Man, the BetaNews article is horrible. Practically everything — except for the direct quotes from the Google blog post — is incorrect. I somehow expect more from someone who goes by "Scott M. Fulton, III".

Google's public documentation shows Protocol Buffers (which has yet to be formally abbreviated) is indeed conceptually different from XML, in that it's rooted more in procedural logic than structural declaration. In XML, there's a schema which defines the structures of tables and recordsets, which is separate from the document that relates the contents of records in that structure.

Nope, they're conceptually the same. The ".proto" files are like DTD or XSD. The actual document data is stored in a binary format (though there's also a text representation). The data manipulation API is similar what you get from Castor or JAX-B.

But here, in an unusual departure from the norm, the default values for these members are set to digits (for strings or literals) or values (for numerals) that define their place in a sequence -- where they fall within a record. Imagine if data were streamed onto recording tape, the way it used to be in the late 1960s and '70s. It's that streaming of the data sequence, without all the fenceposts, that differentiates XML from Protocol Buffers, by taking out all those markups that say when an entry or a record starts and stops.

The "= number" at the end of a field definition is not a "default value". It is a numeric tag that identifies that field. That said, "= number" is quite unintuitive syntax; maybe something like "@number" would have been less confusing.

Looking at some of the documentation, I don't think the aforementioned numbers directly index the field's location in the record. They lay down the present fields one after another, probably putting each field's tag number before the field data. This also allows them to avoid sending fields that use the default value. So they still need to specify how long each record is — either with "fenceposts" between records or a "length" specifier before each record.