TinyDNSSD

TinyDNSSD is a Java library for sending and receiving Multicast DNS packets to perform DNS Service Discovery.

From Android 4.1, service discovery can be performed using the NsdManager. However some use cases make use of the DNS TXT record to efficiently add extra key-value metadata, and Android has a bug that causes the returned data to always be empty. This library can be used to work around this bug.

This library has an Android specific class, the DiscoverResolver, which still uses NsdManager to leverage the system's already running discovery service, but will send another unicast query packet in order to retrieve the TXT record. It also simplifies the API usage compared to calling NsdManager directly.

Another feature is service visibility debouncing: sometimes NsdManager will signal onServiceLost() then shortly afterwards report the same service in onServiceFound(). With this library a tolerance to this can be configured - removed services are not notified to the client until some time elapses without the service reappearing.

Usage

DiscoverResolver resolver = new DiscoverResolver(context, "_androidtvremote._tcp",
        new DiscoverResolver.Listener() {
    @Override
    public void onServicesChanged(Map<String, MDNSDiscover.Result> services) {
        for (MDNSDiscover.Result result : services.values()) {
            // access the Bluetooth MAC from the TXT record
            String mac = result.txt.dict.get("bt");
            String name = result.srv.fqdn;
            Log.d(TAG, name + " -> " + mac);
        }
    }
});
resolver.start();

Download

Download the latest JAR or add Gradle dependency:

dependencies {
    compile 'com.youview:tinydnssd:1.2.7'
}

or Maven:

<dependency>
    <groupId>com.youview</groupId>
    <artifactId>tinydnssd</artifactId>
    <version>1.2.7</version>
</dependency>

License

The MIT License (MIT)
Copyright (c) 2016 YouView TV Ltd

Permission is hereby granted, free of charge, to any person obtaining a copy of
this software and associated documentation files (the "Software"), to deal in
the Software without restriction, including without limitation the rights to
use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
the Software, and to permit persons to whom the Software is furnished to do so,
subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.