@ohos.net.mdns (mDNS Management)

Multicast DNS (mDNS) provides functions such as adding, removing, discovering, and resolving local services on a LAN.

NOTE The initial APIs of this module are supported since API version 10. Newly added APIs will be marked with a superscript to indicate their earliest API version.

Modules to Import

import mdns from '@ohos.net.mdns'

mdns.addLocalService

addLocalService(context: Context, serviceInfo: LocalServiceInfo, callback: AsyncCallback<LocalServiceInfo>): void

Adds an mDNS service. This API uses an asynchronous callback to return the result.

System capability: SystemCapability.Communication.NetManager.MDNS

Parameters

Name	Type	Mandatory	Description
context	Context	Yes	Application context. For details about the application context of the FA model, see Context. For details about the application context of the stage model, see Context.
serviceInfo	LocalServiceInfo	Yes	mDNS service information.
callback	AsyncCallback<LocalServiceInfo>	Yes	Callback used to return the result. If the operation is successful, error is undefined and data is the mDNS service information.

Error codes

ID	Error Message
401	Parameter error.
2100002	Operation failed. Cannot connect to service.
2100003	System internal error.
2204003	Callback duplicated.
2204008	Service instance duplicated.
2204010	Send packet failed.

NOTE For details about the error codes, see mDNS Error Codes.

Example

Stage model:

// Obtain the context.
import mdns from '@ohos.net.mdns'
import { BusinessError } from '@ohos.base';

let context = getContext(this) as Context;

let localServiceInfo: mdns.LocalServiceInfo = {
  serviceType: "_print._tcp",
  serviceName: "servicename",
  port: 5555,
  host: {
  address: "10.14.**.***",
  },
  serviceAttribute: [{key: "111", value: [1]}]
}

mdns.addLocalService(context, localServiceInfo, (error:BusinessError, data:mdns.LocalServiceInfo) =>  {
  console.log(JSON.stringify(error));
  console.log(JSON.stringify(data));
});

mdns.addLocalService

addLocalService(context: Context, serviceInfo: LocalServiceInfo): Promise<LocalServiceInfo>

Adds an mDNS service. This API uses a promise to return the result.

System capability: SystemCapability.Communication.NetManager.MDNS

Parameters

Name	Type	Mandatory	Description
context	Context	Yes	Application context. For details about the application context of the FA model, see Context. For details about the application context of the stage model, see Context.
serviceInfo	LocalServiceInfo	Yes	mDNS service information.

Return value

Type	Description
Promise<LocalServiceInfo>	Promise used to return the result.

Error codes

ID	Error Message
401	Parameter error.
2100002	Operation failed. Cannot connect to service.
2100003	System internal error.
2204003	Callback duplicated.
2204008	Service instance duplicated.
2204010	Send packet failed.

NOTE For details about the error codes, see mDNS Error Codes.

Example

Stage model:

// Obtain the context.
import mdns from '@ohos.net.mdns'
import { BusinessError } from '@ohos.base';

let context = getContext(this) as Context;

let localServiceInfo: mdns.LocalServiceInfo = {
  serviceType: "_print._tcp",
  serviceName: "servicename",
  port: 5555,
  host: {
    address: "10.14.**.***",
  },
  serviceAttribute: [{key: "111", value: [1]}]
}

mdns.addLocalService(context, localServiceInfo).then((data: mdns.LocalServiceInfo) => {
  console.log(JSON.stringify(data));
});

mdns.removeLocalService

removeLocalService(context: Context, serviceInfo: LocalServiceInfo, callback: AsyncCallback<LocalServiceInfo>): void

Removes an mDNS service. This API uses an asynchronous callback to return the result.

System capability: SystemCapability.Communication.NetManager.MDNS

Parameters

Name	Type	Mandatory	Description
context	Context	Yes	Application context. For details about the application context of the FA model, see Context. For details about the application context of the stage model, see Context.
serviceInfo	LocalServiceInfo	Yes	mDNS service information.
callback	AsyncCallback<LocalServiceInfo>	Yes	Callback used to return the result. If the operation is successful, error is undefined and data is the mDNS service information.

Error codes

ID	Error Message
401	Parameter error.
2100002	Operation failed. Cannot connect to service.
2100003	System internal error.
2204002	Callback not found.
2204008	Service instance not found.
2204010	Send packet failed.

