Develop Reference

How does this log method work in a .NET application?

I am working on a .NET project using C# and I have the following doubt.
I have this method that write some error information into a .log file in a specific directory on my file system:
private static void writeErrorLog(string error)
{
string date = DateTime.Now.ToString("yyyyMMdd_HHmmss");
string currDir = Directory.GetCurrentDirectory();
System.IO.File.AppendAllText(currDir + "\\FILE\\LOG\\Error_" + date + ".txt", error);
}
Ok this writeErrorLog() method will be called into some try catch block of my code, something like this:
try
{
currentAttachmentFileData = currentAttachmentFile.OpenBinary();
currentAttachementModel = new AttachmentModel(currentAttachment, currentAttachmentFileData);
attachmentsModelList.Add(currentAttachementModel);
}
catch (Exception ex)
{
//writeLog(2, String.Format("Unable to read the attachment, it may be corrupted {0} - {1}", fileName, ex.Message));
writeErrorLog("Errore inserimento attachment. Numero protocollo: " + recNumber
+ " Data protocollo: " + recDate
+ " Nome attachment: " + currentAttachmentFile
+ " INFO: " + ex.ToString() + " | " + ex.Message + " | " + ex.StackTrace);
}
It happens in different places of my code.
My doubt is: the file is the same, so it means that it will be added a new line to this file every time that an error occours.
Is it my reasnong correct?

The file name is string date = DateTime.Now.ToString("yyyyMMdd_HHmmss"); so it changes every second.
You should definitely add some abstraction here and hide writeErrorLog behind an interface. Behind the interface you could have your own implementation of writeErrorLog, but as others suggested I would strongly recommend using libs over your custom solution.
More on available libraries:
benchmarking-5-popular-net-logging-libraries
dotnetlogging.com

Best way to fix: Acces to path 'C:\..\USB-map' is denied because map is already used

I am trying to make to create a .cmd file with this code into it: call .\CopyToTarget.cmd w60 glb "C:\Users\oma\me\trunk-r664\USB-map". I am creating this code ~5 times.
But since \trunk-r664\ is already in use it seems like I cannot write: #"\trunk-r664\USB-map" into the .cmd file for some reason. Does anyone know how to fix it? It keeps getting me the error: UnauthorizedAccesExpection was unhandled, ccess to the path 'C:\Users\me\Desktop\trunk-r664\USB-map' is denied.
using (StreamWriter sw = File.CreateText(Environment.GetFolderPath(Environment.SpecialFolder.Desktop)
+ "\\trunk-r664\\trunk\\cmd\\custom\\RunAll.cmd"))
{
for (int j=0;j<installeerlijst64.Count;j++)
{
sw.WriteLine("call .\\CopyToTarget.cmd " + installeerlijst64[j] + " glb" +
File.CreateText(Environment.GetFolderPath(Environment.SpecialFolder.Desktop) + #"\trunk-r664\USB-map"));
}
}
I tried this too, but it tells me I am using an illegal character:
"\""+File.CreateText(Environment.GetFolderPath(Environment.SpecialFolder.Desktop)
+ #"\trunk-r664\USB-map" + "\""));

File.CreateText will create a new file. First time when for loop execute, it will create and open the file USB-map and hold the handle of that file. During second iteration of for loop, it will try to do the same thing. Hence, already in use error.
Remove File.CreateText and you will get the desired result.
sw.WriteLine("call .\\CopyToTarget.cmd " + installeerlijst64[j] + " glb " + "\"" +
Environment.GetFolderPath(Environment.SpecialFolder.Desktop) + #"\trunk-r664\USB-map" + "\"");

Saving values from recurring function into file

I have this piece of code written in C# (it's part of implementation of ID3 algorithm)
public static void printNode(TreeNode root, string tabs, ref StreamWriter xa)
{
//Console.ReadKey();
Console.WriteLine(tabs + '|' + root.attribute + '|');
if (root.attribute.values != null)
{
for (int i = 0; i < root.attribute.values.Length; i++)
{
Console.WriteLine(tabs + "\t" + "<" + root.attribute.values[i] + ">");
xa.WriteLine(tabs + "\n" + root.attribute.values[i] +"\n");
TreeNode childNode = root.getChildByBranchName(root.attribute.values[i]);
printNode(childNode, "\t" + tabs, ref xa);
}
}
}
I also have this declaration.
StreamWriter xa = new StreamWriter("tree1.txt");
And issue is that after running code file 'tree1.txt' is always empty. Any idea how to handle this? As you can see I tried references cause it seems to me like right course of action but I don't really know much about C# and recurrence function behaviour.

You need to close the StreamWriter to force it to flush to disk.
You also need to look in the current directory, which might not be what you think it is.

