1.. _example_asynch:
2
3==============================
4Asynchronous lookup
5==============================
6
7This example performs the name lookup in the background. 
8The main program keeps running while the name is resolved. 
9
10::
11
12	#!/usr/bin/python
13	import time
14	import unbound
15	
16	ctx = unbound.ub_ctx()
17	ctx.resolvconf("/etc/resolv.conf")
18	
19	def call_back(my_data,status,result):
20		print "Call_back:", my_data
21		if status == 0 and result.havedata:
22			print "Result:", result.data.address_list
23			my_data['done_flag'] = True
24	
25	
26	my_data = {'done_flag':False,'arbitrary':"object"}
27	status, async_id = ctx.resolve_async("www.seznam.cz", my_data, call_back, unbound.RR_TYPE_A, unbound.RR_CLASS_IN)
28	        
29	while (status == 0) and (not my_data['done_flag']):
30		status = ctx.process()
31		time.sleep(0.1)
32	
33	if (status != 0):
34		print "Resolve error:", unbound.ub_strerror(status)
35
36The :meth:`unbound.ub_ctx.resolve_async` method is able to pass on any Python object. In this example, we used a dictionary object `my_data`.
37