feat!: Updating to newest proto to align with 1.0 Draft specifications by ehsavoie · Pull Request #484 · a2aproject/a2a-java

ehsavoie · Nov 24, 2025

[Feat]: Use protobuf as the serialization mechanism

Fixes #<issue_number_goes_here> 🦕

client/transport/rest/src/main/java/io/a2a/client/transport/rest/RestTransport.java

spec-grpc/pom.xml

fjuma · Nov 24, 2025

It might be good to add some info in the PR description or commit message to indicate the commit hash that was used when copying the .proto file to this repo.

- a2a.proto from commit b0784199543eebf2e95dcb02e9336cb213923506 - use "Dskip.protobuf.generate=false" to generate source code from a2a.proto Signed-off-by: Emmanuel Hugonnet <ehugonne@redhat.com>

The spec-grpc classes are ugly, and we can't let users use them. When using MapStruct an effort has been made to not use 'manual' conversion (i.e. a 'default' implementation of the Mapper interface methods). When automatic conversion happens, when the spec-grpc and spec classes differ a compile error will be raised. Which in turn helps us keep our manually generated spec classes in sync with the spec-grpc ones.

ehsavoie · Dec 2, 2025

/gemini review

gemini-code-assist

Code Review

This pull request introduces a significant and valuable refactoring to align the codebase with the latest protobuf specification. Key changes include the simplification of the AgentCard data model by replacing url, preferredTransport, and additionalInterfaces with a unified supportedInterfaces list. This greatly improves clarity. Another major improvement is the refactoring of the JSON-RPC transport to use protobuf data models internally, which brings consistency across all transport implementations (gRPC, REST, and JSON-RPC) and reduces code duplication. The build process for protobuf generation has also been modernized. Overall, these changes enhance maintainability and consistency. I have a couple of suggestions to further improve readability by using modern Java language features.

reference/jsonrpc/src/main/java/io/a2a/server/apps/quarkus/A2AServerRoutes.java

jmesnil · Dec 2, 2025

client/transport/jsonrpc/src/main/java/io/a2a/client/transport/jsonrpc/JSONRPCTransport.java


    public JSONRPCTransport(AgentCard agentCard) {
-        this(null, agentCard, agentCard.url(), null);
+        this(null, agentCard, agentCard.supportedInterfaces().get(0).url(), null);


can supportedInterfaces() be empty?

According to https://a2a-protocol.org/latest/definitions/, it can be empty:

message AgentCard { [...] // Ordered list of supported interfaces. First entry is preferred. repeated AgentInterface supported_interfaces = 19; }

repeated means 0 or more

@ehsavoie I guess if null/empty we should throw some kind of exception

client/transport/jsonrpc/src/main/java/io/a2a/client/transport/jsonrpc/JSONRPCTransport.java

client/transport/jsonrpc/src/test/java/io/a2a/client/transport/jsonrpc/JsonMessages.java

jmesnil · Dec 2, 2025

spec-grpc/src/main/java/io/a2a/grpc/mapper/DataPartMapper.java

+    /**
+     * Converts domain DataPart to proto DataPart.
+     * Uses CommonFieldMapper for Map → Struct conversion.
+     * Metadata is ignored (not part of proto definition).


does that mean that there can't be metadata attached to a data part?

@kabir maybe you can answer there

So it seems that the DataPartmessage is protobuf does not have metadata according to https://github.com/a2aproject/A2A/blob/b6ef9eec558c877fb69024df090a8bb63c542a1c/specification/grpc/a2a.proto#L228C9-L228C17.
The spec does not mention them either: https://a2a-protocol.org/latest/specification/#418-datapart

So is this something that was present in a previous spec but is no longer relevant?
Now it seems that metadata can only be attached to artifacts and not to their parts.

@ehsavoie @jmesnil Yeah, I remember seeing some issues and discussions about metadata being present in the other protocols but not gRPC.
Maybe we can open a follow-up issue to clean that up? If you agree, please link the issue here so we track it (and add the P0 label)

That'd make sense to me to be able to attach metadata to parts (eg for a file, it would allow to put its creation/update date which would not make sense if it was at the artifact level)

