Posts Tagged ‘Cerflet’

Cerflet: like Servlets, but with more C++

A few months ago I wrote about the research I had been doing on multiple ways to write server-based web applications, using Java Servlets, FastCGI/C++ and Qt/C++. While this showed that C++-based applications tend to be faster than Java-based ones, it only looked at single-threaded, sequential requests.

While looking at ways to get proper concurrent performance out of a Servlet-like C++ implementation I decided to look again at the POCO C++ Libraries [1] and found that its HTTP server implementation implements proper thread-pool-based working threads for excellent scaling across many concurrent requests.

After spending a few hours putting a basic wrapper library together, I wrote the following ‘Hello World’ example code to demonstrate a basic HTTP Cerflet:

#include <httpcerflet.h>

#include <iostream>
#include <string>

using namespace std;

class HelloRequestHandler :	public HTTPRequestHandler {
	void handleRequest(HTTPServerRequest& request, HTTPServerResponse& response) {
		Application& app = Application::instance();
        app.logger().information("Request from " + request.clientAddress().toString());
		std::ostream& ostr = response.send();
		ostr << "<!DOCTYPE html><html><head><title>Hello World</title></head>";
		ostr << "<body>

Hello World!


int main(int argc, char** argv) {
	// 0. Initialise: create Cerflet instance and set routing.
	HttpCerflet cf;
	RoutingMap map;
	map["/"] = &createInstance<HelloRequestHandler>;
	// 1. Start the server	
	return, argv);

In the main() function we create a new HttpCerflet instance and a new RoutingMap. The latter contains the routes we wish to map to a handler, which in this case is the HelloRequestHandler. For the handler instance we create a reference to the template method createInstance<>(), with the name of our custom handler as the template argument.

What this mapping does is that when a new request is mapped against one of the keys of the RoutingMap, it instantiates a copy of the specified handler, pushing it onto a waiting worker thread.

The handler class itself derives from the HTTPRequestHandler class, which is a standard POCO Net class, reimplementing its handleRequest() method. This shows that Cerflet is more of a complement to POCO instead of abstracting it away. The main goal of Cerflet is to hide some of the complexities and boilerplate of POCO’s HTTP server, allowing one to focus on writing the actual business logic.


As for performance, an ApacheBench benchmark was run with a concurrency of 5, for a total of 100,000 requests.

1. Java Servlet

Server Software:        Apache-Coyote/1.1
Server Hostname:
Server Port:            8080

Document Path:          /examples/servlets/servlet/HelloWorldExample
Document Length:        400 bytes

Concurrency Level:      5
Time taken for tests:   7.697 seconds
Complete requests:      100000
Failed requests:        0
Total transferred:      56200000 bytes
HTML transferred:       40000000 bytes
Requests per second:    12992.07 [#/sec] (mean)
Time per request:       0.385 [ms] (mean)
Time per request:       0.077 [ms] (mean, across all concurrent requests)
Transfer rate:          7130.42 [Kbytes/sec] received

Connection Times (ms)
              min  mean[+/-sd] median   max
Connect:        0    0   0.2      0       1
Processing:     0    0   0.5      0      14
Waiting:        0    0   0.4      0      14
Total:          0    0   0.5      0      14

Percentage of the requests served within a certain time (ms)
  50%      0
  66%      1
  75%      1
  80%      1
  90%      1
  95%      1
  98%      1
  99%      1
 100%     14 (longest request)

2. Cerflet

Server Software:
Server Hostname:
Server Port:            9980

Document Path:          /
Document Length:        99 bytes

Concurrency Level:      5
Time taken for tests:   7.220 seconds
Complete requests:      100000
Failed requests:        0
Total transferred:      19900000 bytes
HTML transferred:       9900000 bytes
Requests per second:    13850.42 [#/sec] (mean)
Time per request:       0.361 [ms] (mean)
Time per request:       0.072 [ms] (mean, across all concurrent requests)
Transfer rate:          2691.63 [Kbytes/sec] received

Connection Times (ms)
              min  mean[+/-sd] median   max
Connect:        0    0   0.2      0       1
Processing:     0    0   0.5      0      10
Waiting:        0    0   0.4      0      10
Total:          0    0   0.5      0      10

Percentage of the requests served within a certain time (ms)
  50%      0
  66%      0
  75%      1
  80%      1
  90%      1
  95%      1
  98%      1
  99%      1
 100%     10 (longest request)


In this benchmark, Cerflet is about 7% faster than the equivalent Tomcat-based Hello World example. Cerflet hereby also logs requests to console, slowing it down somewhat, while Tomcat does not. Cerflet’s Hello World example was compiled using -Og optimisation setting in 32-bit GCC 5.3 (on Windows, MSYS2). The POCO libraries version 1.6 were used, as obtained via MSYS2’s Pacman package manager.

For Tomcat the binary distribution for 8.0.30 as obtained via the official Apache site was used, with the server manually started using the provided startup.bat script. Both servers were run on a Windows 7 Ultimate x64 platform (Intel i7 6700K, 32 GB DDR4) with ApacheBench using the loopback device.


Without compensating for all differences between the two examples used and other potential differences, it is fair to say at this point that both Servlets and Cerflets are roughly equivalent in terms of performance for a simple Hello World example. Likely Cerflets are slightly faster (5-10%) with more gains to be obtained via compiler optimisations (-O3).

The type of operations which would be performed further in the business logic likely will have the most influence on the overall performance between these two platforms. Cerflets do however show that C++-based server-side web applications are more than just a viable option, backed by a mature programming language (C++) and cross-platform libraries (POCO).

Cerflets as they exist today are reminiscent of Spring Boot Java applications, which also feature a built-in HTTP server, thus not relying on a Servlet container (e.g. Tomcat). The advantage of Cerflets is however that they only depend on the POCO libraries (if not linked fully statically), and are not dependent on a central runtime (JVM). This significantly eases deployment.

The Cerflet project’s Github page [2] can be accessed to try the here used example oneself, or to use the HTTP Cerflet implementation in a new project. Both feedback and contributions are welcome.



Categories: C++, Cerflet, HTTP Tags: , , , ,