Tornado Coroutines

tornado.py

from tornado import gen, ioloop
from tornado.httpclient import AsyncHTTPClient, HTTPRequest
from tornado.web import HTTPError
AsyncHTTPClient.configure("tornado.curl_httpclient.CurlAsyncHTTPClient")

class CoroutineModel(object):
    @gen.coroutine
    def send_ok(self):
        try:
            request = HTTPRequest('https://google.com')
            response = yield AsyncHTTPClient().fetch(request)
        except Exception, e:
            response = e
        raise gen.Return(response)
        
    @gen.coroutine
    def send_error(self):
        try:
            request = HTTPRequest('https://google.com', 'POST', body='a=1')
            response = yield AsyncHTTPClient().fetch(request)
        except Exception, e:
            response = e
        raise gen.Return(response)


@gen.coroutine
def run_coroutine():
    print 'COROUTINE'
    print '*'*80
    c = CoroutineModel()
    _ok = yield c.send_ok()
    print 'OK:', _ok
    _error = yield c.send_error()
    print '\nERROR:', _error
    print '\n'*2


class engine(object):
    @gen.engine
    def send_ok(self, callback):
        request = HTTPRequest('https://google.com')
        response = yield AsyncHTTPClient().fetch(request)
        callback(response)
        
    @gen.engine
    def send_error(self, callback):
        request = HTTPRequest('https://google.com', 'POST', body='a=1')
        response = yield AsyncHTTPClient().fetch(request)
        callback(response)

@gen.engine
def run_engine():
    print 'ENGINE'
    print '*'*80    
    def _on_complete(response):
        print 'OK:', response
    e = engine()
    e.send_ok(_on_complete)
    try:
        e.send_error(_on_complete)
    except Exception, e:
        print '\nERROR:', e


if __name__ == '__main__':
    run_coroutine()
    run_engine()
    ioloop.IOLoop.instance().start()

tornado_handlers.py

from tornado import gen, ioloop, autoreload
from tornado.httpclient import AsyncHTTPClient, HTTPRequest
from tornado.web import HTTPError, RequestHandler, Application

AsyncHTTPClient.configure("tornado.curl_httpclient.CurlAsyncHTTPClient")

@gen.coroutine
def fetch():
    request = HTTPRequest('https://google.com', 'POST', body='a=1')
    raise ValueError('1... 2... 3... ERROR.')
    response = yield AsyncHTTPClient().fetch(request)
    raise gen.Return(response)

class MainHandler(RequestHandler):
    @gen.coroutine
    def get(self):
        self.add_header('Content-Type', 'text/plain; charset=utf-8')
        self.write('Write a message...')
        request = HTTPRequest('https://google.com')
        response = yield AsyncHTTPClient().fetch(request)
        self.write(response.body)
        self.finish()


class MainErrorHandler(RequestHandler):
    @gen.coroutine
    def get(self):
        self.add_header('Content-Type', 'text/plain; charset=utf-8')
        self.write('Write a message...\n')
        try:
            request = HTTPRequest('https://google.com', 'POST')
            response = yield AsyncHTTPClient().fetch(request)
            self.write(response.body)
        except Exception, e:
            self.write('E: %s' % str(e))
        self.finish()
    
    @gen.coroutine
    def post(self):
        self.add_header('Content-Type', 'text/plain; charset=utf-8')
        self.write('Write a message...\n')
        try:
            response = yield fetch()
            self.write(response.body)
        except Exception, e:
            self.write('E: %s' % str(e))
        self.finish()


application = Application([
    (r"/", MainHandler),
    (r"/try", MainErrorHandler),
])


if __name__ == "__main__":
    application.listen(8000)
    ioloop.IOLoop.instance().start()
    autoreload.start()