mirror of
https://github.com/jlengrand/Observer.git
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Julien Lengrand-Lambert
0eefe04c7b
Checks whether the received json object is correct, and formatted as expected. Also tries to create a sublime-project. Let's see what it gives
74 lines
2.9 KiB
Markdown
74 lines
2.9 KiB
Markdown
# Python Observer pattern using Json
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This module contains a Python implementation of the Observer pattern, using json as a format to share information.
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See [Wikipedia for more information]().
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## Short description of the implementation
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### Observer :
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An observer is uniquey defined by its name. This allows Observable to only notify a given Observer if needed.
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Observers can subscribe to an Observable and will then receive all future notifications from it.
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The notifications are sent in json format.
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### Observable :
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An Observable is an entity holding information of interest for other entities.
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Observers subscribe or unsubscribe to an Observable to get notified any time message is updated.
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### JSon Structure:
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As already explained, the messages sent from the observable to the observers are formatted as a JSon Object.
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This allows a simple yet efficient control of the data sent and received while staying in line with the standards.
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Each transmitted object should be divided into 4 sections:
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- name : The name of the Observer to send the data to. As each Observer is uniquely defined by its name, filling this section means the data will be sent to **at most** one Observer.
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- group : The group of Observers to send the data to. Each Observer may belong to a group. All Observers in the group will then be notified.
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- type : the type of message contained in data. This section is not processed by the Observable and is sent as is. It may be blank, or contain anything.
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- data : The actual data to be transmitted to the Observers
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Here is are several examples of valid JSon message :
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#### Data will be sent to Bob only. No particular message type
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{
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"name": 'Bob',
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"group": '',
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"type": '',
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"data": 42
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}
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#### Data will be sent to all Observers in the GUI group. We may assess that this is an update :).
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{
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"name": '',
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"group": 'GUI',
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"type": 'Update',
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"data": 'coffee'
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}
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#### No group, neither name specified. All subscribers will be notified. the message is an array of value object.
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{
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"name": '',
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"group": '',
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"type": '',
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"data": ["baz", null, 1.0, 2]
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}
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According to the [JSon specifications](http://json.org/),
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_A value can be a string in double quotes, or a number, or true or false or null, or an object or an array._
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**NOTE:** group handling is currently not implemented.
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In future improvements, It may also be possible to provide several names or group if needed.
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## Description of the package
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The Observer pattern does not need any external module to work. Any simple Python installation (>= 2.6) should be enough.
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To use it, simply copy/paste the module file into your code base and load it in yuor code (import Observer)
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You are then ready to go !
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This package contains several other ressources :
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- this README, only used to describe the package and give general information
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- testObserver.py, the unit tests of the Observer/Obervable classes.
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- exObserver.py, a simple example to show how the Observer pattern can be used. |