NOTE For details about the error codes, see mDNS Error Codes.

Example

Stage model:

// Obtain the context.
import mdns from '@ohos.net.mdns'
import { BusinessError } from '@ohos.base';

let context = getContext(this) as Context;

let localServiceInfo: mdns.LocalServiceInfo = {
  serviceType: "_print._tcp",
  serviceName: "servicename",
  port: 5555,
  host: {
  address: "10.14.**.***",
  },
  serviceAttribute: [{key: "111", value: [1]}]
}

mdns.removeLocalService(context, localServiceInfo, (error: BusinessError, data: mdns.LocalServiceInfo) =>  {
  console.log(JSON.stringify(error));
  console.log(JSON.stringify(data));
});

mdns.removeLocalService

removeLocalService(context: Context, serviceInfo: LocalServiceInfo): Promise<LocalServiceInfo>

Removes an mDNS service. This API uses a promise to return the result.

System capability: SystemCapability.Communication.NetManager.MDNS

Parameters

Name	Type	Mandatory	Description
context	Context	Yes	Application context. For details about the application context of the FA model, see Context. For details about the application context of the stage model, see Context.
serviceInfo	LocalServiceInfo	Yes	mDNS service information.

Return value

Type	Description
Promise<LocalServiceInfo>	Promise used to return the result.

Error codes

ID	Error Message
401	Parameter error.
2100002	Operation failed. Cannot connect to service.
2100003	System internal error.
2204002	Callback not found.
2204008	Service instance not found.
2204010	Send packet failed.

NOTE For details about the error codes, see mDNS Error Codes.

Example

Stage model:

import mdns from '@ohos.net.mdns'
import { BusinessError } from '@ohos.base';

let context = getContext(this) as Context;

let localServiceInfo: mdns.LocalServiceInfo = {
  serviceType: "_print._tcp",
  serviceName: "servicename",
  port: 5555,
  host: {
  address: "10.14.**.***",
  },
  serviceAttribute: [{key: "111", value: [1]}]
}

mdns.removeLocalService(context, localServiceInfo).then((data: mdns.LocalServiceInfo) => {
  console.log(JSON.stringify(data));
});

mdns.createDiscoveryService

createDiscoveryService(context: Context, serviceType: string): DiscoveryService

Creates a DiscoveryService object, which is used to discover mDNS services of the specified type.

System capability: SystemCapability.Communication.NetManager.MDNS

Parameters

Name	Type	Mandatory	Description
context	Context	Yes	Application context. For details about the application context of the FA model, see Context. For details about the application context of the stage model, see Context.
serviceType	string	Yes	Type of the mDNS services to be discovered.

Return value

Type	Description
DiscoveryService	DiscoveryService object used to discover mDNS services based on the specified serviceType and Context.

Error codes

ID	Error Message
401	Parameter error.

Example

Stage model:

// Obtain the context.
import mdns from '@ohos.net.mdns'
import { BusinessError } from '@ohos.base';

let context = getContext(this) as Context;

let serviceType = "_print._tcp";
let discoveryService : Object = mdns.createDiscoveryService(context, serviceType);

mdns.resolveLocalService

resolveLocalService(context: Context, serviceInfo: LocalServiceInfo, callback: AsyncCallback<LocalServiceInfo>): void

Resolves an mDNS service. This API uses an asynchronous callback to return the result.

System capability: SystemCapability.Communication.NetManager.MDNS

Parameters

Name	Type	Mandatory	Description
context	Context	Yes	Application context. For details about the application context of the FA model, see Context. For details about the application context of the stage model, see Context.
serviceInfo	LocalServiceInfo	Yes	mDNS service information.
callback	AsyncCallback<LocalServiceInfo>	Yes	Callback used to return the result. If the operation is successful, error is undefined and data is the mDNS service information.

Error codes

ID	Error Message
401	Parameter error.
2100002	Operation failed. Cannot connect to service.
2100003	System internal error.
2204003	Callback duplicated.
2204006	Request timeout.
2204010	Send packet failed.

NOTE For details about the error codes, see mDNS Error Codes.

