servus::Servus Class Reference

Simple wrapper for ZeroConf key/value pairs. More...

#include <servus.h>

Collaboration diagram for servus::Servus:

Classes
class	Result
	The ZeroConf operation result code. More...

Public Types
enum	Interface { IF_ALL = 0, IF_LOCAL = (unsigned)(-1) }
typedef std::map< std::string, std::map< std::string, std::string > >	Data

Public Member Functions
	Servus (const std::string &name)
	Create a new service handle. More...
virtual	~Servus ()
	Destruct this service. More...
const std::string &	getName () const
void	set (const std::string &key, const std::string &value)
	Set a key/value pair to be announced. More...
Strings	getKeys () const
const std::string &	get (const std::string &key) const
Result	announce (const unsigned short port, const std::string &instance)
	Start announcing the registered key/value pairs. More...
void	withdraw ()
	Stop announcing the registered key/value pairs. More...
bool	isAnnounced () const
Strings	discover (const Interface addr, const unsigned browseTime)
	Discover all announced key/value pairs. More...
Result	beginBrowsing (const servus::Servus::Interface addr)
	Begin the discovery of announced key/value pairs. More...
Result	browse (int32_t timeout=-1)
	Browse and process discovered key/value pairs. More...
void	endBrowsing ()
	Stop a discovery process and return all results. More...
bool	isBrowsing () const
Strings	getInstances () const
Strings	getKeys (const std::string &instance) const
const std::string &	getHost (const std::string &instance) const
bool	containsKey (const std::string &instance, const std::string &key) const
const std::string &	get (const std::string &instance, const std::string &key) const
void	addListener (Listener *listener)
	Add a listener which is invoked according to its supported callbacks. More...
void	removeListener (Listener *listener)
	Remove a listener to stop invokation on its supported callbacks. More...
void	getData (Data &data)

Static Public Member Functions
static bool	isAvailable ()

Friends
std::ostream &	operator<< (std::ostream &, const Servus &)
	Output the servus instance in human-readable format. More...

Detailed Description

Simple wrapper for ZeroConf key/value pairs.

The servus class allows simple announcement and discovery of key/value pairs using ZeroConf networking. The same instance can be used to announce and/or to browse a ZeroConf service. If the Servus library is compiled without zeroconf support (

See also

isAvailable()), this class does not do anything useful.

Example:

/* Copyright (c) 2012-2016, Stefan.Eilemann@epfl.ch
 *
 * This file is part of Servus <https://github.com/HBPVIS/Servus>
 *
 * This library is free software; you can redistribute it and/or modify it under
 * the terms of the GNU Lesser General Public License version 3.0 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.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */

#define BOOST_TEST_MODULE servus_servus
#include <boost/test/unit_test.hpp>

#include <servus/servus.h>

#include <random>

#ifdef SERVUS_USE_DNSSD
#include <dns_sd.h>
#endif

#ifdef _MSC_VER
#include <windows.h>
#define _sleep Sleep
#else
#define _sleep ::sleep
#endif

static const int _propagationTime = 1000;
static const int _propagationTries = 10;

uint16_t getRandomPort()
{
    static std::random_device device;
    static std::minstd_rand engine(device());
    std::uniform_int_distribution<uint16_t> generator(1024u, 65535u);
    return generator(engine);
}

BOOST_AUTO_TEST_CASE(test_servus)
{
    const uint32_t port = getRandomPort();
    std::string serviceName = "_servustest_" + std::to_string(port) + "._tcp";

    try
    {
        servus::Servus service(serviceName);
    }
    catch (const std::runtime_error& e)
    {
        if (getenv("TRAVIS"))
        {
            std::cerr << "Bailing, no avahi on a Travis CI setup" << std::endl;
            BOOST_CHECK_EQUAL(e.what(),
                              "Can't setup avahi client: Daemon not running");
            return;
        }
        throw;
    }

    servus::Servus service(serviceName);
    const servus::Servus::Result& result =
        service.announce(port, std::to_string(port));

    BOOST_CHECK_EQUAL(service.getName(), serviceName);

    if (!servus::Servus::isAvailable())
    {
        // BOOST_CHECK_EQUAL gives a link error for Result::NOT_SUPPORTED
        BOOST_CHECK(result == servus::Servus::Result::NOT_SUPPORTED);
        return;
    }

