Introducing PoshTwitPic – Use PowerShell To Post Your Images To Twitter Via TwitPic

Twitter, for those who don’t know about it, is a status updating service that is all the rage nowadays. It’s popularity is primarily due to it’s simplistic nature. You post a 140 character status (known as a “tweet”) about what you are doing. You can also friend other folks to see what they are doing. If you are still lost, read up on the entry in Wikipedia and you should get the gist of it.

The downside to this minimalistic approach is that it does not allow for rich multimedia content such as images or videos to be associated with your “tweets”. Let’s face it, posting a tweet about an awesome dinner you just had isn’t as good as posting a picture you took of it. To account for this, various services have arisen to offload the image or video storage for twitter and many of the Twitter clients out there have incorporated these services into their apps. TwitPic was an early entry into this category of services. They allow you to post an image to their site while posting a “tweet” to Twitter including a link to the image. Fortunately for us, TwitPic exposes their API to allow applications to integrate their features.

Since I’ve already tackled the PowerShell Twitter functionality with my PoshTweet library, I figured the next logical step would be to write a TwitPic library to enable posting images to TwitPic through their API.

The biggest challenge in writing this library was getting the multipart/form-data POST format working correctly. Luckily I stumbled across a post by Martin Normark on his blog containing a C# TwitPic API client. It was fairly straightforward coming up with a PowerShell conversion of his C# code.

   1: param(

   2:   [System.IO.FileInfo]$file = $null,

   3:   [string]$twitteruser = $null,

   4:   [string]$twitterpass = $null,

   5:   [string]$message = $null

   6: );

7:

   8: $CODEPAGE = "iso-8859-1";

9:

  10: $TWITPIC_API_UPLOAD = "http://twitpic.com/api/upload";

  11: $TWITPIC_API_UPLOADANDPOST = "http://twitpic.com/api/uploadAndPost";

12:

  13: #--------------------------------------------------------------------------------------------

  14: # function Get-EncodedDataFromFile

  15: #--------------------------------------------------------------------------------------------

  16: function Get-EncodedDataFromFile()

  17: {

  18:   param(

  19:     [System.IO.FileInfo]$file = $null,

  20:     [string]$codePageName = $CODEPAGE

  21:   );

22:

  23:   $data = $null;

24:

  25:   if ( $file -and [System.IO.File]::Exists($file.FullName) )

  26:   {

  27:     $bytes = [System.IO.File]::ReadAllBytes($file.FullName);

  28:     if ( $bytes )

  29:     {

  30:       $enc = [System.Text.Encoding]::GetEncoding($codePageName);

  31:       $data = $enc.GetString($bytes);

  32:     }

  33:   }

  34:   else

  35:   {

  36:     Write-Host "ERROR; File '$file' does not exist";

  37:   }

  38:   $data;

  39: }

40:

  41: #--------------------------------------------------------------------------------------------

  42: # function Get-ImageContentType

  43: #--------------------------------------------------------------------------------------------

  44: function Get-ImageContentType()

  45: {

  46:   param([System.IO.FileInfo]$file = $null);

  47:   $contentType = $null;

  48:   $contentTypeMap = @{

  49:     ".jpg"  = "image/jpeg";

  50:     ".jpeg" = "image/jpeg";

  51:     ".gif"  = "image/gif";

  52:     ".png"  = "image/png";

  53:     ".tiff" = "image/tiff";

  54:   }

55:

  56:   if ( $file )

  57:   {

  58:     $contentType = $contentTypeMap[$file.Extension.ToLower()];

  59:   }

  60:   $contentType;

  61: }

62:

  63: #----------------------------------------------------------------------------

  64: # function Execute-HTTPPostCommand

  65: #----------------------------------------------------------------------------

  66: function Execute-HTTPPostCommand()

  67: {

  68:   param(

  69:     [string] $url = $null,

  70:     [string] $data = $null,

  71:     [System.Net.NetworkCredential]$credentials = $null,

  72:     [string] $contentType = "application/x-www-form-urlencoded",

  73:     [string] $codePageName = "UTF-8",

  74:     [string] $userAgent = $null

  75:   );

76:

  77:   if ( $url -and $data )

  78:   {

  79:     [System.Net.WebRequest]$webRequest = [System.Net.WebRequest]::Create($url);

  80:     $webRequest.ServicePoint.Expect100Continue = $false;

  81:     if ( $credentials )

  82:     {

  83:       $webRequest.Credentials = $credentials;

  84:       $webRequest.PreAuthenticate = $true;

  85:     }

  86:     $webRequest.ContentType = $contentType;

  87:     $webRequest.Method = "POST";

  88:     if ( $userAgent )

  89:     {

  90:       $webRequest.UserAgent = $userAgent;

  91:     }

92:

  93:     $enc = [System.Text.Encoding]::GetEncoding($codePageName);

