WebRequest (Follow up to HttpClient)

As a follow up to the previous post; We did find a limitation is our production environment that forced us to switch to a WebRequest instead of using the HttpClient. Given that this was the method we used to replace the functionality:

public XmlDocument SendServiceRequest(string uri, string xmlRequest)
{
    // Prep the request
    byte[] data = Encoding.ASCII.GetBytes(xmlRequest);
 
    // Create the HTTP request
    HttpWebRequest http = (HttpWebRequest) WebRequest.Create(uri);
    http.Method = "POST";
    http.ContentType = "application/xml";
    http.Accept = "application/xml";
    http.ContentLength = data.Length;
 
    // Place the xml into the stream
    using (Stream stream = http.GetRequestStream())
    {
        stream.Write(data, 0, data.Length);
    }
 
    // Get the response from the remote
    HttpWebResponse response = (HttpWebResponse) http.GetResponse();
 
    // Process the response stream if available. Create an empty XmlDocument if not
    XmlDocument xmlResponse = new XmlDocument();
 
    using (Stream responseStream = response.GetResponseStream())
    {
        if (responseStream != null)
        {
            using (StreamReader sr = new StreamReader(responseStream))
            {
                xmlResponse.LoadXml(sr.ReadToEnd());
            }
        }
    }
 
    return xmlResponse;
}

Using HttpClient for REST service calls

During a recent project we needed to make calls to a REST service out there on the net. I narrowed down the call to a basic method that I can call from other parts of my application.  This uses the HttpClient class and .Net 4.5

internal class RestHttpClient
{
    public async Task<HttpResponseMessage> SendRequestAsync(string uri, string xmlRequest)
    {
        using (HttpClient httpClient = new HttpClient())
        {
            StringContent httpContent = new StringContent(xmlRequest, Encoding.UTF8);
            HttpResponseMessage responseMessage;
            try
            {
                responseMessage = await httpClient.PostAsync(uri, httpContent);
            }
            catch (Exception ex)
            {
                responseMessage = new HttpResponseMessage
                {
                    StatusCode = HttpStatusCode.InternalServerError,
                    ReasonPhrase = string.Format("RestHttpClient.SendRequestAsync failed: {0}", ex)
                };
            }
 
            return responseMessage;
        }
    }
}

Elsewhere in the application this method is called as follows:

public async Task SendRequest(string uri, string xmlRequest)
{
    RestHttpClient restHttpClient = new RestHttpClient();
    return await restHttpClient.SendRequestAsync(uri, xmlRequest);
}

Rant: Microsoft Fakes

Ok, so I was really looking forward to the Fakes framework in VS 2012.  In the end a good portion of us are denied access to this feature because it’s only available in the Ultimate version of the product.

I guess the good thing is that Pex and Moles will still be viable.

Getting a list of domain group membership for a user account

I was looking for a way to get a list of a user’s associated domain groups. The first pass was to query AD using DirectorySearcher but the PrincipalContext was a less painful route to get what I needed. The method below will get the list of groups that the user belong to. Note that the user returned from the logonUserIdentity.Name will be in domain\user format. We split that apart so we can pass in the user part and also construct a domain.com string. That’s not the exact code I used since we have two different domains but it gets the idea across.

Update: I discovered that I needed to use the user name and password of a domain account for the PrincipalContext call. I installed the application on a virtual machine under IIS 7 and it was failing since the pool identity, NETWORKSERVICE, did not have rights to query AD. I ended up getting an exception:

DirectoryServicesCOMException (0x80072020): An operations error occurred

    public List<string> GetUserDomainGroups(WindowsIdentity logonUserIdentity)
    {
        List<string> groupList = new List<string>();

        string[] user = logonUserIdentity.Name.Split("\\".ToCharArray());
        user[0] += ".com";

        SecurityKey securityKey = GetSecurityKeyFromConfiguration();

        using (PrincipalContext ctx = new PrincipalContext(ContextType.Domain, user[0], securityKey.UserName, securityKey.Password))
        {
            using (Principal principal = Principal.FindByIdentity(ctx, user[1]))
            {
                if (principal != null)
                {
                    PrincipalSearchResult<Principal> groups = principal.GetGroups();
                    using (groups)
                    {
                        groupList.AddRange(groups.Select(group => group.SamAccountName));
                    }
                }
            }
        }

        return groupList;
    }

Converting strings/byte arrays to encoded strings

I ran into this problem not to long ago where I needed to round trip strings between a coded format and their normal human readable format.

The basic idea was to take the string, and convert it to a byte array and then make a string representing the values in the byte array.  The resulting string would be used for a query string parameter and a few other things.

