inet::httptools::HttpController Class Reference

The controller module for HttpTools simulations. More...

#include <HttpController.h>

Inheritance diagram for inet::httptools::HttpController:

Classes
struct	WebServerEntry
	Registration entry for Web servers. More...

Public Member Functions
	HttpController ()
	~HttpController ()
public interface used by server and browser objects in the simulation
void	registerServer (const char *objectName, const char *wwwName, int port, int rank=INSERT_RANDOM, simtime_t activationTime=0.0)
	Register a WWW server object. More...
cModule *	getServerModule (const char *wwwName)
	Get a specific server module reference. More...
cModule *	getAnyServerModule ()
	Get a random server object. More...
int	getServerInfo (const char *wwwName, char *module, int &port)
	Get module and port for a server. More...
int	getAnyServerInfo (char *wwwName, char *module, int &port)
	Get module and port for a random server. More...

Protected Types
enum	ServerStatus { SS_NORMAL, SS_SPECIAL }

Protected Member Functions
cModule *	getTcpApp (const char *node)
	Helper used by the server registration to locate the tcpApp getModule(server or browser) More...
void	setSpecialStatus (const char *www, ServerStatus status, double p, double amortize)
	Set special status of a WWW server. More...
void	cancelSpecialStatus (const char *www)
	Cancel special popularity status for a server. More...
WebServerEntry *	selectFromSpecialList ()
	Select a server from the special list. More...
std::string	listRegisteredServers ()
	List the registered servers. More...
std::string	listSpecials ()
	List the servers on the special list, i.e. More...
std::string	listPickOrder ()
	List the registered servers in the order of the general population pick list. More...
void	parseOptionsFile (std::string file, std::string section)
	Parse a popularity modification events definition file at startup (if defined). More...
cSimpleModule redefinitions
virtual void	initialize (int stage) override
	Initialization of the component and startup of browse event scheduling. More...
virtual void	finish () override
	Report final statistics. More...
virtual void	handleMessage (cMessage *msg) override
	Handle incoming messages. More...
virtual int	numInitStages () const override
	Returns the number of initialization stages. More...

Protected Attributes
std::map< std::string, WebServerEntry * >	webSiteList
	A list of registered web sites (server objects) More...
std::vector< WebServerEntry * >	pickList
	The picklist used to select sites at random. More...
std::list< WebServerEntry * >	specialList
	The special list – contains sites with active popularity modification events. More...
double	pspecial = NaN
	The probability [0,1) of selecting a site from the special list. More...
unsigned long	totalLookups = 0
	A counter for the total number of lookups. More...
rdObject *	rdServerSelection = nullptr
	The random object for the server selection. More...

Private Member Functions
WebServerEntry *	__getRandomServerInfo ()
	Get a random server from the special list with p=pspecial or from the general population with p=1-pspecial. More...

Detailed Description

The controller module for HttpTools simulations.

A controller object for OMNeT++ simulations which use the HttpTools browser and server components. A single controller must exist at the scenario level in each simulation.

See also

HttpBrowserBase

HttpServerBase

Author

Kristjan V. Jonsson

Member Enumeration Documentation

enum inet::httptools::HttpController::ServerStatus

protected

Enumerator
SS_NORMAL
SS_SPECIAL

{ SS_NORMAL, SS_SPECIAL };

Constructor & Destructor Documentation

inet::httptools::HttpController::HttpController

(

)

                               :
    rdServerSelection(nullptr)
{
}

inet::httptools::HttpController::~HttpController

(

)

{
    // Clean up the server references
    for (auto & elem : webSiteList)
        delete elem.second;

    delete rdServerSelection;
}

Member Function Documentation

HttpController::WebServerEntry * inet::httptools::HttpController::__getRandomServerInfo ( )

private

Get a random server from the special list with p=pspecial or from the general population with p=1-pspecial.

Referenced by getAnyServerInfo(), and getAnyServerModule().

