ServiceBrowser Class Reference

from PyKDE4.dnssd import *

Inherits: QObject
Namespace: DNSSD

Detailed Description

ServiceBrowser servicebrowser.h DNSSD/ServiceBrowser Browses for network services advertised over DNS-SD

This is the central class in the DNSSD library for applications that want to discover services on network.

Suppose that you need list of web servers running. Then you might do something like

 DNSSD.ServiceBrowser* browser = new DNSSD.ServiceBrowser("_http._tcp");
 connect(browser, SIGNAL(serviceAdded(RemoteService.Ptr)),
         this,    SLOT(addService(RemoteService.Ptr)));
 connect(browser, SIGNAL(serviceRemoved(RemoteService.Ptr)),
         this,    SLOT(delService(RemoteService.Ptr)));
 browser->startBrowse();

In above example addService() will be called for every web server already running and for every web service that subsequently appears on the network and delService() will be called when a server previously advertised is stopped.

Because no domain was passed to constructor, the default domain will be searched. To find other domains to browse for services on, use DomainBrowser.

Author:: Jakub Stachowski

Enumerations
State	{ Working, Stopped, Unsupported }
Signals
	finished ()
	serviceAdded (DNSSD.RemoteService.Ptr service)
	serviceRemoved (DNSSD.RemoteService.Ptr service)
Methods
	__init__ (self, QString type, bool autoResolve=0, QString domain=QString(), QString subtype=QString())
	finished (self)
bool	isAutoResolving (self)
	serviceAdded (self, DNSSD.RemoteService.Ptr service)
	serviceRemoved (self, DNSSD.RemoteService.Ptr service)
[DNSSD::RemoteService::Ptr]	services (self)
	startBrowse (self)
	virtual_hook (self, int a0, void a1)
Static Methods
QString	getLocalHostName ()
DNSSD.ServiceBrowser.State	isAvailable ()
QHostAddress	resolveHostName (QString hostname)

Method Documentation

__init__	(	self,
		QString	type,
		bool	autoResolve=0,
		QString	domain=QString(),
		QString	subtype=QString()
	)

Create a ServiceBrowser for a particular service type

DomainBrowser can be used to find other domains to browse on. If no domain is given, the default domain is used.

The service type is the high-level protocol type, followed by a dot, followed by the transport protocol type (@c _tcp or _udp). The DNS-SD website maintains a full list of service types.

The subtype parameter allows you to do more fine-grained filtering on the services you are interested in. So you might request only FTP servers that allow anonymous access by passing "_ftp._tcp" as the type and "_anon" as the subtype. Subtypes are particularly important for types like _soap and _upnp, which are far too generic for most applications. In these cases, the subtype can be used to specify the particular SOAP or UPnP protocol they want.

Warning:: Enabling autoResolve will increase network usage by resolving all services, so this feature should be used only when necessary.

Parameters:

	type	service types to browse for (example: "_http._tcp")
	autoResolve	discovered services will be resolved before being reported with the serviceAdded() signal
	domain	a domain to search on instead of the default one
	subtype	only browse for a specific subtype

See also:: startBrowse() and isAvailable()

finished ( self )

Emitted when the list of published services has settled

This signal is emitted once after startBrowse() is called when all the services of the requested type that are currently published have been reported (even if none are available or the DNS-SD service is not available). It is emitted again when a new batch of services become available or disappear.

For example, if a new host is connected to network and announces some services watched for by this ServiceBrowser, they will be reported by one or more serviceAdded() signals and the whole batch will be concluded by finished().

This signal can be used by applications that just want to get a list of the currently available services (similar to a directory listing) and do not care about adding or removing services that appear or disappear later.

Warning:: There is no guarantee any RemoteService pointers received by serviceAdded() will be valid by the time this signal is emitted, so you should either do all your work involving them in the slot receiving the serviceAdded() signal, or you should listen to serviceRemoved() as well.

