FastCGI for Desktop Applications

FastCGIfor Desktop Applications

Development Considerations
Fast to develop
Same language
Same code at each end
Reliable
Scalable
Zero Configuration (Ports, Firewalls etc)
No additional support load

Windows Libraries
1 Application Side – HTTP ->(TCP/IP)
(TCP is optimized for non-real-time applications such as file transfer)

- WinINet
- WinHTTP

2 Server Side: (IIS)

- ISAPI
- CGI
- FastCGI

WinHTTP

Designed to provide client side HTTP services
More secure and robust than WinINet
Fewer dependencies on platform-related APIs
Supports HTTP/1.1 chunked transfer support for HTTP responses.
Geared towards a non-interactive environment
Called with the Win32 API set or a COM interface
Secure Sockets Layer (SSL) functionality
Unique Error codes

WinINet

Legacy library
Designed for interactive message dialogs
Supports FTP, URL caching and persistent cookies

1. WinInet Vs WinHTTP

FastCGI is not proprietary
FastCGI is portable across multiple languages, with zero code changes
A FastCGI app is an isolated process (no web server reset)
A Poorly written FastCGI app won't crash the web server.
FastCGI app servers can run on different hosts from the web server (allows for extremely high performance, distributed web sites.)
FastCGI app servers can run on many OS's
FastCGI is Mature
FastCGI on IIS is actively developed and well supported by Microsoft

ISAPI vs CGI/FastCGI

FastCGIvs CGI (powerpoint)
Persistence – Retains Context
Now with SIGTERM Handler (pipes)
FastCGI will outperform standard CGI
(by a factor of 4:1 ~200 rps vs. ~50 rps)
You don't lose your context:
Allows efficient caching,
Share results between requests

FastCGI

The main task of converting a CGI program into
FastCGI program is separating the initialization
code from the code that needs to run for each request.
The structure should look something like this:

- Initialization code
- Start of response loop

'
' body code
'

- End of response loop

Writing a FastCGI Application

FCGX_InitRequest()
Initializes a FastCGI instance
FCGX_Accept_r()
Blocks until a new FastCGI request is received
FCGX_PutStr()
Return a valid HTTP header
Return nBytes of text/data

FastCGI Library Functions:

Hello World in BASIC
#INCLUDE "FCGX_Header.bas"
FUNCTION WINMAIN
LOCAL Count as LONG
LOCAL sReply AS STRING
LOCAL FCGXReq AS FCGX_REQUEST '// FCGX Structure
'// Open Databases
CALL FCGX_InitRequest(FCGXReq, 0, 0)
DO '// Main Request processing loop
INCR Count
IF FCGX_Accept_r(FCGXReq) < 0 THEN EXIT LOOP '//Execution blocked until HTTP request arrives
sReply = "Content-Type: text/html"+$CRLF+$CRLF '// The reply begins with a valid HTTP header
sReply = sReply + “Hello World, Count=" + STR$(Count)
FCGX_PutStr( STRPTR(sReply), LEN(sReply), FCGXReq.pOut)
LOOP
'// Close Databases etc here
END FUNCTION

Hello World in C++
#include <libfcgi2.h>
int main( ) {
req FCGX_REQUEST;
int count(0);
string sReply ;
ostringstreamss;
// Open Database
FCGX_InitRequest( req, 0, 0 );
while (true) {
if( FCGX_Accept_r(req) < 0 ) break; // Execution is blocked until a Request is received
count++;
ss << count; // Typesafe conversion to text
sReply = "Content-Type: text/html Hello World " + ss.str();
FCGX_PutStr( sReply.data(), sReply.size(), req->pOut) ;
}
// Close Database
return 0;
}

Completely new library
Gracefull exit – close databases etc
The 'SignalBeforeTerminateSeconds' property in fcgiext.ini determins timing of the SIGTERM notification event to be sent by the Web Server to this library under IIS
Request Method is available as an int(4 byte signed integer)
CONTENT_LENGTH is available as an int(4 byte signed integer)
GET method Query String is directly available
Open access to input/output buffers

Libfcgi2 - SIGTERM

SQL requests can generate large responses!
XML introduces severe bloat
An example framework for interacting with a
database on a server
- Chunks
- Encryption/Compression
- Binary Data
Chunk Protocol:
HEADER
DATA BODY
STRINGS
Remote SQL

Request/Response Model:
Authorization
Feature control
Billing
Updating
Data transfer
Pushing marketing content
Deter Piracy
Example Application

http://www.coastrd.com/
http://www.fastcgi.com/
http://www.aprelium.com/
http://forums.iis.net/
WebSites