{
    WebServerEntry *en;
    int selected = 0;
    // @todo Reimplement! This is a ugly hack to enable easy activation of servers - can lead to problems if no servers active!!!
    do {
        if (pspecial > 0.0 && bernoulli(pspecial)) {
            // Pick from the special list. Each node can have different probabilities
            en = selectFromSpecialList();
            EV_DEBUG << "Selecting from special list. Got node " << en->name << endl;
        }
        else {
            // Pick from the probability distribution which applies to the general population.
            selected = (int)rdServerSelection->draw();
            en = pickList[selected];
            if (en == nullptr)
                throw cRuntimeError("Invalid node selected at index %d", selected);
            EV_DEBUG << "Selecting from normal list. Got node " << en->name << endl;
        }
        EV_DEBUG << "Activation time of the node is " << en->activationTime << " and the current time is " << simTime() << endl;
    } while (en->activationTime > simTime());
    return en;
}

void inet::httptools::HttpController::cancelSpecialStatus ( const char *  www )

protected

Cancel special popularity status for a server.

Called when popularity has been amortized to zero.

Referenced by selectFromSpecialList().

{
    if (specialList.size() == 0)
        return;
    WebServerEntry *en;
    for (auto i = specialList.begin(); i != specialList.end(); i++) {
        en = (*i);
        if (strcmp(en->name.c_str(), www) == 0) {
            pspecial -= en->pvalue;
            en->statusSetTime = simTime();
            en->serverStatus = SS_NORMAL;
            en->pvalue = 0.0;
            en->pamortize = 0.0;
            specialList.erase(i);
            EV_DEBUG << "Special status for " << www << " cancelled" << endl;
            break;
        }
    }
    if (pspecial < 0.0)
        pspecial = 0.0;
    if (specialList.size() == 0)
        pspecial = 0.0;
    EV_DEBUG << "Size of special list is now " << specialList.size() << endl;
}

void inet::httptools::HttpController::finish ( )

overrideprotectedvirtual

Report final statistics.

{
    EV_INFO << "Invoking finish on the controller. Total lookups " << totalLookups << endl;

    WebServerEntry *en;
    std::map<std::string, WebServerEntry *>::const_iterator iter;
    for (iter = webSiteList.begin(); iter != webSiteList.end(); ++iter) {
        en = (*iter).second;
        EV_INFO << "Server " << (*iter).first << ": Access count " << en->accessCount << endl;
    }

    // Clean up the server references
    for (iter = webSiteList.begin(); iter != webSiteList.end(); ++iter)
        delete (*iter).second;
    webSiteList.clear();
}

int inet::httptools::HttpController::getAnyServerInfo	(	char *	wwwName,
		char *	module,
		int &	port
	)

Get module and port for a random server.

Returns a OMNeT++ module name and port number for a randomly chosen server. The general popularity distribution is used in conjunction with the special list to determine the module returned. Called by browser modules to get a random communications partner.

See also

HttpBrowserBase

Referenced by inet::httptools::HttpBrowser::sendRequestToRandomServer().

{
    Enter_Method_Silent();

    if (webSiteList.size() == 0) {
        EV_WARN << "No modules registered. Cannot select a random module" << endl;
        return -1;
    }

    if (pickList.size() == 0) {
        EV_ERROR << "No modules currently in the picklist. Cannot select a random module" << endl;
        return -2;
    }

    EV_DEBUG << "Getting a random server module with pspecial=" << pspecial << endl;

    WebServerEntry *en = __getRandomServerInfo();
    EV_DEBUG << "Got a random www module: " << en->name << ", " << en->host << " (" << en->port << ")\n";

    totalLookups++;
    en->accessCount++;

    strcpy(wwwName, en->name.c_str());
    strcpy(module, en->host.c_str());
    port = en->port;

    return 0;
}

cModule * inet::httptools::HttpController::getAnyServerModule

(

)

Get a random server object.

Returns a OMNeT++ module reference to a randomly chosen server. The general popularity distribution is used in conjunction with the special list to determine the module returned. Called by browser modules to get a random communications partner.

