Metadata-Version: 2.0
Name: mg-conveyor
Version: 1.0.0
Summary: A tool for having a sequential execution of plugins
Home-page: https://sourceforge.net/projects/mobgenconveyor
Author: Ronaldo Webb
Author-email: mobil3.g3nius@gmail.com
License: UNKNOWN
Keywords: tool plugin utility development dev
Platform: UNKNOWN
Classifier: Development Status :: 4 - Beta
Classifier: Environment :: Console
Classifier: Intended Audience :: End Users/Desktop
Classifier: Intended Audience :: Developers
Classifier: Intended Audience :: System Administrators
Classifier: Programming Language :: Python
Classifier: Topic :: Communications :: Email
Classifier: Topic :: Software Development :: Bug Tracking
Requires-Dist: yapsy

============
Introduction
============

Sometime in the development or implementation we encounter things to be processed by different specialization. For example, we receive a CSV file that is intended from importing to a table. We found out that the CSV file is not formatted to what the table can consume. Thus, we need to do two thing:

1. Transform or create a CSV file to meet the table requirement based on the CSV file at hand.
2. Wrap the contents of the transformed and newly created CSV to create the SQL statements that can be readily run against a database.

As we can see above, these then can be created by two different individuals one that is specialized in manipulating CSV file and knowledge in generating SQL scripts. Addition, these two thing must be run in sequence and not on the other way around. 

This is the idea around the conveyor that the work is done in sequence and can use some tools.

============
Installation
============

The installation is as easy as downloading the conveyor-<version>-py3-none-any.whl package and run the following command in the download folder in the command line:

**Command 1. Using pip module for installation**

If you have the wheel package
::

  python -m pip install mg_conveyor-<version>-py3-none-any.whl

Or simply

::

  python -m pip install mg_conveyor

==================
Using the conveyor 
==================

**Conveyor** is not intended be used as a standalone command but a least a plugin must be made available to it to process. 

The ISequencialPlugin Interface
-------------------------------

As its name suggests it is executed based on sequence. This plugin needs the following methods to be implemented:

Methods to be implemented
^^^^^^^^^^^^^^^^^^^^^^^^^

::

	def sequence(self)
	def process(self, identity, context, *args, **kwargs)

The **sequence method** must return an integer that will dictate sequence on when it must be executed.

.. note:: **Every plugin** must return a different sequence number.

The **process method** is the entrypoint for each plugin and this is where our plugin logic must reside. This method has two important parameters namely identity and context. Currently the identity is the name of the plugin (i.e. defined in the yapsy configuration file that is particularly the **Name** attribute) and the context contains some information about the plugin. Also this method must return one of the predefined status.

**ISequencialPlugin Return Status**

======================= ======================================================
Status                  Description
======================= ======================================================
STATUS_SUCCESS			Finished successfully.
STATUS_FAILED			Error encountered also abort the execution of conveyor
STATUS_ABORT            Abort the execution of conveyor.
STATUS_RETRY            The plugin is requesting an interactive retry.
STATUS_CONFIRM_RETRY    The user responded Y to the interactive retry.
STATUS_CONFIRM_ABORT    The user responded N to the interactive retry.
STATUS_SKIPPED          Skipped plugin
STATUS_STARTED          Plugin is currently started.
======================= ======================================================

**Example 1. Simple Plugin Implementation**

::

	import mg_conveyor as conveyor
	class PluginOne(conveyor.ISequencialPlugin):
	    def sequence(self):
	        return 100
	    def process(self, identity, context, *args, **kwargs):
	    	print("Hello Worlds.")
	        return conveyor.STATUS_SUCCESS

Using the context Parameter
^^^^^^^^^^^^^^^^^^^^^^^^^^^

The context parameter contains some information about the plugin like its status (i.e. CONTEXT_KEY_STATUS) and its instance (i.e. CONTEXT_KEY_PLUGIN_OBJECT). This parameter is just a simple dictionary. By default each plugin has its own context inside the context with the key as its identity (i.e. context[identity]). Thus, to get the plugin object of the current plugin we should access it like the following snippet inside the process method.

