gRPC client in Java

mkdir machrpc-java && cd machrpc-java

mkdir -p src/main/proto
curl -o src/main/proto/machrpc.proto https://raw.githubusercontent.com/machbase/neo-grpc/main/proto/machrpc.proto

option java_package = "com.machbase.neo.rpc";

<dependencies>
    <dependency>
        <groupId>io.grpc</groupId>
        <artifactId>grpc-netty-shaded</artifactId>
        <version>1.52.1</version>
        <scope>runtime</scope>
    </dependency>
    <dependency>
        <groupId>io.grpc</groupId>
        <artifactId>grpc-protobuf</artifactId>
        <version>1.52.1</version>
    </dependency>
    <dependency>
        <groupId>io.grpc</groupId>
        <artifactId>grpc-stub</artifactId>
        <version>1.52.1</version>
    </dependency>
    <dependency> <!-- necessary for Java 9+ -->
        <groupId>org.apache.tomcat</groupId>
        <artifactId>annotations-api</artifactId>
        <version>6.0.53</version>
        <scope>provided</scope>
    </dependency>
</dependencies>

ManagedChannel channel = Grpc.newChannelBuilder("127.0.0.1:5655", InsecureChannelCredentials.create()).build();
MachbaseBlockingStub stub = MachbaseGrpc.newBlockingStub(channel);
try {
    // do job
} finally {
    channel.shutdown();
}

QueryRequest.Builder builder = Machrpc.QueryRequest.newBuilder();
builder.setSql("select * from example order by time desc limit ?");
builder.addParams(Any.pack(Int32Value.of(10)));

QueryRequest req = builder.build();
QueryResponse rsp = stub.query(req);

ColumnsResponse cols = stub.columns(rsp.getRowsHandle());
ArrayList<String> headers = new ArrayList<String>();
headers.add("RowNum");
for (int i = 0; i < cols.getColumnsCount(); i++) {
    Column c = cols.getColumns(i);
    headers.add(c.getName() + "(" + c.getType() + ")");
}

int nrow = 0;
RowsFetchResponse fetch = null;
while (true) {
    fetch = stub.rowsFetch(rsp.getRowsHandle());
    if (fetch == null || fetch.getHasNoRows()) {
        break;
    }
    nrow++;

    ArrayList<String> line = new ArrayList<String>();
    line.add(Integer.toString(nrow, 10));
    List<Any> row = fetch.getValuesList();
    for (Any anyv : row) {
        line.add(convpb(anyv));
    }
    System.out.println(String.join("    ", line));
}

static DateTimeFormatter sdf = DateTimeFormatter.ofPattern("yyyy.MM.dd HH:mm:ss.SSS");

static String convpb(Any any) {
    try {
        switch (any.getTypeUrl()) {
            case "type.googleapis.com/google.protobuf.StringValue": {
                StringValue v = any.unpack(StringValue.class);
                return v.getValue();
            }
            case "type.googleapis.com/google.protobuf.Timestamp": {
                Timestamp v = any.unpack(Timestamp.class);
                LocalDateTime ldt = java.time.LocalDateTime.ofEpochSecond(v.getSeconds(), v.getNanos(), ZoneOffset.UTC);
                return ldt.format(sdf);
            }
            case "type.googleapis.com/google.protobuf.DoubleValue": {
                DoubleValue v = any.unpack(DoubleValue.class);
                return Double.toString(v.getValue());
            }
            default:
                return "unsupproted " + any.getTypeUrl();
        }
    } catch (Exception e) {
        return "error " + e.getMessage();
    }
}