How to receive binary data from a request in TIdHTTPWebBrokerBridge?

Question

I'm using Indy to build both a client and server application using HTTP. On the Client, I'm using TIdHTTP and on the server I'm using TIdHTTPWebBrokerBridge with a web module. I need the Client to be able to post any type of data via a Stream to the Server. This is done through a universal command I have called /set?Key=API_KEY&Name=FILE_NAME where Key is the API Key for authentication and Name is the name of the file being posted.

On the client, I am posting the data like so:

function TInnoCloudClient.SetData(const Name: String; AStream: TStream): Bool;
var
  U: String;
begin
  U:= FServerURL; //Base URL of Server
  if Copy(U, Length(U)-1, 1) <> '/' then
    U:= U + '/';
  U:= U + 'get?Key='+Encode(FAPIKey);
  U:= U + '&Name='+Encode(Name);
  try
    FWeb.Post(U, AStream);
  except
    on e: exception do begin
      //Handle Exception
    end;
  end;
end;

This function is supposed to save the data inside AStream to a file on the server with the filename of Name. On the Server end, however, in the request handler, I see no corresponding TStream property in the Request which I can read this from.

In the Server, how do I acquire the data which I sent as a TStream descendant? I don't need to know how to save it or handle the request, just how do I obtain this Stream from the Request (TWebRequest)?

Jerry Dodge · Accepted Answer · 2013-02-28 18:45:04Z

4

Use the TWebRequest.ReadClient() or TWebClient.ReadString() method to read the posted binary data, or the TWebRequest.RawContent property to retreive the posted data as an AnsiString.

Something like this should work:

procedure TWebModule1.GetAllDataAsStream(ARequest: TWebRequest; AStream: TMemoryStream);
var
  BytesRead, ContentLength: Integer;
  Buffer: array[0..1023] of Byte;
begin
  AStream.Clear;
  ContentLength := ARequest.ContentLength;
  while ContentLength > 0 do begin
    BytesRead := ARequest.ReadClient(Buffer[0], Min(ContentLength, SizeOf(Buffer)));
    if BytesRead < 1 then Break;
    AStream.WriteBuffer(Buffer[0], BytesRead);
    Dec(ContentLength, BytesRead);
  end;
  AStream.Position:= 0;
end;

edited Feb 28, 2013 at 18:45

Jerry Dodge

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answered Feb 26, 2013 at 20:10

Remy Lebeau

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6 Comments

Vector Over a year ago

From what I saw in the Delphi docs and what my own tests seem to prove is that this code results in truncated content - the first 48k(?) will be missing. It's necessary to read content before calling ReadClient, which retrieves only the rest of the buffer after the first 48k of content .

Remy Lebeau Over a year ago

I don't use WebBroker, so I can't say if that is true or not. All I do know is that TIdHTTPWebBrokerBridge uses TIdHTTPServer internally and exposes its functionality to WebBroker. The various TWebRequest.Read...() methods read directly from Indy's TIdHTTPRequestInfo.PostStream object if the client posted data, otherwise it reads from a TStringStream containing data from TIdHTTPRequestInfo.FormParams and TIdHTTPRequestInfo.UnparsedParams. So, if reading in the manner I showed above is missing data, chances are that it was already read prior to this code being run.

Remy Lebeau Over a year ago

WebBroker's Content value reads from the same stream, and in the case of a client-posted stream, Content seeks the PostStream to the beginning, reads the entire stream, and then seeks it back to where it was previously, whereas the Read...() methods read from the current position onward.

Vector Over a year ago

@RemyLebeau - chances are that it was already read prior to this code being run - I understand, yet i have code that seems to prove otherwise. A colleague sent me this link also along the same lines: Re: Reading with IDThhp.Post sended data in ISAPI-DLL: data get messed up - Hello Remy, sorry for the inconvenience but your code doesn't work:

Remy Lebeau Over a year ago

I have never used DataSnap/WebBroker, so I can't comment on how it actually works. I can only comment on what I see in the TIdHTTPWebBrokerBridge source code.

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