diff --git a/src/main/java/ru/dragonestia/loadbalancer/model/Bucket.java b/src/main/java/ru/dragonestia/loadbalancer/model/Bucket.java
new file mode 100644
index 0000000..8299228
--- /dev/null
+++ b/src/main/java/ru/dragonestia/loadbalancer/model/Bucket.java
@@ -0,0 +1,26 @@
+package ru.dragonestia.loadbalancer.model;
+
+import lombok.Getter;
+import lombok.RequiredArgsConstructor;
+import ru.dragonestia.loadbalancer.model.type.SlotLimit;
+
+@Getter
+@RequiredArgsConstructor
+public class Bucket {
+
+    private final String identifier;
+    private final String nodeIdentifier;
+    private final SlotLimit slots;
+    private final String payload;
+    private boolean locked = false;
+
+    public void setLocked(boolean value) {
+        locked = value;
+    }
+
+    public boolean isAvailable(int usedSlots, int requiredSlots) {
+        if (locked) return false;
+        if (slots.isUnlimited()) return true;
+        return slots.getSlots() >= usedSlots + requiredSlots;
+    }
+}
diff --git a/src/main/java/ru/dragonestia/loadbalancer/model/Node.java b/src/main/java/ru/dragonestia/loadbalancer/model/Node.java
new file mode 100644
index 0000000..6ecc450
--- /dev/null
+++ b/src/main/java/ru/dragonestia/loadbalancer/model/Node.java
@@ -0,0 +1,6 @@
+package ru.dragonestia.loadbalancer.model;
+
+import lombok.NonNull;
+import ru.dragonestia.loadbalancer.model.type.LoadBalancingMethod;
+
+public record Node(@NonNull String identifier, @NonNull LoadBalancingMethod method) {}
diff --git a/src/main/java/ru/dragonestia/loadbalancer/model/User.java b/src/main/java/ru/dragonestia/loadbalancer/model/User.java
new file mode 100644
index 0000000..3014a28
--- /dev/null
+++ b/src/main/java/ru/dragonestia/loadbalancer/model/User.java
@@ -0,0 +1,5 @@
+package ru.dragonestia.loadbalancer.model;
+
+import lombok.NonNull;
+
+public record User(@NonNull String identifier) {}
diff --git a/src/main/java/ru/dragonestia/loadbalancer/model/type/LoadBalancingMethod.java b/src/main/java/ru/dragonestia/loadbalancer/model/type/LoadBalancingMethod.java
new file mode 100644
index 0000000..682cc28
--- /dev/null
+++ b/src/main/java/ru/dragonestia/loadbalancer/model/type/LoadBalancingMethod.java
@@ -0,0 +1,7 @@
+package ru.dragonestia.loadbalancer.model.type;
+
+public enum LoadBalancingMethod {
+    SEQUENTIAL_FILLING,
+    ROUND_ROBIN,
+    LEAST_PICKED,
+}
diff --git a/src/main/java/ru/dragonestia/loadbalancer/model/type/SlotLimit.java b/src/main/java/ru/dragonestia/loadbalancer/model/type/SlotLimit.java
new file mode 100644
index 0000000..7d6a6a9
--- /dev/null
+++ b/src/main/java/ru/dragonestia/loadbalancer/model/type/SlotLimit.java
@@ -0,0 +1,27 @@
+package ru.dragonestia.loadbalancer.model.type;
+
+import lombok.Getter;
+
+@Getter
+public class SlotLimit {
+
+    private final static int UNLIMITED_VALUE = -1;
+
+    private final int slots;
+
+    private SlotLimit(int slots) {
+        this.slots = slots;
+    }
+
+    public static SlotLimit unlimited() {
+        return new SlotLimit(UNLIMITED_VALUE);
+    }
+
+    public static SlotLimit of(int slots) {
+        return new SlotLimit(slots);
+    }
+
+    public boolean isUnlimited() {
+        return slots == UNLIMITED_VALUE;
+    }
+}
diff --git a/src/main/java/ru/dragonestia/loadbalancer/service/BucketService.java b/src/main/java/ru/dragonestia/loadbalancer/service/BucketService.java
new file mode 100644
index 0000000..20926c7
--- /dev/null
+++ b/src/main/java/ru/dragonestia/loadbalancer/service/BucketService.java
@@ -0,0 +1,22 @@
+package ru.dragonestia.loadbalancer.service;
+
+import ru.dragonestia.loadbalancer.model.Bucket;
+import ru.dragonestia.loadbalancer.model.Node;
+import ru.dragonestia.loadbalancer.model.User;
+
+import java.util.List;
+
+public interface BucketService {
+
+    void createBucket(Node node, Bucket lobby);
+
+    void removeBucket(Node node, Bucket lobby);
+
+    List<Bucket> allBuckets(Node node);
+
+    int countAvailableBuckets(Node node);
+
+    Bucket pickAvailableBucket(Node node, List<User> users);
+
+    void freeBucket(Node node, List<User> users);
+}
diff --git a/src/main/java/ru/dragonestia/loadbalancer/service/NodeService.java b/src/main/java/ru/dragonestia/loadbalancer/service/NodeService.java
new file mode 100644
index 0000000..db04204
--- /dev/null
+++ b/src/main/java/ru/dragonestia/loadbalancer/service/NodeService.java
@@ -0,0 +1,14 @@
+package ru.dragonestia.loadbalancer.service;
+
+import ru.dragonestia.loadbalancer.model.Node;
+
+import java.util.List;
+
+public interface NodeService {
+
+    void createNode(Node node);
+
+    void removeNode(Node node);
+
+    List<Node> allNodes();
+}
diff --git a/src/main/java/ru/dragonestia/loadbalancer/service/UserService.java b/src/main/java/ru/dragonestia/loadbalancer/service/UserService.java
new file mode 100644
index 0000000..e2b748e
--- /dev/null
+++ b/src/main/java/ru/dragonestia/loadbalancer/service/UserService.java
@@ -0,0 +1,11 @@
+package ru.dragonestia.loadbalancer.service;
+
+import ru.dragonestia.loadbalancer.model.Bucket;
+import ru.dragonestia.loadbalancer.model.User;
+
+import java.util.List;
+
+public interface UserService {
+
+    List<Bucket> getUserBuckets(User user);
+}