EpcDispatcher

EpcDispatcher — publish DNS-SD services

Stability Level

Unstable, unless otherwise indicated

Properties

EpcCollisionHandling collision-handling Read / Write / Construct
gchar * cookie Read / Write / Construct
gchar * name Read / Write / Construct

Object Hierarchy

    GEnum
    ├── EpcAddressFamily
    ╰── EpcCollisionHandling
    GObject
    ╰── EpcDispatcher

Includes

#include <libepc/dispatcher.h>

Description

The EpcDispatcher object provides an easy method for publishing DNS-SD services. Unlike established APIs like Avahi or HOWL the EpcDispatcher doesn't expose any state changes reported by the DNS-SD daemon, but instead tries to handle them automatically. Such state changes include, for instance, name collisions or a restart of the DNS-SD daemon.

Example 7. Publish a printing service

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dispatcher = epc_dispatcher_new ("Dead Tree Desecrator");

epc_dispatcher_add_service (dispatcher, EPC_ADDRESS_IPV4, "_ipp._tcp",
                            NULL, NULL, 651, "path=/printers", NULL);
epc_dispatcher_add_service (dispatcher, EPC_ADDRESS_UNSPEC,
                            "_duplex._sub._printer._tcp",
                            NULL, NULL, 515, NULL);


Functions

epc_dispatcher_new ()

EpcDispatcher *
epc_dispatcher_new (const gchar *name);

Creates a new EpcDispatcher object for announcing a DNS-SD service. The service is announced on all network interfaces.

Call epc_dispatcher_add_service() to actually announce a service.

Parameters

name

the human friendly name of the service

 

Returns

the newly created EpcDispatcher object.


epc_dispatcher_run ()

gboolean
epc_dispatcher_run (EpcDispatcher *dispatcher,
                    GError **error);

Starts the Avahi client of the EpcDispatcher. If the client was not started, the function returns FALSE and sets error . The error domain is EPC_AVAHI_ERROR. Possible error codes are those of the

Avahi library.

Parameters

dispatcher

a EpcDispatcher

 

error

return location for a GError, or NULL

 

Returns

TRUE when the dispatcher was started successfully, FALSE if an error occurred.


epc_dispatcher_reset ()

void
epc_dispatcher_reset (EpcDispatcher *dispatcher);

Revokes all service announcements of this EpcDispatcher.

Parameters

dispatcher

a EpcDispatcher

 

epc_dispatcher_add_service ()

void
epc_dispatcher_add_service (EpcDispatcher *dispatcher,
                            EpcAddressFamily protocol,
                            const gchar *type,
                            const gchar *domain,
                            const gchar *host,
                            guint16 port,
                            ...);

Announces a TCP/IP service via DNS-SD.

The service type shall be a well-known DNS-SD service type as listed on

http://www.dns-sd.org/ServiceTypes.html. This function tries to announce both the base service type and the sub service type when the service name contains more than just one dot: Passing "_anon._sub._ftp._tcp" for @type will announce the services "_ftp._tcp" and "_anon._sub._ftp._tcp". The function can be called more than once. Is this necessary when the server provides different access methods. For instance a web server could provide HTTP and encrypted HTTPS services at the same time. Calling this function multiple times also is useful for servers providing the same service at different, but not all network interfaces of the host. When passing %NULL for @domain, the service is announced within the local network only, otherwise it is announced at the specified DNS domain. The responsible server must be configured to support DNS-SD.

Pass NULL for host to use the official host name of the machine to announce the service. On machines with multiple DNS entries you might want to explictly choose a fully qualified DNS name to announce the service.

Parameters

dispatcher

a EpcDispatcher

 

protocol

the EpcAddressFamily this service supports

 

type

the machine friendly name of the service

 

domain

the DNS domain for the announcement, or NULL

 

host

the fully qualified host name of the service, or NULL

 

port

the TCP/IP port of the service

 

...

an optional list of TXT records, terminated by NULL

 

epc_dispatcher_add_service_subtype ()

void
epc_dispatcher_add_service_subtype (EpcDispatcher *dispatcher,
                                    const gchar *type,
                                    const gchar *subtype);

Announces an additional sub service for a registered DNS-SD service.

This function will fail silently, when the service specified by type hasn't been registered yet.

Parameters

dispatcher

a EpcDispatcher

 

type

the base service type

 

subtype

the sub service type

 

epc_dispatcher_set_collision_handling ()

void
epc_dispatcher_set_collision_handling (EpcDispatcher *dispatcher,
                                       EpcCollisionHandling method);

Changes the collision handling strategy the dispatcher uses. See “collision-handling” for details.

