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As mentioned before, Polygon SDK is a set of different modules, all connected to each other.
The Blockchain is connected to the State, or for example Synchronization, which pipes new blocks into the Blockchain.

Minimal is the cornerstone for these inter-connected modules.
It acts as a central hub for all the services that run on the Polygon SDK.

Startup Magic#

Among other things, Minimal is responsible for:

  • Setting up data directories
  • Creating a keystore for libp2p communication
  • Creating storage
  • Setting up consensus
  • Setting up the blockchain object with GRPC, JSON RPC and Synchronization
func NewServer(logger hclog.Logger, config *Config) (*Server, error) {
m := &Server{
logger: logger,
config: config,
chain: config.Chain,
grpcServer: grpc.NewServer(),
m.logger.Info("Data dir", "path", config.DataDir)
// Generate all the paths in the dataDir
if err := setupDataDir(config.DataDir, dirPaths); err != nil {
return nil, fmt.Errorf("failed to create data directories: %v", err)
// Get the private key for the node
keystore := keystore.NewLocalKeystore(filepath.Join(config.DataDir, "keystore"))
key, err := keystore.Get()
if err != nil {
return nil, fmt.Errorf("failed to read private key: %v", err)
m.key = key
storage, err := leveldb.NewLevelDBStorage(filepath.Join(config.DataDir, "blockchain"), logger)
if err != nil {
return nil, err
} = storage
// Setup consensus
if err := m.setupConsensus(); err != nil {
return nil, err
stateStorage, err := itrie.NewLevelDBStorage(filepath.Join(m.config.DataDir, "trie"), logger)
if err != nil {
return nil, err
st := itrie.NewState(stateStorage)
m.state = st
executor := state.NewExecutor(config.Chain.Params, st)
// Blockchain object
m.blockchain, err = blockchain.NewBlockchain(logger, storage, config.Chain, m.consensus, executor)
if err != nil {
return nil, err
executor.GetHash = m.blockchain.GetHashHelper
// Setup sealer
sealerConfig := &sealer.Config{
Coinbase: crypto.PubKeyToAddress(&m.key.PublicKey),
m.Sealer = sealer.NewSealer(sealerConfig, logger, m.blockchain, m.consensus, executor)
// Setup the libp2p server
if err := m.setupLibP2P(); err != nil {
return nil, err
// Setup the GRPC server
if err := m.setupGRPC(); err != nil {
return nil, err
// Setup jsonrpc
if err := m.setupJSONRPC(); err != nil {
return nil, err
// Setup the syncer protocol
m.syncer = protocol.NewSyncer(logger, m.blockchain)
// Register the libp2p GRPC endpoints
proto.RegisterHandshakeServer(m.libp2pServer.GetGRPCServer(), &handshakeService{s: m})
return m, nil