Today we continue discussing the best practice from storage engineering:

160) Nativitity of registries – User registries, on the other hand, are welcome and can be arbitrary. In such cases, the registries are about their own artifacts. However, such rregsitries can be stored just the same way as user data. Consequently, the system does not need to participate in the user registries and they can ear mark storage designated storage artifacts for this purpose.

161) Sequences – Sequences hold a special significance in the storage server. If there are several actions taken by the storage server and the actions don’t belong to the same group and there is no way to assign a sequence number, then we rely on the names of the actions as they appear on the actual timeline such as in the logs. When the names can be collected as sequences, we can perform standard query operations on the collections to determine patterns. This kind of pattern recognition is very useful when there are heterogenous entries and the order in which the user initiates them is dynamic.

162) Event driven framework: Not all user defined actions are fire and forget. Some of them may be interactive and since there can be any amount of delay between interactions, usually some form of event driven framework consistently finds its way into the storage server. From storage drivers, background processors and even certain advanced UI controls use event driven framework.

163) Tracing: The most important and useful application of sequences is the tracing of actions for any activity. Just like logs, event driven framework may provide the ability to trace user actions as different system components participate in their completion. Tracing is very similar to profiling but there needs to be a publisher-subscriber model. Most user mode completion of tasks are done with the help of a message queue and a sink.

164) Event Querying: Event driven framework have the ability to not just operate on whole data but also on streams. This makes it very popular to write stream-based queries involving partitions and going over a partition.

165) Event Subscription versus appenders: Just like log appenders, there is a possibility to transfer the same event collection result to a large number of destinations simultaneously. These destinations can include files, databases, email recipients and so on.