpriseLibrary.Logging.Configuration.RollingFlatFileTr

aceListenerData, Microsoft.Practices.EnterpriseLibrary.Logging, Version=4.0.0.0,

Culture=neutral, PublicKeyToken=31bf3856ad364e35" timeStampPattern="yyyy-MM-dd"

rollFileExistsBehavior="Increment" rollInterval="Day" traceOutputOptions="None"

rollSizeKB="4096" />

</listeners>

<formatters>

<add name="Text Formatter" template="Timestamp: {timestamp}
Message:

{message}
Category: {category}
Priority: {priority}
EventId:

{eventid}
Severity: {severity}
Title:{title}
Machine: {machine}
Application

Domain: {appDomain}
Process Id: {processId}
Process Name: {processName}
Win32

Thread Id: {win32ThreadId}
Thread Name: {threadName}
Extended Properties:

{dictionary({key} - {value}
)}"

type="Microsoft.Practices.EnterpriseLibrary.Logging.Formatters.TextFormatter,


PublicKeyToken=31bf3856ad364e35" />

</formatters>

<categorySources>

<add switchValue="All" name="General">

<listeners>

<add name="Database Trace Listener" /> 

<add name="General Listener" /> 

</listeners>

</add>

</categorySources>

</loggingConfiguration>

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Exception Handling


Logging.Config

Step4 :

Finally add the below configurations in the ExceptionHandling.config file located in Config Folder inside the

Web Project.

ExceptionHandling.config

<exceptionHandling> <exceptionPolicies> <add name="GlobalExceptionLogger"> <exceptionTypes> <add type="System.Exception, mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" postHandlingAction="None" name="Exception"> <exceptionHandlers> <add logCategory="General" eventId="100" severity="Error" title="Enterprise Library Exception Handling" formatterType="Microsoft.Practices.EnterpriseLibrary.ExceptionHandling.XmlExceptionFormatter, Microsoft.Practices.EnterpriseLibrary.ExceptionHandling, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" priority="0" type="Microsoft.Practices.EnterpriseLibrary.ExceptionHandling.Logging.LoggingExceptionHandler, Microsoft.Practices.EnterpriseLibrary.ExceptionHandling.Logging, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" name="General Logging Handler" /> </exceptionHandlers> </add> </exceptionTypes> </add>

</exceptionPolicies>

</exceptionHandling>

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Exception Handling


More information on configuration visit https://entlib.codeplex.com/

Note: Incase if you want to use separate database to store the Exceptions, the necessary Scripts and store

procedures related to Exception management feature are available in the DBScripts.sql provided in the

package.

1.1.5 Viewing Exceptions and logs in UI

CelloSaaS provides User interface to view, search exceptions captured in the application.

To access the Exception details, navigate to Monitor -> Exceptions & Logs

Exception & Logs

Note: Exception User Interface is only applicable when CelloSaaS database trace listener is used and not for

File Listener.

1.1.6 How to disable Logging

Logging can be either disabled throughout the application or disable for selective modules or features. To

avoid Exception logging, you can simply change the configuration in Logging.config present in the Config

folder under the Web Project (Refer the below Screenshot).

Change the Switch Value to either one of the below values.

Switch Value Description

All Allows all events through

Critical Allows only Critical events through. A critical event is a fatal error or application crash

https://entlib.codeplex.com/

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Exception Handling


Error Allows Critical and Error events through. An Error event is a recoverable error.

Information Allows Critical, Error, Warning, and Information events through. An information event is an

informational message.

Off Does not allow any events through.

Verbose Allows Critical, Error, Warning, Information, and Verbose events through. A Verbose event is a

debugging trace.

Warning Allows Critical, Error, and Warning events through. A Warning event is a non-critical problem.

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Exception Handling


2 Contact Information Any problem using this guide (or) using Cello Framework. Please feel free to contact us, we will be happy to

assist you in getting started with Cello.

Email: [email protected]

Phone: +1(609)503-7163

Skype: techcello

mailto:[email protected]

exception management - techcello · 2014. 7. 10. · 6 exception handling exception management...

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