We introduce an elastic MCA called Sandman that allows applications to specify their own policies which may span multiple MCA domains. Background information is given in section . Section discusses basic operations of the Sandman. Light-weight virtual networks or netlets are introduced in section and dynamic code loading in section . Techniques to achieve interoperability are the topic of section , while global policies are discussed in section . Implementation details are mentioned in section . Related work and conclusions, finally, are the topics of section and respectively.