Distributed Breadth-First Search (BFS):

Distributed Breadth-First Search (BFS) is an algorithm used to traverse and explore nodes in a distributed graph or network.

BFS is commonly used to find the shortest path between two nodes in an unweighted graph.

In a distributed setting, each node in the graph is a separate computing entity, and the BFS algorithm is distributed across these nodes.

Distributed BFS Algorithm:

1.    Initialization:

·        Each node is assigned a unique identifier.

·        The source node initiates the BFS exploration.

2.    Local Exploration:

·        Each node explores its local neighbors and identifies nodes not yet visited.

·        It creates messages containing information about the discovered nodes and sends them to neighboring nodes.

3.    Message Propagation:

·        Messages propagate through the network, updating the knowledge of each node about the discovered nodes.

4.    Global Queue:

·        A global queue is maintained, storing the nodes to be explored in the next iteration.

5.    Iterative Exploration:

·        Nodes continue to explore and propagate messages until the entire graph is traversed or the desired condition is met.

Example: Consider a distributed graph

A ---- B

|        |

C ---- D

  • Nodes: A, B, C, D
  • Edges: (A, B), (A, C), (B, D), (C, D)

Initialization:

  • Source Node: A

Iteration 1:

  • A explores neighbors B and C.
  • Messages are sent to B and C containing information about discovered nodes (B, C).
  • Global queue: [B, C]

Iteration 2:

  • B explores neighbor D.
  • Message sent to D containing information about discovered node (D).
  • C explores neighbor D.
  • Message sent to D containing information about discovered node (D).
  • Global queue: [C, D]

Iteration 3:

  • C and D have no unexplored neighbors.
  • The algorithm terminates.

Result:

  • Nodes discovered in BFS order: A, B, C, D

 


Distributed Breadth-First Search (BFS) is an algorithm used to traverse and explore nodes in a distributed graph or network. BFS is commonly used to find the shortest path between two nodes in an unweighted graph. In a distributed setting, each node in the graph is a separate computing entity, and the BFS algorithm is distributed across these nodes.

Distributed BFS Algorithm:

1.    Initialization:

·        Each node is assigned a unique identifier.

·        The source node initiates the BFS exploration.

2.    Local Exploration:

·        Each node explores its local neighbors and identifies nodes not yet visited.

·        It creates messages containing information about the discovered nodes and sends them to neighboring nodes.

3.    Message Propagation:

·        Messages propagate through the network, updating the knowledge of each node about the discovered nodes.

4.    Global Queue:

·        A global queue is maintained, storing the nodes to be explored in the next iteration.

5.    Iterative Exploration:

·        Nodes continue to explore and propagate messages until the entire graph is traversed or the desired condition is met.

Example:

Consider a distributed graph:

|A --- B|

|C --- D|

  • Nodes: A, B, C, D
  • Edges: (A, B), (A, C), (B, D), (C, D)

Initialization:

  • Source Node: A

Iteration 1:

  • A explores neighbors B and C.
  • Messages are sent to B and C containing information about discovered nodes (B, C).
  • Global queue: [B, C]

Iteration 2:

  • B explores neighbor D.
  • Message sent to D containing information about discovered node (D).
  • C explores neighbor D.
  • Message sent to D containing information about discovered node (D).
  • Global queue: [C, D]

Iteration 3:

  • C and D have no unexplored neighbors.
  • The algorithm terminates.

Result:

  • Nodes discovered in BFS order: A, B, C, D

In this example, each node performs local exploration and propagates messages to inform other nodes about discovered neighbors. The global queue ensures the order of exploration across the distributed network. This iterative process continues until all reachable nodes are discovered.