Parameters

dispatcher

a EpcDispatcher

 

method

the new strategy

 

Since: 0.3.1


epc_dispatcher_set_cookie ()

void
epc_dispatcher_set_cookie (EpcDispatcher *dispatcher,
                           const gchar *cookie);

Changes the unique identifier of the service. See “cookie” for details.

Parameters

dispatcher

a EpcDispatcher

 

cookie

the new service identifier, or NULL

 

Since: 0.3.1


epc_dispatcher_set_name ()

void
epc_dispatcher_set_name (EpcDispatcher *dispatcher,
                         const gchar *name);

Changes the user friendly name used for announcing services. See “name”.

Parameters

dispatcher

a EpcDispatcher

 

name

the new user friendly name

 

epc_dispatcher_set_service_details ()

void
epc_dispatcher_set_service_details (EpcDispatcher *dispatcher,
                                    const gchar *type,
                                    ...);

Updates the list of TXT records for a registered DNS-SD service. The TXT records are specified by the service type and usually have the form of key-value pairs:

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path=/dwarf-blog/

This function will fail silently, when the service specified by type hasn't been registered yet.

Parameters

dispatcher

a EpcDispatcher

 

type

the service type

 

...

a list of TXT records, terminated by NULL

 

epc_dispatcher_get_collision_handling ()

EpcCollisionHandling
epc_dispatcher_get_collision_handling (EpcDispatcher *dispatcher);

Queries the collision handling strategy the dispatcher uses. See “collision-handling” for details.

Parameters

dispatcher

a EpcDispatcher

 

Returns

The dispatcher's collision handling strategy, or EPC_COLLISIONS_IGNORE on error.

Since: 0.3.1


epc_dispatcher_get_cookie ()

const gchar *
epc_dispatcher_get_cookie (EpcDispatcher *dispatcher);

Queries the unique identifier of the service. See “cookie” for details.

Parameters

dispatcher

a EpcDispatcher

 

Returns

The unique identifier of the service, or NULL on error.

Since: 0.3.1


epc_dispatcher_get_name ()

const gchar *
epc_dispatcher_get_name (EpcDispatcher *dispatcher);

Queries the user friendly name used for announcing services. See “name”.

Parameters

dispatcher

a EpcDispatcher

 

Returns

The user friendly name of the service.


epc_address_family_get_class ()

GEnumClass *
epc_address_family_get_class (void);

Retrieves the GEnumClass describing the EpcAddressFamily enum.

Returns

The GEnumClass describing EpcAddressFamily.


epc_address_family_to_string ()

const gchar *
epc_address_family_to_string (EpcAddressFamily value);

Retrieves the name of a EpcAddressFamily value , or NULL when value is invalid.

Parameters

value

a EpcAddressFamily value

 

Returns

The string representation of value , or NULL.


epc_collision_handling_get_class ()

GEnumClass *
epc_collision_handling_get_class (void);

Retrieves the GEnumClass describing the EpcCollisionHandling enum.

Returns

The GEnumClass describing EpcCollisionHandling.


epc_collision_handling_to_string ()

const gchar *
epc_collision_handling_to_string (EpcCollisionHandling value);

Retrieves the name of a EpcCollisionHandling value , or NULL when value is invalid.

Parameters

value

a EpcCollisionHandling value

 

Returns

The string representation of value , or NULL.

Types and Values

enum EpcAddressFamily

The address family to use for contacting network services.

Members

EPC_ADDRESS_UNSPEC

No preferences exist. Use all address families supported.

 

EPC_ADDRESS_IPV4

Exclusively use IPv4 for addressing network services.

 

EPC_ADDRESS_IPV6

Exclusively use IPv6 for addressing network services.

 

enum EpcCollisionHandling

Various strategies for handling service name collisions.

Members

EPC_COLLISIONS_IGNORE

Don't handle collisions at all, just fail silently.

 

EPC_COLLISIONS_CHANGE_NAME

Try to announce the service with another name.

 

EPC_COLLISIONS_UNIQUE_SERVICE

Defer own service announcement until the other service. disappears.

 

EpcDispatcherPrivate

typedef struct _EpcDispatcherPrivate EpcDispatcherPrivate;

Private fields of the EpcDispatcher class.

Members


struct EpcDispatcherClass

struct EpcDispatcherClass {
};

Virtual methods of the EpcDispatcher class.


struct EpcDispatcher

struct EpcDispatcher;

Public fields of the EpcDispatcher class.

Property Details

The “collision-handling” property

  “collision-handling”       EpcCollisionHandling

The collision handling method to use.

Flags: Read / Write / Construct

Default value: EPC_COLLISIONS_CHANGE_NAME


The “cookie” property

  “cookie”                   gchar *

Unique identifier of the service.

Flags: Read / Write / Construct

Default value: NULL


The “name” property

  “name”                     gchar *

User friendly name of the service.

Flags: Read / Write / Construct

Default value: NULL