Module translation 

Protocol translation framework (DW-100).

The gateway can sit between clients and upstreams that speak different protocols and translate the request and response bodies on the fly. This module defines the shared, protocol-agnostic seam every translator implements: the ProtocolTranslator trait, the TranslatedRequest / TranslatedResponse carrying the converted bytes, the TranslationError enum, and a TranslationRegistry that maps content-type pairs to translators.

Translators

Three translators compile into every build (no cargo features):

• REST <-> gRPC (DW-101, shared): the gRPC-Web transcoding engine in super::grpc_web already translates JSON <-> protobuf; this seam reuses it through the shared trait.
• REST <-> GraphQL (super::translation_graphql): translates a REST JSON body to a GraphQL query using a config-supplied query template, and a GraphQL response back to a REST JSON body.
• SOAP/XML (super::translation_soap): translates SOAP XML envelopes to REST JSON and back, using a minimal hand-rolled XML parser (no external XML crate, to avoid deny.toml review and binary size).

Why a shared trait

Every translator does the same two things on a route: convert the inbound request body to the upstream’s wire format, and convert the upstream’s response body back to the client’s wire format. Factoring that into one trait lets the dataplane dispatch by content-type pair through a single registry, and lets a new translator (e.g. a future Thrift or AMQP bridge) plug in without touching the request path.

Feature gating

This module compiles only when the protocol_translation cargo feature is enabled. The config schema (Translation, TranslationKind, GraphqlTranslation, SoapTranslation) is always present so configs round-trip without the feature; when the feature is off the block is accepted but inert (validation warns, the runtime translation does not run). The SOAP translator is further gated behind the soap feature for binary size.

Structs

TranslatedRequest

The converted request to send upstream: the method, path, headers, and body the translator produced from the inbound request.

TranslatedResponse

The converted response to send the client: the status, headers, and body the translator produced from the upstream response.

TranslationBody

A complete, buffered body used by the translation seam.

TranslationRegistry

A registry of protocol translators keyed by the (in, out) content-type pair. Built at config publish; held behind an Arc by the request path. A route’s translation.kind resolves to one entry here.

Enums

TranslationError

Errors from protocol translation.

Traits

ProtocolTranslator

Translate a request/response pair between two wire protocols.