See also

HttpBrowserBase

Referenced by inet::httptools::HttpBrowserDirect::sendRequestToRandomServer().

{
    Enter_Method_Silent();

    if (webSiteList.size() == 0) {
        EV_WARN << "No modules registered. Cannot select a random module" << endl;
        return nullptr;
    }

    if (pickList.size() == 0) {
        EV_ERROR << "No modules currently in the picklist. Cannot select a random module" << endl;
        return nullptr;
    }

    EV_DEBUG << "Getting a random server module with pspecial=" << pspecial << endl;

    WebServerEntry *en = __getRandomServerInfo();
    EV_DEBUG << "Got a random www module: " << en->name << ", " << en->host << " (" << en->port << ")\n";

    totalLookups++;
    en->accessCount++;

    return en->module;
}

int inet::httptools::HttpController::getServerInfo	(	const char *	wwwName,
		char *	module,
		int &	port
	)

Get module and port for a server.

Get a module reference and port number for a specific www name. Used by the browser modules when using TCP transport.

See also

HttpBrowser

Referenced by inet::httptools::HttpBrowser::sendRequestsToServer(), and inet::httptools::HttpBrowser::sendRequestToServer().

{
    Enter_Method_Silent();

    std::string serverUrl = extractServerName(wwwName);

    if (webSiteList.find(serverUrl) == webSiteList.end()) {    // The www name is not in the map
        EV_ERROR << "Could not find module name for " << wwwName << endl;
        return -1;
    }

    WebServerEntry *en = webSiteList[serverUrl];
    EV_DEBUG << "Got module object for www name " << wwwName << ": " << en->host << " (" << en->port << ")\n";

    totalLookups++;
    en->accessCount++;

    strcpy(module, en->host.c_str());
    port = en->port;

    return 0;
}

cModule * inet::httptools::HttpController::getServerModule

(

const char *

wwwName

)

Get a specific server module reference.

Returns a OMNeT++ module reference for a specific WWW name. Called by browser modules to get a communications partner.

See also

HttpBrowserBase

Referenced by inet::httptools::HttpBrowserBase::readScriptedEvents(), inet::httptools::HttpBrowserDirect::sendRequestsToServer(), and inet::httptools::HttpBrowserDirect::sendRequestToServer().

{
    Enter_Method_Silent();

    std::string serverUrl = extractServerName(wwwName);

    if (webSiteList.find(serverUrl) == webSiteList.end()) {    // The www name is not in the map
        EV_ERROR << "Could not find module name for " << wwwName << endl;
        return nullptr;
    }

    WebServerEntry *en = webSiteList[serverUrl];
    EV_DEBUG << "Got module object for www name " << wwwName << ": " << en->host << " (" << en->port << ")\n";

    totalLookups++;
    en->accessCount++;

    if (en->module == nullptr)
        EV_ERROR << "Undefined module for " << wwwName << endl;
    return en->module;
}

cModule * inet::httptools::HttpController::getTcpApp ( const char *  node )

protected

Helper used by the server registration to locate the tcpApp getModule(server or browser)

Referenced by registerServer().

{
    cModule *receiverModule = getSimulation()->getModuleByPath(node);
    ASSERT(receiverModule != nullptr);

    return receiverModule->getSubmodule("tcpApp", 0);    // TODO: CHECK INDEX
}

void inet::httptools::HttpController::handleMessage ( cMessage *  msg )

overrideprotectedvirtual

Handle incoming messages.

{
    if (msg->isSelfMessage()) {
        HttpServerStatusUpdateMsg *statusMsg = check_and_cast<HttpServerStatusUpdateMsg *>(msg);
        EV_DEBUG << "Handling a status change message @T=" << simTime() << " for www " << statusMsg->www() << endl;
        setSpecialStatus(statusMsg->www(), (ServerStatus)statusMsg->eventKind(), statusMsg->pvalue(), statusMsg->pamortize());
        delete statusMsg;
    }
    else {
        delete msg;
    }
}

void inet::httptools::HttpController::initialize ( int  stage )

overrideprotectedvirtual

Initialization of the component and startup of browse event scheduling.