#ifdef SERVUS_USE_DNSSD
    BOOST_CHECK(servus::Result::SUCCESS == kDNSServiceErr_NoError);
#endif
    if (result != servus::Result::SUCCESS) // happens on CI VMs
    {
        std::cerr << "Bailing, got " << result
                  << ": looks like a broken zeroconf setup" << std::endl;
        return;
    }
    BOOST_CHECK_EQUAL(result, result);
    BOOST_CHECK_EQUAL(result.getString(), "success");
    BOOST_CHECK_EQUAL(result.getCode(), 0);
    std::cout << result << std::endl; // for coverage

    service.withdraw();
    service.set("foo", "bar");
    BOOST_CHECK_EQUAL(service.get("foo"), "bar");
    BOOST_CHECK_EQUAL(service.get("bar"), std::string());
    BOOST_CHECK(service.announce(port, std::to_string(port)));

    int nLoops = _propagationTries;
    while (--nLoops)
    {
        const servus::Strings& hosts =
            service.discover(servus::Servus::IF_LOCAL, _propagationTime);
        if (hosts.empty() && nLoops > 1)
        {
            if (getenv("TRAVIS"))
            {
                std::cerr << "Bailing, got no hosts on a Travis CI setup"
                          << std::endl;
                return;
            }
            continue;
        }

        BOOST_REQUIRE_EQUAL(hosts.size(), 1);
        BOOST_CHECK_EQUAL(hosts.front(), std::to_string(port));
        BOOST_CHECK(service.containsKey(hosts.front(), "foo"));
        BOOST_CHECK_EQUAL(service.get(hosts.front(), "foo"), "bar");
        BOOST_CHECK_EQUAL(service.get("bar", "foo"), std::string());
        BOOST_CHECK_EQUAL(service.get(hosts.front(), "foobar"), std::string());
        break;
    }

    service.set("foobar", "42");

    nLoops = _propagationTries;
    while (--nLoops)
    {
        const servus::Strings& hosts =
            service.discover(servus::Servus::IF_LOCAL, _propagationTime);
        const bool hasFoobar =
            !hosts.empty() && service.containsKey(hosts.front(), "foobar");
        if ((hosts.empty() || !hasFoobar) && nLoops > 1)
            continue;

        BOOST_REQUIRE_EQUAL(hosts.size(), 1);
        BOOST_CHECK_EQUAL(service.get(hosts.front(), "foobar"), "42");
        BOOST_CHECK_EQUAL(service.getKeys().size(), 2);
        break;
    }

    // continuous browse API
    BOOST_CHECK(!service.isBrowsing());
    BOOST_CHECK(service.beginBrowsing(servus::Servus::IF_LOCAL));
    BOOST_CHECK(service.isBrowsing());
    // BOOST_CHECK_EQUAL gives a link error for Result::PENDING
    BOOST_CHECK(service.beginBrowsing(servus::Servus::IF_LOCAL) ==
                servus::Servus::Result::PENDING);
    BOOST_CHECK(service.isBrowsing());

    BOOST_CHECK_EQUAL(service.browse(_propagationTime), service.browse(0));
    servus::Strings hosts = service.getInstances();
    BOOST_REQUIRE_EQUAL(hosts.size(), 1);
    BOOST_CHECK_EQUAL(service.get(hosts.front(), "foo"), "bar");
    BOOST_CHECK_EQUAL(service.getKeys().size(), 2);

    { // test updates during browsing
        servus::Servus service2(serviceName);
        BOOST_CHECK(service2.announce(port + 1, std::to_string(port + 1)));

        nLoops = _propagationTries;
        while (--nLoops)
        {
            BOOST_CHECK(service.browse(_propagationTime));
            hosts = service.getInstances();
            if (hosts.size() < 2 && nLoops > 1)
                continue;

            BOOST_CHECK_EQUAL(hosts.size(), 2);
            break;
        }
    }

    nLoops = _propagationTries;
    while (--nLoops)
    {
        BOOST_CHECK(service.browse(_propagationTime));
        hosts = service.getInstances();
        if (hosts.size() > 1 && nLoops > 1)
            continue;

        BOOST_CHECK_EQUAL(hosts.size(), 1);
        break;
    }

    BOOST_CHECK(service.isBrowsing());
    service.endBrowsing();
    BOOST_CHECK(!service.isBrowsing());

    hosts = service.getInstances();
    BOOST_REQUIRE_EQUAL(hosts.size(), 1);
    BOOST_CHECK_EQUAL(service.get(hosts.front(), "foo"), "bar");
    BOOST_CHECK_EQUAL(service.getKeys().size(), 2);
}

Definition at line 46 of file servus.h.