I created #497 to track this, and made it a P0 issue in https://github.com/orgs/a2aproject/projects/4. I don't think this needs to block the merge

spec-grpc/pom.xml

spec/src/main/java/io/a2a/spec/InvalidAgentResponseError.java

spec/src/main/java/io/a2a/spec/Message.java

* Update AgentCard and transport discovery. Removing the deprecated fields for now * Added ProtoUtils.FromProto.agentCard() method to convert io.a2a.grpc.AgentCard to io.a2a.spec.AgentCard. * Fixing the AGENT_CARD test constant to use the correct protobuf JSON format * Updated ProtoUtils.ToProto and ProtoUtils.FromProto * Update streaming test JSON to protobuf format * Update SSE listener to use proto JSON instead of Jackson * Updating and renaming all JSON-RPC method names to the new standard. * Fixing NullSpecify * Fixing Making unmarshalResponse type-safe * Fixing cloud example * Fixing streaming tests with http client * Fixing issues with configId * Fixing issues with missing id in jsonrpc requests. * Add comprehensive tests for JSONRPCUtils * Update protocol version to 1.0.0 * Unifying spec/grpc name clashes Signed-off-by: Emmanuel Hugonnet <ehugonne@redhat.com>

a2aproject#484) [Feat]: Use protobuf as the serialization mechanism Fixes #<issue_number_goes_here> 🦕 --------- Signed-off-by: Emmanuel Hugonnet <ehugonne@redhat.com> Co-authored-by: Kabir Khan <kkhan@redhat.com>

ehsavoie requested review from fjuma and kabir November 24, 2025 14:41

ehsavoie force-pushed the updating_payloads branch 2 times, most recently from fb75b4d to 729bc88 Compare November 24, 2025 14:51

kabir reviewed Nov 24, 2025

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client/transport/rest/src/main/java/io/a2a/client/transport/rest/RestTransport.java Outdated Show resolved Hide resolved

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ehsavoie force-pushed the updating_payloads branch 3 times, most recently from 431152c to e879e8c Compare November 24, 2025 15:54

ehsavoie and others added 3 commits November 25, 2025 09:51

Updating to newest proto

dcd8361

- a2a.proto from commit b0784199543eebf2e95dcb02e9336cb213923506 - use "Dskip.protobuf.generate=false" to generate source code from a2a.proto Signed-off-by: Emmanuel Hugonnet <ehugonne@redhat.com>

Remove runtime dependencies on MapStruct

7640e16

ehsavoie force-pushed the updating_payloads branch 3 times, most recently from cd1eaf6 to 6a2441f Compare December 1, 2025 21:01

ehsavoie mentioned this pull request Dec 2, 2025

[Bug]: Payload of resource is not compliant with 1.0 wrapped objects (using removed kind field instead) #491

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reference/jsonrpc/src/main/java/io/a2a/server/apps/quarkus/A2AServerRoutes.java Show resolved Hide resolved

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jmesnil reviewed Dec 2, 2025

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jmesnil mentioned this pull request Dec 2, 2025

[Feat]: Remove Jackson annotation and use protobuf as the serialization mechanism #487

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ehsavoie changed the title ~~Updating to newest proto~~ feat: Updating to newest proto to align with 1.0Draft specifications Dec 2, 2025

ehsavoie changed the title ~~feat: Updating to newest proto to align with 1.0Draft specifications~~ feat!: Updating to newest proto to align with 1.0Draft specifications Dec 2, 2025

kabir mentioned this pull request Dec 2, 2025

[Chore]: Remove metadata fields from user API classes where it no longer exists in the spec protobuf #497

Closed

jmesnil mentioned this pull request Dec 2, 2025

[Feat]: Standardize on builder() method for a2a API #498

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1 task

kabir mentioned this pull request Dec 2, 2025

[Chore]: Remove Jackson mapping annotations from spec/ classes #499

Closed

ehsavoie force-pushed the updating_payloads branch 5 times, most recently from dee90e7 to e81d66f Compare December 3, 2025 08:26

ehsavoie marked this pull request as ready for review December 3, 2025 09:35

ehsavoie force-pushed the updating_payloads branch from e81d66f to 48aa033 Compare December 3, 2025 12:13

Minor fixes

6003c75

ehsavoie changed the title ~~feat!: Updating to newest proto to align with 1.0Draft specifications~~ feat!: Updating to newest proto to align with 1.0 Draft specifications Dec 3, 2025

kabir merged commit cb084ec into a2aproject:main Dec 3, 2025
11 checks passed

jmesnil mentioned this pull request Dec 9, 2025

refactor: Complete migration from Jackson to Gson across codebase #514

Merged

ehsavoie deleted the updating_payloads branch December 11, 2025 08:23

jmesnil added this to the 1.0.0 milestone Dec 11, 2025

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ehsavoie commented Nov 24, 2025 •

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