* Lets programmers write software using Java language
* Preview of the service to launch in second half of 2010
* Companies do not disclose pricing, terms of partnership
BOSTON, April 27 (Reuters) - Software makers Salesforce.com Inc (CRM.N) and VMware Inc (VMW.N) said they will develop a hosted service that companies can use to write and run custom applications via the Web.
The two are joining forces to gain a foothold in the small but rapidly growing area of cloud computing. Rivals include Amazon.com Inc (AMZN.O), Google Inc (GOOG.O), International Business Machines Corp (IBM.N) and Microsoft Corp (MSFT.O).
The new system, dubbed VMforce, will run on Java, the world's most commonly used programming language for business applications. More than 6 million developers create programs using Java.
Salesforce already hosts a similar "cloud computing" product, dubbed Force.com, but programmers need to learn a proprietary language to write software that runs on that system.
The companies declined to disclose pricing or provide financial details of their partnership. They said a preview version of the service will be available in the second half of this year.
Salesforce.com is the world's biggest provider of software delivered via the Web. VMware is the top maker of virtualization programs, which allow companies to boost the efficiency of computer hardware by running multiple virtual machines on a single piece of equipment. (Reporting by Jim Finkle; Editing by Steve Orlofsky)