Member Enumeration Documentation

enum servus::Servus::Interface

Enumerator
IF_ALL	use all interfaces
IF_LOCAL	only local interfaces

Definition at line 49 of file servus.h.

Constructor & Destructor Documentation

servus::Servus::Servus ( const std::string &  name )

explicit

Create a new service handle.

Parameters

name	the service descriptor, e.g., "_hwsd._tcp"

Version

1.1

virtual servus::Servus::~Servus ( )

virtual

Destruct this service.

Version

1.1

Member Function Documentation

void servus::Servus::addListener

(

Listener *

listener

)

Add a listener which is invoked according to its supported callbacks.

Parameters

listener

the listener to be added, must not be nullptr

Version

1.2

Result servus::Servus::announce	(	const unsigned short	port,
		const std::string &	instance
	)

Start announcing the registered key/value pairs.

Parameters

port	the service IP port in host byte order.
instance	a host-unique instance name, hostname is used if empty.

Returns

the success status of the operation.

Version

1.1

Result servus::Servus::beginBrowsing

(

const servus::Servus::Interface

addr

)

Begin the discovery of announced key/value pairs.

Parameters

addr	the scope of the discovery

Returns

the success status of the operation.

Version

1.1

Result servus::Servus::browse

(

int32_t

timeout = -1

)

Browse and process discovered key/value pairs.

Parameters

timeout

The time to spend browsing.

Returns

the success status of the operation.

Version

1.1

bool servus::Servus::containsKey	(	const std::string &	instance,
		const std::string &	key
	)		const

Returns

true if the given key was discovered.

Version

1.1

Strings servus::Servus::discover	(	const Interface	addr,
		const unsigned	browseTime
	)

Discover all announced key/value pairs.

Parameters

addr	the scope of the discovery
browseTime	the browse time, in milliseconds, to wait for new records.

Returns

all instance names found during discovery.

See also

beginBrowsing(), browse(), endBrowsing()

Version

1.1

void servus::Servus::endBrowsing

(

)

Stop a discovery process and return all results.

Version

1.1

const std::string& servus::Servus::get

(

const std::string &

key

)

const

Returns

the value to the given (to be) announced key.

Version

1.1

const std::string& servus::Servus::get	(	const std::string &	instance,
		const std::string &	key
	)		const

Returns

the value of the given key and instance.

Version

1.1

const std::string& servus::Servus::getHost

(

const std::string &

instance

)

const

Returns

the host corresponding to the given instance.

Version

1.3

Strings servus::Servus::getInstances

(

)

const

Returns

all instances found during the last discovery.

Version

1.1

Strings servus::Servus::getKeys

(

)

const

Returns

all (to be) announced keys.

Version

1.1

Strings servus::Servus::getKeys

(

const std::string &

instance

)

const

Returns

all keys discovered on the given instance.

Version

1.1

const std::string& servus::Servus::getName

(

)

const

Returns

the service name.

Version

1.1

bool servus::Servus::isAnnounced

(

)

const

Returns

true if the local data is announced.

Version

1.1

static bool servus::Servus::isAvailable ( )

static

Returns

true if a usable implementation is available.

bool servus::Servus::isBrowsing

(

)

const

Returns

true if the local data is browsing.

Version

1.1

void servus::Servus::removeListener

(

Listener *

listener

)

Remove a listener to stop invokation on its supported callbacks.

Parameters

listener

the listener to be removed, must not be nullptr

Version

1.2

void servus::Servus::set	(	const std::string &	key,
		const std::string &	value
	)

Set a key/value pair to be announced.

Keys should be at most eight characters, and values are truncated to 255 characters. The total length of all keys and values cannot exceed 65535 characters. Setting a value on an announced service causes an update which needs some time to propagate after this function returns, that is, calling discover() immediately afterwards will very likely not contain the new key/value pair.

Version

1.1

void servus::Servus::withdraw

(

)

Stop announcing the registered key/value pairs.

Version

1.1

Friends And Related Function Documentation

std::ostream& operator<< ( std::ostream &  , const Servus &    )

friend

Output the servus instance in human-readable format.

---

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

• servus.h