See also:: serviceAdded() and serviceRemoved()

Signal syntax:: QObject.connect(source, SIGNAL("finished()"), target_slot)

QString getLocalHostName ( )

The mDNS hostname of the local machine

Usually this will return the same as QHostInfo.localHostName(), but it may be changed to something different in the Avahi configuration file (if using the Avahi backend).

Returns:: the hostname, or an empty string on failure

Since:: 4.2

bool isAutoResolving ( self )

Whether discovered services are resolved before being reported

Returns:: the value of the autoResolve parameter passed to the constructor

Since:: 4.1

DNSSD.ServiceBrowser.State isAvailable ( )

Checks availability of DNS-SD services

Although this method is part of ServiceBrowser, none of the classes in this library will be able to perform their intended function if this method does not return Working.

If this method does not return Working, it is still safe to call any of the methods in this library. However, no services will be found or published and no domains will be found.

If you use this function to report an error to the user, below is a suggestion on how to word the errors when publishing a service. The first line of each error message can also be used for reporting errors when browsing for services.

 switch(DNSSD.ServiceBrowser.isAvailable()) {
 case DNSSD.ServiceBrowser.Working:
     return "";
 case DNSSD.ServiceBrowser.Stopped:
     return i18n("<p>The Zeroconf daemon is not running. See the Service"
                 " Discovery Handbook for more information.<br/>"
                 "Other users will not see the services provided by this
                 " system when browsing the network via zeroconf, but "
                 " normal access will still work.</p>");
 case DNSSD.ServiceBrowser.Unsupported:
     return i18n("<p>Zeroconf support is not available in this version of KDE."
                 " See the Service Discovery Handbook for more information.<br/>"
                 "Other users will not see the services provided by this
                 " application when browsing the network via zeroconf, but "
                 " normal access will still work.</p>");
 default:
     return i18n("<p>Unknown error with Zeroconf.<br/>"
                 "Other users will not see the services provided by this
                 " application when browsing the network via zeroconf, but "
                 " normal access will still work.</p>");
 }

QHostAddress resolveHostName	(	QString	hostname
	)

Resolves an mDNS hostname into an IP address

This function is very rarely useful, since a properly configured system is able to resolve an mDNS-based host name using the system resolver (ie: you can just pass the mDNS hostname to KIO or other library).

Parameters:

hostname

the hostname to be resolved

Returns:: a QHostAddress containing the IP address, or QHostAddress() if resolution failed

Since:: 4.2

serviceAdded	(	self,
		DNSSD.RemoteService.Ptr	service
	)

Emitted when new service is discovered

If isAutoResolving() returns true, this will not be emitted until the service has been resolved.

Parameters:

service

a RemoteService object describing the service

See also:: serviceRemoved() and finished()

Signal syntax:: QObject.connect(source, SIGNAL("serviceAdded(Ptr)"), target_slot)

serviceRemoved	(	self,
		DNSSD.RemoteService.Ptr	service
	)

Emitted when a service is no longer published over DNS-SD

The RemoteService object is removed from the services() list and deleted immediately after this signal returns.

Warning:: Do not use a delayed connection with this signal

Parameters:

service

a RemoteService object describing the service

See also:: serviceAdded() and finished()

Signal syntax:: QObject.connect(source, SIGNAL("serviceRemoved(Ptr)"), target_slot)

[DNSSD::RemoteService::Ptr] services ( self )

The currently known services of the specified type

Returns:: a list of RemoteService pointers

See also:: serviceAdded() and serviceRemoved()

startBrowse ( self )

Starts browsing for services

Only the first call to this function will have any effect.

Browsing stops when the ServiceBrowser object is destroyed.

Warning:: The serviceAdded() signal may be emitted before this function returns.

See also:: serviceAdded(), serviceRemoved() and finished()

virtual_hook	(	self,
		int	a0,
		void	a1
	)

Enumeration Documentation

State

the service is available

Enumerator:

Working
Stopped
Unsupported

ServiceBrowser Class Reference

Detailed Description

Enumerations

Signals

Methods

Static Methods

Method Documentation

Enumeration Documentation

Modules