Update introductions.md

proposals/introductions.md

@@ -8,35 +8,13 @@
 - CoRE Link Format and CoRE Resource Directory
 - DID Docuemnts
 
-## Other ecosystem's discovery mechanisms
+## Other SDO's discovery mechanisms
+- [OASIS/MQTT](introductions/oasis.md)
+- [OPC Foundation/OPC UA](introductions/opcf.md)
 
-### MQTT
-
-- There is no standard mechanism for discovering MQTT broker.
-- [MQTT-SN (MQTT for sensor Netoworks)](https://www.oasis-open.org/committees/document.php?document_id=66091&wg_abbrev=mqtt)
-  - UDP-based
-  - Advertise a broker presense by ADVERTISE message.
-    - no information other than the gateway's ID can be sdvertised.
-- [MQTT Discovery in Home Assistant](https://www.home-assistant.io/integrations/mqtt/#mqtt-discovery)
-  - They have predefined topic for Discovery:
-    - `<discovery_prefix>/<component>/[<node_id>/]<object_id>/config` where:
-        - `discovery_prefix`: default to `homeassistant`
-        - `component`: `binary_sensor` etc.
-        - `node_id`: ID of the node
-        - `object_id`: ID of the device
-    - payload is serialized JSON object.
-
-### OPC UA
-- [Local Discovery Server]
-  - use mDNS to advertise Discovery Server. Similar approach to WoT Discovery.
-    - `_opcua-tcp._tcp.example.com. 86400 IN SRV 0 5 4840 uaserver.example.com.`
-    - `   TXT path=/discoveryURL,  caps=LDS,...`
-
-### Other protocol/platform/ecosystem
+### Other protocol/platform/ecosystems
 - DHCP Options ([RFC2132](https://datatracker.ietf.org/doc/html/rfc2132))
 - SSDP ([draft-cai-ssdp-v1-03](https://datatracker.ietf.org/doc/html/draft-cai-ssdp-v1-03); expired in April 2000)
-- [WS-Discovery](https://docs.oasis-open.org/ws-dd/discovery/1.1/wsdd-discovery-1.1-spec.html)
-
 
 ## How to incorporate new mechanism in WoT Discovery?
 - It might be good to initially collect proposals *with implementation* in the form of markdown document.  After that, we can decide whether to incorporate it into the spec.