Software Design

Truffle DB defines a schema for this smart contract data model, but seeks to remain agnostic to resolver. This provides the desired flexibility while affording options for compatibility.

skinparam nodesep 50 component "Truffle DB" as DB () GraphQL DB -right- GraphQL () "GraphQL Resolver" as Resolver DB .down. Resolver

Interface Compatibility

To conform to existing code, Truffle DB can implement the artifactor and resolver interfaces.

skinparam nodesep 50 component "Truffle DB" as DB () Resolver () Artifactor ' positioning Artifactor -[hidden]right-> Resolver DB -up- Artifactor DB -up- Resolver

This can serve to make Truffle DB a viable drop-in replacement.

skinparam nodesep 50 component Config () Artifactor () Resolver ' positioning Artifactor -[hidden]right-> Resolver Config .down. Artifactor Config .down. Resolver component "Truffle DB" as DB DB -up- Artifactor DB -up- Resolver

Artifact Compatibility

In addition, this effort requires that artifact files are maintained in their current format in the project’s contracts_build_directory, as these files are widely recognized/used/generated by both internal and external tooling.

That is: Truffle’s artifacts are an interface.

Naive Approach

By adding an interface for obtaining contract abstractions, and by introducing an adapter component, it may be possible to drop in the existing artifactor/resolver implementations.

skinparam nodesep 50 component "Truffle DB" as DB () Abstractions DB -left- Abstractions component "Abstraction Adapter" as Adapter () "Persistence Controller" as Controller Adapter -up- Controller DB .down. Controller Abstractions ... Adapter ' drop-in () "Artifactor" as OriginalArtifactor () "Resolver" as OriginalResolver component "Artifactor" as BaseArtifactor component "Resolver" as BaseResolver ' positioning OriginalArtifactor -[hidden]right-> OriginalResolver BaseArtifactor -up- OriginalArtifactor BaseResolver -up- OriginalResolver Adapter .down. OriginalArtifactor Adapter .down. OriginalResolver

In this model, Truffle DB interacts with the adapter by way of a controller interface for performing persistence operations.

Using GraphQL Internally

Contract abstractions are currently widely used as a data transfer object.

This may be limiting, since they are not plain data objects, but instead also encapsulate behavior.

A better approach might be to make internal use of the GraphQL mechanism to hook into the existing artifactor/resolver implementations.

This approach would not prohibit the re-use of existing artifactor/resolver implementations, but re-use here would require the introduction of an additional component to instantiate contract abstractions via GraphQL queries.

skinparam nodesep 50 component "Truffle DB" as DB () GraphQL DB -right- GraphQL component "Abstraction Adapter" as Adapter () "Persistence Controller" as Controller Adapter -up- Controller DB .down. Controller component "Query Translation" as Translation () Abstractions Translation -down- Abstractions Translation .up. GraphQL Abstractions .. Adapter ' drop-in () Artifactor () Resolver ' positioning Artifactor -[hidden]right-> Resolver component "Artifactor" as BaseArtifactor component "Resolver" as BaseResolver BaseArtifactor -up- Artifactor BaseResolver -up- Resolver Adapter .down. Artifactor Adapter .down. Resolver

Here, Truffle DB performs persistence operations by way of this modified abstraction adapter, which interacts with a discrete translation layer for converting between GraphQL queries and abstraction objects.