diff --git a/src/main/kotlin/chatserver/MessageResult.kt b/src/main/kotlin/chatserver/MessageResult.kt
new file mode 100644
index 0000000..56f4c5e
--- /dev/null
+++ b/src/main/kotlin/chatserver/MessageResult.kt
@@ -0,0 +1,16 @@
+package chatserver
+
+import chatserver.ReadChatRepository.ReadResult
+
+data class MessageResult(
+    override val isOk: Boolean,
+    override val item: List<String>,
+    override val error: Exception?,
+) :
+    ReadResult<List<String>> {
+    companion object {
+        fun ok(item: List<String>): MessageResult = MessageResult(true, item, null)
+
+        fun fail(e: Exception? = null): MessageResult = MessageResult(false, emptyList(), e)
+    }
+}
diff --git a/src/main/kotlin/chatserver/PresenceResult.kt b/src/main/kotlin/chatserver/PresenceResult.kt
new file mode 100644
index 0000000..048bf07
--- /dev/null
+++ b/src/main/kotlin/chatserver/PresenceResult.kt
@@ -0,0 +1,16 @@
+package chatserver
+
+import chatserver.ReadChatRepository.ReadResult
+
+data class PresenceResult(
+    override val isOk: Boolean,
+    override val item: Map<String, Boolean>,
+    override val error: Exception?,
+) :
+    ReadResult<Map<String, Boolean>> {
+    companion object {
+        fun ok(item: Map<String, Boolean>): PresenceResult = PresenceResult(true, item, null)
+
+        fun fail(e: Exception? = null): PresenceResult = PresenceResult(false, emptyMap(), e)
+    }
+}
diff --git a/src/main/kotlin/chatserver/ProfileResult.kt b/src/main/kotlin/chatserver/ProfileResult.kt
new file mode 100644
index 0000000..2dca804
--- /dev/null
+++ b/src/main/kotlin/chatserver/ProfileResult.kt
@@ -0,0 +1,16 @@
+package chatserver
+
+import chatserver.ReadChatRepository.ReadResult
+
+data class ProfileResult(
+    override val isOk: Boolean,
+    override val item: Map<String, String>,
+    override val error: Exception?,
+) :
+    ReadResult<Map<String, String>> {
+    companion object {
+        fun ok(item: Map<String, String>): ProfileResult = ProfileResult(true, item, null)
+
+        fun fail(e: Exception? = null): ProfileResult = ProfileResult(false, emptyMap(), e)
+    }
+}
diff --git a/src/main/kotlin/chatserver/ReadChatRepository.kt b/src/main/kotlin/chatserver/ReadChatRepository.kt
new file mode 100644
index 0000000..935ba4b
--- /dev/null
+++ b/src/main/kotlin/chatserver/ReadChatRepository.kt
@@ -0,0 +1,15 @@
+package chatserver
+
+import kotlinx.coroutines.flow.Flow
+
+interface ReadChatRepository<T : ReadChatRepository.ReadResult<*>> {
+    fun latest(): T
+
+    fun observe(): Flow<T>
+
+    interface ReadResult<T> {
+        val isOk: Boolean
+        val item: T
+        val error: Exception?
+    }
+}
diff --git a/src/main/kotlin/chatserver/SubscribeChatRepository.kt b/src/main/kotlin/chatserver/SubscribeChatRepository.kt
new file mode 100644
index 0000000..96c8cb3
--- /dev/null
+++ b/src/main/kotlin/chatserver/SubscribeChatRepository.kt
@@ -0,0 +1,7 @@
+package chatserver
+
+interface SubscribeChatRepository {
+    fun subscribe()
+
+    fun unsubscribe()
+}
diff --git a/src/main/kotlin/chatserver/WriteChatRepository.kt b/src/main/kotlin/chatserver/WriteChatRepository.kt
new file mode 100644
index 0000000..eb4c523
--- /dev/null
+++ b/src/main/kotlin/chatserver/WriteChatRepository.kt
@@ -0,0 +1,5 @@
+package chatserver
+
+interface WriteChatRepository<T> {
+    fun write(item: T)
+}