Develop Reference

Confirm a Folder Exists on a Web Server from a C# Desktop Application

I am trying to confirm that a folder has been uploaded to my Website folder so that it can be accessed by a Desktop application. I keep getting an error that states that there is a URI format error on the connection string. There is no shortage of 'solutions' on the general internet but I cannot get anything to work, even ones on this site (of which I am a member for many years). Forward slashes, back slashes, no slashes ... on and on. I am thoroughly confused. The following seems to be a simple and correct code, but it does not work either even though it is a direct copy of a solution that was offered as correct! The passed string 's' is the name of the folder I am trying to look for. A polite simple answer, perhaps with an example, is my desperate request. Thank You.
private bool CheckFiles(string s)
{
bool exists = System.IO.Directory.Exists(#"\\\\http:/www.myserver.com/sites/"+ s);
return exists;
}

System.IO.Directory.Exists checks for a directory in the file system. The address that is provided as a parameter is a http-URL that is not supported by file system access.
If you want to check for the presence of the folder on a webserver, you need to use a http client to "talk" to the server. Send a GET or HEAD request to the URL. If this returns a 200 (ok), the folder exists, if it returns 404 (not found), it doesn't.
As you are using .NET Framework 4.5 (or 4.0), you can use WebClient or better HttpClient for this. The following should give you an idea of how to check for the folder:
using (var http = new HttpClient())
{
using (var req = new HttpWebRequest(HttpMethod.Head, "https://..."))
{
using (var resp = http.Send(req))
{
// This is a very broad condition;
// you can also check the StatusCode property against HttpStatusCode.NotFound
return resp.IsSuccessStatusCode;
}
}
}

Microsoft Dynamics CRM SDK CRMServiceClient connection string cache bug

Caching behavior of the last Dynamics SDK is driving me crazy.
First, if you want to use CrmServiceClient to access different environments you have to use the parameter RequireNewInstance=True; in the connection string. If not, every instance of CrmServiceClient will use the same connection, even if you create and dispose instances to different environments.
Now, even if you use the RequireNewInstance=True; in the connection string I found that cache still occurs in some scenarios.
var client1 = new CrmServiceClient("RequireNewInstance=True;
Url=https://myCompany.crm.dynamics.com;
Username=myUser#myCompany.onmicrosoft.com; Password=myPassowrd;
AuthType=Office365");
//Now, client 2 points to a url that doesn’t exists:
var client2 = new CrmServiceClient("RequireNewInstance=True;
Url=https://xxx.crm.dynamics.com; Username=myUser#myCompany.onmicrosoft.com;
Password=myPassowrd; AuthType=Office365");
The client2 keeps using the first connection string, so you cannot determine if the new connection string is correct.
Any ideas how to test Dynamics Crm connections strings correctly in my asp.net application?

Late reply, but the behavior you're seeing is because when you're specifying an erroneous URL the discovery service is used to ascertain which instance to connect to.
To prevent this specify SkipDiscovery=True in your connection string:
var connectionString2 = #"AuthType=Office365;Url=https://FAKE.crm.dynamics.com;Username=USERNAME;Password=PASSWORD;RequireNewInstance=True;SkipDiscovery=True;";
Edit: SkipDiscovery is true by default starting with 9.0.7, kudos to #mwardm

I think I found the problem. It seems to only happens on Dynamics 365 online trials, that was the reason we were getting inconsistent results depending on the environment.
Apparently, the url doesn't need to be completely valid to establish a connection to a CRM online trial environment, as long as the credentials are valid and the url structure is kept.
Let's consider the following example:
var client1 = new CrmServiceClient("RequireNewInstance=True;
Url=https://fake.crm.dynamics.com;
Username=myUser#myCompany.onmicrosoft.com; Password=myPassowrd;
AuthType=Office365");
In this case I can substitute the "fake" part of the url with whatever I want, but still execute requests correctly using the CrmServiceClient service.
If I try to do this with another environment (e.g. 2015, on premise, not-trial crm online, etc.), the IsReady property of the CrmServiceClient would return false and I would get an error in the LastCrmError property.
Very weird behavior, and difficult to pinpoint.
Now that I think I understand the inconsistent behavior I know that finally it will not affect our clients, so I will mark this response as the answer even if I still do not know why we have different behavior between a trial and a normal environment..

