[fpc-devel] Customize TRequest and TResponse

[Michael Van Canneyt]

On Sun, 5 Feb 2012, Joao Morais wrote:

> Hello fpc-devel list.
>
> I need to implement some customizations to the request and response
> classes of the fastcgi implementation -- maybe others as well -- but
> afaics I cannot override such classes without copy/paste the whole
> FCGI.ProcessRecord method.
>
> A draft of the implementation I'd like to see in the fcl-web is
> described below. Is it possible to implement? Perhaps 2.6 branch?

It is possible to implement this, and I even have started the process.

However, I don't see the use of adding the abstract calls ?
Implementing this in src/base/custweb.pp gives the impression that you can use 
any TRequest/TResponse descendent, which definitely is not the case.

Each descendent needs to be sure that it gets the correct TRequest descendent.

I think it is sufficient to make sure that every webhandler has 2 virtual calls 
that create the correct descendents. You can then override these 2 virtual calls.

for instance in src/base/custfcgi.pp I would add

     function CreateRequest: TFCGIRequest; virtual;
     function CreateResponse(ARequest: TFCGIRequest): TFCGIResponse; virtual;

And similar functions in the other webhandler components.

I started on this procedure already.

For instance in custcgi, it is already implemented like that:

    Function CreateResponse(AOutput : TStream) : TCGIResponse; virtual;
    Function CreateRequest : TCGIRequest; virtual;

I just need to complete the work.

If you want, you can of course provide a patch that completes the work.

Michael.

>
> Joao Morais
>
>
>
> 1. New virtual methods used to create requests and responses:
>
> --- src/base/custweb.pp (revision 20261)
> +++ src/base/custweb.pp (workcopy)
> @@ -108,6 +108,8 @@
>     Procedure SetBaseURL(AModule : TCustomHTTPModule; Const
> AModuleName : String; ARequest : TRequest); virtual;
>     function GetApplicationURL(ARequest : TRequest): String; virtual;
>     procedure ShowRequestException(R: TResponse; E: Exception); virtual;
> +    function CreateRequest: TRequest; virtual; abstract;
> +    function CreateResponse(ARequest: TRequest): TResponse; virtual; abstract;
>     Procedure InitRequest(ARequest : TRequest); virtual;
>     Procedure InitResponse(AResponse : TResponse); virtual;
>     Function GetEmail : String; virtual;
>
> 2. Patch every fcl-web implementation in order to use the virtual
> method instead of a hardcoded class:
>
> --- src/base/custfcgi.pp        (revision 20261)
> +++ src/base/custfcgi.pp        (workcopy)
> @@ -119,6 +119,8 @@
>     function Read_FCGIRecord : PFCGI_Header;
>     function DataAvailable : Boolean;
>   protected
> +    function CreateRequest: TRequest; override;
> +    function CreateResponse(ARequest: TRequest): TResponse; override;
>     Function DoFastCGIRead(AHandle : THandle; Var ABuf; ACount :
> Integer) : Integer; virtual;
>     Function DoFastCGIWrite(AHandle : THandle; Const ABuf; ACount :
> Integer) : Integer; virtual;
>     function  ProcessRecord(AFCGI_Record: PFCGI_Header; out ARequest:
> TRequest;  out AResponse: TResponse): boolean; virtual;
> @@ -793,6 +795,16 @@
> end;
> {$endif}
>
> +function TFCgiHandler.CreateRequest: TRequest;
> +begin
> +  Result := TFCGIRequest.Create;
> +end;
> +
> +function TFCgiHandler.CreateResponse(ARequest: TRequest): TResponse;
> +begin
> +  Result := TFCGIResponse.Create(ARequest);
> +end;
> +
> function TFCgiHandler.DoFastCGIRead(AHandle: THandle; var ABuf;
> ACount: Integer): Integer;
> begin
> {$ifdef windowspipe}
> @@ -831,7 +843,7 @@
>       end;
>     assert(not assigned(FRequestsArray[ARequestID].Request));
>     assert(not assigned(FRequestsArray[ARequestID].Response));
> -    ATempRequest:=TFCGIRequest.Create;
> +    ATempRequest:=CreateRequest as TFCGIRequest;
>     InitRequest(ATempRequest);
>     ATempRequest.RequestID:=ARequestID;
>     ATempRequest.Handle:=FHandle;
> @@ -848,7 +860,7 @@
>   else if FRequestsArray[ARequestID].Request.ProcessFCGIRecord(AFCGI_Record)
> then
>     begin
>     ARequest:=FRequestsArray[ARequestID].Request;
> -    FRequestsArray[ARequestID].Response := TFCGIResponse.Create(ARequest);
> +    FRequestsArray[ARequestID].Response := CreateResponse(ARequest)
> as TFCGIResponse;
>     InitResponse(FRequestsArray[ARequestID].Response);
>     FRequestsArray[ARequestID].Response.ProtocolOptions:=Self.ProtocolOptions;
>     FRequestsArray[ARequestID].Response.FOnWrite:=@DoFastCGIWrite;
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