WebSocket Server (Delphi)

Overview

TsgcWebSocketHTTPServer implements Server WebSocket Component and can handle multiple threaded client connections as TsgcWebSocketServer, and allows you to serve HTML pages using a built-in HTTP Server, sharing the same port for WebSocket connections and HTTP requests.

At a glance

Features

• Native Delphi implementation with full ANSI/Unicode support.

Technical specification

Main properties

The principal published / public properties used to configure and drive the component. Consult the online help for the full list.

Main methods

The principal public methods exposed by the component.

Public events

The component exposes the following published events; consult the online help for full event-handler signatures.

Quick Start

Drop the component on a form, configure the properties below and activate it. The snippet that follows shows the typical TsgcWebSocketHTTPServer configuration sourced from the online help.

Delphi (VCL / FireMonkey)

procedure OnHTTP2BeforeAsyncRequest(Sender: TObject; Connection: TsgcWSConnection; const ARequestInfo: TIdHTTPRequestInfo; var Async: Boolean);
begin
  if ARequestInfo.Document = '/fast-request' then
    ASync := False;
end;

C++ Builder

void __fastcall TForm1::OnHTTP2BeforeAsyncRequest(TObject *Sender, TsgcWSConnection *Connection, const TIdHTTPRequestInfo &ARequestInfo, bool &Async)
{
    if (ARequestInfo.Document == "/fast-request")
        Async = false;
}

.NET (C#)

void OnHTTP2BeforeAsyncRequest(object Sender, TsgcWSConnection Connection, TIdHTTPRequestInfo ARequestInfo, ref bool Async)
{
  if (ARequestInfo.Document == "/fast-request")
    Async = false;
}

Common scenarios

The following scenarios are lifted verbatim from the online help. Each shows the configuration and method calls needed to drive the component through a specific real-world flow.

1 · TsgcWebSocketHTTPServer | 404 Error without Response Body

By default, the Indy library adds a content body to HTTP responses if there is no ContentText or ContentStream assigned. If you want to return an empty response body (for a 404 error or similar), you can use the following approach.

procedure OnCommandGet(AContext: TIdContext; ARequestInfo: TIdHTTPRequestInfo; 
 AResponseInfo: TIdHTTPResponseInfo);
begin
AResponseInfo.ContentStream := TStringStream.Create('');
AResponseInfo.ContentType := 'text/html';
AResponseInfo.ResponseNo := 404;
end;

private void OnCommandGet(TIdContext *AContext, TIdHTTPRequestInfo *ARequestInfo, 
  TIdHTTPResponseInfo *AResponseInfo)
{
AResponseInfo->ContentStream = new TStringStream("");
AResponseInfo->ContentType = "text/html";
AResponseInfo->ResponseNo = 404;
}

2 · TsgcWebSocketHTTPServer | Stream Video

If you want to stream a video file using the server, you can use the function IndyStreamFileVideo to stream the file using chunked transfer encoding.

procedure OnServerCommandGet(AContext: TIdContext; ARequestInfo: TIdHTTPRequestInfo; AResponseInfo: TIdHTTPResponseInfo);
begin
  if ARequestInfo.Document = '/video.mp4' then
    IndyStreamFileVideo(Acontext, AResponseInfo, 'C:\videos\video.mp4')
  else
    AResponseInfo.ResponseNo := 404;
end;

void OnServerCommandGet(TIdContext *AContext, TIdHTTPRequestInfo *ARequestInfo, TIdHTTPResponseInfo *AResponseInfo)
{
  if (ARequestInfo->Document == "/video.mp4") {
    IndyStreamFileVideo(Acontext, AResponseInfo, "C:\\videos\\video.mp4");
  } else {
    AResponseInfo->ResponseNo = 404;
  }
}

void OnServerCommandGet(TIdContext AContext, TIdHTTPRequestInfo ARequestInfo, TIdHTTPResponseInfo AResponseInfo)
{
  if (ARequestInfo.Document == "/video.mp4")
  {
    IndyStreamFileVideo(AContext, AResponseInfo, "C:\\videos\\video.mp4");
  }
  else
  {
    AResponseInfo.ResponseNo = 404;
  }
}

3 · Certificate from Windows Store

If the certificate is already installed in the Windows Certificate Store, provide the certificate thumbprint and indicate where it is located.

oServer := TsgcWebSocketHTTPServer.Create(nil);
oServer.SSL := True;
oServer.SSLOptions.IOHandler := iohSChannel;
oServer.SSLOptions.Version := tls1_2;
oServer.SSLOptions.Port := 443;
oServer.Port := 443;
oServer.SSLOptions.SChannel_Options.CertHash := 'C12A8FC8AE668F866B48F23E753C93D357E9BE10';
oServer.SSLOptions.SChannel_Options.CertStoreName := scsnMY;
oServer.SSLOptions.SChannel_Options.CertStorePath := scspStoreLocalMachine;
oServer.Active := True;

oServer = new TsgcWebSocketHTTPServer();
oServer->SSL = true;
oServer->SSLOptions->IOHandler = iohSChannel;
oServer->SSLOptions->Version = tls1_2;
oServer->SSLOptions->Port = 443;
oServer->Port = 443;
oServer->SSLOptions->SChannel_Options->CertHash = "C12A8FC8AE668F866B48F23E753C93D357E9BE10";
oServer->SSLOptions->SChannel_Options->CertStoreName = scsnMY;
oServer->SSLOptions->SChannel_Options->CertStorePath = scspStoreLocalMachine;
oServer->Active = true;

