OperaORB provides very simple API for distributed computing. You can send messages to local/remote objects in transparent way.
OperaORB runs on not only well-known HTTP, but also SQTP, a Squeak specific binary transport protocol. SQTP is extremely fast in bulky objects sending, but it loses interoperability with other SOAPs (normally running on text-based HTTP).
*SQTP is not included in SAR version of SoapCore. You have to install all-package-version of SoapCore from: http://www.mars.dti.ne.jp/~umejava/smalltalk/soapOpera/index.html