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#!/usr/bin/env kal
# This demo executes GET requests in parallel and in series
# using `for` loops and `wait for` statements.
# Notice how the serial GET requests always return in order
# and take longer in total. Parallel requests come back in
# order of receipt.
http = require 'http'
urls = ['http://www.google.com'
'http://www.apple.com'
'http://www.microsoft.com'
'http://www.nodejs.org'
'http://www.yahoo.com']
# This function does a GET request for each URL in series
# It will wait for a response from each request before moving on
# to the next request. Notice the output will be in the same order as the
# urls variable every time regardless of response time.
# It is a task rather than a function because it is called asynchronously
# This allows us to use `return` to implicitly call back
task series_demo()
# The `series` keyword is optional here (for loops are serial by default)
total_time = 0
for series url in urls
timer = new Date
# we use the `safe` keyword because get is a "nonstandard" task
# that does not call back with an error argument
safe wait for response from http.get url
delay = new Date() - timer
total_time += delay
print "GET #{url} - #{response.statusCode} - #{response.connection.bytesRead} bytes - #{delay} ms"
# because we are in a task rather than a function, this actually exectutes a callback
return total_time
# This function does a GET request for each URL in parallel
# It will NOT wait for a response from each request before moving on
# to the next request. Notice the output will be determined by the order in which
# the requests complete!
task parallel_demo()
total_time = 0
# The `parallel` keyword is only meaningful here because the loop contains
# a `wait for` statement (meaning callbacks are used)
for parallel url in urls
timer = new Date
# we use the `safe` keyword because get is a "nonstandard" task
# that does not call back with an error argument
safe wait for response from http.get url
delay = new Date() - timer
total_time += delay
print "GET #{url} - #{response.statusCode} - #{response.connection.bytesRead} bytes - #{delay}ms"
# because we are in a task rather than a function, this actually exectutes a callback
return total_time
print 'Series Requests...'
wait for time1 from series_demo()
print "Total duration #{time1}ms"
print ''
print 'Parallel Requests...'
wait for time2 from parallel_demo()
print "Total duration #{time2}ms"
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