Jason's Code Journal

Adding Security to a WebService

My latest project involves opening up my current companies product catalog to our partners so they can display that product data on their web site. We don't want to expose this data to just anyone, and we want to set up the system to require the partner to register with us before they can use it. The idea is that once they register, they will get a username and password.

The process of adding authentication to your web service methods is pretty easy. There are four steps.

Web Service Series Part 1 – Creating a Simple Web Service with .Net

Recently, I've been doing a bunch of work with .Net Web Services. I love how easy it is to set up a new Web Service and open up functionality to organizations outside or inside your company. For example, my team has written a bunch of classes for exposing our companies product data to our web site. It turns out, that some of our partners wanted to have access to that data as well on their web sites. The mechanisms were always there to accomplish this; I could have done one of the following:

• Send them a daily Excel spreadsheet with the product data using SQL Server and DTS
• Write an XML-RPC method that returned and XML document of our product data

These methods however, took a lot more time to develop than .Net Web Services do. Plus, in both the above methods, there was a lot more work to be done on the client side to call the service.

With .Net Web Services, I can quickly create a new project for the Web Service, import any classes with methods I want to expose, write a proxy method to call the methods I want to expose, compile and whala...A whole new web service for the client to use.

Assuming the client is using .Net, it's simple for them to use as well. All they have to do is add a web reference to the new Web Service and they are ready to start using the methods that it exposes.

Rather than write a whole article on how to create a simple Web Service, I figured I would just post a bunch of good links on this since there are tons of articles out there on creating .Net Web Services. Overall, creating a Web Service is quite simple and using a one is pretty simple as well, assuming you are using .Net Studio. What is not so simple is adding security, writing asynchronous Web Services, and calling Web Services from non-.Net clients. I will be writing articles about my experiences with these later.

• http://www.dotnet247.com/247reference/a.aspx?u=http://www.dotnetjunkies.com/Tutorial/4D13CEFA-D0FD-44BE-8749-8D17B5757564.dcik


• http://www.15seconds.com/Issue/010430.htm


• http://builder.com.com/5100-6389-1045209.html


• http://www.ondotnet.com/pub/a/dotnet/excerpt/progdotnetws_2/index1.html


• http://www.west-wind.com/presentations/dotnetwebservices/DotNetWebServices.asp


• http://aspnet.4guysfromrolla.com/articles/062602-1.aspx


• http://searchwebservices.techtarget.com/originalContent/0,289142,sid26_gci815684,00.html


• http://www.perfectxml.com/dotnetexample.asp?id=1


• http://www.topxml.com/asp+/articles/webservices/

Final FileSystemWatcher Service Code

Here is my final code for the FileSystemWatcher class. I added two things. One, I noted in my last post. I also updated the code to make a change to the properties of the file I am overwriting on the target servers. I found that if the file was read-only on the target server, it raised an error and did not overwrite the file.

using System;
using System.Collections;
using System.ComponentModel;
using System.Data;
using System.Diagnostics;
using System.ServiceProcess;
using System.IO;
using System.Xml;

namespace Replicator
{
public class FileReplicator : System.ServiceProcess.ServiceBase
{
private FileSystemWatcher FileWatcher;
private XmlDocument Config;
private System.Collections.Hashtable TargetServers;

///

/// Required designer variable.
///

private System.ComponentModel.Container components = null;

public FileReplicator()
{
// This call is required by the Windows.Forms Component Designer.
InitializeComponent();
}

// The main entry point for the process
static void Main()
{
System.ServiceProcess.ServiceBase[] ServicesToRun;

// More than one user Service may run within the same process. To add
// another service to this process, change the following line to
// create a second service object. For example,
//
// ServicesToRun = New System.ServiceProcess.ServiceBase[] {new Service1(), new MySecondUserService()};
//
ServicesToRun = new System.ServiceProcess.ServiceBase[] { new FileReplicator() };

System.ServiceProcess.ServiceBase.Run(ServicesToRun);
}

///

/// Required method for Designer support - do not modify
/// the contents of this method with the code editor.
///

private void InitializeComponent()
{
this.FileWatcher = new System.IO.FileSystemWatcher();
((System.ComponentModel.ISupportInitialize)(this.FileWatcher)).BeginInit();
//
// FileWatcher
//
this.FileWatcher.EnableRaisingEvents = true;
this.FileWatcher.Changed += new System.IO.FileSystemEventHandler(this.FileWatcher_Changed);
this.FileWatcher.Created += new System.IO.FileSystemEventHandler(this.FileWatcher_Changed);
//Allow Pause and Continue actions on the service
this.CanPauseAndContinue = true;
//Allow people to shutdown the service
this.CanShutdown = true;
//The name that will show in the services control panel
this.ServiceName = "Production Image Replicator";
((System.ComponentModel.ISupportInitialize)(this.FileWatcher)).EndInit();
this.EventLog.WriteEntry("Production Image Replicator Service Initializing.",System.Diagnostics.EventLogEntryType.Information,1,1);
}

