GDB

Working with Groups in Cellframe Node

The Cellframe Node Python extensions provide classes and functions for working with groups in the GDB (Global DataBase). GDB is a key-value store where keys can be grouped into tables (groups). Each group represents a unique string in the GDB, and the values are typically arrays of bytes, though other data types can also be stored.

Additional info:

Some groups are subject to synchronization.

• Global groups synchronize with all nodes.
• Local groups do not synchronize.
• Netname groups synchronize within a specific network.

Networks can contain blacklists and whitelists for groups, which are manually denied or allowed to synchronize between nodes.

Overview

In this example, we will:

1. Define the group name and keys.
2. Set and retrieve values by key using the GlobalDB.set and GlobalDB.get methods.
3. Retrieve a list of key-value pairs in a group using the GlobalDB.grLoad method.
4. Delete entries from the group using the GlobalDB.delete method.

Code Example

Below is an example of working with groups in Cellframe Node using the GlobalDB class:

from DAP.Core import logIt
from CellFrame.Chain import GlobalDB
 
def init():
    logIt.notice("Running plugin client")
 
    # Define the group name
    group_name = "local.mygroup"
 
    # Set or receive the key and its corresponding value.
    key1 = "my_key1"
    value1 = "my_value1".encode("utf-8")
 
    key2 = "my_key2"
    value2 = "my_value2".encode("utf-8")
 
    # Set the preset values encoded in bytes.
    GlobalDB.set(key1, group_name, value1)
    GlobalDB.set(key2, group_name, value2)
 
    # Get the value for the specified keys and decode them back:
    value_from_group1 = GlobalDB.get(key1, group_name).decode("utf-8")
    value_from_group2 = GlobalDB.get(key2, group_name).decode("utf-8")
 
    logIt.notice(f"Value from group {group_name} key {key1}: {value_from_group1}")
    logIt.notice(f"Value from group {group_name} key {key2}: {value_from_group2}")
 
    # It is possible to view all key-value pairs using the method group_list()
    # Assuming such method exists, if not, this is a placeholder for the actual implementation
    # For now, we will simulate it
    group_list = [element.key for element in GlobalDB.grLoad(group_name)]  # Placeholder, replace with actual call to list keys if available
    logIt.notice(f"Group {group_name} list: {group_list}")
 
    # Delete the created entries
    GlobalDB.delete(key1, group_name)
    GlobalDB.delete(key2, group_name)
 
    logIt.notice(f"Deleted keys {key1} and {key2} from group {group_name}")
 
    return 0
 

Explanation

• Defining Group and Keys: Define the group name and the keys to set and retrieve values.
• Setting Values: Use GlobalDB.set(key, group, value) to store values in the GDB, encoding the values in bytes.
• Retrieving Values: Use GlobalDB.get(key, group) to fetch the stored values, decoding them from bytes back to strings.
• Listing Group Keys: The GlobalDB.grLoad(group) method is used to list all keys in the group. Note that this is a placeholder and should be replaced with the actual method to list keys if available.
• Deleting Entries: Use GlobalDB.delete(key, group) to remove entries from the group.