Sun Microsystems, Inc.

Eric C Hill

Norman Hardy

E Dean Tribble

Mark S Miller

Christopher T Hibbert

Jacob Y Levy

John D Corbett

A system and method are disclosed that enable exclusive rights in generic goods to be transferred from one party to another. A party holds an exclusive right to a good through a rescindable capability. When two parties agree on a transfer of the exclusive right to the good, a goods description memorializing the agreement is created which is in synergy with the rescindable capability. The goods description includes an acquire method that is the only method that can extract rights from the rescindable capability with which it is in synergy. The object from which the generic right is being transferred sends a message to the recipient with a reference to the rescindable capability. Upon receiving the message, the recipient invokes the acquire method of the referenced goods description, which returns a new rescindable capability that encompasses the generic right just transferred. Once the recipient holds a reference to the new rescindable capability, the sender has had its rights rescinded. Because details of a transfer are implemented between a rescindable capability and a goods description, rights to goods of any type can be transferred. This is useful in escrow transactions, where a trusted third party with no knowledge of goods being exchanged can effect exchanges of exclusive rights to generic goods by two mutually-suspicious parties.

Generic transfer of exclusive rights

A system and method is disclosed that provides persistent capabilities for distributed, object-oriented applications running on generally available hardware. The disclosed system and method operate in a transparent distributed object system where inter-process messaging between the program objects is effected by paired transport managers, proxies and matched in-table and out-table slots. Each object needing to communicate with an object in another address space does so by transparently issuing messages to that object's local proxy. Each process provides a registrar that includes a secret code table wherein an object is registered with a unique, practically unguessable secret code. Anticipating the need to re-establish object-proxy links following a inter-process communications fault, proxies are made revivable, meaning that their links with corresponding remote objects can be revived following a communications interruption. This is accomplished by a makeRevivable method that stores a revivable proxy's expiration date (the date beyond which the proxy is not revivable) and its corresponding remote object's secret code into the proxy's out-table slot. Upon the occurrence of a communications fault, all transport managers and tables are nulled out and then, when the communications fault is corrected, rebuilt by the transport managers. Sometime after the restoration of communications, a revived method is invoked that restores the links between, registered objects and proxies. The objects and proxies are brought back in a consistent state based on limited checkpointed data stored by the distributed program for the registered objects.

Persistent distributed capabilities

A distributed garbage collection system and method is disclosed that is compatible with local ref-count or full garbage collection and that ensures that no local object's storage is deleted by the local garbage collector unless it is certain that there are no actual or potential remote references to that local object. The disclosed system and method are implemented in the context of a transparent distributed object system in which communications between objects in different processes are enabled by dedicated proxy objects that are linked to corresponding remote objects via a pair of transport objects. Additional proxy holder objects and proxy holder proxies ensure that objects for which third-party object references are passed (i.e., where one object in a first process passes a remote object in a second process a reference to a third object in a third process) are not collected until a direct link is established between the remote object in the second process and the third object in the third object space. As appropriate, secret number table pointers maintained by a local registrar for each object that has been accessed via a third party message are deleted, allowing the objects to be collected when there are no other actual or pending remote references to that object. The transport managers encrypt all inter-process messages so as to provide full capability security within the distributed system. This enables the disclosed garbage collection system and methods to operate under attack from misbehaving participants.

Distributed garbage collection system and method

A system providing capability security for distributed object systems is disclosed. The basic tenet of capability security is that the right to do something to an object (e.g., invoke a particular object's methods) is represented solely by the holding of a reference to that object. In each of the preferred embodiments described herein, an object is presumed to hold legitimately a reference to a particular object only if the object knows some unpublicized (except under the conditions required by capability security) key associated with the particular object. That is, an object's key is required along with the object's reference. So that capability security is preserved when object references are passed between objects in different processes, the object references being passed are encrypted upon transmission and then decrypted upon arrival at their intended destination. This cryptography can be performed by objects or processes using a variety of techniques, including Diffie-Helman or public/private key cryptography. The cryptography performed in the various embodiments ensures that only the intended recipient of the message can decode the object reference and that a misbehaving object cannot convince another object that it possesses a capability it does not have. Some of the disclosed embodiments provide capability security for distributed object systems wherein the objects and processes directly handle inter-object and inter-process communications and message encryption and decryption.

Capability security for distributed object systems

A system providing capability security for distributed object systems is disclosed. The basic tenet of capability security is that the right to do something to an object (e.g., invoke a particular object's methods) is represented solely by the holding of a reference to that object. In each of the preferred embodiments described herein, an object is presumed to hold legitimately a reference to a particular object only if the object knows some unpublicized (except under the conditions required by capability security) key associated with the particular object. That is, an object's key is required along with the object's reference. So that capability security is preserved when object references are passed between objects in different processes, the object references being passed are encrypted upon transmission and then decrypted upon arrival at their intended destination. This cryptography can be performed by objects or processes using a variety of techniques, including Diffie-Helman or public/private key cryptography. The cryptography performed in the various embodiments ensures that only the intended recipient of the message can decode the object reference and that a misbehaving object cannot convince another object that it possesses a capability it does not have. Some of the disclosed embodiments provide capability security for transparent distributed object systems, wherein a pair of matched transports handle and encrypt inter-process communications between objects in their respective processes.

Growing community of inventors

Palo Alto, CA, United States of America

Eric C Hill