July 08, 2008, 11:01 AM — Google has open-sourced its protocol buffers, the company's lingua franca for encoding various types of data, in order to set the stage for a wave of new releases, according to official company blog posts and documents.
"Practically everyone inside Google" uses protocol buffers, states a FAQ page. "We have many other projects we would like to release as open source that use protocol buffers, so to do this, we needed to release protocol buffers first."
Google uses "thousands of different data formats to represent networked messages between servers, index records in repositories, geospatial datasets, and more," wrote Kenton Varda, a member of Google's software engineering team, in a blog post. "Most of these formats are structured, not flat. This raises an important question: How do we encode it all?"
The ubiquitous XML (extensible markup language) is not efficient enough for Google's data-sharing needs, according to Varda: "When all of your machines and network links are running at capacity, XML is an extremely expensive proposition."
With protocol buffers, "you define how you want your data to be structured once, then you can use special generated source code to easily write and read your structured data to and from a variety of data streams and using a variety of languages," according to a documentation page. "You can even update your data structure without breaking deployed programs that are compiled against the 'old' format."
Protocol buffers are three to 10 times smaller and 20 to 100 times faster than XML, according to Google.
But XML has some advantages for certain tasks, according to the documentation: "Protocol buffers would not be a good way to model a text-based document with markup (e.g. HTML), since you cannot easily interleave structure with text. In addition, XML is human-readable and human-editable; protocol buffers, at least in their native format, are not."
Google has prepared a download page that contains protocol buffer compilers for Java, C++ and Python.
