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Create a Streaming Request
let GetUnixEpochTimeStamp =
//test: "1318622958"
let secs = (System.DateTime.UtcNow.Subtract(new DateTime(1970,1,1))).TotalSeconds
Convert.ToInt64(secs).ToString(System.Globalization.CultureInfo.InvariantCulture)
let GetNonce =
//test: let nonce = "kYjzVBB8Y0ZFabxSWbWovY3uYSQ2pTgmZeNu2VS4cg"
Guid.NewGuid().ToString().Replace("-", String.Empty) //32 alphanumeric chars
let EncodeChar (c:char) =
let bytes = System.Text.Encoding.UTF8.GetBytes([|c|])
bytes
|> Seq.map(fun b -> "%" + b.ToString("X2"))
|> System.String.Concat
let PercentEncode (s:string) =
let chars = s.ToCharArray()
chars
|> Seq.map(fun c->
match c with
| c when c >= '0' && c <= '9' -> System.Convert.ToString(c)
| c when c >= 'a' && c <= 'z' -> System.Convert.ToString(c)
| c when c >= 'A' && c <= 'Z' -> System.Convert.ToString(c)
| '.' | '-' | '_' |'~' -> System.Convert.ToString(c)
| _ -> EncodeChar(c)
)
|> System.String.Concat
let Sign_HMAC_SHA1 (sig_ready:string) =
let signing_key = (PercentEncode consumer_secret) + "&" + (PercentEncode access_token_secret)
let keyBytes = System.Text.Encoding.ASCII.GetBytes(signing_key)
use hmac = new System.Security.Cryptography.HMACSHA1(keyBytes)
let byteArray = System.Text.Encoding.ASCII.GetBytes(sig_ready)
use mem_stream = new MemoryStream(byteArray)
let signed = hmac.ComputeHash(mem_stream)
Convert.ToBase64String(signed,Base64FormattingOptions.None)
let ComposeSignatureParamString (keyvalues:SortedDictionary<string,string>) =
keyvalues
|> Seq.sortBy(fun (KeyValue(k,v)) -> PercentEncode k ) //twitter needs keys to be percent encoded before sorting
|> Seq.map(fun kvp -> (PercentEncode kvp.Key) + "=" + (PercentEncode kvp.Value) + "&" )
|> System.String.Concat
|> fun k-> k.TrimEnd('&') //remove the excess & at the end
let ComposeOAuthString (keyvalues:SortedDictionary<string,string>) (sig_base_string:string) =
keyvalues.Add("oauth_consumer_key",consumer_key)
keyvalues.Add("oauth_token",access_token)
keyvalues.Add("oauth_nonce", GetNonce)
keyvalues.Add("oauth_version","1.0")
keyvalues.Add("oauth_timestamp", GetUnixEpochTimeStamp)
keyvalues.Add("oauth_signature_method","HMAC-SHA1")
let param_string = ComposeSignatureParamString keyvalues
let pre_signed_sig = sig_base_string + "&" + (PercentEncode param_string)
let signed_sig = Sign_HMAC_SHA1 pre_signed_sig
keyvalues.Add("oauth_signature", signed_sig)
//Authorization header should only contain oauth_ prefixed keys
keyvalues
|> Seq.filter(fun x-> x.Key.StartsWith("oauth_"))
|> Seq.map(fun x-> PercentEncode x.Key + "=" + "\"" + PercentEncode x.Value + "\", ")
|> System.String.Concat
|> fun k->k.TrimEnd(' ',',')
let GetStreamingWebResource (endpoint:string) (optional_params:SortedDictionary<string,string>) =
let url = StreamBaseUrl + endpoint
let sig_base_string = WebRequestMethods.Http.Get + "&" + (PercentEncode url)
let dict = optional_params
let query_string =
dict
|> Seq.map( fun kv-> String.Format("{0}={1}", (System.Net.WebUtility.UrlEncode kv.Key),
(System.Net.WebUtility.UrlEncode kv.Value)) )
|> Seq.fold(fun s1 s2-> s1 + s2 + "&") "?"
let url = endpoint + query_string.TrimEnd(' ','&')
let w = WebRequest.Create(StreamBaseUrl + url) :?> HttpWebRequest
w.UserAgent <- "ixmx"
let oauth = ComposeOAuthString dict sig_base_string
w.Headers.Add("Authorization", "OAuth " + oauth)
w.Method <- WebRequestMethods.Http.Get
w.ContentType <- "application/x-www-form-urlencoded"
w
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