::

	pluginObj = context[identity][CONTEXT_KEY_PLUGIN_OBJECT]

**Pre-defined Context Keys per identity**

========================= ============================================================
Status                    Description
========================= ============================================================
CONTEXT_KEY_STATUS		  Contains the numerical equivalent of the **ISequencialPlugin Return Status**.
CONTEXT_KEY_PLUGIN_OBJECT The instance of the plugin associated with the identity.
========================= ============================================================

The context has another purpose that it can hold custom plugin information. To add a new entry to the context it is better to add it under the identity key. This can be done by the snippet below (i.e. inside the process method):

::

	plugin_context = context[identity]
	plugin_context['item1']='This is item 1'
	plugin_context['item2']='This is item 2'

More over this context is shared by all the plugins loaded by the conveyor. Therefore, we can use the context to pass information between plugins. For example the result of the first plugin can be stored in the context and that item will be processed by the following plugin.

Yapsy Configuration File
------------------------

Once the plugin is ready we must create a configuration file. Since we are using yapsy the sample configuration file is as follows:

::

	[Core]
	Name = Hello World
	Module = helloworld

	[Documentation]
	Author = Ronaldo Webb
	Version = 0.1
	Website = http://www.ronella.xyz
	Description = Test only

.. note:: The **Name attribute** in this configuration file is the one being used as the **identity parameter** in the process method.

See `yapsy-plugin`_ for more information about the content of the configuration file.

.. _yapsy-plugin: http://yapsy.sourceforge.net/PluginFileLocator.html

The IUtilityPlugin Interface
-------------------------------

This plugin is the one that can be shared by all ISequencialPlugin implementations. Thus, we can think of the IUtilityPlugin implementation as a **tool** that the ISequencialPlugin (i.e. activing as a worker) can use to do its job properly. This tool is always available in the context and only has one method to be implemented. 

Method to be implemented
^^^^^^^^^^^^^^^^^^^^^^^^^

::

	def use(self, *args, **kwargs)

The **use method** must contain the implmentation on what the ISequencialPlugin implementaion demands it to do according to what it's purpose as a tool. It can return any type therefore the a proper documentation of the return type is necessary.

Built-in Properties
^^^^^^^^^^^^^^^^^^^

The IUtilityPlugin has built-in properties as we can see in the following table:

============ ==========================================================================================
Property     Description
============ ==========================================================================================
identity     Contains the identity of the plugin (i.e. the Name attribute in yapsy configuration file.)
context      The context shared by all the plugins.
localContext This is equals to context[identity].
============ ==========================================================================================

Acquiring IUtilityPlugin from context
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

To acquire an instance of the IUtilityPlugin we must know its identity (i.e. Name attribute in yapsy configuraiton file.). Once we have the instance we can call it's use method.

**Example 2: Acquiring IUtilityPlugin**

If have **Utility** as the identity then in the process method of the ISequencialPlugin implementation we can retrieve its instance like in the snippet below:

::

    def process(self, identity, context, *args, **kwargs):

        utilObj = context['Utility'][conveyor.CONTEXT_KEY_PLUGIN_OBJECT].use()

.. note:: We can pass any number of arguments to the use method.

Starting The Conveyor
---------------------

Once the plugin is working fine and the configuration file were created, we can now create an implmenetation to start the conveyor. The first thing that we must do is to instantiate the Conveyor class then load the plugins and finally start it. See the sample snippet below:

**Example 3: Starting the Conveyor**

::

	conv = conveyor.Conveyor()
	conv.loadPlugins(["plugins"])
	conv.start()

.. note:: In the **loadPlugins method** we must pass in an **array of locations** of the plugins.

========
Appendix
========

Complete Hello World Implementation
-----------------------------------

plugins/helloworld_plugin.py
^^^^^^^^^^^^^^^^^^^^^^^^^^^^

::

	import mg_conveyor as conveyor
	class PluginOne(conveyor.ISequencialPlugin):
	    def sequence(self):
	        return 100
	    def process(self, identity, context, *args, **kwargs):
	    	print("Hello World.")
	        return conveyor.STATUS_SUCCESS

plugins/helloworld.yapsy-plugin
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

::

	[Core]
	Name = Hello World
	Module = helloworld_plugin

	[Documentation]
	Author = Ronaldo Webb
	Version = 0.1
	Website = http://www.ronella.xyz
	Description = Test only

helloworld.py
^^^^^^^^^^^^^

::

    import mg_conveyor as conveyor

    if __name__ == '__main__':

        conv=conveyor.Conveyor()
        conv.loadPlugins(["plugins"])
        conv.start()      

Sample Context Usage
--------------------

plugins/plugin1.py
^^^^^^^^^^^^^^^^^^

::

	import mg_conveyor as conveyor
	class Plugin(conveyor.ISequencialPlugin):
	    def sequence(self):
	        return 100

	    def process(self, identity, context, *args, **kwargs):
	        plugin_context = context[identity]

	        plugin_context['Message'] = "From plugin 1"

	        return conveyor.STATUS_SUCCESS

plugins/plugin1.yapsy-plugin
^^^^^^^^^^^^^^^^^^^^^^^^^^^^

::

