EHS Embedded HTTP Server  1.5.1.0
ehs_exception.cpp

This example shows, how to handle excetions in your code.

In your derived EHS class, reimplement EHS::HandleThreadException. Its return value determines, if EHS responds with an HTTP error response (return a response) or terminates (return NULL). In your main code, you should have a try/catch block around StartServer, the main loop and StopServer. The main loop should use EHS::ShouldTerminate to check for an eventual termination.
/* $Id: ehs_exception.cpp 81 2012-03-20 12:03:05Z felfert $
*
* EHS is a library for embedding HTTP(S) support into a C++ application
*
* Copyright (C) 2004 Zachary J. Hansen
*
* Code cleanup, new features and bugfixes: Copyright (C) 2010 Fritz Elfert
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License version 2.1 as published by the Free Software Foundation;
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
* This can be found in the 'COPYING' file.
*
*/
#ifdef HAVE_CONFIG_H
# include "config.h"
#endif
#include <ehs.h>
#include <sstream>
#include <iostream>
#include <stdexcept>
#include <typeinfo>
#include <cstdlib>
#include "btexception.h"
#include "common.h"
using namespace std;
// subclass of EHS that defines a custom HTTP response.
class TestException : public EHS
{
HttpResponse *HandleThreadException(ehs_threadid_t, HttpRequest *request, exception &ex)
{
HttpResponse *ret = NULL;
string msg(ex.what());
cerr << "##################### Catched " << msg << endl;
cerr << "request: " << hex << request << dec << endl;
tracing::exception *btx =
dynamic_cast<tracing::exception*>(&ex);
if (NULL != btx) {
string tmsg = btx->where();
cerr << "Backtrace:" << endl << tmsg;
if (0 != msg.compare("fatal")) {
ret = HttpResponse::Error(HTTPRESPONSECODE_500_INTERNALSERVERERROR, request);
string body(ret->GetBody());
tmsg.insert(0, "<br>\n<pre>").append("</pre><p><a href=\"/\">Back to main page</a>");
body.insert(body.find("</body>"), tmsg);
ret->SetBody(body.c_str(), body.length());
}
}
return ret;
}
// generates a page for each http request
ResponseCode HandleRequest(HttpRequest *request, HttpResponse *response)
{
if (0 == request->Uri().compare("/runtime")) {
throw runtime_error("test exception");
}
if (0 == request->Uri().compare("/nonfatal")) {
throw tracing::runtime_error("regular");
}
if (0 == request->Uri().compare("/fatal")) {
throw tracing::runtime_error("fatal");
}
string body("<html><head><title>TestException</title></head><body>");
body.append("<h2>Regular output</h2>");
body.append("Try the following:");
body.append("<ul><li><a href=\"/nonfatal\">Show an exception an continue</a>\n");
body.append("<li><a href=\"/fatal\">Backtrace in console and terminate</a>\n");
body.append("<li><a href=\"/runtime\">Runtime error in console and terminate</a>\n");
body.append("</ul></body></html>");
response->SetBody(body.c_str(), body.length());
return HTTPRESPONSECODE_200_OK;
}
};
// basic main that creates a threaded EHS object and then
// sleeps forever and lets the EHS thread do its job.
int main (int argc, char **argv)
{
cout << getEHSconfig() << endl;
if (argc != 2) {
cerr << "Usage: " << basename(argv[0]) << " [port]" << endl;
return 0;
}
cerr << "binding to " << atoi(argv[1]) << endl;
TestException srv;
EHSServerParameters oSP;
oSP["port"] = argv[1];
oSP["mode"] = "threadpool";
oSP["threadcount"] = 10;
try {
srv.StartServer(oSP);
kbdio kbd;
cout << "Press q to terminate ..." << endl;
while (!(srv.ShouldTerminate() || kbd.qpressed())) {
usleep(300000);
}
srv.StopServer();
} catch (exception &e) {
cerr << "ERROR: " << e.what() << endl;
}
return 0;
}
EHS provides HTTP server functionality to a child class.
Definition: ehs.h:147
std::string & GetBody()
retrieves the body of this response.
Definition: ehstypes.h:116
This class represents a clients HTTP request.
Definition: httprequest.h:51
const std::string & Uri() const
Retrieves this request's URI.
Definition: httprequest.h:143
This class represents what is sent back to the client.
Definition: httpresponse.h:54
static HttpResponse * Error(ResponseCode code, int inResponseId, EHSConnection *ipoEHSConnection)
Constructs a new standardized error response.
void SetBody(const char *ipsBody, size_t inBodyLength)
Sets the body of this instance.