Kent Beck introduced the term User Story as part of
Extreme Programming
to foster a more agile and conversational style of
requirements gathering. A few years later, Mike Cohn released his book
User Stories Applied: For Agile Software Development (2003), which is
considered one of the great references on the topic.

Originally, anyone on an agile team used to write …

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Solution

The cluster node maintains a waiting list which maps a key and
a callback function. The key is chosen depending on the specific
criteria to invoke the callback.
For example if it needs to be invoked whenever
a message from other cluster node is received, it can be the
Correlation Identifer of the message.
In the case of Replicated

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In many organizations, once the work has been done to integrate a
new system into the mainframe, say, it becomes much
easier to interact with that system via the mainframe rather than
repeat the integration each time. For many legacy systems with a
monolithic architecture this made sense, integrating the
same system into the same monolith multiple times would have

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Problem

Consider a key-value store where values are stored with a timestamp
to designate each version. Any cluster node that handles the client request
will be able to read the latest version using the current timestamp
at the request processing node.

In the following example, the value ‘Before Dawn’ is updated
to value “After Dawn” at time 2, as per

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Solution

One of the common techniques used in peer-to-peer systems is to
order cluster nodes according to their ‘age’. The oldest member of
the cluster plays the role of the coordinator for the cluster.
The coordinator is responsible for deciding on membership changes
as well as making decisions such as where
Fixed Partitions should be placed
across cluster nodes.

To

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