	[Core]
	Name = Plugin1
	Module = plugin1

	[Documentation]
	Author = Ronaldo Webb
	Version = 0.1
	Website = http://www.ronella.xyz
	Description = Test only

plugins/plugin2.py
^^^^^^^^^^^^^^^^^^

::

	import mg_conveyor as conveyor
	class Plugin(conveyor.ISequencialPlugin):
	    def sequence(self):
	        return 200

	    def process(self, identity, context, *args, **kwargs):

	        #Plugin1 is the Name found in plugin1.yapsy-plugin
	        plugin1_context = context['Plugin1']


	        print("I'm in plugin 2...")
	        print("Message from plugin 1: " + plugin1_context['Message'])
	        return conveyor.STATUS_SUCCESS

plugins/plugin2.yapsy-plugin
^^^^^^^^^^^^^^^^^^^^^^^^^^^^

::

	[Core]
	Name = Plugin2
	Module = plugin2

	[Documentation]
	Author = Ronaldo Webb
	Version = 0.1
	Website = http://www.ronella.xyz
	Description = Test only

context_usage.py
^^^^^^^^^^^^^^^^

::

	import mg_conveyor as conveyor

	if __name__ == '__main__':

	    conv=conveyor.Conveyor()
	    conv.loadPlugins(["plugins"])
	    conv.start()      

Passing Parameter to the Process Method
---------------------------------------

plugins/parameter.py
^^^^^^^^^^^^^^^^^^^^

::

    import mg_conveyor as conveyor
    class PluginOne(conveyor.ISequencialPlugin):

        def sequence(self):
            return 100

        def process(self, identity, context, *args, **kwargs):
            print("Argument 1: " + args[0])
            print("Arguemnt 2: " + args[1])
            print("Parameter 1: " + kwargs['param1'])
            print("Parameter 2: " + kwargs['param2'])

            return conveyor.STATUS_SUCCESS

plugins/parameter.yapsy-plugin
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

::

	[Core]
	Name = Parameter Passing
	Module = parameter

	[Documentation]
	Author = Ronaldo Webb
	Version = 0.1
	Website = http://www.ronella.xyz
	Description = Test only

process_parameter.py
^^^^^^^^^^^^^^^^^^^^

::

    import mg_conveyor as conveyor

    if __name__ == '__main__':

        conv=conveyor.Conveyor()
        conv.loadPlugins(["plugins"])
        conv.start("arg0"
            , "arg1"
            , param1="This is parameter 1"
            , param2="This is parameter 2") 

Basic Sample for using IUtilityPlugin
-------------------------------------

utility.py
^^^^^^^^^^

::

    import mg_conveyor as conveyor

    class Utility(conveyor.IUtilityPlugin):

        def __init__(self):
            super().__init__()

        def use(self, *args, **kwargs):

            self.localContext['Message'] = "I'm in Utility plugin"
            return "This is a test."

utility.yapsy-plugin
^^^^^^^^^^^^^^^^^^^^

::

    [Core]
    Name = Utility
    Module = utility

    [Documentation]
    Author = Ronaldo Webb
    Version = 0.1
    Website = http://www.ronella.xyz
    Description = Test only

sequence.py
^^^^^^^^^^^

::

    import mg_conveyor as conveyor

    class PluginOne(conveyor.ISequencialPlugin):
        def sequence(self):
            return 100

        def process(self, identity, context, *args, **kwargs):

            utilCtx = context['Utility']
            utilOutput = utilCtx[conveyor.CONTEXT_KEY_PLUGIN_OBJECT].use()

            if 'util_message' in kwargs:
                kwargs['util_message'](utilCtx['Message'])

            if 'util_output' in kwargs:
                kwargs['util_output'](utilOutput)

            return conveyor.STATUS_SUCCESS

sequence.yapsy-plugin
^^^^^^^^^^^^^^^^^^^^^

::

    [Core]
    Name = Sequence
    Module = sequence

    [Documentation]
    Author = Ronaldo Webb
    Version = 0.1
    Website = http://www.ronella.xyz
    Description = Test only

utility_usage.py
^^^^^^^^^^^^^^^^

::

	import mg_conveyor as conveyor

	if __name__ == '__main__':

	    conv=conveyor.Conveyor()
	    conv.loadPlugins(["plugins"])
	    conv.start()      



