the art of debugging

The Art of Debugging

Shlomy GantzShlomy Gantz

02/13/0102/13/01

MDCFUGMDCFUG

““The Art of Debugging - Copyright Shlomy Gantz 2001 – 03/13/01The Art of Debugging - Copyright Shlomy Gantz 2001 – 03/13/01

Introduction - Famous Last words

“…“…if debugging is defined as the art of taking if debugging is defined as the art of taking bugs out of a program , programming must be bugs out of a program , programming must be putting them in…”putting them in…”

““..It’s not a bug, It’s a feature “ (Microsoft)..It’s not a bug, It’s a feature “ (Microsoft)


Types of bugs

Syntax ErrorSyntax Error

Run-Time ErrorsRun-Time Errors

Logical ErrorsLogical Errors


Types of bugs - Syntax Errors

Syntax Error ExampleSyntax Error Example

<CFSET ClientName = “Shlomy Gantz”>

<CFSET URLstr = URLstr & urlendcodedformat(ClientName) >

View ExampleView Example


Types of bugs - Run-Time Errors

Run-Time Error ExampleRun-Time Error Example

<CFQUERY NAME=“GetOverPaidEmp” Datasource=“Payroll”>

SELECT

SUM(Salary) AS TotalSalary,

COUNT(Emp_ID) as NumOfEmployees

FROM AnnualSalary

WHERE SALARY > 100000

</CFQUERY>

<CFSET AVGSalary = GetOverPaidEmp.TotalSalary / GetOverPaidEmp.NumOfEmployees >

<CFOUTPUT>#AVGSalary#</CFOUTPUT>



Types of bugs - Logical Errors

Logical Error exampleLogical Error example

<CFSET MyList=“Shlomy,Michael,Emily,Abraham”>

<CFSET ShlomyExists_YN = listfind(MyList,”shlomy”)>

<CFOUTPUT>#YesNoFormat(ShlomyExists_YN)#</CFOUTPUT>



Other things that can go wrong

Database connection (ODBC,MDAC …)Database connection (ODBC,MDAC …) Cold Fusion server Cold Fusion server Web ServerWeb Server OSOS HardwareHardware


Debugging Steps

PlanPlan Back-upBack-up IsolateIsolate Find The errorFind The error Fix - Don’t patchFix - Don’t patch Look for similarLook for similar DocumentDocument


“Debugger’s Block”

If all else failsIf all else fails

… … and if that doesn’t workand if that doesn’t work


Cold Fusion Administrator


Enable Performance Monitoring



Enable CFML stack trace

CF tracks what tags have run during page CF tracks what tags have run during page process. process.

Can be used either through CFTRY/CFCATCH Can be used either through CFTRY/CFCATCH or the Studio or the Studio

DebuggerDebugger


Show Variables

Show all variables processed by ColdFusion:Show all variables processed by ColdFusion:

• FORMFORM• URLURL• CGICGI• CookieCookie


Show Processing Time

Show how long, in milliseconds, it takes for a Show how long, in milliseconds, it takes for a page process to page process to

run to completionrun to completion


Detail View

Breakdown of all templates run during a page Breakdown of all templates run during a page process.process.

Proccessing time for each templateProccessing time for each template


Show SQL and Datasource Name

Shows SQL Statement & DSN in error messagesShows SQL Statement & DSN in error messages


Show Query Information

Query Name Query Name RecordCountRecordCount Processing Time Processing Time Query ExecutedQuery Executed


Display Template Path in Error Msg

Show the name of the actual template in which Show the name of the actual template in which with the error occurredwith the error occurred


Restrict Debug Access

By Default All when debugging is turned on all By Default All when debugging is turned on all users can see debug information.users can see debug information.

You can restrict access to the debugging info You can restrict access to the debugging info through this feature by IP addressthrough this feature by IP address


Debugging with studio

Setting up Development Mapping.Setting up Development Mapping.


Using the interactive debugger


Debugging CF applications

Show your variables (not only once)Show your variables (not only once) Create breakpoints and Follow the flowCreate breakpoints and Follow the flow Use Exception handlingUse Exception handling Look at your application logsLook at your application logs CF_ObjectDumpCF_ObjectDump


<CFABORT> & <CFOUTPUT>

Using CFABORT to create breakpointsUsing CFABORT to create breakpoints

<cfinclude template="Header.cfm">

<cfquery datasource="#dsn#" name="getContacts"> Select * from Contacts WHERE Active_YN=1 </cfquery>

<cfoutput>#getContacts.recordcount#</cfoutput> <cfabort>


<CFABORT> & <CFOUTPUT>

Following the flowFollowing the flow

<CFIF …………> Step 1

<CFIF ………………..> Step 1.1

<CFELSE>Step 1.2</CFIF>

<CFELSE> Step 2 </CFIF>



Debugging in CFML

<cfquery debug> <cfquery debug>

<cfstoredproc debug=“yes|no”><cfstoredproc debug=“yes|no”>

<cfsetting showdebug output=“yes/no”><cfsetting showdebug output=“yes/no”>




Debugging CF applications

<CFERROR><CFERROR> <CFTHROW><CFTHROW> <CFRETHROW><CFRETHROW> <CFCATCH><CFTRY><CFCATCH><CFTRY>


<CFERROR>

<CFERROR TYPE="Request" or <CFERROR TYPE="Request" or "Validation" or "Monitor" or "Exception" "Validation" or "Monitor" or "Exception" TEMPLATE="template_path" TEMPLATE="template_path" MAILTO="email_address" MAILTO="email_address" EXCEPTION="exception_type">EXCEPTION="exception_type">


<CFTRY><CFCATCH>

<CFTRY><CFTRY> ... Add code here... Add code here <CFCATCH TYPE="exceptiontype"> <CFCATCH TYPE="exceptiontype"> ... Add exception processing code here ... Add exception processing code here

</CFCATCH> </CFCATCH> ... Additional CFCATCH blocks go here ... Additional CFCATCH blocks go here

</CFTRY> </CFTRY>


Application Logs

Read your application logs regularly Read your application logs regularly

Error","TID=199","07/27/00","13:32:35","127.0.0.1","Mozilla/4.0 (compatible; MSIE 4.01; Windows NT)","An error has occurred. HTTP/1.0 404 Object Not Found" "Error","TID=199","07/27/00","13:32:45","127.0.0.1","Mozilla/4.0 (compatible; MSIE 4.01; Windows NT)","Error resolving parameter SLOT_IDColdFusion was unable to determine the value of the parameter. This problem is very likely due to the fact that either: You have misspelled the parameter name, or You have not specified a QUERY attribute for a CFOUTPUT, CFMAIL, or CFTABLE tag.The error occurred while evaluating the expression: #slot_id# The error occurred while processing an element with a general identifier of (#slot_id#), occupying document position (4:12) to (4:20) in the template file D:\wwwroot\cfun2000\Examples\JS\JSexample1_CFMW\edit_def.cfmThe specific sequence of files included or processed is:D:\WWWROOT\CFUN2000\EXAMPLES\JS\JSEXAMPLE1_CFMW\EDIT_DEF.CFM .Date/Time: 07/27/00 13:32:45Browser: Mozilla/4.0 (compatible; MSIE 4.01; Windows NT)Remote Address: 127.0.0.1HTTP Referer: http://127.0.0.1/cfun2000/Examples/JS/JSexample1_CFMW/EDIT.HTMLTemplate: D:\wwwroot\cfun2000\Examples\JS\JSexample1_CFMW\edit_def.cfm" "Warning","TID=152","07/27/00","15:07:21","In a CF_TagName construct custom tag file 'C:\CFUSION\CustomTags\Pages.cfm' will occlude custom tag file 'C:\CFUSION\CustomTags\cf_pages\Pages.cfm'." "Warning","TID=152","07/27/00","15:07:21","In a CF_TagName construct custom tag file 'C:\CFUSION\CustomTags\Pages.cfm' will occlude custom tag file 'C:\CFUSION\CustomTags\cf_pages\images\Pages.cfm'."



CF_Objectdump

Read your application logs regularly Read your application logs regularly

<CF_ObjectDump Object="#Object#" Deserialize="yes|no" >



Debugging Databases

SQL query analyzerSQL query analyzer


Debugging JavaScript

““Microsoft Script debugger”/“Netscape Microsoft Script debugger”/“Netscape JavaScript Debugger”JavaScript Debugger”

Using alert() and return false;Using alert() and return false;


Debugging flash

No debug outputNo debug output

simulated flash requestssimulated flash requests

output in flashoutput in flash


Tools

http://www.secretagents.com/http://www.secretagents.com/ BugTraqBugTraq http://www.logviewer.com/ http://www.logviewer.com/ Automatic Code Generation ToolsAutomatic Code Generation Tools

• CodeSaver / CodeCharge / CommerceBlocksCodeSaver / CodeCharge / CommerceBlocks


What’s new in 5.0

Easier Log AnalysisEasier Log Analysis


What’s new in 5.0

New options on CF Admin debug settingNew options on CF Admin debug setting


Thank You

Michael Dinowitz, Emily Kim, Michael Imhoff Michael Dinowitz, Emily Kim, Michael Imhoff and Abraham Lloyd.and Abraham Lloyd.

… … Michael SmithMichael Smith


QA

Shlomy GantzShlomy Gantz

[email protected]@hotmail.com

http://www.shlomygantz.comhttp://www.shlomygantz.com

the art of debugging

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