The notification example demonstrates how you can create a notification handler. This example consists of one python script /exampleCreateTx.py and manifest file /manifest.json.
from DAP.Core import logIt
from CellFrame.Network import Net
def notify_net_db(op_code, group, key, value, arg):
logIt.notice("Notificator")
logIt.notice(" op_code: "+op_code)
logIt.notice(" group: "+group)
logIt.notice(" key:"+key)
logIt.notice(" value:"+str(value))
logIt.notice(" Arg: "+str(arg))
def init():
logIt.notice("Start plugin notifyDB")
net = Net.byName("kelvin-testnet")
net.addNotify(notify_net_db, "This is notificator work with net db in network "+str(net))
return 0
{
"name": "notifyDB",
"version": "1.0",
"author": "DEMLABS (C) 2021",
"dependencies": [],
"description": "This plugin demonstrates a work with notification."
}
This /exampleCreateTx.py script contains two function: init and notify_net_db.
The execution of the plugin starts with the init. The notify_net_db function is passed to the addNotify method as an argument. The notify_net_db function will be called when records are added or deleted in GDB.
1. The plugin is initialized by the init function:
def init():
2. Getting a net by name using a byName static method of the Net class:
net = Net.byName("kelvin-testnet")
The "kelvin-testnet" is a net name. The net is a instance of the Net object.
3. Adding a handler for the net notifier using the addNotify method:
net.addNotify(notify_net_db, "This is notificator work with net db in network "+str(net))
The notify_net_db is a function that will handle GDB change notifications. The second argument can be object of any type, in this example str
4. Returning 0. This means that the plugin has been successfully initialized:
return 0
1. The function must take four arguments: an operation code, a group, a key and a value:
def notify_net_db(op_code, group, key, value, arg):
The op_code, group, key are strings and value is bytes.
2. We logging the information received from the notifier:
logIt.notice("Notificator")
logIt.notice(" op_code: "+op_code)
logIt.notice(" group: "+group)
logIt.notice(" key:"+key)
logIt.notice(" value:"+str(value))
logIt.notice(" Arg: "+str(arg))