Example

Stage model:

// Obtain the context.
import mdns from '@ohos.net.mdns'
import { BusinessError } from '@ohos.base';

let context = getContext(this) as Context;

let localServiceInfo: mdns.LocalServiceInfo = {
  serviceType: "_print._tcp",
  serviceName: "servicename",
  port: 5555,
  host: {
  address: "10.14.**.***",
  },
  serviceAttribute: [{key: "111", value: [1]}]
}

mdns.resolveLocalService(context, localServiceInfo, (error: BusinessError, data: mdns.LocalServiceInfo) =>  {
  console.log(JSON.stringify(error));
  console.log(JSON.stringify(data));
});

mdns.resolveLocalService

resolveLocalService(context: Context, serviceInfo: LocalServiceInfo): Promise<LocalServiceInfo>

Resolves an mDNS service. This API uses a promise to return the result.

System capability: SystemCapability.Communication.NetManager.MDNS

Parameters

Name	Type	Mandatory	Description
context	Context	Yes	Application context. For details about the application context of the FA model, see Context. For details about the application context of the stage model, see Context.
serviceInfo	LocalServiceInfo	Yes	mDNS service information.

Return value

Type	Description
Promise<LocalServiceInfo>	Promise used to return the result.

Error codes

ID	Error Message
401	Parameter error.
2100002	Operation failed. Cannot connect to service.
2100003	System internal error.
2204003	Callback duplicated.
2204006	Request timeout.
2204010	Send packet failed.

NOTE For details about the error codes, see mDNS Error Codes.

Example

Stage model:

// Obtain the context.
import mdns from '@ohos.net.mdns'
import { BusinessError } from '@ohos.base';

let context = getContext(this) as Context;

let localServiceInfo: mdns.LocalServiceInfo = {
  serviceType: "_print._tcp",
  serviceName: "servicename",
  port: 5555,
  host: {
  address: "10.14.**.***",
  },
  serviceAttribute: [{key: "111", value: [1]}]
}

mdns.resolveLocalService(context, localServiceInfo).then((data: mdns.LocalServiceInfo) => {
  console.log(JSON.stringify(data));
});

DiscoveryService

Defines a DiscoveryService object for discovering mDNS services of the specified type.

startSearchingMDNS

startSearchingMDNS(): void

Searches for mDNS services on the LAN.

System capability: SystemCapability.Communication.NetManager.MDNS

Example

Stage model:

// Obtain the context.
import mdns from '@ohos.net.mdns'
import { BusinessError } from '@ohos.base';

let context = getContext(this) as Context;
let serviceType = "_print._tcp";
let discoveryService = mdns.createDiscoveryService(context, serviceType);
discoveryService.startSearchingMDNS();

stopSearchingMDNS

stopSearchingMDNS(): void

Stops searching for mDNS services on the LAN.

System capability: SystemCapability.Communication.NetManager.MDNS

Example

Stage model:

// Obtain the context.
import mdns from '@ohos.net.mdns'
import { BusinessError } from '@ohos.base';

let context = getContext(this) as Context;
let serviceType = "_print._tcp";
let discoveryService = mdns.createDiscoveryService(context, serviceType);
discoveryService.stopSearchingMDNS();

on('discoveryStart')

on(type: 'discoveryStart', callback: Callback): void

Enables listening for discoveryStart events.

System capability: SystemCapability.Communication.NetManager.MDNS

Parameters

Name	Type	Mandatory	Description
type	string	Yes	Event type. This field has a fixed value of discoveryStart. discoveryStart: event of starting discovery of mDNS services on the LAN.
callback	Callback<{serviceInfo: LocalServiceInfo, errorCode?: MdnsError}>	Yes	Callback used to return the mDNS service and error information.

Example

import mdns from '@ohos.net.mdns'
import { BusinessError } from '@ohos.base';

// See mdns.createDiscoveryService.
let context = getContext(this) as Context;
let serviceType = "_print._tcp";
let discoveryService = mdns.createDiscoveryService(context, serviceType);
discoveryService.startSearchingMDNS();

discoveryService.on('discoveryStart', (data: mdns.DiscoveryEventInfo) => {
  console.log(JSON.stringify(data));
});

discoveryService.stopSearchingMDNS();

off('discoveryStart')

off(type: 'discoveryStart', callback?: Callback<DiscoveryEventInfo>): void

Disables listening for discoveryStart events.

