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The observer design pattern is a behavioural pattern listed among the 23 well-known "Gang of Four" design patterns that address recurring design challenges in order to design flexible and reusable object-oriented software, yielding objects that are easier to implement, change, test and reuse.
Angular 2.0 was announced at the ng-Europe conference 22–23 October 2014. [16] On April 30, 2015, the Angular developers announced that Angular 2 moved from Alpha to Developer Preview. [17] Angular 2 moved to Beta in December 2015, [18] and the first release candidate was published in May 2016. [19] The final version was released on 14 ...
The term is borrowed from control theory, where the "observability" of a system measures how well its state can be determined from its outputs.Similarly, software observability measures how well a system's state can be understood from the obtained telemetry (metrics, logs, traces, profiling).
A system is said to be observable if, for every possible evolution of state and control vectors, the current state can be estimated using only the information from outputs (physically, this generally corresponds to information obtained by sensors). In other words, one can determine the behavior of the entire system from the system's outputs.
In physics, an observable is a physical property or physical quantity that can be measured. In classical mechanics , an observable is a real -valued "function" on the set of all possible system states, e.g., position and momentum .
A simple example is that of vehicles in a tunnel: the rates and velocities at which vehicles enter and leave the tunnel can be observed directly, but the exact state inside the tunnel can only be estimated. If a system is observable, it is possible to fully reconstruct the system state from its output measurements using the state observer.
Many observable variables can be aggregated in a model to represent an underlying concept, making it easier to understand the data. In this sense, they serve a function similar to that of scientific theories. At the same time, latent variables link observable "sub-symbolic" data in the real world to symbolic data in the modeled world.
An operational data store (ODS) is used for operational reporting and as a source of data for the enterprise data warehouse (EDW). It is a complementary element to an EDW in a decision support environment, and is used for operational reporting, controls, and decision making, as opposed to the EDW, which is used for tactical and strategic decision support.