I agree choosing to reuse the existing connection if you don't include RequireNewInstance=true seems counter-intuitive, but I can't reproduce what you're seeing. If I try the following from LinqPad crmSvcClient2 will print out errors and then throw a null ref on the Execute call (8.2.0.2 version of the SDK). With this version of the SDK you'll want to always check LastCrmError after connecting to see if the connection failed.
var connectionString = #"AuthType=Office365;Url=https://REAL.crm.dynamics.com;Username=USERNAME;Password=PASSWORD;RequireNewInstance=True;";
var connectionString2 = #"AuthType=Office365;Url=https://FAKE.crm.dynamics.com;Username=USERNAME;Password=PASSWORD;RequireNewInstance=True;";
using (var crmSvcClient = new CrmServiceClient(connectionString))
{
"crmSvcClient".Dump();
crmSvcClient.LastCrmError.Dump();
((WhoAmIResponse)crmSvcClient.Execute(new WhoAmIRequest())).OrganizationId.Dump();
crmSvcClient.ConnectedOrgFriendlyName.Dump();
}
using (var crmSvcClient2 = new CrmServiceClient(connectionString2))
{
"crmSvcClient2".Dump();
crmSvcClient2.LastCrmError.Dump();
((WhoAmIResponse)crmSvcClient2.Execute(new WhoAmIRequest())).OrganizationId.Dump();
crmSvcClient2.ConnectedOrgFriendlyName.Dump();
}

Getting Exception from HRESULT: 0x80072F0D when posting to a service in Windows phone 8.1

When I am trying to post a data to an API using HttpClient in Windows Phone 8.1, I am always getting Exception from HRESULT: 0x80072F0D exception. In fiddler, it works fine.
try
{
var requestbody="json data"
HttpClient httpClient = new HttpClient();
HttpRequestMessage msg = new HttpRequestMessage(new HttpMethod("POST"), new Uri(addressUri));
msg.Content = new HttpStringContent(requestbody);
msg.Content.Headers.ContentType = new HttpMediaTypeHeaderValue("application/json");
HttpResponseMessage response = await httpClient.SendRequestAsync(msg).AsTask();
}
catch (Exception ex)
{
getting **Exception from HRESULT: 0x80072F0D**
}
Please tell me what went wrong?
---FYI----
For getting additional information about the HRESULT code : Follow this WebErrorStatus enumeration
var exceptionDetail = WebError.GetStatus(ex.GetBaseException().HResult);
if (exceptionDetail == WebErrorStatus.HostNameNotResolved)
{
//
}

This looks like a certificate related problem. Maybe you are using SSL. While lots of programs gracefully override missing certificates if not explicitly necessary (e.g.: browsers) the HttpClient is pretty sensitive against that.
You should try to download the certificate for the connection you're using and store the cert file in your assets folder. When your app starts, push it into the certificate store. This is a snippet I am using in one of my apps. Maybe this makes your exception go away.
Read more here: http://blogs.msdn.com/b/wsdevsol/archive/2014/06/05/including-self-signed-certificates-with-your-windows-runtime-based-windows-phone-8-1-apps.aspx
// Add our custom certificate
try
{
// Read the contents of the Certificate file
System.Uri certificateFile = new System.Uri("ms-appx:///Assets/ca.cer");
Windows.Storage.StorageFile file = await Windows.Storage.StorageFile.GetFileFromApplicationUriAsync(certificateFile);
Windows.Storage.Streams.IBuffer certBlob = await Windows.Storage.FileIO.ReadBufferAsync(file);
// Create an instance of the Certificate class using the retrieved certificate blob contents
Windows.Security.Cryptography.Certificates.Certificate rootCert = new Windows.Security.Cryptography.Certificates.Certificate(certBlob);
// Get access to the TrustedRootCertificationAuthorities for your own app (not the system one)
Windows.Security.Cryptography.Certificates.CertificateStore trustedStore = Windows.Security.Cryptography.Certificates.CertificateStores.TrustedRootCertificationAuthorities;
// Add the certificate to the TrustedRootCertificationAuthorities store for your app
trustedStore.Add(rootCert);
}
catch (Exception oEx)
{
// Catch that exception. We don't really have a choice here..
var msg = oEx.Message;
}

You might be able to bypass the error with this code:
var baseFilter = new HttpBaseProtocolFilter();
baseFilter.IgnorableServerCertificateErrors.Add(Windows.Security.Cryptography.Certificates.ChainValidationResult.InvalidCertificateAuthorityPolicy);
var httpClient = new HttpClient(baseFilter);
This merely silences the error rather than solving the problem, though. I'm not too knowledgeable with SSL errors, and this may not be a safe option, and may not pass app certification. According to the docs:
SSL server certificate errors should only be ignored in advanced scenarios. Disregarding server certificate errors classified as either Ignorable or Fatal may result in the loss of privacy or integrity of the content passed over the SSL session.

