03-20-2002
You are partially correct! The data does traverse down the OSI model on the source node.......across the network medium.......to the destination node....and back up the OSI model.
BUT, transmissions do not have to actually start at the application level. Have you ever heard of two or three tier routers? They only use part of the OSI model.....hence two or three layers are transmitted....not all 7.
It goes like this:
Data to be sent in this datagram = XXXXXXXXXX
Layer 7 puts on application specific headers:
AAXXXXXXXXXXA
Then Layer 6 for presentation:
PPAAXXXXXXXXXXAP
Then Layer 5 does the same on a session basis:
SSPPAAXXXXXXXXXXAPS
Layer 4 for transport portion:
TTSSPPAAXXXXXXXXXXAPST
Layer 3 goes next:
NNTTSSPPAAXXXXXXXXXXAPSTN
Layer 2 puts on the Data Link layer stuff:
DDNNTTSSPPAAXXXXXXXXXXAPSTND
The finally the Physical layer:
PPDDNNTTSSPPAAXXXXXXXXXXAPSTNDP
This is then transmitted. At the destination...each layer strips the corresponding layer and sends it up to the next layer....etc.
This is very basic...it's more complex than this tutorial...each layer does not have the same size of headers...and such...but this gets the idea across.
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LEARN ABOUT DEBIAN
jifty::plugin::classloader
Jifty::Plugin::ClassLoader(3pm) User Contributed Perl Documentation Jifty::Plugin::ClassLoader(3pm)
NAME
Jifty::Plugin::ClassLoader - Automatically generates application classes
DESCRIPTION
"Jifty::Plugin::ClassLoader" loads additional model and action classes on behalf of the application out of the configured plugin classes.
Unlike, "Jifty::ClassLoader", this class will only autogenerate classes if the plugin provides them. The plugin classes are checked before
the base Jifty classes, so that a plugin can override the Jifty class, just as any existing application classes will be loaded first.
new
Returns a new ClassLoader object. Doing this installs a hook into @INC that allows Jifty::Plugin::ClassLoader to dynamically create needed
classes if they do not exist already. This works because if use/require encounters a blessed reference in @INC, it will invoke the INC
method with the name of the module it is searching for on the reference.
Takes two mandatory arguments, "base", which should be the application's base path; and "plugin" which is the plugin classname.
INC
The hook that is called when a module has been "require"'d that cannot be found on disk. The following stub classes are auto-generated:
Application
An empty application base class is created that doesn't provide any methods or inherit from anything.
Application::Record
An empty class that descends from Jifty::Record is created.
Application::Collection
An empty class that descends from Jifty::Collection is created.
Application::Notification
An empty class that descends from Jifty::Notification.
Application::Dispatcher
An empty class that descends from Jifty::Dispatcher.
Application::Bootstrap
An empty class that descends from Jifty::Bootstrap.
Application::Upgrade
An empty class that descends from Jifty::Upgrade.
Application::CurrentUser
An empty class that descends from Jifty::CurrentUser.
Application::Model::AnythingCollection
If "Application::Model::Something" is a valid model class, then it creates a subclass of Jifty::Collection whose "record_class" is
"Application::Model::Something".
Application::Action::(Create or Update or Delete)Anything
If "Application::Model::Something" is a valid model class, then it creates a subclass of Jifty::Action::Record::Create,
Jifty::Action::Record::Update, or Jifty::Action::Record::Delete whose record_class is "Application::Model::Something".
require
Loads all of the application's Actions and Models. It additionally "require"'s all Collections and Create/Update actions for each Model
base class -- which will auto-create them using the above code if they do not exist on disk.
DESTROY
When the ClassLoader gets garbage-collected, its entry in @INC needs to be removed.
perl v5.14.2 2010-12-08 Jifty::Plugin::ClassLoader(3pm)