Abstract: Maintaining, for each target key in a key-value computer database, a signature policy; creating a transaction candidate in the database based on a transaction context submitted to the database by a first user, the transaction candidate comprising: a key, a value comprising a transaction content and a signature of the first user, and a signors list of additional one or more users who are required to co-sign the transaction candidate before the transaction candidate is committed in the database as a transaction, wherein the signors list is automatically computed based on the signature policies of the one or more target keys; collecting a signature for the transaction candidate from at least one of the additional one or more users, according to the signors list; verifying that all signatures required by the signors list have been collected; and in response to the verification, committing the transaction content of the transaction candidate.

Abstract: An example operation may include one or more of encrypting content via an encryption key to generate encrypted content, storing the encrypted content via a distributed ledger, splitting the encrypted encryption key into a set of key shares via a threshold secret sharing scheme, and distributing the set of key shares among a plurality of nodes of a distributed vault, where each key share is distributed with an expiry value that identifies when the respective key share is to be deleted by a node.

Abstract: An example operation includes one or more of receiving view change messages which request a view change from a previous primary peer of a blockchain to the primary peer, identifying that a change to a state of the blockchain is in process with the previous primary peer based on metadata of the received view change messages, verifying that the change to the state of the blockchain corresponds to a latest change to the blockchain based on a received view data message, and transmitting a new view message to following peers which includes the in-process change to the state of the blockchain.

Abstract: An example operation includes one or more of receiving view change messages which request a view change from a previous primary peer of a blockchain to the primary peer, identifying that a change to a state of the blockchain is in process with the previous primary peer based on metadata of the received view change messages, verifying that the change to the state of the blockchain corresponds to a latest change to the blockchain based on a received view data message, and transmitting a new view message to following peers which includes the in-process change to the state of the blockchain.

Abstract: Maintaining, for each target key in a key-value computer database, a signature policy; creating a transaction candidate in the database based on a transaction context submitted to the database by a first user, the transaction candidate comprising: a key, a value comprising a transaction content and a signature of the first user, and a signors list of additional one or more users who are required to co-sign the transaction candidate before the transaction candidate is committed in the database as a transaction, wherein the signors list is automatically computed based on the signature policies of the one or more target keys; collecting a signature for the transaction candidate from at least one of the additional one or more users, according to the signors list; verifying that all signatures required by the signors list have been collected; and in response to the verification, committing the transaction content of the transaction candidate.

Abstract: An example system includes a processor to receive updates for a database of a publish and subscribe system. The processor is to generate an optimistic update based on the received updates. The processor is also to adaptively update the database using the optimistic update. In some examples, the processor generates a bulk optimistic update based on the optimistic update and adaptively updates the database using the bulk optimistic update or a read-modify-write sequence.

Abstract: An example operation may include one or more of encrypting content via an encryption key to generate encrypted content, storing the encrypted content via a distributed ledger, splitting the encrypted encryption key into a set of key shares via a threshold secret sharing scheme, and distributing the set of key shares among a plurality of nodes of a distributed vault, where each key share is distributed with an expiry value that identifies when the respective key share is to be deleted by a node.

Abstract: Examples of techniques for tracking client sessions in a publish and subscribe system using a shared repository are described herein. An example system includes a processor of a server to receive a connection request with a client identifier from a client a predefined policy for duplicate client sessions. The processor is to query a shared repository of the system using the client identifier. The processor is to also execute a set of actions based on the predefined policy, a query result including a detected duplicate client session from the shared repository, and a set of parameters.

Abstract: An example operation includes one or more of receiving view change messages which request a view change from a previous primary peer of a blockchain to the primary peer, identifying that a change to a state of the blockchain is in process with the previous primary peer based on metadata of the received view change messages, verifying that the change to the state of the blockchain corresponds to a latest change to the blockchain based on a received view data message, and transmitting a new view message to following peers which includes the in-process change to the state of the blockchain.

Abstract: A processor may endorse the group of transactions received from one or more clients. The processor may provide a read-set and a write-set for each transaction of the group of transactions. The processor may order the group of transactions at an ordering service. The ordering service may have a group of orderers and may order the group of transactions. The order of the transactions may be based on the read-set and the write-set of each transaction. The processor may commit the group of transactions to the blockchain.

Abstract: An example operation includes one or more of receiving view change messages which request a view change from a previous primary peer of a blockchain to the primary peer, identifying that a change to a state of the blockchain is in process with the previous primary peer based on metadata of the received view change messages, verifying that the change to the state of the blockchain corresponds to a latest change to the blockchain based on a received view data message, and transmitting a new view message to following peers which includes the in-process change to the state of the blockchain.

