Merge pull request #183 from husigeza/PYFW-389

PYFW-389: Support MDNS

Author: geza-pycom

content/firmwareapi/pycom/network/mdns.md

@@ -0,0 +1,147 @@
+---
+title: "MDNS"
+aliases:
+    - firmwareapi/pycom/network/mdns.html
+    - firmwareapi/pycom/network/mdns.md
+    - chapter/firmwareapi/pycom/network/mdns
+---
+This class provides an interface to use the MDNS functionality.
+
+## Quick Usage Example
+
+Example for advertising own services:
+
+```python
+import time
+from network import MDNS
+# As a first step connection to network should be estbalished, e.g. via WLAN
+
+# Initialize the MDNS module
+MDNS.init()
+# Set the hostname and instance name of this device
+MDNS.set_name(hostname = "my_hostname", instance_name = "my_instance")
+# Add a TCP service to advertise
+MDNS.add_service("_http", MDNS.PROTO_TCP, 80)
+# Add an UDP service to advertise
+MDNS.add_service("_myservice", MDNS.PROTO_UDP, 1234, txt= (("board","esp32"),("u","user"),("p","password")))
+
+# Give the other devices time to discover the services offered
+time.sleep(60)
+
+# Remove a service, it will no longer be advertised
+MDNS.remove_service("_http", MDNS.PROTO_TCP)
+
+```
+
+Example for querying:
+
+```python
+import time
+from network import MDNS
+# As a first step connection to network should be estbalished, e.g. via WLAN
+
+# Initialize the MDNS module
+MDNS.init()
+
+# Perform a query for 2000 ms
+q = MDNS.query(2000, "_http", MDNS.PROTO_TCP)
+
+# Print out the query's result
+if q is not None:
+    for elem in q:
+        print(elem.instance_name())
+        print(elem.hostname())
+        print(elem.addr())
+        print(elem.port())
+        print(elem.txt())
+
+```
+
+## Constructor
+
+### class network.MDNS()
+
+Initializes the MDNS module.
+
+## Methods
+
+#### MDNS.deinit()
+
+Deinitializes the MDNS module and removes all registered services.
+
+#### MDNS.set_name(\*, hostname=None, instance_name=None)
+
+Sets the hostname and instance name of the device that is going to be advertised.
+
+The arguments are:
+
+* `hostname` is the hostname to set
+* `instance_name` is the instance name to set
+
+#### MDNS.add_service(service_type, proto, port, \*, txt)
+
+Adds a service to the MDNS module which will be advertised.
+
+The arguments are:
+
+* `service_type` is the type of the offered service, e.g.: _http, _ftp or can be custom service
+* `proto` is the Layer 4 protocol (TCP or UDP), can be `MDNS.PROTO_TCP` or `MDNS.PROTO_UDP`
+* `port` is the port number
+* `txt` is the TXT entries to be placed into the advertisement. The TXT entry is a (key, value) tuple and several TXT entries can be included in an advertisement. In that case, 'txt' must be given as a list of tuples.
+
+#### MDNS.remove_service(service_type, proto)
+
+Removes a service from the MDNS module so it will not be advertised anymore.
+
+The arguments are:
+
+* `service_type` is the type of the service, e.g.: _http, _ftp or can be custom service
+* `proto` is the Layer 4 protocol (TCP or UDP), can be `MDNS.PROTO_TCP` or `MDNS.PROTO_UDP`
+
+#### MDNS.query(timeout, service_type, proto, \*, instance_name=None)
+
+Performs a query with the given parameters.
+
+The arguments are:
+
+* `timeout` is the timeout value in milliseconds to wait to receive the results
+* `service_type` is the type of the service to be queried, e.g.: _http, _ftp or can be custom service
+* `proto` is the Layer 4 protocol (TCP or UDP), can be `MDNS.PROTO_TCP` or `MDNS.PROTO_UDP`
+* `instance_name` is the instance name of the service to be queried
+
+If the service is found then the function returns with a list of `MDNS_Query` objects.
+
+## MDNS_Query class
+
+The `MDNS_Query` aggregates all of the properties of a successful query session entry:
+* `hostname` is the hostname of the host advertising the service
+* `instance_name` is the instance_name of the service
+* `addr` is the IPv4 address belonging to the service
+* `port` is the port number belonging to the service
+* `txt` is the TXT entries from the advertisement. The TXT entry is a (key, value) tuple, and several TXT entries can be included in an advertisement.
+
+#### MDNS_Query.hostname()
+
+Returns with the hostname of the queried service.
+
+#### MDNS_Query.instance_name()
+
+Returns with the instance name of the queried service.
+
+#### MDNS_Query.addr()
+
+Returns with the IPv4 address of the queried service.
+
+#### MDNS_Query.port()
+
+Returns with the port of the queried service.
+
+#### MDNS_Query.txt()
+
+Returns with the TXT entries of the queried service.
+
+## Constants
+
+* TCP and UDP protocol types: `MDNS.PROTO_TCP`, `MDNS.PROTO_UDP`
+
+