Received the same Error as originator. I do not use a proxy.
This worked for me. netsh winhttp reset proxy
Next Fax transmitted without error.

Experienced the 0x80072efd problem. Has cost me hours if not days to solve. The solution that gave instant resolution is the following command from a admin command prompt:
netsh winhttp reset proxy

How to check if a web service is up and running without using ping?

How can i check if a method in a web service is working fine or not ? I cannot use ping. I still want to check any kind of method being invoked from the web service by the client. I know it is difficult to generalize but there should be some way.

I use this method and it works fine :
public bool IsAddressAvailable(string address)
{
try
{
System.Net.WebClient client = new WebClient();
client.DownloadData(address);
return true;
}
catch
{
return false;
}
}

The only way to know if a web service method is working "fine" is to call the method and then to evaluate whether the result is "fine". If you want to keep a record of "fine" vs. time, then you can log the result of the evaluation.
There's no more general way to do this that makes any sense. Consider:
You could have code that creates an HTTP connection to the service endpoint, but success doesn't tell you whether the service will immediately throw an exception as soon as you send it any message.
You could connect and send it an invalid message, but that doesn't tell you much.
You could connect and send it a valid message, then check the result to ensure that it is valid. That will give you a pretty good idea that when a real client calls the service immediately afterwards, the real client should expect a valid result.
Unless the service takes that as an opportunity to crash, just to spite you!
The best technique would be to use WCF tracing (possibly with message-level tracing) to log what actually happens with the service, good or bad. A human can then look at the logs to see if they are "fine".

Powershell is by far an easy way to 'ping' a webservice endpoint.
Use the following expression:
Test-NetConnection -Port 4408 -ComputerName 192.168.134.1
Here is a failure response for a port that does not exist or is not listening;
WARNING: TCP connect to 192.168.134.1:4408 failed
ComputerName : 192.168.134.1
RemoteAddress : 192.168.134.1
RemotePort : 4408
InterfaceAlias : Ethernet0
SourceAddress : 192.168.134.1
PingSucceeded : True
PingReplyDetails (RTT) : 0 ms
TcpTestSucceeded : False
Here is a success result if the address/port is listening and accessible:
ComputerName : 192.168.134.1
RemoteAddress : 192.168.134.1
RemotePort : 4407
InterfaceAlias : Ethernet0
SourceAddress : 192.168.134.1
TcpTestSucceeded : True

just use try catch inside the method of your webservice and log exceptions to a log file or to the event log.
Example:
[OperationContract]
public bool isGUID(string input)
{
bool functionReturnValue = false;
try
{
Guid guid;
functionReturnValue = Guid.TryParse(input, guid);
}
catch (Exception ex)
{
Log.WriteServerErrorLog(ex);
}
return functionReturnValue;
}
You don't need to ping the webservice, but instead ping the server with a watchdog service or something. There is no need to "ping" the webservice. I also think you don't need to do this anyway.
Either your webservice works or it doesn't because of bad code.

You may try curl. It's a Linux tool, should be there in Cygwin too.
$ curl http://google.com
<HTML><HEAD><meta http-equiv="content-type" content="text/html;charset=utf-8">
<TITLE>301 Moved</TITLE></HEAD><BODY>
<H1>301 Moved</H1>
The document has moved
here.
</BODY></HTML>
There are lots of options; examples can be found in the 'net.

You can write your self a little tool or windows service or whatever you need then look at these 2 articles:
C#: How to programmatically check a web service is up and running?
check to if web-service is up and running - efficiently
EDIT:
This was my implementation in a similar scenario where I need to know if an external service still exists every time before the call is made:
bool IsExternalServiceRunning
{
get
{
bool isRunning = false;
try
{
var endpoint = new ServiceClient();
var serviceUri = endpoint.Endpoint.Address.Uri;
var request = (HttpWebRequest)WebRequest.Create(serviceUri);
request.Timeout = 1000000;
var response = (HttpWebResponse)request.GetResponse();
if (response.StatusCode == HttpStatusCode.OK)
isRunning = true;
}
#region
catch (Exception ex)
{
// Handle error
}
#endregion
return isRunning;
}
}

As I see it, you have 2 options:
If you can access the server it is running on, Log every call (and exceptions thrown). Read the log file with a soft like baretail that updates as the file is being written.
If you can't access the server, then you have to make the webservice write that log remotely to another computer you have access to.
Popular loggers have this functionality built in. (Log4Net, ...)

You could also use tracing.
http://msdn.microsoft.com/en-us/library/ms732023.aspx
http://msdn.microsoft.com/en-us/library/ms733025.aspx

How to catch ConfigurationErrorsException for violating maxRequestLength?

