Add protocol dto classes #5

src/main/java/com/github/nginate/kafka/protocol/ApiKeys.java

@@ -6,25 +6,17 @@
 @Getter
 @AllArgsConstructor
 public enum ApiKeys {
-    PRODUCE(0, "produce"),
-    FETCH(1, "fetch"),
-    LIST_OFFSETS(2, "list_offsets"),
-    METADATA(3, "metadata"),
-    LEADER_AND_ISR(4, "leader_and_isr"),
-    STOP_REPLICA(5, "stop_replica"),
-    OFFSET_COMMIT(8, "offset_commit"),
-    OFFSET_FETCH(9, "offset_fetch"),
-    CONSUMER_METADATA(10, "consumer_metadata"),
-    JOIN_GROUP(11, "join_group"),
-    HEARTBEAT(12, "heartbeat");
+    PRODUCE(0),
+    FETCH(1),
+    LIST_OFFSETS(2),
+    METADATA(3),
+    LEADER_AND_ISR(4),
+    STOP_REPLICA(5),
+    OFFSET_COMMIT(8),
+    OFFSET_FETCH(9),
+    CONSUMER_METADATA(10),
+    JOIN_GROUP(11),
+    HEARTBEAT(12);
 
-    /**
-     * the perminant and immutable id of an API--this can't change ever
-     */
     private final int id;
-    /**
-     * an english description of the api--this is for debugging and can change
-     */
-    private final String name;
-
 }

src/main/java/com/github/nginate/kafka/protocol/messages/Message.java

@@ -0,0 +1,12 @@
+package com.github.nginate.kafka.protocol.messages;
+
+import com.github.nginate.kafka.protocol.types.Type;
+import lombok.Data;
+
+import static com.github.nginate.kafka.protocol.types.TypeName.INT8;
+
+@Data
+public abstract class Message {
+    @Type(INT8)
+    private int size;
+}

src/main/java/com/github/nginate/kafka/protocol/messages/Request.java

@@ -0,0 +1,22 @@
+package com.github.nginate.kafka.protocol.messages;
+
+import com.github.nginate.kafka.protocol.types.Type;
+import lombok.Data;
+import lombok.EqualsAndHashCode;
+
+import static com.github.nginate.kafka.protocol.types.TypeName.INT16;
+import static com.github.nginate.kafka.protocol.types.TypeName.INT32;
+import static com.github.nginate.kafka.protocol.types.TypeName.STRING;
+
+@Data
+@EqualsAndHashCode(callSuper = true)
+public abstract class Request extends Message{
+    @Type(INT16)
+    private int apiKey;
+    @Type(INT16)
+    private int apiVersion;
+    @Type(INT32)
+    private int correlationId;
+    @Type(STRING)
+    private String clientId;
+}

src/main/java/com/github/nginate/kafka/protocol/messages/Response.java

@@ -0,0 +1,15 @@
+package com.github.nginate.kafka.protocol.messages;
+
+import com.github.nginate.kafka.protocol.types.Type;
+import com.github.nginate.kafka.protocol.types.TypeName;
+import lombok.Data;
+import lombok.EqualsAndHashCode;
+
+import static com.github.nginate.kafka.protocol.types.TypeName.*;
+
+@Data
+@EqualsAndHashCode(callSuper = true)
+public abstract class Response extends Message {
+    @Type(INT32)
+    private int correlationId;
+}

src/main/java/com/github/nginate/kafka/protocol/types/Type.java

@@ -0,0 +1,11 @@
+package com.github.nginate.kafka.protocol.types;
+
+import java.lang.annotation.*;
+
+@Target(ElementType.FIELD)
+@Retention(RetentionPolicy.RUNTIME)
+@Documented
+public @interface Type {
+    TypeName value();
+    boolean repeatable() default false;
+}

src/main/java/com/github/nginate/kafka/protocol/types/TypeName.java

@@ -0,0 +1,28 @@
+package com.github.nginate.kafka.protocol.types;
+
+public enum TypeName {
+    /**
+     *  Signed integer (1 byte) with the given precision (in bits) stored in big endian order.
+     */
+    INT8,
+    /**
+     *  Signed integer (2 bytes) with the given precision (in bits) stored in big endian order.
+     */
+    INT16,
+    /**
+     *  Signed integer (4 bytes) with the given precision (in bits) stored in big endian order.
+     */
+    INT32,
+    /**
+     *  Signed integer (8 bytes) with the given precision (in bits) stored in big endian order.
+     */
+    INT64,
+    /**
+     * Consist of a signed int16 giving a length N followed by N bytes of content. A length of -1 indicates null.
+     */
+    STRING,
+    /**
+     * Consist of a signed int32 giving a length N followed by N bytes of content. A length of -1 indicates null.
+     */
+    BYTES
+}