Strategists are users or organizations responsible for submitting parameters for Cellar rebalances and other contract calls to Sommelier through the Steward API. To accomplish this they use the Steward API. The Steward API is defined by a protobuf package and can be used with a gRPC client. Strategists must generate proto bindings and a client from the Steward API protobuf files for their preferred language.

Strategists must also generate a Certificate Authority and use it to generate a self-signed certificate, which is the representation of a strategist's identity as a Publisher on the Sommelier chain required to create a trusted connection with the Steward API.

Strategists are also responsible for writing their own logic for interacting with the Steward API in the language of their choice. The Steward API interfaces and gRPC client can be generated in many different languages.

Requests to the Steward API use the type ScheduleRequest. This request contains contract call data and information used by the Sommelier chain to determine the destination of the contract and the timing of transaction execution. The response type ScheduleResponse contains information that can be used to query the Sommelier chain in order to confirm that a call, referred to on-chain as a Cork, was submitted and scheduled successfully.

// Defined in steward/proto/steward/v4/steward.proto

// Represents a scheduled function call to a particular Cellar
message ScheduleRequest {
    // The ID (currently simply an Ethereum address) of the target Cellar
    string cellar_id = 1;
    // The Sommelier block height at which to schedule the contract call
    uint64 block_height = 2;
    // The data from which the desired contract function will be encoded
    oneof call_data {
        AaveV2Stablecoin aave_v2_stablecoin = 3;
        CellarV1 cellar_v1 = 4;
        CellarV2 cellar_v2 = 5;
        CellarV2_2 cellar_v2_2 = 6;
        CellarV2_5 cellar_v2_5 = 7;
    // The ID of the chain on which the target Cellar resides
    uint64 chain_id = 8;
    // The unix timestamp deadline for the contract call to be executed.
    // Ignored for Ethereum Cellars.
    uint64 deadline = 9;

message ScheduleResponse {
    // The hex encoded ID of the scheduled cork
    string id = 1;
    // The ID of the chain on which the target Cellar resides
    uint64 chain_id = 2;

The request's call_data field contains the actual contract call arguments. Most strategists will be using the CellarV2_5 call data type, which represents calls structured after the Cellar v2.5 architecture.

Strategists can execute a single function call or multiple function calls in the same transaction using the Multicall call type. The most important and complex function callable in Cellar v2.5 is CallOnAdaptor. It allows one or more adaptor function calls to be executed against a large selection of Sommelier adaptors defined in the Steward API.

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