Abstract: An example operation includes one or more of receiving view change messages which request a view change from a previous primary peer of a blockchain to the primary peer, identifying that a change to a state of the blockchain is in process with the previous primary peer based on metadata of the received view change messages, verifying that the change to the state of the blockchain corresponds to a latest change to the blockchain based on a received view data message, and transmitting a new view message to following peers which includes the in-process change to the state of the blockchain.

Abstract: Migration of a durable client in a publish/subscribe system from a first server of a cluster to a second server of the cluster. The method comprises the second server receiving subscription information of the durable client; the second server establishing a message queue for the durable client; the second server sending a switch command to all active servers of the cluster; in response to the second server obtaining, from an active server, an acknowledgement of the switch command, the second server inserting a marker to the message queue indicating switching point of the active server; and in response to the second server obtaining, from the first server, a message indicating the first server flushed all messages prior to respective switching points for all active servers, connecting the durable client to the second server and transmitting messages thereto by the second server.

Abstract: Examples of techniques for tracking client sessions in a publish and subscribe system using a shared repository are described herein. An example system includes a processor of a server to receive a connection request with a client identifier from a client a predefined policy for duplicate client sessions. The processor is to query a shared repository of the system using the client identifier. The processor is to also execute a set of actions based on the predefined policy, a query result including a detected duplicate client session from the shared repository, and a set of parameters.

Abstract: An example system includes a processor to receive updates for a database of a publish and subscribe system. The processor is to generate an optimistic update based on the received updates. The processor is also to adaptively update the database using the optimistic update. In some examples, the processor generates a bulk optimistic update based on the optimistic update and adaptively updates the database using the bulk optimistic update or a read-modify-write sequence.

Abstract: A method comprising obtaining a Bloom filter array, wherein a size of a first Bloom filter is smaller than a size of a second Bloom filter and modifying at least a portion of the plurality of Bloom filters to create a modified Bloom filter array comprising a modified plurality of Bloom filters each of which having a same size, wherein the same size is greater than the size of the first Bloom filter, wherein said modifying comprises: duplicating the first Bloom filter to create a modified first Bloom filter comprising two or more concatenated copies of the first Bloom filter. The method may also include performing lookup in the Bloom filter array by computing a hash value of a key and accessing a bit in the hash value location in each Bloom filter of the modified Bloom filter array to determine lookup outcome in each Bloom filter.

Abstract: Method, system and product for efficient size reduction of a Bloom filter. The method includes: creating an interleaved Bloom filter based on a Bloom filter, wherein the interleaved Bloom filter is defined so as to have non-sequential cells of the Bloom filter be positioned sequentially, wherein the interleaved Bloom filter interleaves segments of the Bloom filter, wherein a size of the segments is based on an interleaving factor. A reduced size Bloom filter having a number cells below the number of cells of the Bloom filter is computed. The computation includes computing a value of a cell in the reduced size Bloom filter based on two or more values of cells in the interleaved Bloom filter.

Abstract: A computer implemented method of improving server coverage of a publish-subscribe cluster of servers, comprising using a cluster comprising a plurality of servers each having hardware processor(s), the cluster is adapted to execute messaging engines of a publish-subscribe service for forwarding a plurality of messages to a plurality of subscribing clients, each message is associated with one of a plurality of topics, wherein distributed subscriptions client(s) applies shared subscriptions for one or more topics through subscription group(s) each comprising a subset of the subscribing clients, monitor shared subscriptions made by the subscription group(s) to each of the messaging engines for each topic, generate a shared subscriptions information for each topic by analyzing the shared subscriptions and publish the shared subscriptions information to the clients to allow client(s) of the subscription group(s) to subscribe for the topic(s) on a preferred messaging engine to improve a server coverage of their sub

Abstract: Embodiments of the present systems and methods may provide the capability to monitor and detect failure of nodes in a data center environment by using a software defined failure detector that can be adjusted to varying conditions and data center topology. In an embodiment, a computer-implemented method for monitoring and detecting failure of electronic systems may comprise, in a system comprising a plurality of networked computer systems, defining at least one failure detection agent to monitor operation of other failure detection agents running on at least some of the electronic systems, and defining, at the controller, and transmitting, from the controller, topology information defining a topology of the failure detection agents to the failure detection agents, wherein the topology information includes information defining which failure detection agents each failure detection agent is to monitor.

Abstract: Migration of a durable client in a publish/subscribe system from a first server of a cluster to a second server of the cluster. The method comprises the second server receiving subscription information of the durable client; the second server establishing a message queue for the durable client; the second server sending a switch command to all active servers of the cluster; in response to the second server obtaining, from an active server, an acknowledgement of the switch command, the second server inserting a marker to the message queue indicating switching point of the active server; and in response to the second server obtaining, from the first server, a message indicating the first server flushed all messages prior to respective switching points for all active servers, connecting the durable client to the second server and transmitting messages thereto by the second server.