Workkow Management Systems (WFMSs) automate the execution of business processes allowing the concurrent execution of multiple process instances. Existing systems do not provide a mechanism to guarantee correct concurrent execution and, as a result, it is not possible to coordinate and synchronize diierent process instances. Part of the problem is that conventional techniques are not entirely su...

An atomic commit protocol (ACP) is a distributed algorithm used to ensure the atomicity property of transactions in distributed database systems. Although ACPs are designed to guarantee atomicity, they add a significant extra cost to each transaction execution time. This added cost is due to the overhead of the required coordination messages and log writes at each involved database site to achi...

Two-phase locking (2PL) is the concurrency control mechanism that is used in most commercial database systems. In 2PL, for a transaction to access a data item, it has to hold the appropriate lock (read or write) on the data item by issuing a lock request. While the way transactions set their lock requests and the way the requests are granted would certainly affect a system’s performance, such a...

The Hadoop Distributed File System (HDFS) scales to store tens of petabytes of data despite the fact that the entire le system's metadata must t on the heap of a single Java virtual machine. The size of HDFS' metadata is limited to under 100 GB in production, as garbage collection events in bigger clusters result in heartbeats timing out to the metadata server (NameNode). In this paper, we addr...

Abstract Piloting in the Panama Canal is exceptional as, due to its importance, functions of captains vessels are taken over by pilots. Hence, prior inauguration expanded canal, a limited number pilots experienced on existing canal were certified for transit Neopanamax means planned and innovative individual learning. After this organisational training through operative training, with implement...