Proton 1.0

Key Concepts

Signals

The fundamental data unit in Proton. A signal represents a single typed value that can be a:

• Primitive type: double, float, int32, int64, uint32, uint64, bool, string, bytes
• List type: Arrays of any primitive type (list_double, list_float, etc.)

Each signal is encoded as a Protocol Buffer message with a oneof field, allowing efficient serialization of different data types.

message Signal {
  oneof signal {
    double double_value = 1;
    float float_value = 2;
    int32 int32_value = 3;
    int64 int64_value = 4;
    uint32 uint32_value = 5;
    uint64 uint64_value = 6;
    bool bool_value = 7;
    string string_value = 8;
    bytes bytes_value = 9;

    ListDoubles list_double_value = 10;
    ListFloats list_float_value = 11;
    ListInt32s list_int32_value = 12;
    ListInt64s list_int64_value = 13;
    ListUint32s list_uint32_value = 14;
    ListUint64s list_uint64_value = 15;
    ListBools list_bool_value = 16;
    ListStrings list_string_value = 17;
    ListBytes list_bytes_value = 18;
  }
}

Bundles

A bundle is a collection of related signals that are transmitted together. Think of it as a message or packet containing multiple data fields. Each bundle has:

• Unique ID: A 32-bit identifier (e.g., 0x100 for logs, 0x101 for status)
• Signal list: An ordered collection of signals

message Bundle {
  uint32 id = 1;
  repeated Signal signals = 2;
}

The Signal list can vary in length, and each Signal in the list can use a different value type.

Heartbeat

Proton reserves the Bundle ID 0 for the heartbeat bundle. This is an optional bundle that can be periodically sent out by each node to indicate to other peers in the network that this node is active. The heartbeat bundle has a single uint32 signal which should be incremented on each heartbeat as a sign of liveliness.

Nodes

A node represents a participant in the communication network. Each node can:

• Produce bundles (send data)
• Consume bundles (receive data)
• Communicate with multiple peer nodes
• Send periodic heartbeats to indicate liveliness

A node is also defined with a list of endpoints at which it can be reached.

Node states:

• PROTON_NODE_UNCONFIGURED: Initial state
• PROTON_NODE_INACTIVE: Configured but not actively communicating
• PROTON_NODE_ACTIVE: Fully operational

Peers

Peers are other nodes in the Proton network that a given node can communicate with. A node is paired with a peer with a pair of endpoints called a connection.