1. A computer-implemented method of restricting data access, comprising: performing the following on a computer: detecting an attempt by a first requester to access a first data resource, said first requester comprising computer executable instructions for accessing data; if the attempted access is to retrieve data: allowing the attempted access; and adding a get token corresponding to the first data resource to a first set of get tokens maintained for the first requester; and if the attempted access is to send data: if said first set of get tokens is empty, allowing the attempted access; if said first set of get tokens includes only a single get token, allowing the attempted access if the first data resource is the same data resource corresponding to said single get token; and if said first set of get tokens includes multiple get tokens, restricting the attempted access if the first requestor previously sent data to the first data resource and said first set of get tokens has changed since the first requester last sent data to the first data resource.
4. The method of claim 1 , wherein said restricting comprises: allowing the attempted access only if the attempted access is approved by an operator.