1. At a computer system, the computer system including a transaction manager, the transaction manager configured to interoperate with one or more other transaction related components to perform transaction related operations within distributed transactions in accordance with a two-phase commit protocol, the one or more other transaction related components selected from among: applications, resource managers, databases, message queues, and other transaction managers, a method for controlling a distributed transaction based on role based transaction control information listing transaction related operations the one or more other transaction related components are permitted to assume relative to the transaction manager, the method comprising: an act of the transaction manager receiving a transaction related message, including a request from a transaction related component to perform a requested transaction related operation within the distributed transaction in accordance with the two-phase commit protocol on behalf of the transaction related component, the requested transaction related operation instructing the transaction manager to communicate with at least one other transaction related component on behalf of the transaction related component, the requested transaction related operation selected from among: beginning a transaction, marshalling data for a transaction, unmarshalling data for a transaction, enlisting in a transaction, propagating data from the transaction manager, and propagating data to the transaction manager, the corresponding transaction to include the transaction manager, the transaction related component, and the at least one other transaction related component as participants; in response to receiving the transaction related message: an act of the transaction manager authenticating that the transaction related message originated from the transaction related component; an act of the transaction manager referring to the role based transaction control information in response to receiving authentication that the transaction related message originated from the transaction related component, the role based transaction control information having been previously configured by a user and expressly listing transaction related operations the transaction related component is permitted to perform relative to the transaction manager for transactions in which the transaction manager and the transaction related component are participants, the listing permitting the transaction manager to perform transaction related operations on behalf of the transaction related component including one or more of: beginning a transaction, marshalling data for a transaction, unmarshalling data for a transaction, enlisting in a transaction, propagating data from the transaction manager, and propagating data to the transaction manager; an act of comparing the requested transaction related operation to the role based transaction control information to determine if the transaction related component is permitted to assume a role of the requested transaction related operation relative to the transaction manager that allows the transaction manager to perform the requested transaction related operation on behalf of the transaction related component; and an act of implementing the requested transaction related operation in accordance with the results of the comparison.