Code for Zato article on InfoQ http://www.infoq.com/articles/zato

stockmarket.py

# anyjson
from anyjson import loads

# bunch
from bunch import bunchify

# decimal
from decimal import Decimal

# lxml
from lxml.objectify import fromstring

# Zato
from zato.server.service import Service

class GetMarketCap(Service):
    """ Returns market capitalization value in billion USD by a company's symbol.

    """
    class SimpleIO:
        response_elem = 'market_cap'
        input_required = ('symbol',)
        output_required = ('provider', 'value')

    def handle(self):

        # . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

        # Yahoo
        # . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

        # Fetch a connection to Y! by its name
        yahoo = self.outgoing.plain_http.get('Yahoo! YQL')

        # Build URL params to issue a YQL query with.
        q = 'select * from yahoo.finance.quotes where symbol="{}"'.format(
            self.request.input.symbol)
        url_params = {'q':q, 'format':'json', 'env':'http://datatables.org/alltables.env'}

        # Invoke Y! and create a bunch instance out of the JSON response so
        # we can reference the elements using dot notation.
        yahoo_response = bunchify(loads(yahoo.conn.get(self.cid, url_params).text))

        # Clean up the response from Y! - chop off the last character if there
        # was a business response at all. Assumes the response is always
        # in billions.
        if yahoo_response.query.results.quote:
            value1 = yahoo_response.query.results.quote.MarketCapitalization
            value1 = Decimal(value1[:-1]) if value1 else 'n/a'
        else:
            value1 = 'n/a'

        # A new response item is appended to the list of items Zato will
        # serialize to JSON or XML, depending on how the service was invoked.
        item1 = {'provider':'Yahoo!', 'value': str(value1)}
        self.response.payload.append(item1) 

        # . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

        # Google
        # . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

        # Fetch a connection to Google by its name
        google = self.outgoing.plain_http.get('Google Finance')

        # Build URL params to invoke Google with
        url_params = {'stock':self.request.input.symbol}

        # Invoke Google and create an Objectify instance out of the XML response
        # so we can reference the elements using dot notation.
        google_response = fromstring(google.conn.get(self.cid, url_params).text)

        # Clean up the response from Google - convert from millions to billions
        # if there was a business response at all.
        if hasattr(google_response.finance, 'market_cap'):
            value2 = Decimal(google_response.finance.market_cap.get('data')) / 1000
        else:
            value2 = 'n/a'

        # Again, a plain Python dict (hashmap) is appended to the response object
        # and serialization will be done by Zato.
        item2 = {'provider':'Google', 'value': str(value2)}
        self.response.payload.append(item2)