Expanding its line of real-time data-management software, Progress Software Corp. said Monday it will acquire Persistence Software Inc., a developer of distributed data-access and caching software, for approximately $16 million in cash.

The deal has been approved by the companies' boards and is subject to stockholder approval. The acquisition is expected to close within 90 days.

Progress plans to make Persistence and its product line part of its ObjectStore operating company, which markets real-time data-management software and services. The Persistence EdgeXtend distributed-data-caching software will replace Progress' current ObjectCache product, says Peter Sliwkowski, ObjectStore president.

Although some of Persistence's staff of 40 will likely be laid off in the acquisition, the company's core engineering, customer support, and executive-management teams are expected to join Progress, says Chris Keene, Persistence CEO. Persistence is based in San Mateo, Calif., while Progress is located in Bedford, Mass.

Progress expects the acquisition to add about $8 million to $9 million to its revenue in the first year.