About 25 percent of software development projects within IBM are now employing some manner of "agile" methodology, a company official said Monday.

"This is not a fashion trend," said Sue McKinney, vice president of strategy, integration and development transformation, IBM Software Group. "We believe this is going to be the way we develop software."

The agile approach differs from traditional waterfall-style development, where a project begins with a set of requirements and proceeds sequentially through various stages, such as design, implementation and testing.

Agile instead sees programmers completing multiple "iterations" of a project within discrete chunks of time, such as once per month. This system theoretically allows application requirements to be tweaked along the way and provides business-side users or clients greater input into the final result.

But IBM's sheer size means a top-down mandate to adopt agile practices won't work, according to McKinney. "You can't be too dictatorial or say, one size fits all," she said.

McKinney, a 23-year IBM veteran, has faced some resistance. "We'd bring some of the legacy guys in and they'd say, 'My release takes three years. This is a bunch of bunk,'" she said. Certain projects may in fact require multiyear gaps between ship dates, but agile development presents an opportunity for more customer involvement and additional beta releases along the way, she said.

Another challenge lies in applying agile broadly within the huge programming teams that produce IBM's major product lines, such as Websphere. "Agile really works well within small- and medium-sized teams. The question is, how do you scale it?" she said.

IBM's Jazz project, a collaborative development platform, is attempting to tackle that question.

It is unclear when IBM will see truly widespread use of agile, but McKinney asserted that tangible progress has already been made. "It's not like a foreign concept when I talk about it anymore," she said.

IBM is logically pursuing this direction, according to James Governor, an analyst with Redmonk. "Waterfall has demonstrably failed," he said. "It has failed to deliver on its promise. Requirements always change on an ongoing basis. If you don't give users input early on in the process, you end up giving them something they didn't ask for.

The IDG News Service is a Network World affiliate.