System capability: SystemCapability.Communication.NetManager.MDNS

Parameters

Name	Type	Mandatory	Description
type	string	Yes	Event type. This field has a fixed value of discoveryStart. discoveryStart: event of starting discovery of mDNS services on the LAN.
callback	Callback<{serviceInfo: LocalServiceInfo, errorCode?: MdnsError}>	No	Callback used to return the mDNS service and error information.

Example

import mdns from '@ohos.net.mdns'
import { BusinessError } from '@ohos.base';

// See mdns.createDiscoveryService.
let context = getContext(this) as Context;
let serviceType = "_print._tcp";
let discoveryService = mdns.createDiscoveryService(context, serviceType);
discoveryService.startSearchingMDNS();

discoveryService.on('discoveryStart', (data: mdns.DiscoveryEventInfo) => {
  console.log(JSON.stringify(data));
});

discoveryService.stopSearchingMDNS();

discoveryService.off('discoveryStart', (data: mdns.DiscoveryEventInfo) => {
  console.log(JSON.stringify(data));
});

on('discoveryStop')

on(type: 'discoveryStop', callback: Callback<DiscoveryEventInfo>): void

Enables listening for discoveryStop events.

System capability: SystemCapability.Communication.NetManager.MDNS

Parameters

Name	Type	Mandatory	Description
type	string	Yes	Event type. This field has a fixed value of discoveryStop. discoveryStop: event of stopping discovery of mDNS services on the LAN.
callback	Callback<{serviceInfo: LocalServiceInfo, errorCode?: MdnsError}>	Yes	Callback used to return the mDNS service and error information.

Example

import mdns from '@ohos.net.mdns'
import { BusinessError } from '@ohos.base';

// See mdns.createDiscoveryService.
let context = getContext(this) as Context;
let serviceType = "_print._tcp";
let discoveryService = mdns.createDiscoveryService(context, serviceType);
discoveryService.startSearchingMDNS();

discoveryService.on('discoveryStop', (data: mdns.DiscoveryEventInfo) => {
  console.log(JSON.stringify(data));
});

discoveryService.stopSearchingMDNS();

off('discoveryStop')

off(type: 'discoveryStop', callback?: Callback<DiscoveryEventInfo>): void

Disables listening for discoveryStop events.

System capability: SystemCapability.Communication.NetManager.MDNS

Parameters

Name	Type	Mandatory	Description
type	string	Yes	Event type. This field has a fixed value of discoveryStop. discoveryStop: event of stopping discovery of mDNS services on the LAN.
callback	Callback<{serviceInfo: LocalServiceInfo, errorCode?: MdnsError}>	No	Callback used to return the mDNS service and error information.

Example

import mdns from '@ohos.net.mdns'
import { BusinessError } from '@ohos.base';

// See mdns.createDiscoveryService.
let context = getContext(this) as Context;
let serviceType = "_print._tcp";
let discoveryService = mdns.createDiscoveryService(context, serviceType);
discoveryService.startSearchingMDNS();

discoveryService.on('discoveryStop', (data: mdns.DiscoveryEventInfo) => {
  console.log(JSON.stringify(data));
});

discoveryService.stopSearchingMDNS();

discoveryService.off('discoveryStop', (data: mdns.DiscoveryEventInfo) => {
  console.log(JSON.stringify(data));
});

on('serviceFound')

on(type: 'serviceFound', callback: Callback<LocalServiceInfo>): void

Enables listening for serviceFound events.

System capability: SystemCapability.Communication.NetManager.MDNS

Parameters

Name	Type	Mandatory	Description
type	string	Yes	Event type. This field has a fixed value of serviceFound. serviceFound: event indicating an mDNS service is found.
callback	Callback<LocalServiceInfo>	Yes	mDNS service information.

Example

import mdns from '@ohos.net.mdns'
import { BusinessError } from '@ohos.base';

// See mdns.createDiscoveryService.
let context = getContext(this) as Context;
let serviceType = "_print._tcp";
let discoveryService = mdns.createDiscoveryService(context, serviceType);
discoveryService.startSearchingMDNS();

discoveryService.on('serviceFound', (data: mdns.LocalServiceInfo) => {
  console.log(JSON.stringify(data));
});

discoveryService.stopSearchingMDNS();

off('serviceFound')

off(type: 'serviceFound', callback?: Callback<LocalServiceInfo>): void

Disables listening for serviceFound events.

