Redis Lettuce: Sending Custom Commands

Question

I'm using tile38.com with lettuce.io on Java. I'm trying to send a custom NEARBY fleet FENCE POINT 33.462 -112.268 6000 command as per the docs enter link description here, but I don't know how to.

I've been using the CommandType in Lettuce, but I can't find a way of sending a NEARBY. Does someone know how I could do it?

Thanks

Answer 1

You have multiple options to send custom commands:

Custom Commands

With custom commands, you basically define a type implementing the ProtocolKeyword interface which helps you as a single point of reference for all your keywords involved in your commands. You can use synchronous, asynchronous, or reactive APIs to invoke the command:

enum MyKeywords implements ProtocolKeyword {
    NEARBY, FENCE, POINT;

    private final byte name[];

    MyKeywords() {
        // cache the bytes for the command name. Reduces memory and cpu pressure when using commands.
        name = name().getBytes();
    }

    @Override
    public byte[] getBytes() {
        return name;
    }
}

CommandArgs<String, String> args = new CommandArgs<>(codec).addKey(key).add(MyKeywords.FENCE).add("POINT").add(lon).add(lat)
List<Object> response = connection.sync().dispatch(MyCommands.FENCE, new NestedMultiOutput<>(codec), args);

Command Interfaces

Command interfaces provide you a higher level of abstraction by declaring command methods on a Java interface. It's declared by a method signature that matches your command to invoke and less verbose than custom commands:

interface Tile38 {

  @Command("NEARBY ?0 FENCE POINT ?1 ?2")
  List<Object> nearByFence(String key, double lon, double lat);
}

RedisClient client = …
RedisCommandFactory factory = new RedisCommandFactory(client.connect());
Tile38 commands = factory.getCommands(Tile38.class);

Please note that I'm not familiar with Tile38 command responses. Therefore, all code uses List<Object> which is the most generic return type.

See also

• Lettuce Documentation: Custom Commands.
• Lettuce Documentation: Command Interfaces.
• Lettuce JavaDoc: BaseRedisCommands.dispatch(…).
• Lettuce JavaDoc: CommandOutput.