Abstract: In a cloud computing environment, a cache and a memory are partitioned into “colors”. The colors of the cache and the memory are allocated to virtual machines independently of one another. In order to provide cache isolation while allocating the memory and cache in different proportions, some of the colors of the memory are allocated to a virtual machine, but the virtual machine is not permitted to directly access these colors. Instead, when a request is received from the virtual machine for a memory page in one of the non-accessible colors, a hypervisor swaps the requested memory page with a memory page with a color that the virtual machine is permitted to access. The virtual machine is then permitted to access the requested memory page at the new color location.

Abstract: A cloud infrastructure that communicates with computing devices is provided. The computing devices install filters on other computing devices that they wish to receive items from including pictures, messages, and documents. The filters include criteria that are evaluated on the computing devices, rather than at a server, to determine if an item may be sent to another computing device. The computing devices may then send items that match the criteria to the cloud infrastructure, and the items may be stored and queued for delivery to other computing devices. The items may be encrypted before being provided to the cloud infrastructure, and decrypted when received by the computing devices.

Abstract: In a cloud computing environment, a cache and a memory are partitioned into “colors”. The colors of the cache and the memory are allocated to virtual machines independently of one another. In order to provide cache isolation while allocating the memory and cache in different proportions, some of the colors of the memory are allocated to a virtual machine, but the virtual machine is not permitted to directly access these colors. Instead, when a request is received from the virtual machine for a memory page in one of the non-accessible colors, a hypervisor swaps the requested memory page with a memory page with a color that the virtual machine is permitted to access. The virtual machine is then permitted to access the requested memory page at the new color location.

Abstract: A distributed system includes full and partial replicas of a set of data items that may be inserted, modified, or deleted by any replica. Replicas may occasionally synchronize with other arbitrarily chosen replicas to learn about updates. A replica's knowledge includes one or more knowledge fragments, where each fragment indicates a set of items. A type of knowledge fragment, called a star knowledge fragment, contains versions associated with all items in the system. Star knowledge fragments are compact because the set of items stored at a replica need not be explicitly listed. Once all replicas know of all updates in the system, partial and full replicas will have the same compact star knowledge fragment.

Abstract: A cloud infrastructure that communicates with computing devices is provided. The computing devices install filters on other computing devices that they wish to receive items from including pictures, messages, and documents. The filters include criteria that are evaluated on the computing devices, rather than at a server, to determine if an item may be sent to another computing device. The computing devices may then send items that match the criteria to the cloud infrastructure, and the items may be stored and queued for delivery to other computing devices. The items may be encrypted before being provided to the cloud infrastructure, and decrypted when received by the computing devices.

Abstract: A distributed system synchronizes replica devices with respect to items that may be inserted, modified, or deleted by any of the replica devices. Replicas may synchronize with other replicas to learn about updates to items. Each replica device may include a high-fidelity replication platform and/or a low-fidelity replication platform. The low-fidelity replication platforms may synchronize low-fidelity versions of items among the replica devices, and the high-fidelity replication platforms may synchronize high-fidelity versions of items among the replica devices. Each replica device may include a fidelity manager that copies high-fidelity versions of items from the high-fidelity replication platform, generates low-fidelity versions of the items from the high-fidelity versions of the items, and adds the low-fidelity versions of the items to the low-fidelity replication platforms.

Abstract: Multiple versions of data on different sets of machines allow a system to degrade gracefully even when experiencing excessive failures. When excessive failures cause the latest versions to be unavailable, the system becomes degraded, but still offers an old version if available. A most recent coherent set of the available older versions is found and provided. The degree of degradation increases gradually as the system experiences more and more failures. Graceful degradation is desirably complementary to fault tolerance.

Abstract: A distributed system includes full and partial replicas of a set of data items that may be inserted, modified, or deleted by any replica. Replicas may occasionally synchronize with other arbitrarily chosen replicas to learn about updates. A replica's knowledge includes of one or more knowledge fragments, where each fragment indicates a set of items. A type of knowledge fragment, called a star knowledge fragment, contains versions associated with all items in the system. Star knowledge fragments are compact because the set of items stored at a replica need not be explicitly listed. Once all replicas know of all updates in the system, partial and full replicas will have the same compact star knowledge fragment.

Abstract: Multiple versions of data on different sets of machines allow a system to degrade gracefully even when experiencing excessive failures. When excessive failures cause the latest versions to be unavailable, the system becomes degraded, but still offers an old version if available. A most recent coherent set of the available older versions is found and provided. The degree of degradation increases gradually as the system experiences more and more failures. Graceful degradation is desirably complementary to fault tolerance.

Abstract: A system is disclosed for synchronizing partially-replicated collections while keeping synchronization overhead low by using the concept of item-set knowledge. Item-set knowledge uses knowledge fragments, which associate knowledge vectors with item-sets. An item-set consists of an explicitly represented list of items. In a partial replica, this item set may be the items known to a replica within which a filter is applied limiting the items known to some subset of the overall items in the collection.

Abstract: A system is disclosed for recovery from a compromise of a replica in a weakly-consistent distributed collection. The system employs a collection manager for revoking a compromised replica, and one or more archival replicas for storing time-stamped versions. Upon a compromise, versions tainted by the compromised replica may be expunged from the collection. Thereafter, versions determined to be unaffected by the compromise may be returned to the collection using the time-stamped versions stored in the one or more archival replicas.

Abstract: A distributed data store employs replica placement techniques in which a number k hash functions are used to compute k potential locations for a data item. A number r of the k locations are chosen for storing replicas. These replica placement techniques provide a system designer with the freedom to choose r from k, are structured in that they are determined by a straightforward functional form, and are diffuse such that the replicas of the items on one server are scattered over many other servers. The resulting storage system exhibits excellent storage balance and request load balance in the presence of incremental system expansions, server failures, and load changes. Data items may be created, read, and updated or otherwise modified.