In another acquisition involving companies focused on open source, proponents of the Spring Framework and Apache software have joined forces in a merger being announced Tuesday.

SpringSource, developer of the Spring Framework for Java, has acquired Covalent Technologies, which provides services for users of Apache Software Foundation projects. These include the Apache Tomcat and Geronimo application servers and the Apache Axis Web Framework.

"Putting together the two companies that have the strongest product and services offering around Spring and Tomcat is, we feel, a very natural move," said Rod Johnson, CEO of SpringSource, formerly known as Interface21.

An analyst concurred. The SpringSource-Covalent merger serves as "an alliance of two complementary technology [assets]," said analyst Steve O'Grady, of RedMonk.

Financial details of the acquisition were not disclosed. The deal already has been completed and follows by two weeks Sun's acquisition of open-source database vendor MySQL.

Through the acquisition, SpringSource plans to offer a single source of products and services to develop and run enterprise applications using the Spring Portfolio and Apache projects. The Spring Portfolio of applications has been downloaded more than 4 million times, according to SpringSource.

Covalent, meanwhile, has staff members actively involved in Apache software projects and has a lead developer working on Apache Tomcat, said Mark Brewer, CEO of Covalent. He will become vice president and general manager of SpringSource's Covalent business unit.

SpringSource has ambitions to provide a Java alternative to the full, complex J2EE programming model, said analyst Yefim Natis, vice president at Gartner. "SpringSource is taking the best of J2EE," Natis said.

SpringSource said enterprises are increasingly opting for Spring, Tomcat, and open source over bloated, complex legacy Java platforms. These legacy platforms include Java servers from such companies as BEA Systems, Oracle, and even open source proponent JBoss, according to Brewer.

Covalent, with its Apache bent, offers a simpler, lightweight solution, Brewer said. SpringSource, for its part, has had business relationships with Java application server vendors like BEA and Oracle, Johnson acknowledged. "On the other hand, if you look at the take-up of Tomcat as the platform to run Spring on, as a platform for run enterprise Java applications, there is no question that it is the most popular choice right now," Johnson said. He further noted that enterprises are moving to open source not just because of cost considerations but because these products give customers what they want.

The SpringSource-Covalent merger follows Sun's $1 billion acquisition of MySQL and Red Hat's buying of JBoss in 2006 for about $350 million. According to Johnson, there are two courses for open-source companies to follow: Get acquired by a large company like Sun or build an independent business. SpringSource is looking to build critical mass and become a leader in its own right, he said.

"We don't need to look to a large incumbent as an exit strategy," said Johnson.

Offering support services for its various Spring projects, SpringSource cites more than 1,000 paying customers and has focused on the large enterprise market. Included on SpringSource's customer list are nine of the world's largest 10 banks, the company said. Covalent has sold support contracts to more than 3,000 customers and serves more than half of the Fortune 500, SpringSource and Covalent representatives said.