Python for Finance: Analyze Big Financial Data

Web Services

The last topic in this chapter — and a very interesting and important one — is web

services. Web services provide a simple and efficient means to access server-based

functionality via web protocols. For example, one of the web services with the highest

traffic is the Google search functionality. We are used to visiting http://www.google.com

and typing some words of interest into the search/text input field provided on the website.

However, what happens after you press the Return key or push the Search button is that

the page translates all the information it has (from the search field and maybe your

personal preferences) into a more or less complex URL.

Such a URL could, for example, take on the form http://www.google.de/search?

num=5&q=yves+python. When you click this link or copy it into your web browser,

Google Search returns those five search results (num=5) that the engine considers the best

matches given the words provided (q=Yves+Python). Your web browser then displays

something similar to Figure 14-11.

Using web services, any kind of data- and transaction-oriented financial service can be

provided via web technologies. For instance, Yahoo! Finance and Google Finance offer

historical stock price information via such a web service approach. More complex services

such as derivatives pricing and risk analytics are also available via such services (for

example, the web-based analytics solution DEXISION; cf. http://derivatives-

analytics.com). The following example illustrates the implementation of such a service in

the context of option pricing.