Web Services Architecture and Its Specifications [Electronic resources] : Essentials for Understanding WS-* نسخه متنی

Hello and Bye

When a service connects and disconnects from the network, it can notify other endpoints with the Hello and Bye messages. In the following example, our book printer sends notifications that it is available and then that it is about to disconnect from the network:

Hello
(01) <env:Envelope>
(02)  <env:Header>
(03)   <wsa:Action>
(04)       http://schemas.xmlsoap.org/ws/2004/10/discovery/Hello
(05)   </wsa:Action>
(06)   <wsa:To>urn:schemas-xmlsoap-org:ws:2004:10:discovery</wsa:To>
(07)   <wsd:AppSequence InstanceId="23452123" MessageNumber="1"/>
(08)  </env:Header>
(09)  <env:Body>
(10)   <wsd:Hello>
(11)    <wsa:EndpointReference>
(12)     <wsa:Address>uuid:12345678-1234-1234-1234-111122223333</wsa:Address>
(13)    </wsa:EndpointReference>
(14)    <wsd:Types>sfa:Binder sfa:Secure</wsd:Types>
(15)    <wsd:Scopes>ldap://ou=faculty,o=fineartschool,c=us</wsd:Scopes>
(16)    <wsd:MetadataVersion>56</wsd:MetadataVersion>
(17)   </wsd:Hello>
(18)  </env:Body>
(19) </env:Envelope>

Lines 0305 The Action element specifies that this is a WS-Discovery Hello message.

Line 06 The message is multicast to the network through the distinguished URI as specified.

Line 07 The AppSequence element uniquely identifies the instance of the service that is announcing itself on the network, as well as what message number this instance is sending.

Lines 1017 The same information that is returned in a Probe Match message is transmitted in a Hello.

If possible, the printer transmits a Bye message when it is about to disconnect from the network. This message is shown in this example:

Bye
(01) <env:Envelope>
(02)  <env:Header>
(03)   <wsa:Action>
(04)       http://schemas.xmlsoap.org/ws/2004/02/discovery/Bye
(05)   </wsa:Action>
(06)   <wsa:To>http://schemas.xmlsoap.org/ws/2004/02/discovery</wsa:To>
(07)   <wsd:AppSequence InstanceId="23452123" MessageNumber="2"/>
(08)  </env:Header>
(09)  <env:Body>
(10)   <wsa:EndpointReference>
(11)    <wsa:Address>uuid:12345678-1234-1234-1234-111122223333</wsa:Address>
(12)   </wsa:EndpointReference>
(13)  </env:Body>
(14) </env:Envelope>

Lines 0305 The Action element specifies that this is a WS-Discovery Bye message.

Line 06 The message is multicast to the network through the distinguished URI as specified.

Line 07 The AppSequence element uniquely identifies the instance of the service that is leaving the network, as well as what message number this instance is sending.

Lines 1012 Only the Address element for the endpoint reference is required in a Bye message.