Hello Message

A Hello message is a WS-Discovery message used to announce the presence of a device or service on the network. Hello messages are also sent in other scenarios. For more information about Hello messages, see section 4.1 of the WS-Discovery Specification.

A Hello message is sent by UDP multicast to port 3702. This message is unsolicited.

Note  This topic shows a sample DPWS message generated by WSDAPI clients and hosts. WSDAPI will parse and accept other DPWS-compliant messages that do not conform to this sample. Do not use this sample to verify DPWS interoperability; use the WSDAPI Basic Interoperability Tool (WSDBIT) instead.
 

The following SOAP message shows a sample Hello message.

<?xml version="1.0" encoding="utf-8" ?>
<soap:Envelope
    xmlns:soap="http://www.w3.org/2003/05/soap-envelope"
    xmlns:wsa="http://schemas.xmlsoap.org/ws/2004/08/addressing"
    xmlns:wsd="http://schemas.xmlsoap.org/ws/2005/04/discovery"
    xmlns:wsdp="http://schemas.xmlsoap.org/ws/2006/02/devprof">
<soap:Header>
    <wsa:To>
        urn:schemas-xmlsoap-org:ws:2005:04:discovery
    </wsa:To>
    <wsa:Action>
        http://schemas.xmlsoap.org/ws/2005/04/discovery/Hello
    </wsa:Action>
    <wsa:MessageID>
        urn:uuid:0f5d604c-81ac-4abc-8010-51dbffad55f2
    </wsa:MessageID>
    <wsd:AppSequence InstanceId="2"
        SequenceId="urn:uuid:369a7d7b-5f87-48a4-aa9a-189edf2a8772"
        MessageNumber="14">
    </wsd:AppSequence>
</soap:Header>
<soap:Body>
    <wsd:Hello>
        <wsa:EndpointReference>
            <wsa:Address>
                urn:uuid:37f86d35-e6ac-4241-964f-1d9ae46fb366
            </wsa:Address>
        </wsa:EndpointReference>
        <wsd:Types>wsdp:Device</wsd:Types>
        <wsd:MetadataVersion>2</wsd:MetadataVersion>
    </wsd:Hello>
</soap:Body>

A Hello message has the following focus points.

Focus pointXMLDescription
Hello
<wsa:Action>
    http://schemas.xmlsoap.org/ws/2005/04/discovery/Hello
</wsa:Action>
The Hello SOAP action identifies the message as a Hello message.
AppSequence
<wsd:AppSequence InstanceId="2"
    SequenceId="urn:uuid:369a7d7b-5f87-48a4-aa9a-189edf2a8772"
    MessageNumber="14">
</wsd:AppSequence>
Contains application sequencing information, which helps to maintain the sequence of messages even if they are received out of order. The AppSequence is validated as described in AppSequence Validation Rules.
Address
<wsa:Address>
    urn:uuid:37f86d35-e6ac-4241-964f-1d9ae46fb366
</wsa:Address>
Contains the endpoint address. This addressed may be referenced in a Resolve message.
Types
<wsd:Types>wsdp:Device</wsd:Types>
Contains the WS-Discovery types advertised by the host.

 

Related topics

Discovery and Metadata Exchange Messages
Bye Message

 

 

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