TsgcWebSocketHTTPServer oServer = new TsgcWebSocketHTTPServer();
oServer.SSL = true;
oServer.SSLOptions.IOHandler = TsgcSSLIOHandler.iohSChannel;
oServer.SSLOptions.Version = TsgcTLSVersion.tls1_2;
oServer.SSLOptions.Port = 443;
oServer.Port = 443;
oServer.SSLOptions.SChannel_Options.CertHash = "C12A8FC8AE668F866B48F23E753C93D357E9BE10";
oServer.SSLOptions.SChannel_Options.CertStoreName = TsgcSChannelCertStoreName.scsnMY;
oServer.SSLOptions.SChannel_Options.CertStorePath = TsgcSChannelCertStorePath.scspStoreLocalMachine;
oServer.Active = true;

4 · Configure Server Push

Following the screenshots above, you can configure your server so that every time there is a new request for the /index.html file, the server will send index.html and styles.css.

server := TsgcWebSocketHTTPServer.Create(nil);
oLinks := TStringList.Create;
Try
  oLinks.Add('/styles.css');
  server.PushPromiseAddPreLoadLinks('/index.html', oLinks);
Finally
  oLinks.Free;
End;
      
      procedure OnCommandGet(AContext: TIdContext; ARequestInfo: TIdHTTPRequestInfo; AResponseInfo:
TIdHTTPResponseInfo);
begin
  if ARequestInfo.Document = '/index.html' then
  begin
    AResponseInfo.ContentText := '';
    AResponseInfo.ContentType := 'text/html';
    AResponseInfo.ResponseNo := 200;
  end
  else if ARequestInfo.Document = '/styles.css' then
  begin
    AResponseInfo.ContentText := '';
    AResponseInfo.ContentType := 'text/css';
    AResponseInfo.ResponseNo := 200;
  end;
end;

TsgcWebSocketHTTPServer *server = new TsgcWebSocketHTTPServer(this);
TStringList *oLinks = new TStringList();
try
{
  oLinks->Add("/styles.css");
  server->PushPromiseAddPreLoadLinks("/index.html", oLinks);
}  
__finally
{
  oLinks->Free();
}
      
void OnCommandGet(TIdContext *AContext, TIdHTTPRequestInfo *ARequestInfo, TIdHTTPResponseInfo *AResponseInfo)
{
  if (ARequestInfo->Document == "/index.html")
  {
    AResponseInfo->ContentText = "";
    AResponseInfo->ContentType = "text/html";
    AResponseInfo->ResponseNo = 200;
  }
  else if (ARequestInfo->Document == "/styles.css")
  {
    AResponseInfo->ContentText = "";
    AResponseInfo->ContentType = "text/css";
    AResponseInfo->ResponseNo = 200;
  }
}

TsgcWebSocketHTTPServer server = new TsgcWebSocketHTTPServer(this);
server.PushPromiseAddPreLoadLinks("/index.html", "/styles.css");
void OnCommandGet(TsgcWSConnection Connection, TsgcWSHTTPRequestInfo RequestInfo, ref TsgcWSHTTPResponseInfo ResponseInfo)
{
  if (RequestInfo.Document == "/index.html")
  {
    ResponseInfo.ContentText = "";
    ResponseInfo.ContentType = "text/html";
    ResponseInfo.ResponseNo = 200;
  }
  else if (RequestInfo.Document == "/styles.css")
  {
    ResponseInfo.ContentText = "";
    ResponseInfo.ContentType = "text/css";
    ResponseInfo.ResponseNo = 200;
  }
}

5 · HTTP Server Sessions — Configuration

There are some properties in TsgcWebSocketHTTPServer that enable/disable sessions in the server component. The most important are:

TsgcWebSocketHTTPServer1.SessionState := True;
TsgcWebSocketHTTPServer1.SessionTimeout := 600000;
AutoStartSession := False;

TsgcWebSocketHTTPServer1->SessionState = true;
TsgcWebSocketHTTPServer1->SessionTimeout = 600000;
AutoStartSession = false;

TsgcWebSocketHTTPServer1.SessionState = true;
TsgcWebSocketHTTPServer1.SessionTimeout = 600000;
AutoStartSession = false;

6 · OnBeforeCommand

Use this event to customize the HTTP response. For example, if you want some endpoints to use an authorization scheme while others can be accessed without authorization, use the options parameter to allow or disable it. Below is an example where Authorization Basic is enabled, but when a user requests the endpoint /public, authorization is not required.

procedure OnBeforeCommand(const aConnection: TsgcWSConnection; ARequestInfo: TIdHTTPRequestInfo; AResponseInfo: TIdHTTPResponseInfo; var aOptions: TsgcHTTPCommandOptions);
begin
  if aRequestInfo.Document = '/public' then
    aOptions := [hcoAuthorizedBasic];
end;

void __fastcall TForm1::OnBeforeCommand(TsgcWSConnection* aConnection, TIdHTTPRequestInfo* ARequestInfo, TIdHTTPResponseInfo* AResponseInfo, TsgcHTTPCommandOptions &aOptions)
{
  if (ARequestInfo->Document == "/public")
    aOptions << hcoAuthorizedBasic;
}

public void OnBeforeCommand(TsgcWSConnection aConnection, TIdHTTPRequestInfo ARequestInfo, TIdHTTPResponseInfo AResponseInfo, ref TsgcHTTPCommandOptions aOptions)
{
    if (ARequestInfo.Document == "/public")
        aOptions = TsgcHTTPCommandOptions.hcoAuthorizedBasic;
}

Sources used to build this document

Every external claim links back to a primary source. The online-help references decode the canonical deep-link the company maintains for this component.