System capability: SystemCapability.Communication.NetManager.MDNS

Parameters

Name	Type	Mandatory	Description
type	string	Yes	Event type. This field has a fixed value of serviceFound. serviceFound: event indicating an mDNS service is found.
callback	Callback<LocalServiceInfo>	No	mDNS service information.

Example

import mdns from '@ohos.net.mdns'
import { BusinessError } from '@ohos.base';

// See mdns.createDiscoveryService.
let context = getContext(this) as Context;
let serviceType = "_print._tcp";
let discoveryService = mdns.createDiscoveryService(context, serviceType);
discoveryService.startSearchingMDNS();

discoveryService.on('serviceFound', (data: mdns.LocalServiceInfo) => {
  console.log(JSON.stringify(data));
});

discoveryService.stopSearchingMDNS();

discoveryService.off('serviceFound', (data: mdns.LocalServiceInfo) => {
  console.log(JSON.stringify(data));
});

on('serviceLost')

on(type: 'serviceLost', callback: Callback<LocalServiceInfo>): void

Enables listening for serviceLost events.

System capability: SystemCapability.Communication.NetManager.MDNS

Parameters

Name	Type	Mandatory	Description
type	string	Yes	Event type. This field has a fixed value of serviceLost. serviceLost: event indicating that an mDNS service is removed.
callback	Callback<LocalServiceInfo>	Yes	mDNS service information.

Example

import mdns from '@ohos.net.mdns'
import { BusinessError } from '@ohos.base';

// See mdns.createDiscoveryService.
let context = getContext(this) as Context;
let serviceType = "_print._tcp";
let discoveryService = mdns.createDiscoveryService(context, serviceType);
discoveryService.startSearchingMDNS();

discoveryService.on('serviceLost', (data: mdns.LocalServiceInfo) => {
  console.log(JSON.stringify(data));
});

discoveryService.stopSearchingMDNS();

off('serviceLost')

off(type: 'serviceLost', callback?: Callback<LocalServiceInfo>): void

Disables listening for serviceLost events.

System capability: SystemCapability.Communication.NetManager.MDNS

Parameters

Name	Type	Mandatory	Description
type	string	Yes	Event type. This field has a fixed value of serviceLost. serviceLost: event indicating that an mDNS service is removed.
callback	Callback<LocalServiceInfo>	No	mDNS service information.

Example

import mdns from '@ohos.net.mdns'
import { BusinessError } from '@ohos.base';

// See mdns.createDiscoveryService.
let context = getContext(this) as Context;
let serviceType = "_print._tcp";
let discoveryService = mdns.createDiscoveryService(context, serviceType);
discoveryService.startSearchingMDNS();

discoveryService.on('serviceLost', (data: mdns.LocalServiceInfo) => {
  console.log(JSON.stringify(data));
});

discoveryService.stopSearchingMDNS();

discoveryService.off('serviceLost', (data: mdns.LocalServiceInfo) => {
  console.log(JSON.stringify(data));
});

LocalServiceInfo

Defines the mDNS service information.

System capability: SystemCapability.Communication.NetManager.MDNS

Name	Type	Mandatory	Description
serviceType	string	Yes	Type of the mDNS service. The value is in the format of _<name>.<_tcp/_udp>, where name contains a maximum of 63 characters excluding periods (.).
serviceName	string	Yes	Name of the mDNS service.
port	number	No	Port number of the mDNS server.
host	NetAddress	No	IP address of the device that provides the mDNS service. The IP address is not effective when an mDNS service is added or removed.
serviceAttribute	serviceAttribute<ServiceAttribute>	No	mDNS service attribute information.

ServiceAttribute

Defines the mDNS service attribute information.

System capability: SystemCapability.Communication.NetManager.MDNS

Name	Type	Mandatory	Description
key	string	Yes	mDNS service attribute key. The value contains a maximum of 9 characters.
value	Array<number>	Yes	mDNS service attribute value.

MdnsError

Defines the mDNS error information.

System capability: SystemCapability.Communication.NetManager.MDNS

Name	Value	Description
INTERNAL_ERROR	0	Operation failed because of an internal error. (not supported currently)
ALREADY_ACTIVE	1	Operation failed because the service already exists. (not supported currently)
MAX_LIMIT	2	Operation failed because the number of requests exceeds the maximum value. (not supported currently)