  94:     [byte[]]$bytes = $enc.GetBytes($data);

  95:     $webRequest.ContentLength = $bytes.Length;

  96:     [System.IO.Stream]$reqStream = $webRequest.GetRequestStream();

  97:     $reqStream.Write($bytes, 0, $bytes.Length);

  98:     $reqStream.Flush();

99:

 100:     $resp = $webRequest.GetResponse();

 101:     $rs = $resp.GetResponseStream();

 102:     [System.IO.StreamReader]$sr = New-Object System.IO.StreamReader -argumentList $rs;

 103:     $sr.ReadToEnd();

 104:   }

 105: }

 106:

 107: #--------------------------------------------------------------------------------------------

 108: # function Post-TwitPic

 109: #--------------------------------------------------------------------------------------------

 110: function Post-TwitPic()

 111: {

 112:   param

 113:   (

 114:     [System.IO.FileInfo]$file = $null,

 115:     [string]$twitteruser = $null,

 116:     [string]$twitterpass = $null,

 117:     [string]$message = $null

 118:   );

 119:

 120:   if ( $file -and $twitteruser -and $twitterpass )

 121:   {

 122:     $boundary = [System.Guid]::NewGuid().ToString();

 123:     $header = "--{0}" -f $boundary;

 124:     $footer = "--{0}--" -f $boundary;

 125:

 126:     [System.Text.StringBuilder]$contents = New-Object System.Text.StringBuilder;

 127:     [void]$contents.AppendLine($header);

 128:

 129:     $filedata = Get-EncodedDataFromFile -file $file -codePageName $CODEPAGE;

 130:     if ( $filedata )

 131:     {

 132:       $fileContentType = Get-ImageContentType -file $file;

 133:       $fileHeader = "Content-Disposition: file; name=""{0}""; filename=""{1}""" -f "media", $file.Name;

 134:

 135:       [void]$contents.AppendLine($fileHeader);

 136:       [void]$contents.AppendLine("Content-Type: {0}" -f $fileContentType);

 137:       [void]$contents.AppendLine();

 138:       [void]$contents.AppendLine($fileData);

 139:

 140:       [void]$contents.AppendLine($header);

 141:       [void]$contents.AppendLine("Content-Disposition: form-data; name=""username""");

 142:       [void]$contents.AppendLine();

 143:       [void]$contents.AppendLine($twitteruser);

 144:

 145:       [void]$contents.AppendLine($header);

 146:       [void]$contents.AppendLine("Content-Disposition: form-data; name=""password""");

 147:       [void]$contents.AppendLine();

 148:       [void]$contents.AppendLine($twitterpass);

 149:

 150:       $url = $TWITPIC_API_UPLOAD;

 151:       if ( $message )

 152:       {

 153:         [void]$contents.AppendLine($header);

 154:         [void]$contents.AppendLine("Content-Disposition: form-data; name=""message""");

 155:         [void]$contents.AppendLine();

 156:         [void]$contents.AppendLine($message);

 157:

 158:         $url = $TWITPIC_API_UPLOADANDPOST;

 159:       }

 160:

 161:       [void]$contents.AppendLine($footer);

 162:

 163:       $contents.ToString() > ".\out.txt";

 164:

 165:       $postContentType = "multipart/form-data; boundary={0}" -f $boundary;

 166:

 167:       [xml]$resp = Execute-HTTPPostcommand -url $url -data $contents.ToString() `

 168:         -contentType $postContentType -codePageName $CODEPAGE -userAgent "PoshTwitPic";

 169:

 170:       if ( $resp )

 171:       {

 172:         switch ($resp.rsp.stat)

 173:         {

 174:           "ok" {

 175:             $obj = 1 | select mediaid, mediaurl;

 176:             $obj.mediaid = $resp.rsp.mediaid;

 177:             $obj.mediaurl = $resp.rsp.mediaurl;

 178:             $obj;

 179:           }

 180:           "fail" {

 181:             $errcode = $resp.rsp.err.code;

 182:             $errmsg = $resp.rsp.err.msg;

 183:             Write-Host "Post Error: Code = '$errcode'; Message = '$errmsg'";

 184:           }

 185:         }

 186:       }

 187:     }

 188:   }

 189:   else

 190:   {

 191:     Write-Host "USAGE: Post-TwitPic.ps1 -file file -twitteruser user -twitterpass pass";

 192:   }

 193: }

 194:

 195: if ( $file -and $twitteruser -and $twitterpass )

 196: {

 197:   Post-TwitPic -file $file -twitteruser $twitteruser -twitterpass $twitterpass -message $message;

 198: }

 199: else

 200: {

 201:   Write-Host "USAGE: Post-TwitPic.ps1 -file file -twitteruser user -twitterpass pass";

 202: }

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