An example: If I have two words I would put a | between them.  hello there would be hello|there and the coded form would be 68656C6C6F7C7468657265

After a bit of digging I found a couple of threads on the net that gave me these two bits of code to go both directions.

string coded = new string(Encoding.UTF8.GetBytes(asciiString).SelectMany(x => x.ToString(“X2”).ToCharArray()).ToArray())

And to go back to the normal string

string notcoded = Encoding.UTF8.GetString(Enumerable.Range(0, hexString.Length / 2).Select(x => Byte.Parse(hexString.Substring(2 * x, 2), NumberStyles.HexNumber)).ToArray())

Not to bad at all with the LINQ in there, before that was around there were loops to get the whole thing done.

Beginners JQuery Video Series

I ran into a video tutorial for learning JQuery over at ThemeForest.net
I’m one of the people they talked about; I know its out there, I know it uses css selectors, and I know that it does a lot to hide some of the javascript pain. So I’m finally checking it out in more detail. Even though my preferred area is web services and other business layer on down I do still have to do some gui work from time to time.

WCF CreateChannel and no App.config

Alright; so I was working on a new project and I wanted to create a Windows Service that would host a WCF Service. The basic idea is that the Windows Service will use the WCF Service to do it’s heavy lifting on a schedule. The WCF Service will also be called from a management web site later on. In the past I’ve always wanted to reduce the amount of coding and configuration required to call one of these services.

So.. what did i come up with? The following lines create the service host in my Windows Service:

_wcfAsnService = new ServiceHost(typeof(Edi.Wcf.AsnService));
_wcfAsnService.AddServiceEndpoint(typeof(IAsnService), new NetTcpBinding(), Settings.Default.WcfAsnServer);
_wcfAsnService.Open();

The setting for that last parameter is defined as: net.tcp://localhost:8000

And I created this class to use for managing the life cycle of the client proxy:
using System;
using System.ServiceModel;
namespace EDI.AsnService

{
public class ServiceProxy : IDisposable
{

private readonly T _endPoint;
private readonly ICommunicationObject _proxy;

public ServiceProxy(string endPointAddress)

{
// Create a service client proxy
_endPoint = ChannelFactory.CreateChannel(new NetTcpBinding(), new EndpointAddress(endPointAddress));

// Create a CommunicationObject for state and end point closure
_proxy = _endPoint as ICommunicationObject;

}

public void Dispose()

{
// Close down the communication channel
if (_proxy != null)
_proxy.Close();
}

///
/// Returns the state object from the communication end point
///
public CommunicationState State
{
get { return _proxy.State; }
}

///

/// Returns the Endpoint where methods can be called

///

public T Client { get { return _endPoint; } }

}

}

Pretty simple. All you have to do is pass in the contract as the type and the proxy is created on the fly. Inside my method that executes the service client I have the following code to invoke the service:

using (ServiceProxy service = new ServiceProxy(Settings.Default.WcfAsnServer))
{

eventLog.WriteEntry(“Processing Start”);

eventLog.WriteEntry(service.Client.ExtractFromVisual().Message);

eventLog.WriteEntry(service.Client.UpdateGentran().Message);

eventLog.WriteEntry(“Processing Completed”);

}

The end result is that I don’t have to worry about configuring bindings in the config file. In fact the only thing I have in the config file in the endpoint address and port. I think this is much lighter weight and reduces some of the problems I’ve run into in the past with updating service references and duplication of the bindings in the config file.

Little Gems – Balsamiq Mockups

If you are like me you tend to download a lot of software from the net. Open Source, Demos, Free/Share ware and the list goes on. I happened onto a little gem that is starting to make my life easier.
Here is the problem:
I write software for a living.. period. One of the hardest things is trying to come up with a solid user interface with your clients. Sure I’ve used things like Visio and PowerPoint in the past with decent results. There is a tendency with some clients to not make the logical leap that it takes time to actually implement the screen design. What they see is rapid layout and assume thats as hard as it gets.
Enter Balsamiq Mockups. How is this application any different? Well first off the mockups look like they are hand drawn; something you might come up with if you sat down with your client and grabbed a stack paper and a pen.

SilverLight Debugging

I was working through a tutorial for SilverLight over the weekend and things were going just fine until the debugger just didn’t seem to want to hit my break points. Oddly they were working fine but I did see on the net that some people had problems a while back with this. In those cases there is a check box added to the project properties where you select ASP.NET debugging that was getting turned off. For those the solution had been moved.. this is not the case for me of course so maybe there is another issue there someplace.
Has anyone run into this situation? I guess I can try the old standby of making a new project to see if it still fails to hit the break points or try not hosting in a web page.
Update: I found out that using a browser other then IE will cause this to happen. Sure enough.. after I reset IE as the default browser then the debugger hit my break points once again. The odd thing is it was working just fine for a while.. go figure.

