ADR 009: ChainEndpoint/ChainHandle Consolidation

docs/architecture/README.md

@@ -25,12 +25,14 @@ To suggest an ADR, please make use of the [ADR template](./adr-template.md) prov
 
 ## Table of Contents
 
-| ADR \#                                           | Description                       | Status |
-|--------------------------------------------------|-----------------------------------| ------ |
-| [001](./adr-001-repo.md)                         | Repository structure for `ibc-rs` | Accepted    |
-| [002](./adr-002-ibc-relayer.md)                  | IBC Relayer in Rust               | Accepted |
-| [003](./adr-003-handler-implementation.md)       | IBC handlers implementation       | Accepted |
-| [004](./adr-004-relayer-domain-decomposition.md) | Relayer domain decomposition      | Accepted |
-| [005](./adr-005-relayer-v0-implementation.md)    | Relayer v0 implementation         | Accepted |
-| [006](./adr-006-hermes-v0.2-usecases.md)         | Hermes v0.2.0 Use-Cases           | Proposed |
-| [007](./adr-007-ics20-implementation.md)         | ICS20 implementation              | Proposed |
+| ADR \# | Description | Status |
+| ------ | ----------- | ------ |
+| [001](./adr-001-repo.md) | Repository structure for `ibc-rs` | Accepted    |
+| [002](./adr-002-ibc-relayer.md) | IBC Relayer in Rust | Accepted |
+| [003](./adr-003-handler-implementation.md) | IBC handlers implementation | Accepted |
+| [004](./adr-004-relayer-domain-decomposition.md) | Relayer domain decomposition | Accepted |
+| [005](./adr-005-relayer-v0-implementation.md) | Relayer v0 implementation | Accepted |
+| [006](./adr-006-hermes-v0.2-usecases.md) | Hermes v0.2.0 Use-Cases | Proposed |
+| [007](./adr-007-error.md) | Error Management | Accepted |
+| [008](./adr-008-ics20-implementation.md)         | ICS20 implementation              | Accepted |
+| [009](./adr-009-chain-endpoint-handle-standardization.md) | ChainEndpoint and ChainHandle methods standardization | Accepted |

docs/architecture/adr-007-ics20-implementation.md → docs/architecture/adr-008-ics20-implementation.md

@@ -1,4 +1,8 @@
-# ADR 007: ICS20 Implementation Proposal
+# ADR 008: ICS20 Implementation Proposal
+
+## Status
+
+Accepted
 
 ## Changelog
 
@@ -213,9 +217,6 @@ pub fn refund_packet_token<Ctx>(_ctx: &Ctx, _data: &FungibleTokenPacketData) ->
 }
 ```
 
-## Status
-
-Proposed
 
 ## Consequences
 

docs/architecture/adr-009-chain-endpoint-handle-standardization.md

@@ -0,0 +1,51 @@
+# ADR 009: ChainEndpoint and ChainHandle methods standardization
+
+## Status
+
+Accepted - The PR has been merged in [#2108](https://github.com/informalsystems/ibc-rs/pull/2108)
+
+## Changelog
+* 2022-04-19: Initial Proposal
+
+## Context
+There is a lot of common methods in the `ChainHandle` and `ChainEndpoint` traits, sometimes with minute differences between one another. This document provides a way to remove the duplication of methods for increased maintainability of the codebase, along with a few suggestions to standardize the method signatures. 
+
+## Decision
+
+### Query methods parameters
+There are currently discrepancies between how methods take their arguments. Some take a `request` object, and others take fine-grained arguments that will be used to build a `request` object in the implementation of the method. For example, `query_consensus_state()` takes arguments that will be used to build a request object, whereas `query_consensus_states()` takes a request object directly.
+```rust
+fn query_consensus_state(
+    &self,
+    client_id: ClientId,
+    consensus_height: Height,
+    query_height: Height,
+) -> ...;
+
+fn query_consensus_states(
+    &self,
+    request: QueryConsensusStatesRequest,
+) -> ...;
+```
+
+All methods will be refactored to take a request object as argument.
+
+### Query request objects
+Currently, the type for the request objects is the "raw type", coming from the compiled protobuf files. For each such type, we will create a corresponding domain type, following a similar pattern as elsewhere in the codebase.
+
+This will allow us to modify the domain type as we wish, without requiring a change in the protobuf file (and thus, requiring a change in the communication protocol). A first such change of the domain type we foresee would alter the type to specify a height in queries; however this is out of scope for this particular ADR.
+
+
+## Consequences
+
+### Positive
++ The protobuf types are not exposed directly, which allows `hermes` to work with future non-tendermint chains
++ Increased readability of the codebase; similar methods have a similar format
+
+### Negative
+
+
+## References
+
+* [Option type should be used with non-zero Height #1009](https://github.com/informalsystems/ibc-rs/issues/1009)
+    + The new domain types proposed here, as well as the reduced deduplication of methods, will make fixing this issue easier