JBossTS supports both local and distributed transactions. A transaction is considered to be distributed if it spans multiple process instances, i.e., VMs. Typically a distributed transaction will contain participants (e.g., XAResources) that are located within multiple VMs but the transaction is coordinated in a separate VM (or co-located with one of the participants). If your architecture requires distributed transactions then you should consider using either the JTS implementation from JBossTS, which uses CORBA for communication, or the Web Services transactions component, which uses SOAP/HTTP.