(Delphi DLL) How to Avoid Large Strings in HTTP Responses

In some programming languages/environments, returning and passing large strings is problematic for both performance and other reasons (for example, with SQL Server limitations on sizes varchar variables).

One way of avoiding the need to return the actual string data, is to pass the data from one place to another via a Chilkat StringBuilder or BinData object. This example demonstrates a simple HTTP GET where the response body contains XML approximately 274K in size. The response body is loaded into the Chilkat.Xml without the XML content ever needing to leave the native code internal to Chilkat.

Note: This example requires Chilkat v9.5.0.64 or greater.

Chilkat for Delphi Downloads Chilkat non-ActiveX DLL for Delphi Chilkat ActiveX DLL for Delphi * The examples here use the non-ActiveX DLL.

uses
    Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
    Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls, Http, StringBuilder, Xml, HttpResponse;

...

procedure TForm1.Button1Click(Sender: TObject);
var
http: HCkHttp;
resp: HCkHttpResponse;
sb: HCkStringBuilder;
success: Boolean;
xml: HCkXml;
bAutoTrim: Boolean;

begin
// This example assumes the Chilkat HTTP API to have been previously unlocked.
// See Global Unlock Sample for sample code.

http := CkHttp_Create();

resp := CkHttp_QuickGetObj(http,'https://www.chilkatsoft.com/hamlet.xml');
if (CkHttp_getLastMethodSuccess(http) <> True) then
  begin
    Memo1.Lines.Add(CkHttp__lastErrorText(http));
    Exit;
  end;

sb := CkStringBuilder_Create();
// Copy the response body to sb.
success := CkHttpResponse_GetBodySb(resp,sb);

xml := CkXml_Create();
// Load the XML from the sb.
bAutoTrim := False;
success := CkXml_LoadSb(xml,sb,bAutoTrim);

Memo1.Lines.Add('The response body was ' + IntToStr(CkStringBuilder_getLength(sb)) + ' characters in length.');
Memo1.Lines.Add('Success.');

// The output is:
// 
// 	The response body was 279658 characters in length.
// 	Success.

CkHttp_Dispose(http);
CkStringBuilder_Dispose(sb);
CkXml_Dispose(xml);

end;