Multi-stage is required to properly initialize the object for random site selection after all servers have been registered.

{
    cSimpleModule::initialize(stage);

    EV_DEBUG << "Initializing stage " << stage << endl;

    if (stage == INITSTAGE_LOCAL) {
        EV_INFO << "Initializing HTTP controller. First stage" << endl;

        cXMLElement *rootelement = par("config").xmlValue();
        if (rootelement == nullptr)
            throw cRuntimeError("Configuration file is not defined");

        cXMLAttributeMap attributes;
        cXMLElement *element;
        // Initialize the random object for random site selection
        rdObjectFactory rdFactory;
        element = rootelement->getFirstChildWithTag("serverPopularityDistribution");
        if (element == nullptr)
            throw cRuntimeError("Server popularity distribution parameter undefined in XML configuration");
        attributes = element->getAttributes();
        rdServerSelection = rdFactory.create(attributes);
        if (rdServerSelection == nullptr)
            throw cRuntimeError("Server popularity distribution random object could not be created");
        EV_INFO << "Using " << rdServerSelection->typeStr() << " for server popularity distribution." << endl;

        pspecial = 0.0;    // No special events by default
        totalLookups = 0;
    }
    else if (stage == INITSTAGE_APPLICATION_LAYER) {
        // Two stages are required to finalize the initialization of the random object for the site selection
        // once the final number of web sites is known.

        EV_INFO << "Initializing HTTP controller. Second stage" << endl;
        EV_INFO << "Registered servers are " << webSiteList.size() << endl;
        // Finish initialization of the probability distribution objects which depend on the number of servers.
        if (rdServerSelection->getType() == dt_uniform)
            ((rdUniform *)rdServerSelection)->setEnd(webSiteList.size());
        else if (rdServerSelection->getType() == dt_zipf)
            ((rdZipf *)rdServerSelection)->setN(webSiteList.size());

        EV_DEBUG << "Server selection probability distribution: " << rdServerSelection->toString() << endl;

        std::string optionsfile = (const char *)par("events");
        std::string optionssection = (const char *)par("eventsSection");
        if (optionsfile.size() != 0)
            parseOptionsFile(optionsfile, optionssection);
    }
}

std::string inet::httptools::HttpController::listPickOrder ( )

protected

List the registered servers in the order of the general population pick list.

Useful for debug.

{
    std::ostringstream str;
    WebServerEntry *en;
    for (auto & elem : pickList) {
        en = (elem);
        str << en->name << ";" << en->host << ";" << en->port << ";" << en->serverStatus
            << ";" << en->pvalue << ";" << en->pamortize << endl;
    }
    return str.str();
}

std::string inet::httptools::HttpController::listRegisteredServers ( )

protected

List the registered servers.

Useful for debug.

{
    std::ostringstream str;
    WebServerEntry *en;
    std::map<std::string, WebServerEntry *>::const_iterator iter;
    for (iter = webSiteList.begin(); iter != webSiteList.end(); ++iter) {
        en = (*iter).second;
        str << (*iter).first << ";" << en->host << ";" << en->port << endl;
    }
    return str.str();
}

std::string inet::httptools::HttpController::listSpecials ( )

protected

List the servers on the special list, i.e.

those with custom selection probability. Useful for debug.

{
    std::ostringstream str;
    WebServerEntry *en;
    for (auto & elem : specialList) {
        en = (elem);
        str << en->name << ";" << en->host << ";" << en->port << ";" << en->serverStatus
            << ";" << en->pvalue << ";" << en->pamortize << endl;
    }
    return str.str();
}

virtual int inet::httptools::HttpController::numInitStages ( ) const

inlineoverrideprotectedvirtual

Returns the number of initialization stages.

Two required.

{ return NUM_INIT_STAGES; }

void inet::httptools::HttpController::parseOptionsFile ( std::string  file, std::string  section  )

protected

Parse a popularity modification events definition file at startup (if defined).

