Remote object persistence support is included in the standard Cayenne distribution. System requirements are the same as for the rest of Cayenne, and there is no special installation procedure. Check the Installation chapter of Cayenne User Guide for details.
Cayenne web service is no different from a regular Cayenne application, so it requires cayenne.jar or cayenne-nodeps.jar. One additional required third party library is hessian.jar, version 3.0.13 or newer. Hessian can be downloaded from http://www.caucho.com/hessian/.
On the client cayenne-client-nodeps.jar is needed. This is a stripped down version of Cayenne runtime. It doesn't bundle any dependencies, so the following third-party libraries need to be installed: