Class GrpcWeb

java.lang.Object

com.codename1.io.grpc.GrpcWeb

public final class GrpcWeb
extends Object

High-level gRPC-Web invoker used by generated @GrpcClient implementations. Handles HTTP-level transport, gRPC-Web payload framing (flags + length + payload), and trailer parsing (grpc-status, grpc-message).

Wire details (from the upstream gRPC-Web spec):

• URL: <baseUrl>/<service-fqn>/<method-name> (no trailing slash).
• HTTP method: POST.
• Request Content-Type: application/grpc-web+proto.
• Request headers: X-Grpc-Web: 1, X-User-Agent: grpc-web-cn1/<ver>.
• Request body: 0x00 <length-be32> <payload> -- one data frame.
• Response body: zero or more data frames (flags low bit 0) followed by one trailer frame (flags high bit 0x80) carrying grpc-status:<n>\r\ngrpc-message:<text>\r\n.

All methods are static. Generated impls call invokeUnary(String, String, String, String, Req, ProtoCodec, ProtoCodec, OnComplete) and receive the parsed GrpcResponse on the supplied callback.

Field Summary

Fields

Modifier and Type	Field	Description
static final String	CONTENT_TYPE	Content type for binary gRPC-Web payloads.
static final int	FLAG_TRAILER	gRPC-Web frame flag set in the trailer frame's first byte.

Method Summary

Modifier and Type	Method	Description
static <Resp> GrpcResponse<Resp>	decode(byte[] response, int httpCode, ProtoCodec<Resp> respCodec)	Decodes a complete gRPC-Web response body.
static <T> byte[]	frame(T request, ProtoCodec<T> codec)	Wraps a serialised request message in a single gRPC-Web data frame: [0x00][length-be32][payload].
static <Req,Resp> void	invokeUnary(String baseUrl, String service, String method, String bearerToken, Req request, ProtoCodec<Req> reqCodec, ProtoCodec<Resp> respCodec, OnComplete<GrpcResponse<Resp>> callback)	Sends a unary gRPC-Web request and invokes callback with the decoded response (or a transport-failure marker).

Methods inherited from class Object

clone, equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Details

CONTENT_TYPE

public static final String CONTENT_TYPE

Content type for binary gRPC-Web payloads. The text variant (application/grpc-web-text, base64-encoded) is not supported -- modern Envoy/gRPC-Web proxies all speak binary.

See Also:

• Constant Field Values

FLAG_TRAILER

public static final int FLAG_TRAILER

gRPC-Web frame flag set in the trailer frame's first byte.

See Also:

• Constant Field Values

Method Details

invokeUnary

public static <Req,Resp> void invokeUnary(String baseUrl,
 String service,
 String method,
 String bearerToken,
 Req request,
 ProtoCodec<Req> reqCodec,
 ProtoCodec<Resp> respCodec,
 OnComplete<GrpcResponse<Resp>> callback)

Sends a unary gRPC-Web request and invokes callback with the decoded response (or a transport-failure marker).

The baseUrl should not include a trailing slash; the service is the fully qualified service path (e.g. helloworld.Greeter) and method is the gRPC method name (e.g. SayHello). The resulting URL is <baseUrl>/<service>/<method>.

frame

public static <T> byte[] frame(T request,
 ProtoCodec<T> codec)
                        throws IOException

Wraps a serialised request message in a single gRPC-Web data frame: [0x00][length-be32][payload]. Public so unit tests can verify framing independently of the network path.

Throws:

IOException

decode

public static <Resp> GrpcResponse<Resp> decode(byte[] response,
 int httpCode,
 ProtoCodec<Resp> respCodec)

Decodes a complete gRPC-Web response body. Iterates frames, concatenates data payloads, and parses the trailer frame for grpc-status / grpc-message. Public so callers can replay canned responses in unit tests.