Executor is a small but perfectly functional Java (1.5 or higher) JAR executable that is used to run programs in shared computer resources like a pool of computers that you and your friends own. Moreover, it can be used as a simple file sharing program: you can access the files of your home computer from your office computer. Executor uses a shared or synchronized file system. The user creates a task in one computer (just by uploading a file), and another computer that has the required program will execute the task.
wsh allows you to execute commands on multiple machines in parallel. It is secure and fast, and even outperforms ansible. It works by having an agent live on the machine. When you run wshc, it sshes and execs wshd and sends commands over the encrypted channel. wshd executes the commands and sends the results back.
Overthere is a Java library to manipulate files and execute processes on remote hosts, i.e. do stuff "over there". It was built for and is used in the XebiaLabs deployment automation product Deployit as a way to perform tasks on remote hosts, e.g. copy configuration files, install EAR files, or restart Web servers. Another way of looking at it is to say that Overthere gives you java.io.File and java.lang.Process as they should have been: as interfaces, created by a factory and extensible through an SPI mechanism.