C# / Webservice app on server throwing strange exception

We use ADP for employee information. I had to create a small app that called some web services that ADP has to pull employee information. The app is fairly procedural..not really object orientated in a sense. Basically I go through some web services to pull general information, work information, employee status, etc.
I have most of this data writing out to a text file as a log so I can ensure that everything is working correctly. Finally got it all done, and it works perfect on my local machine. Thought I'd just copy the entire structure onto a server and use windows scheduler to schedule the exe to run nightly (once a day). When it tries to run the app it looks like it is dying when it calls the first web service. The task scheduler log says:
""ADP.job" (ADP.exe)
Started 2/11/2010 2:14:34 PM
"ADP.job" (ADP.exe)
Finished 2/11/2010 2:14:38 PM
Result: The task completed with an exit code of (e0434f4d)."
So I checked the event viewer and it says this:
EventType clr20r3, P1 adp.exe, P2 1.0.0.0, P3 4b745bb9, P4 adp, P5 1.0.0.0, P6 4b745bb9, P7 289, P8 2d, P9 system.io.filenotfoundexception, P10 NIL.
For more information, see Help and Support Center at http://go.microsoft.com/fwlink/events.asp.
I put in some console.writelines to see where it is failing...
Here is a simple example of main:
static void Main(string[] args)
{
OpenTextFile();
Console.WriteLine("About to process employee work information...");
tw.WriteLine("About to process employee work information...");
//work info service
EmpWorkInfo();
}
And inside of opentextfile:
public static void OpenTextFile()
{
//used to log data
String sLogName;
Console.WriteLine("Inside of opentextfile");
if (Directory.Exists(logPath))
{
//directory exists
}
else
{
Directory.CreateDirectory(logPath);
}
Console.WriteLine("Inside of opentextfile2");
sLogName = "log_" + DateTime.Today.ToString("MM_dd_yyyy") + ".txt";
tw = new StreamWriter(logPath + sLogName);
}
I see all the console.writelines on the server but as soon as it hits this line from main:
EmpWorkInfo();
Thats when all hell breaks lose (basically it doesn't work). The EmpWorkInfo() is simply a function to get work related information from a web service (as I said this works locally).
static void EmpWorkInfo()
{
Console.Writeline("THIS NEVER PRINTS!!!");
SQLClass s=null;
// Create the web service proxy client.
GetEmployeeWorkInfoService oService = new GetEmployeeWorkInfoService();
oService.Timeout = Int32.MaxValue;
// Serialize the UsernameToken into XML.
// Create the UsernameToken as defined in the WS-I secure profile.
UsernameToken oUsernameToken = new UsernameToken(USERNAME, SECRET);
System.Xml.XmlElement oSecurityHeaderXml =
oUsernameToken.GetXml(new System.Xml.XmlDocument());
ADP.GetEmployeeWorkInfoWebService.SecurityHeaderType oSecurityHeader = new ADP.GetEmployeeWorkInfoWebService.SecurityHeaderType();
oSecurityHeader.Any = new System.Xml.XmlElement[] { oSecurityHeaderXml };
oService.Security = oSecurityHeader;
GetEmployeeWorkInfoRequestFilter oFilter = new GetEmployeeWorkInfoRequestFilter();
//filter by thyssenkrupp company
oFilter.Companies = new String[] { COMPANY_IDENTIFIER };
GetEmployeeWorkInfoRequest oRequest = new GetEmployeeWorkInfoRequest();
oRequest.Filter = oFilter;
try
{
EmployeeWorkInfoType[] arPersonalInfo = oService.GetEmployeeWorkInfo(oRequest);
try
{
s = new SQLClass();
}
catch (Exception e)
{
throw new System.Exception(e.Message.ToString());
}
for (int i = 0; i < arPersonalInfo.Length; i++)
{
String stID = arPersonalInfo[i].EmployeeKey.Identifier.EmployeeId; //employee number
String stEmailAddress = arPersonalInfo[i].WorkInfo.EmailAddress; //employee email address (work)
String stFax = arPersonalInfo[i].WorkInfo.Fax; //employee fax number
DateTime dtHireDate = arPersonalInfo[i].WorkInfo.OriginalHireDate;
String stPhone = arPersonalInfo[i].WorkInfo.Phone; //employee phone number
String stWireless = arPersonalInfo[i].WorkInfo.Wireless; //employee wireless number
tw.WriteLine("Processing ID:" + stID + " Email Work: " + stEmailAddress + " Fax Work: " + stFax + " Hire Date: " + dtHireDate + " Phone Work: " + stPhone + " Wireless Work: " + stWireless + ".");
Console.WriteLine("Processing ID:" + stID + " Email Work: " + stEmailAddress + " Fax Work: " + stFax + " Hire Date: " + dtHireDate + " Phone Work: " + stPhone + " Wireless Work: " + stWireless + ".");
s.SetSQLCommand("dbo.ADP_uiEmployeeWorkInfo");
s.AddSQLCmdParameter("#EmployeeNumber", System.Data.SqlDbType.VarChar, stID);
s.AddSQLCmdParameter("#EmailAddress", System.Data.SqlDbType.VarChar, stEmailAddress);
s.AddSQLCmdParameter("#Fax", System.Data.SqlDbType.VarChar, stFax);
s.AddSQLCmdParameter("#HireDate", System.Data.SqlDbType.DateTime, dtHireDate);
s.AddSQLCmdParameter("#Telephone", System.Data.SqlDbType.VarChar, stPhone);
s.AddSQLCmdParameter("#Mobile", System.Data.SqlDbType.VarChar, stWireless);
s.SQLExecuteNonQuery();
Console.WriteLine("Processed ID:" + stID + " Email Work: " + stEmailAddress + " Fax Work: " + stFax + " Hire Date: " + dtHireDate + " Phone Work: " + stPhone + " Wireless Work: " + stWireless + ".");
Console.WriteLine(Environment.NewLine);
}
s.CloseSQLDB();
s.Dispose();
}
//catch any exception from adp side.
catch (Exception e)
{
throw new System.Exception(e.Message.ToString());
}
}
This functions code is irrelevant (its ugly but do not let that bother you, the code works...). My issue is I cannot even get to the first console.writeline of that function. Is there anything special I need to do when it comes to working with webservices?
Edit
Logpath is defined as simply a static string outside of main:
private static string logPath = Environment.CurrentDirectory + "\\log\\";

