Have done similar to fire off tasks from Powershell.

Posting a rough no error checking Powershell example that authenticates then get's remaining timeout, may help with at least authenticating.

$webhost= "http://your.site.com"
$authurl= $webhost + "/umbraco/backoffice/UmbracoApi/Authentication/PostLogin"
$taskurl= $webhost + "/umbraco/backoffice/UmbracoApi/Authentication/GetRemainingTimeoutSeconds"
$cookiejar = New-Object System.Net.CookieContainer
$webrequest = [System.Net.HTTPWebRequest]::Create($authurl);
$webrequest.CookieContainer = New-Object System.Net.CookieContainer;
$webrequest.Method = "POST"
$webrequest.ContentType = "application/json; charset=utf-8";
if ($cookiejar -ne $null) { $webrequest.CookieContainer = $cookiejar }
$stream = [System.IO.Streamwriter] $webrequest.GetRequestStream();
$json = @"
{"username":"userxyz","password":"password1234"}
"@
$stream.Write($json);
$stream.Flush();
$stream.Close();
$response = $webrequest.GetResponse()
$responseStream = $response.GetResponseStream()
$streamReader = New-Object System.IO.Streamreader($responseStream)
$output = $streamReader.ReadToEnd()
Write-Host $output
$taskrequest = [System.Net.HTTPWebRequest]::Create($taskurl)
if ($cookiejar -ne $null) { $taskrequest.CookieContainer=$cookiejar }
$taskrequest.Method = "GET"
$taskresponse = $taskrequest.GetResponse()
$taskresponseStream = $taskresponse.GetResponseStream()
$taskstreamReader = New-Object System.IO.Streamreader($taskresponseStream)
$taskoutput = $taskstreamReader.ReadToEnd()
Write-Host $taskoutput

I do have a C# example but it's a basic ServiceStack Auth provider against Umbraco back office and once authenticated has no further interaction with Umbraco, hence posting Powershell example.

Unsure why Umbraco returns the JSON starting with )]}',; I parse it before converting from JSON to a POCO.

Hey James - have you considered the Umbraco Rest API?

https://github.com/umbraco/UmbracoRestApi

Some Code:

var restClient = new RestClient(Settings.UmbracoUrl);
var request = new RestRequest(String.Format("{0}/content/createorupdate", Settings.RestApiUrl));
request.AddHeader("Authorization", "Bearer " + _umbracoAccessToken);
request.Method = Method.POST;
var body = JsonConvert.SerializeObject(content);
request.AddParameter("application/json", body, ParameterType.RequestBody);
var response = restClient.Execute(request);

Yeah you might be surprised how far you'd get with it. Some are unfinished (e.g. remove content). There is authentication built in with backoffice users so that helps.

Best

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