Therefore, these four "classic" layers can be split into additional tiers, including client, Web, middleware, and others.

因此，可以将这4个“传统”层次拆分成其他层，其中包括客户机、Web和中间件等。

youdao

And rather than envision some sort of uber developer, who understands big data, web performance optimization, application middleware, and fault tolerance in a massively distributed environment, we need operations specialists on the development teams.

FORBES: DevOps: What It Is And Where It Came From

Such "middleware" software is in high demand as businesses move more tasks onto the Web, but competition has held down prices.

FORBES: Oracle Offers A Lot, BEA Wants More