Reading Excel Files

I’ve run into the problem a few times of needing to convert rows in an Excel file into an object for some kind of processing. I found an example that was pretty trim in what it was doing so I ended up using it as a model for a new template class.

The basic idea is that you create a new class and provide the overrides for converting a row into an object and after the main method returns you end up with a Collection where T is the type of Data Transfer Object (DTO) that your application can use.

One more modification that I’m planning on adding is to stream the DTOs to a method instead of returning a collection. Calling a processor will allow for a large number of rows to be processed without storing the DTOs in a collection and thus not incurring the memory overhead.

Here is the code so far: [more]

1:using System;
2:using System.Collections.ObjectModel;
3:using System.Data.OleDb;
4:using System.IO;
5:
6:namespace SomeNameSpace
7: {
8:publicclass DigestExcel
9: {
10:///
11:/// True if exceptions should be thrown during processing
12:///
13:publicbool ThrowExceptions { get; set; }
14:
15:///
16:/// Output StringToWrite to a log
17:///
18:/// A string to be written to a log
19:protectedvirtualvoid WriteLogFileEntry(string StringToWrite)
20: {
21:// This method should be implemented if logging is desired
22: }
23:
24:///
25:/// Convert a row to a DTO
26:///
27:/// The DataReader to build DTOs from
28:/// A new DTO object
29:protectedvirtual T ParseDataRow(OleDbDataReader DataReader)
30: {
31:// This method should be implemented
32:thrownew NotImplementedException(“You must implement ParseDataRow”);
33: }
34:
35:///
36:/// Reads each row of an Excel file sheet and returns a collection of DTOs
37:///
38:/// The fully qualified path to the exxcell file
39:/// The sheet/tab name to be processed
40:/// A collection of T objects
41:public Collection ProcessExcelFile(string FileName, string SheetName)
42: {
43: Collection objectList = new Collection();
44:
45: OleDbConnection conn = new OleDbConnection();
46:try
47: {
48: WriteLogFileEntry(String.Format(“Opening File: {0}”, FileName));
49:
50:// Make sure the file exists first
51:if( File.Exists( FileName ) == false )
52: {
53:thrownew FileNotFoundException(String.Format(” Unable to locate requested file, aborting: {0}”, FileName));
54: }
55:
56: conn = new OleDbConnection(“Provider=Microsoft.Jet.OLEDB.4.0;Data Source=” + FileName + “;Extended Properties=\”Excel 8.0;\””);
57: conn.Open();
58:
59: OleDbCommand cmd = new OleDbCommand(String.Format(“SELECT * FROM [{0}$]”, SheetName), conn);
60:
61: OleDbDataReader dataReader = cmd.ExecuteReader();
62:
63:int rowCounter = 0;
64:while (dataReader.Read())
65: {
66:// Advance the row number for logging
67: ++rowCounter;
68:
69: WriteLogFileEntry(String.Format(” Processing data row {0}”, rowCounter));
70:
71:try
72: {
73:// Add the next row to the collection
74: objectList.Add(ParseDataRow(dataReader));
75: }
76:catch(Exception up)
77: {
78:string exceptionMessage = String.Format(” Exception processing row {0}: {1}”, rowCounter, up.Message);
79:
80:// If we throw exceptions up then the outer catch will describe the exception so we wont log it here
81:if( ThrowExceptions )
82: {
83:thrownew ApplicationException(exceptionMessage, up);
84: }
85:
86:// If there is an exception then log it
87: WriteLogFileEntry(exceptionMessage);
88: }
89: }
90: }
91:catch(Exception up)
92: {
93:string exceptionMessage = String.Format(” Exception processing file {0}: {1}”, FileName, up.Message);
94:
95:// If there is an exception then log it
96: WriteLogFileEntry(exceptionMessage);
97:
98:if (ThrowExceptions)
99: {
100:thrownew ApplicationException(exceptionMessage, up);
101: }
102: }
103:finally
104: {
105: conn.Close();
106: WriteLogFileEntry(” Processing file completed”);
107: }
108:
109:return objectList;
110: }
111: }
112: }
In order to use the template you can define a new class and inherit from the DigestExcel class like this:
1:publicclass DigestSample : DigestExcel
2: {
3:protectedoverridevoid WriteLogFileEntry(string StringToWrite)
4: {
5: Console.WriteLine(StringToWrite);
6: }
7:
8:protectedoverride SampleDTO ParseDataRow(System.Data.OleDb.OleDbDataReader DataReader)
9: {
10: SampleDTO newRow = new SampleDTO();
11:
12: newRow.Value1 = DataReader[0].ToString().Trim();
13: newRow.Value2 = DataReader[1].ToString().Trim();
14:
15:return newRow;
16: }
17: }