Well, this may seem a little like a cheat (it is!), but I had a requirement to interface a barcode reader (via a ComPort) to a database via the network. Developing an html/idc/htx interface to the data was simple enough, but there was no simple way to connect the barcode reader using either Internet Explorer or Netscape.

This page presents several ways to accomplish this

• One based on TWebBrowser
• Another based on TClientSocket
• TNMHTTP

WebBrowser1: TWebBrowser;

procedure TForm1.Button3Click(Sender: TObject);
var
 URL: WideString;
 Flags: OleVariant;
 TargetFrameName: OleVariant;
 PostData: OleVariant;
begin
  Flags := 12;
  TargetFrameName := null;
  PostData := Barcode_UIEdit.Text;
  URL := 'www.SomePage.com/Script/Items_3.IDC?barcode=' + PostData;

  WebBrowser1.Navigate (URL, Flags, TargetFrameName, PostData);
end;

• You can highlight text, but neither Ctrl-Ins nor Ctrl-C will copy the selection to the clipboard
• Each time a given page is read (via Navigate), the cached page is returned. The noCache flags are simply ignored. Right click and select Refresh for new data.
• WebBrowser1.Navigate followed by WebBrowser1.Refresh hangs the application. WebBrowser1.Refresh works ok by itself. This especially affects debugging related idc/htx development.
• Context sensitive help (F1 help) for the component does not work. Instead, open regular help and search for TWebBrowser. In code, if you click on a method and press F1, that works.
• If PostData is NULL (Null is supposed to produce an HTTP GET message), the application crashes.
• There is no way to set the font size. I have seen pages printed via TWebBrowser (right click) use a different size font than Internet Explorer.
• WebBrowser1.ExecWB(OLECMDID_COPY, OLECMDEXECOPT_DODEFAULT); Fails
  (Copy highlighted text to the clipboard)
  Error: Trying to revoke a drop target which has not been registered.

• Use WebBrowser1.Document to access the contents of the page.
• Use WebBrowser1.ExecWB to perform several functions, such as Save, Print, Refresh, and Copy.
• In order to disable the mouse inside a TWebBrowser, place a TPanel on the form, drop the TWebBrowser on top of the TPanel, and set the TPanel's Enabled property to false.

procedure TForm1.Button1Click(Sender: TObject);
var
  DOM : variant;
begin
  DOM := WebBrowser1.Document;
  if Webbrowser1.LocationURL <> '' then begin
     Memo1.text := DOM.Body.OuterHTML;
     end else
     ShowMessage('No page available!');
end;

The problem is that the source is reformatted!

<font face="Verdana" size="2" color="Black">

<FONT face=Verdana color=Black size=2>

• W3C Document Object Model (DOM) Level 1 Specification (Second Edition) provides some general documentation. Good luck understanding it. It is very detailed and long winded with no examples.
• TWebBrowser points to an IHTMLElement interface which includes Document and OuterHTML.
• Document points to an IHTMLDocument2 Interface which includes body which, in turn, points to an IHTMLElement.
• OuterHTML defined - associated with html, head, body and others.

When a form Gets data, the query parameters are added to the html address (the question mark - ? - marks the beginning of the parameters and the ampersand - & - separates the individual parameters.)

URL := 'www.SomePage.com/Script/Some.IDC?Parm1=Value1&Parm2=Value2';

So, other than hiding the parameters, why do we care? Well, it appears that ColdFusion is capable of accepting only Posted parameters and ignoring those attached to the url.

Unfortunately, if you follow the instructions in the Delphi 5 help, the Post fails. A solution is presented in Delphi tips and FAQs. Basically,

• You can not simply assign a string to the PostData (OleVariant) variable - instead, you need to make it an array and load each character - one at a time.
• You must use a special header.

var
 URL: WideString;
 Flags: OleVariant;
 TargetFrameName: OleVariant;
 PostData: OleVariant;
 Headers: OleVariant;
 tempStr: string;
 i: Integer;
begin
 Flags := 12;           // Do not use the cache
 TargetFrameName := ''; // Not '' to open a new browser window
 URL := 'https://dodaac.wpafb.af.mil/results.cfm?requesttimeout=1000';

 tempStr := 'Param1Name=value1&Param2Name=value2';
 PostData := VarArrayCreate([0, Length(tempStr) - 1], varByte);

  { copy the ordinal value of the character into the PostData array}
 for i := 1 to Length(tempStr) do
    PostData[i-1] := Ord(tempStr[i]);
 Headers := 'Content-Type: application/x-www-form-urlencoded' + #10#13;
 
WebBrowser1.Navigate (URL, Flags, TargetFrameName, PostData, Headers);

Note: When TargetFrameName is a null string, and the target page has a security certificate that you must manually accept, the parameters do not work the first time that the page is called - they work fine after that (ie the second time Navigate is called).

• How to print an HTML document from inside of your application
• Example code - Most components and samples on this website make use of Microsoft HTML Object Library and Microsoft Shell Doc Object and Control Library.
• Delphi tips and FAQs - How to pass data via PostData.

Assuming that you are expecting data (as opposed to a formatted web page), you will want to include some kind of delimiters to simplify parsing the file. xml is one standard that can be used for that purpose.

Use a TWinSocketStream object to read from the connection when ClientType=ctBlocking.

TCustomWinSocket.ReceiveText works when ClientType=ctNonBlocking.

ReceiveText is not listed as a method of TClientSocket which is derived from TCustomSocket. There are 2 main types of sockets

TObject -> TPersistent -> TComponent -> 
           TAbstractSocket -> TCustomSocket -> TClientSocket
TObject -> TCustomWinSocket ->TClientWinSocket

See the CHAT demo for an example of how to use TClientSocket.

This code will create a file in the same directory as the exe-file.

procedure TForm1.Button1Click(Sender: TObject);
begin
  NMHTTP1.Body := 'default.html';
  NMHTTP1.InputFileMode := true;
  NMHTTP1.Get('http://www.google.com/');
end;

URL: http:// cpcug.org / user / clemenzi / technical / Databases / Delphi / WebClients.html