I am limiting file size users can upload to the site from Web.config. As explained here, it should throw a ConfigurationErrorsException if size is not accepted. I tried to catch it from the action method or controller for upload requests but no luck. Connection is resetted and I can't get it to show an error page.
I tried catching it in BeginRequest event but no matter what I do the exception is unhandled.
Here's the code:
protected void Application_BeginRequest(Object sender, EventArgs e)
{
HttpContext context = ((HttpApplication)sender).Context;
try
{
if (context.Request.ContentLength > maxRequestLength)
{
IServiceProvider provider = (IServiceProvider)context;
HttpWorkerRequest workerRequest = (HttpWorkerRequest)provider.GetService(typeof(HttpWorkerRequest));
// Check if body contains data
if (workerRequest.HasEntityBody())
{
// get the total body length
int requestLength = workerRequest.GetTotalEntityBodyLength();
// Get the initial bytes loaded
int initialBytes = 0;
if (workerRequest.GetPreloadedEntityBody() != null)
initialBytes = workerRequest.GetPreloadedEntityBody().Length;
if (!workerRequest.IsEntireEntityBodyIsPreloaded())
{
byte[] buffer = new byte[512];
// Set the received bytes to initial bytes before start reading
int receivedBytes = initialBytes;
while (requestLength - receivedBytes >= initialBytes)
{
// Read another set of bytes
initialBytes = workerRequest.ReadEntityBody(buffer, buffer.Length);
// Update the received bytes
receivedBytes += initialBytes;
}
initialBytes = workerRequest.ReadEntityBody(buffer, requestLength - receivedBytes);
}
}
}
}
catch(HttpException)
{
context.Response.Redirect(this.Request.Url.LocalPath + "?action=exception");
}
}
But I still get this:
Maximum request length exceeded.
Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.
Exception Details: System.Web.HttpException: Maximum request length exceeded.
Source Error:
An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below.
Update:
What method raises the exception anyway? If I read the request it raises exception If I don't read it at all, I get "101 Connection Reset" in browser. What can be done here?

You cant catch error in action method becouse exception comes earlier, but you can catch it here
protected void Application_Error() {
var lastError = Server.GetLastError();
if(lastError !=null && lastError is HttpException && lastError.Message.Contains("exceed")) {
Response.Redirect("~/errors/RequestLengthExceeded");
}
}
Actualy when file size exceeds limits HttpException error arise.
There is also IIS limit on content - wich can't be catched in application. IIS 7 throws
HTTP Error 404.13 - Not Found The
request filtering module is configured
to deny a request that exceeds the
request content length.
You can google it, there is a lot of information about this iis error.

There is no way to do it right without a client-side help. You cannot determine if the request is too long unless you read all of it. If you read each request to the end, anyone come and keep your server busy. If you just look at content length and drop the request, other side is going to think there is a connection problem. It's nothing you can do with error handling, it's a shortcoming of HTTP.
You can use Flash or Javascript components to make it right because this thing can't fail nicely.

I am not 100% on this, but I think it might help if you tried changing:
context.Response.Redirect(this.Request.Url.LocalPath + "?action=exception");
to
Server.Transfer(this.Request.Url.LocalPath + "?action=exception,false)
My thinking is that the the over-max-request-length Request is still being processed in the Redirect call but if you tell it to ditch the form data, it will become under the max request length and then it might behave differently.
No guarantees, but its easy to check.

catch (Exception ex)
{
if (ex is HttpException && (ex as HttpException).WebEventCode == 3004)
{
//-- you can now inform the client that file uploaded was too large.
}
else
throw;
}

I have a similar issue in that I want to catch the 'Maximum request length exceeded' exception within the Application_Error handler and then do a Redirect.
(The difference is that I am writing a REST service with ASP.Net Web API and instead of redirecting to an error page, I wanted to redirect to an Error controller which would then return the appropriate response).
However, what I found was that when running the application through the ASP.Net Development Server, the Response.Redirect didn't seem to be working. Fiddler would state "ReadResponse() failed: The server did not return a response for this request."
My client (Advanced REST Client for Chrome) would simply show "0 NO RESPONSE".
If I then ran the application via a local copy of IIS on my development machine then the redirect would work correctly!
I'm not sure i can definitively say that Response.Redirect does not work on the ASP.Net Development Server but it certainly wasn't working in my situation.
So, I recommend trying to run your application through IIS instead of IIS Express or the Development Server and see if you get a different result.
See this link on how to Specify the Web Server for Web Projects in Visual Studio:
http://msdn.microsoft.com/en-us/library/ms178108(v=vs.100).aspx