///

/// Clean up any resources being used.
///

protected override void Dispose( bool disposing )
{
this.EventLog.WriteEntry("Production Image Replicator Service Dispose.",System.Diagnostics.EventLogEntryType.Information,1,1);
if( disposing )
{
if (components != null)
{
components.Dispose();
}
}
base.Dispose( disposing );
}

///

/// Set things in motion so your service can do its work.
///

protected override void OnStart(string[] args)
{
this.EventLog.WriteEntry("Starting Production Image Replicator Service.",System.Diagnostics.EventLogEntryType.Information,1,1);
this.FileWatcher.EnableRaisingEvents = true;
Config = new XmlDocument();
TargetServers = new Hashtable();
string localpath = System.IO.Path.GetDirectoryName( System.Reflection.Assembly.GetExecutingAssembly().GetName().CodeBase );

try
{
Config.Load(localpath+"\\config.xml");
this.EventLog.WriteEntry("Loaded Config File at "+localpath+"\\config.xml",System.Diagnostics.EventLogEntryType.Information,1,1);
}
catch (System.Xml.XmlException xex)
{
this.EventLog.WriteEntry("Could not open config file. Error was:\n"+xex.Message,System.Diagnostics.EventLogEntryType.Error,1,1);
}

FileWatcher.Path = Config.SelectSingleNode("configuration/sourceserver/@path").Value;

foreach (XmlNode node in Config.SelectNodes("configuration/targetserver"))
{
TargetServers.Add(node.SelectSingleNode("@name").Value,node.SelectSingleNode("@path").Value);
}
FileWatcher.Filter = "*.gif";
FileWatcher.NotifyFilter=NotifyFilters.FileName | NotifyFilters.LastWrite | NotifyFilters.Size;
FileWatcher.IncludeSubdirectories=false;
FileWatcher.InternalBufferSize=40960;
this.EventLog.WriteEntry("Production Image Replicator Service Started.",System.Diagnostics.EventLogEntryType.Information,1,1);
}

///

/// Pause this service.
///

protected override void OnPause()
{
this.FileWatcher.EnableRaisingEvents = false;
this.EventLog.WriteEntry("Production Image Replicator Service Paused.",System.Diagnostics.EventLogEntryType.Information,1,1);
}

///

/// Stop this service.
///

protected override void OnStop()
{
this.FileWatcher.EnableRaisingEvents = false;
this.EventLog.WriteEntry("Production Image Replicator Service Stopped.",System.Diagnostics.EventLogEntryType.Information,1,1);
}

private void FileWatcher_Changed(object sender, System.IO.FileSystemEventArgs e)
{
this.EventLog.WriteEntry("In FileWatcher_Changed.",System.Diagnostics.EventLogEntryType.Information,1,1);
IDictionaryEnumerator ListEnumerator = TargetServers.GetEnumerator();
string strCopyToPath = "";

try
{

if (e.ChangeType==WatcherChangeTypes.Created || e.ChangeType==WatcherChangeTypes.Changed)
{
while (true)
{
//don't do anything till the file has finished copying to the source server
try
{
if (File.Exists(e.FullPath))
break;
}
catch(IOException ix)
{
//ignore the exception, continue trying to open file
}
}
this.EventLog.WriteEntry("Create Event Triggered: "+e.FullPath,System.Diagnostics.EventLogEntryType.Information,1,1);
while (ListEnumerator.MoveNext())
{
strCopyToPath = ListEnumerator.Value.ToString()+"\\"+e.Name;
try
{
if (File.Exists(strCopyToPath))
{
File.SetAttributes(strCopyToPath,FileAttributes.Normal);
}
File.Copy(e.FullPath, strCopyToPath, true);
this.EventLog.WriteEntry("Copied File to "+strCopyToPath,System.Diagnostics.EventLogEntryType.Information,1,1);
}
catch(IOException ix)
{
this.EventLog.WriteEntry("IOException while copying to " + strCopyToPath + ". Error was:\n"+ix.Message,System.Diagnostics.EventLogEntryType.Error,1,1);
}
}
}
}
catch (IOException ix)
{
this.EventLog.WriteEntry("IOException while copying files. Error was:\n"+ix.Message,System.Diagnostics.EventLogEntryType.Error,1,1);
}
catch (Exception x)
{
this.EventLog.WriteEntry("Unknown Exception while copying files. Error was:\n"+x.Message,System.Diagnostics.EventLogEntryType.Error,1,1);
}
}
}
}

More on FileSystemWatcher

Ok, I have been ignoring this blog for a while now, but now I am back. I finally have some time again. Sorry everyone.

