“远程服务器返回错误：（417）期望失败。”

Question

i'm writing windows 8 app.(on Visiual Studio 2012) which uses my wcf service. It works well when i try at my home, so it can connect to the wcf. But when i tried at my office, it cannot connect to wcf and returns error :

The remote server returned an error: (417) Expectation Failed.

I think its causing by firewall in the office network.. Googled too much, tried a lot of however the problem still here.

System.Net.ServicePointManager.Expect100Continue = false;

Doesn't work because .Net Framework 4.5 has not ServicePointManager Class but msdn says there is ServicePointManager on .Net 4.5.. http://msdn.microsoft.com/en-us/library/system.net.servicepointmanager.expect100continue.aspx

<system.net>
    <settings>
        <servicePointManager expect100Continue="false" />
    </settings>
</system.net>

Cannot try this to write on web.config or app.config because win8 app has not these files..

some people wrote above code to devenv.exe.config file of VS 2012. I tried it but nothing changed.

http://www.jlpaonline.com/?p=176

Answer 1

Well, you posted the question here , and Can Bilgin gave an answer. I post it here for those who have the problem than you.

I think it should be possible to add the header manually... I would give it a go with the operationscope... from an earlier example:

Task<GetADGroupMemberResponse> AccountManagement.GetADGroupMemberAsync(GetADGroupMemberRequest request)
{
    // CB: Creating the OperationContext
    using (var scope = new OperationContextScope(this.InnerChannel))
    {
        // CB: Creating and Adding the request header
        var header = MessageHeader.CreateHeader("Server", "http://schemas.microsoft.com/2008/1/ActiveDirectory/CustomActions", request.Server);
        OperationContext.Current.OutgoingMessageHeaders.Add(header);

        return base.Channel.GetADGroupMemberAsync(request);
    }
}

cause on the http requests with the httpclient you can do something like (again from an earlier example):

var httpClient = new HttpClient(); 
var httpContent = new HttpRequestMessage(HttpMethod.Post, "http://app.proceso.com.mx/win8/login");

// NOTE: Your server was returning 417 Expectation failed, 
// this is set so the request client doesn't expect 100 and continue.
httpContent.Headers.ExpectContinue = false;

var values = new List<KeyValuePair<string, string>>(); 
values.Add(new KeyValuePair<string, string>("user", "******"));
values.Add(new KeyValuePair<string, string>("pass", "******"));

httpContent.Content = new FormUrlEncodedContent(values);

HttpResponseMessage response = await httpClient.SendAsync(httpContent);

// here is the hash as string 
var result = await response.Content.ReadAsStringAsync();

Answer 2

For reference, the following is a full example of using WebClient to post a JSON request to a REST webservice. It sets the Expect100Continue flag to false , includes proxy authentication using default credentials if required, and catches non-200 response codes.

void Main()
{
    var ms = new MemoryStream();
    var ser = new DataContractJsonSerializer(typeof(Job));
    ser.WriteObject(ms, new Job { Comments = "Test", Title = "TestTitle", Id = 1 });

    var uri = new Uri("http://SomeRestService/Job");
    var servicePoint = ServicePointManager.FindServicePoint(uri);
    servicePoint.Expect100Continue = false;

    var webClient = new WebClient();
    webClient.Headers["Content-type"] = "application/json";

    IWebProxy defaultProxy = WebRequest.DefaultWebProxy;
    if (defaultProxy != null){
        defaultProxy.Credentials = CredentialCache.DefaultCredentials;
        webClient.Proxy = defaultProxy;
    }

    try {
        var result = webClient.UploadData(uri, "POST", ms.ToArray());
    } catch (WebException we) {
        var response = (HttpWebResponse)we.Response;
    }
}

[DataContract]
public class Job
{
    [DataMember (Name="comments", EmitDefaultValue=false)]
    public string Comments { get; set; }
    [DataMember (Name="title", EmitDefaultValue=false)]
    public string Title { get; set; }
    [DataMember (Name="id", EmitDefaultValue=false)]
    public int Id { get; set; }
}

Answer 3

Although adding this line
() as a setting to the config may fix the initial error you are likely to still get (504) Gateway Timeout if your proxy settings are not allowing you to use the correct open port open to your on the target server. To add a proxy exception for the server you are sending to, add it via internet explorer as a proxy exclusion on connections tab -> LAN settings -> Advanced. I hope you'll be able to connect then.