Format: {time};{www name};{event kind};{p value};{amortization factor} Event kind is not used at the present – use 1 as a default here.

Referenced by initialize().

{
    bool bSectionFound = false;
    std::ifstream tracefilestream;
    tracefilestream.open(file.c_str());
    if (!tracefilestream.is_open())
        throw cRuntimeError("Could not open events file %s", file.c_str());

    if (section.size() == 0)
        bSectionFound = true; // Grab first section

    double pval;
    double amortizeval;
    simtime_t activationtime;
    std::string line;
    int linecount = 0;
    HttpServerStatusUpdateMsg *statusChange;
    while (!std::getline(tracefilestream, line).eof()) {
        linecount++;
        if (line.empty() || line[0] == '#')
            continue;
        if (line[0] == '[') {
            // Section
            bSectionFound = false;
            std::string sectionsub = line.substr(1, line.size() - 2);
            bSectionFound = sectionsub == section;
        }
        else {
            if (bSectionFound) {
                // Format: {time};{www name};{event kind};{p value};{amortization factor}
                // Event kind is not used at the present

                cStringTokenizer tokenizer = cStringTokenizer(line.c_str(), ";");
                std::vector<std::string> res = tokenizer.asVector();
                if (res.size() != 5)
                    throw cRuntimeError("Invalid format of event config line in '%s' Line: '%s'", file.c_str(), line.c_str());
                try {
                    activationtime = (simtime_t)atof(res[0].c_str());
                    pval = atof(res[3].c_str());
                    amortizeval = atof(res[4].c_str());
                }
                catch (...) {
                    throw cRuntimeError("Invalid format of event config line in '%s' Line: '%s'", file.c_str(), line.c_str());
                }
                EV_DEBUG << "Scheduling a status change for " << res[1] << " @ T=" << activationtime << ". Parameters: " << line << endl;
                statusChange = new HttpServerStatusUpdateMsg();
                statusChange->setWww(res[1].c_str());
                statusChange->setEventKind(1);
                statusChange->setPvalue(pval);
                statusChange->setPamortize(amortizeval);
                scheduleAt(activationtime, statusChange);
            }
        }
    }
    tracefilestream.close();
}

void inet::httptools::HttpController::registerServer	(	const char *	objectName,
		const char *	wwwName,
		int	port,
		int	rank = INSERT_RANDOM,
		simtime_t	activationTime = 0.0
	)

Register a WWW server object.

Called by server objects at startup.

See also

HttpServerBase. A data structure is created for the registered server for easy lookup. It is entered into the site picklist which is used to select servers in the general population. The insertion is specified by the INSERT_* defines: Registered sites can be inserted at the end, in the middle or at random. This does play a role when zipf or other non-uniform selection probability is used (the pick list is basically mapped to the non-uniform distribution).

Referenced by inet::httptools::HttpServerBase::registerWithController().

{
    Enter_Method_Silent();

    std::string serverName = extractServerName(wwwName);

    EV_DEBUG << "Registering www server: " << objectName << ", " << wwwName
             << " (" << port << "). Activation time is " << activationTime << endl;

    if (webSiteList.find(wwwName) != webSiteList.end())
        EV_ERROR << "Server " << wwwName << " is already registered\n";

    WebServerEntry *en = new WebServerEntry;

    en->name = serverName;
    en->host = objectName;
    en->port = port;
    en->module = getTcpApp(objectName);
    en->activationTime = activationTime;
    en->statusSetTime = simTime();
    en->serverStatus = SS_NORMAL;
    en->pvalue = 0.0;
    en->pamortize = 0.0;
    en->accessCount = 0;

    if (en->module == nullptr)
        throw cRuntimeError("Server %s does not have a WWW module", wwwName);

    webSiteList[en->name] = en;

    int pos;
    auto begin = pickList.begin();
    if (rank == INSERT_RANDOM) {
        if (pickList.size() == 0) {
            pickList.push_back(en);
        }
        else {
            pos = (int)uniform(0, pickList.size() - 1);
            pickList.insert(begin + pos, en);
        }
    }
    else if (rank == INSERT_MIDDLE) {
        pos = pickList.size() / 2;
        pickList.insert(begin + pos, en);
    }
    else if (rank == INSERT_END || rank >= (int)pickList.size()) {
        pickList.push_back(en);
    }
    else {
        pickList.insert(begin + rank, en);
    }
}

HttpController::WebServerEntry * inet::httptools::HttpController::selectFromSpecialList ( )

protected

Select a server from the special list.