Due to numerous requests for a way to tell the FileSystemWatcher control to wait for a file to finish uploading before it performs an action, I am creating this post. I was actually having the same problem and it took me a while to figure out that this was actually the problem I was having. So here is my fix.

If you have read my previous post on the FileSystemWatcher control, I posted code for a simple service that runs in the background ad copies files from one server to another. Basically, the fix is to add the following few lines of code to the create and change events:

while (!File.Exists(sample.file))
{
//keep looping until the file is unlocked.
}

Basically, when the file is still being uploaded, the file is locked and the Exists function will return false. Once it is done uploading, the program will continue, and it will be able to copy the file to perform actions on the file.

Let me know if you have any problems.

Oh boy

Let's see. This presidential election we have choice between a liar and....oh right, another liar.

Day from Hell

This week, work gave me a new laptop, an IBM ThinkPad P4 2.4 Ghz. It is freekin huge. I mean, it is bigger than my old laptop that is 3 years old. Personally I don’t care how big a laptop is, cause I don’t do a whole lot of traveling. The good news is the laptop it super fast compared to my old one. I’m still getting used to the keyboard so if my typing is off in this post you’ll know why.

I was installing the OS and software I needed – Windows 2003 Server, SQL Server 2000, and Studio .Net 2003, etc. When I rebooted, I noticed that a service was not starting correctly. I checked the event log which said that the Machine Debug Manager could not start because the path could not be found. WTF? I just installed that with Studio. So I did a search for the EXE. Guess where it was found? My work network drive. How in God’s name did that happen? It turns out that when Studio .Net installed, it put all of the files that should have gone in c:\program files\common files and c:\program files\windows in my network drive. When the machine was booting, it did not have access to this drive and the OS could not start the services Studio installed there.

I tried uninstalling Studio.Net, but no luck. Everything was still left there. Also, I could not tell Studio to change where it was installing these files.

After about 4 hours of troubleshooting this problem, I gave up. I put the Windows 2003 Server disk back in the cd-rom, rebooted and formatted the drive again, starting from scratch. Luckily I had not installed that much software yet. This time I installed everything as the administrator of the local machine before I logged in as myself. I was not going to let Studio install anything on my network drive. Pain in the ASS.

Thanks for letting me vent after a frustrating day of setting up my new laptop.

Code Reviews

A friend of mine sent me this article today. I found it very interesting. For those of you that participate in or coordinate code reviews, it can be very helpful. I especially found the point about how manager participation can hinder code review productivity because people are hesitant to criticize their peer's code infront of their manager.

I love Buck Rogers Reruns

Recently Sci-fi channel started re-running old Buck Rogers episode. I can't believe I used to watch this show when I was young. It is laughable the sexual innuendo that this show got away with. Of course when they were on originally, I was to young and ignorant to get any of it. Gee I wonder why the princess needs three clones of Buck? Why is she having them come to her room? What would they possibly be doing there? Oh, and the porno music is way too much. All I can say is thank god for TiVo cause without it, I would never stay up till 2:30 AM to watch this show.

Creating a Collection using CollectionBase

In a purchase, you have to collect many different types of addresses: billing, shipping and credit. Rather than have a separate class for each address, create a single class to hold address information and include an address type. You then can create a collection of the Address objects and assign it to a customer. Here is an example:

Public Enum OrderAddressType
    Billing
    Credit
    Shipping
End Enum

Public Class OrderAddress
    Public orderAddressType As OrderAddressType
    Public strFirstName As String
    Public strMI As String
    Public strLastName As String
    Public strStreet1 As String
    Public strStreet2 As String
    Public strCity As String
    Public strStateProv As String
    Public strPostalCode As String
    Public strCountry As String
End Class

Public Class OrderAddressCollection
    Inherits System.Collections.CollectionBase

    Public Sub Add(ByVal oa As OrderAddress)
        List.Add(oa)
    End Sub

    Public Sub Remove(ByVal index As Integer)
        If index > Count - 1 Or index < 0 Then
            'ignore request
        Else
            List.RemoveAt(index)
        End If
    End Sub

    Default Public ReadOnly Property Item(ByVal index As Integer) As OrderAddress
        Get
            Return CType(list.Item(index), OrderAddress)
        End Get
    End Property

End Class

In the code above, CollectionBase was used as the base of the collection. In a simple Collection you only have the ability to identify the items in the collection by their location. If you need to identify the items in the collection by something other than the numeric index, then you have to use a DictionaryBase.

In my next post, I will give an examples of using DictionaryBase which I am working on now.

Woohoo!!!

Now I can start stealing music again ;)