I suspect that your application is not able to load the types referenced in that function - EmpWorkInfo.
1) Can you run this application on the target server in a commannd window (cmd.exe) ?
2) Are you using any assemblies from ADP that are installed in the global assembly cache (GAC)? Run "gacutil -l" on your localmachine to see if you are using any assemblies from ADP that are installed in thr gac. If they are, you will need to install these into the machine on which you are running the app.

Does logPath have a trailing backslash? Either way, you ought to use Path.Combine, rather than the string catenation operator (+).

What happens if you comment out all the code in EmpWorkInfo() apart from the first Console.Writeline? Does it still not get written out?

Found out I need the Microsoft.Web.Services3 dll installed on the server.

Continuation on "feroze" answer;
If you want to figure out if the 'loading of dependencies' is causing you grief here, i suggest using the "FUSLOGVW.EXE" tool *(part of .Net). When you run this it will give you a little dialog window with a few options. Create a directory somewhere (like "c:\temp\fusion_logs"), set the mode of FUSLOGVW to "log bind failures only", "custom location->c:\temp\fusion_logs".
Now restart your application and check that it failed. Now look into your fusion_logs directory. This should give you sub directories with different (maybe only 1 for now) application names. Inside each directory you will find the log files. These log files contain the "failed assembly loads" and who (which calling assembly) caused them.
They might help your hunt for a working application,
Hope this helps,
Edit: Posted this after you found the cause. The fuslogvw.exe would have shown you the missing assembly.

When to use try/catch blocks?

