8.6 KiB
ADR 035: Rosetta API Support
Authors
- Jonathan Gimeno (@jgimeno)
- David Grierson (@senormonito)
- Alessio Treglia (@alessio)
Context
Rosetta API is an open-source specification and set of tools developed by Coinbase to standardise blockchain interactions.
Through the use of a standard API for integrating blockchain applications it will
- Be easier for a user to interact with a given blockchain
- Allow exchanges to integrate new blockchains quickly and easily
- Enable application developers to build cross-blockchain applications such as block explorers, wallets and dApps at considerably lower cost and effort.
Decision
It is clear that adding Rosetta API support to the Cosmos SDK will bring value to all the developers and Cosmos SDK based chains in the ecosystem. How it is implemented is key.
The driving principles of the proposed design are:
- Extensibility: it must be as riskless and painless as possible for application developers to set-up network configurations to expose Rosetta API-compliant services.
- Long term support: This proposal aims to provide support for all the supported Cosmos SDK release series.
- Cost-efficiency: Backporting changes to Rosetta API specifications from
masterto the various stable branches of Cosmos SDK is a cost that needs to be reduced.
We will achieve these delivering on these principles by the following:
- There will be an external repo called cosmos-rosetta-gateway
for the implementation of the core Rosetta API features, particularly:
a. The types and interfaces. This separates design from implementation detail.
b. Some core implementations: specifically, the
Servicefunctionality as this is independent of the Cosmos SDK version. - Due to differences between the Cosmos release series, each series will have its own specific API implementations of
Networkstruct andAdapterinterface. - There will be two options for starting an API service in applications: a. API shares the application process b. API-specific process.
Architecture
The External Repo
As section will describe the proposed external library, including the service implementation, plus the defined types and interfaces.
Service
Service is a simple struct that is started and listens to the port specified in the options. This is meant to be used across all the Cosmos SDK versions that are actively supported.
The constructor follows:
func New(options Options, network Network) (*Service, error)
Types
Service accepts an Options struct that holds service configuration values, such as the port the service would be listening to:
type Options struct {
ListenAddress string
}
The Network type holds network-specific properties (i.e. configuration values) and adapters. Pre-configured concrete types will be available for each Cosmos SDK release. Applications can also create their own custom types.
type Network struct {
Properties rosetta.NetworkProperties
Adapter rosetta.Adapter
}
A NetworkProperties struct comprises basic values that are required by a Rosetta API Service:
type NetworkProperties struct {
// Mandatory properties
Blockchain string
Network string
SupportedOperations []string
}
Rosetta API services use Blockchain and Network as identifiers, e.g. the developers of gaia, the application that powers the Cosmos Hub, may want to set those to Cosmos Hub and cosmos-hub-3 respectively.
SupportedOperations contains the transaction types that are supported by the library. At the present time,
only cosmos-sdk/MsgSend is supported in Launchpad. Additional operations will be added in due time.
For Launchpad we will map the amino type name to the operation supported, in Stargate we will use the protoc one.
Interfaces
Every SDK version uses a different format to connect (rpc, gRpc, etc), we have abstracted this in what is called the
Adapter. This is an interface that defines the methods an adapter implementation must provide in order to be used
in the Network interface.
Each Cosmos SDK release series will have their own Adapter implementations. Developers can implement their own custom adapters as required.
type Adapter interface {
DataAPI
ConstructionAPI
}
type DataAPI interface {
server.NetworkAPIServicer
server.AccountAPIServicer
server.MempoolAPIServicer
server.BlockAPIServicer
server.ConstructionAPIServicer
}
type ConstructionAPI interface {
server.ConstructionAPIServicer
}
Example in pseudo-code of an Adapter interface:
type SomeAdapter struct {
cosmosClient client
tendermintClient client
}
func NewSomeAdapter(cosmosClient client, tendermintClient client) rosetta.Adapter {
return &SomeAdapter{cosmosClient: cosmosClient, tendermintClient: tendermintClient}
}
func (s SomeAdapter) NetworkStatus(ctx context.Context, request *types.NetworkRequest) (*types.NetworkStatusResponse, *types.Error) {
resp := s.tendermintClient.CallStatus()
// ... Parse status Response
// build NetworkStatusResponse
return networkStatusResp, nil
}
func (s SomeAdapter) AccountBalance(ctx context.Context, request *types.AccountBalanceRequest) (*types.AccountBalanceResponse, *types.Error) {
resp := s.cosmosClient.Account()
// ... Parse cosmos specific account response
// build AccountBalanceResponse
return AccountBalanceResponse, nil
}
// And we repeat for all the methods defined in the interface.
For further information about the Servicer interfaces, please refer to the Coinbase's rosetta-sdk-go's documentation.
2. Cosmos SDK Implementation
As described, each Cosmos SDK release series will have version specific implementations of Network and Adapter, as
well as a NewNetwork constructor.
Due to separation of interface and implementation, application developers have the option to override as needed, using this code as reference.
// NewNetwork returns the default application configuration.
func NewNetwork(options Options) service.Network {
cosmosClient := cosmos.NewClient(fmt.Sprintf("http://%s", options.CosmosEndpoint))
tendermintClient := tendermint.NewClient(fmt.Sprintf("http://%s", options.TendermintEndpoint))
return service.Network{
Properties: rosetta.NetworkProperties{
Blockchain: options.Blockchain,
Network: options.Network,
SupportedOperations: []string{OperationTransfer},
},
Adapter: newAdapter(
cosmosClient,
tendermintClient,
properties{
Blockchain: options.Blockchain,
Network: options.Network,
OfflineMode: options.OfflineMode,
},
),
}
}
3. API service invocation
As stated at the start, application developers will have two methods for invocation of the Rosetta API service:
- Shared process for both application and API
- Standalone API service
Shared Process (Only Stargate)
Rosetta API service could run within the same execution process as the application. New configuration option and command line flags would be provided to support this:
if config.Rosetta.Enable {
....
get contecxt, flags, etc
...
h, err := service.New(
service.Options{ListenAddress: config.Rosetta.ListenAddress},
rosetta.NewNetwork(cdc, options),
)
if err != nil {
}
...
go func() {
if err := h.Start(config); err != nil {
errCh <- err
}
}()
}
Separate API service
Client application developers can write a new command to launch a Rosetta API server as a separate process too:
func RosettaCommand(cdc *codec.Codec) *cobra.Command {
...
cmd := &cobra.Command{
Use: "rosetta",
....
RunE: func(cmd *cobra.Command, args []string) error {
....
get contecxt, flags, etc
...
h, err := service.New(
service.Options{Endpoint: endpoint},
rosetta.NewNetwork(cdc, options),
)
if err != nil {
return err
}
...
h.Start()
}
}
...
}
Status
Proposed
Consequences
Positive
- Out-of-the-box Rosetta API support within Cosmos SDK.
- Blockchain interface standardisation