This method is called with the pspecial probability.

Referenced by __getRandomServerInfo().

{

    if (specialList.empty()) {
        EV_ERROR << "No entries in special list. Cannot select server with special probability" << endl;
        return nullptr;
    }

    WebServerEntry *en = specialList.front();

    if (specialList.size() > 1) {
        double p = uniform(0, 1);
        double pcumulative = 0.0;
        for (auto & elem : specialList) {
            en = (elem);
            pcumulative += en->pvalue;
            if (pcumulative / pspecial > p)
                break;
        }
    }

    if (en->pamortize > 0.0) {
        double newp = en->pvalue - en->pamortize;
        if (newp > 0.0) {
            en->pvalue = newp;
            pspecial -= en->pamortize;
            EV_DEBUG << "Amortizing special probability for " << en->name << ". Now at " << en->pvalue << endl;
        }
        else {
            pspecial -= en->pvalue;
            en->pvalue = 0.0;
            cancelSpecialStatus(en->name.c_str());
            EV_DEBUG << "Cancelling special status for " << en->name << endl;
        }
    }

    return en;
}

void inet::httptools::HttpController::setSpecialStatus ( const char *  www, ServerStatus  status, double  p, double  amortize  )

protected

Set special status of a WWW server.

Triggered by an event message.

Referenced by handleMessage().

{
    if (webSiteList.find(www) == webSiteList.end()) {    // The www name is not in the map
        EV_ERROR << "Could not find module name for " << www << ". Cannot set special status" << endl;
        return;
    }

    EV_DEBUG << "Setting special status for " << www << ", p=" << p << " and amortize=" << amortize << endl;

    WebServerEntry *en = webSiteList[www];

    en->statusSetTime = simTime();
    en->serverStatus = status;
    en->pvalue = p;
    en->pamortize = amortize;

    specialList.push_front(en);

    pspecial += p;
}

Member Data Documentation

std::vector<WebServerEntry *> inet::httptools::HttpController::pickList

protected

The picklist used to select sites at random.

Referenced by __getRandomServerInfo(), getAnyServerInfo(), getAnyServerModule(), listPickOrder(), and registerServer().

double inet::httptools::HttpController::pspecial = NaN

protected

The probability [0,1) of selecting a site from the special list.

Referenced by __getRandomServerInfo(), cancelSpecialStatus(), getAnyServerInfo(), getAnyServerModule(), initialize(), selectFromSpecialList(), and setSpecialStatus().

rdObject* inet::httptools::HttpController::rdServerSelection = nullptr

protected

The random object for the server selection.

Referenced by __getRandomServerInfo(), initialize(), and ~HttpController().

std::list<WebServerEntry *> inet::httptools::HttpController::specialList

protected

The special list – contains sites with active popularity modification events.

Referenced by cancelSpecialStatus(), listSpecials(), selectFromSpecialList(), and setSpecialStatus().

unsigned long inet::httptools::HttpController::totalLookups = 0

protected

A counter for the total number of lookups.

Referenced by finish(), getAnyServerInfo(), getAnyServerModule(), getServerInfo(), getServerModule(), and initialize().

std::map<std::string, WebServerEntry *> inet::httptools::HttpController::webSiteList

protected

A list of registered web sites (server objects)

Referenced by finish(), getAnyServerInfo(), getAnyServerModule(), getServerInfo(), getServerModule(), initialize(), listRegisteredServers(), registerServer(), setSpecialStatus(), and ~HttpController().

---

The documentation for this class was generated from the following files:

• HttpController.h
• HttpController.cc