I've done my reading and understand what a Try/Catch block does and why it's important to use one. But I'm stuck on knowing when/where to use them. Any advice? I'll post a sample of my code below in hopes that someone has some time to make some recommendations for my example.
public AMPFileEntity(string filename)
{
transferFileList tfl = new transferFileList();
_AMPFlag = tfl.isAMPFile(filename);
_requiresPGP = tfl.pgpRequired(filename);
_filename = filename.ToUpper();
_fullSourcePathAndFilename = ConfigurationSettings.AppSettings.Get("sourcePath") + _filename;
_fullDestinationPathAndFilename = ConfigurationSettings.AppSettings.Get("FTPStagePath") + _filename;
_hasBeenPGPdPathAndFilename = ConfigurationSettings.AppSettings.Get("originalsWhichHaveBeenPGPdPath");
}
public int processFile()
{
StringBuilder sb = new StringBuilder();
sb.AppendLine(" ");
sb.AppendLine(" --------------------------------");
sb.AppendLine(" Filename: " + _filename);
sb.AppendLine(" AMPFlag: " + _AMPFlag);
sb.AppendLine(" Requires PGP: " + _requiresPGP);
sb.AppendLine(" --------------------------------");
sb.AppendLine(" ");
string str = sb.ToString();
UtilityLogger.LogToFile(str);
if (_AMPFlag)
{
if (_requiresPGP == true)
{
encryptFile();
}
else
{
UtilityLogger.LogToFile("This file does not require encryption. Moving file to FTPStage directory.");
if (File.Exists(_fullDestinationPathAndFilename))
{
UtilityLogger.LogToFile(_fullDestinationPathAndFilename + " alreadyexists. Archiving that file.");
if (File.Exists(_fullDestinationPathAndFilename + "_archive"))
{
UtilityLogger.LogToFile(_fullDestinationPathAndFilename + "_archive already exists. Overwriting it.");
File.Delete(_fullDestinationPathAndFilename + "_archive");
}
File.Move(_fullDestinationPathAndFilename, _fullDestinationPathAndFilename + "_archive");
}
File.Move(_fullSourcePathAndFilename, _fullDestinationPathAndFilename);
}
}
else
{
UtilityLogger.LogToFile("This file is not an AMP transfer file. Skipping this file.");
}
return (0);
}
private int encryptFile()
{
UtilityLogger.LogToFile("This file requires encryption. Starting encryption process.");
// first check for an existing PGPd file in the destination dir. if exists, archive it - otherwise this one won't save. it doesn't overwrite.
string pgpdFilename = _fullDestinationPathAndFilename + ".PGP";
if(File.Exists(pgpdFilename))
{
UtilityLogger.LogToFile(pgpdFilename + " already exists in the FTPStage directory. Archiving that file." );
if(File.Exists(pgpdFilename + "_archive"))
{
UtilityLogger.LogToFile(pgpdFilename + "_archive already exists. Overwriting it.");
File.Delete(pgpdFilename + "_archive");
}
File.Move(pgpdFilename, pgpdFilename + "_archive");
}
Process pProc = new Process();
pProc.StartInfo.FileName = "pgp.exe";
string strParams = #"--encrypt " + _fullSourcePathAndFilename + " --recipient infinata --output " + _fullDestinationPathAndFilename + ".PGP";
UtilityLogger.LogToFile("Encrypting file. Params: " + strParams);
pProc.StartInfo.Arguments = strParams;
pProc.StartInfo.UseShellExecute = false;
pProc.StartInfo.RedirectStandardOutput = true;
pProc.Start();
pProc.WaitForExit();
//now that it's been PGPd, save the orig in 'hasBeenPGPd' dir
UtilityLogger.LogToFile("PGP encryption complete. Moving original unencrypted file to " + _hasBeenPGPdPathAndFilename);
if(File.Exists(_hasBeenPGPdPathAndFilename + _filename + "original_which_has_been_pgpd"))
{
UtilityLogger.LogToFile(_hasBeenPGPdPathAndFilename + _filename + "original_which_has_been_pgpd already exists. Overwriting it.");
File.Delete(_hasBeenPGPdPathAndFilename + _filename + "original_which_has_been_pgpd");
}
File.Move(_fullSourcePathAndFilename, _hasBeenPGPdPathAndFilename + _filename + "original_which_has_been_pgpd");
return (0);
}
}
}

The basic rule of thumb for catching exceptions is to catch exceptions if and only if you have a meaningful way of handling them.
Don't catch an exception if you're only going to log the exception and throw it up the stack. It serves no meaning and clutters code.
Do catch an exception when you are expecting a failure in a specific part of your code, and if you have a fallback for it.
Of course you always have the case of checked exceptions which require you to use try/catch blocks, in which case you have no other choice. Even with a checked exception, make sure you log properly and handle as cleanly as possible.

Like some others have said, you want to use try-catch blocks around code that can throw an Exception AND code that you are prepared to deal with.
Regarding your particular examples, File.Delete can throw a number of exceptions, for example, IOException, UnauthorizedAccessException. What would you want your application to do in those situations? If you try to delete the file but someone somewhere else is using it, you will get an IOException.
try
{
File.Delete(pgpdFilename + "_archive")
}
catch(IOException)
{
UtilityLogger.LogToFile("File is in use, could not overwrite.");
//do something else meaningful to your application
//perhaps save it under a different name or something
}
Also, keep in mind that if this does fail, then the File.Move you do outside of your if block next will also fail (again to an IOException - since the file was not deleted it is still there which will cause the move to fail).

I was taught to use try/catch/finally for any methods/classes where multiple errors could occur and that you can actually handle. Database transactions, FileSystem I/O, streaming, etc. Core logic usually doesn't require try/catch/finally.
The great part about try/catch/finally is that you can have multiple catches so that you can create a series of exception handlers to deal with very specific error or use a general exception to catch whatever errors you don't see coming.
In your case, you're using File.Exists which is good, but their maybe another problem with the disk that may throw another error that File.Exists cannot handle. Yes, it's a boolean method, but say the File is locked and what happens if you try to write to it? With the catch, you can plan for a rare scenario, but without try/catch/finally, you may be exposing the code to completely unforeseen conditions.

The other guys have given quite a number of good pointers and references.
My input is a short one:
When to use it is one thing, equally or more importanly is how to use it properly.
PS: "it" is refeings to "trying-catching exceptions".