diff --git a/gradle.properties b/gradle.properties
index 8e4fd10..0870c91 100644
--- a/gradle.properties
+++ b/gradle.properties
@@ -4,7 +4,7 @@ kotlin.code.style=official
 specifyKotlinAsDependency=false
 
 projectGroup=ru.dbotthepony.kommons
-projectVersion=2.1.1
+projectVersion=2.1.2
 
 guavaDepVersion=33.0.0
 gsonDepVersion=2.8.9
diff --git a/src/main/kotlin/ru/dbotthepony/kommons/io/InputStreamUtils.kt b/src/main/kotlin/ru/dbotthepony/kommons/io/InputStreamUtils.kt
index 666545f..54ebae7 100644
--- a/src/main/kotlin/ru/dbotthepony/kommons/io/InputStreamUtils.kt
+++ b/src/main/kotlin/ru/dbotthepony/kommons/io/InputStreamUtils.kt
@@ -1,7 +1,9 @@
 package ru.dbotthepony.kommons.io
 
 import it.unimi.dsi.fastutil.bytes.ByteArrayList
+import it.unimi.dsi.fastutil.objects.Object2ObjectOpenHashMap
 import ru.dbotthepony.kommons.math.Decimal
+import ru.dbotthepony.kommons.util.KOptional
 import java.io.DataInput
 import java.io.EOFException
 import java.io.IOException
@@ -218,4 +220,36 @@ fun InputStream.readDecimal(): Decimal {
 	val bytes = ByteArray(size)
 	read(bytes)
 	return Decimal.fromByteArray(bytes)
-}
\ No newline at end of file
+}
+
+fun <S : InputStream, M : MutableMap<K, V>, K, V> S.readMap(keyReader: S.() -> K, valueReader: S.() -> V, constructor: (Int) -> M): M {
+	val size = readVarInt()
+	require(size >= 0) { "Negative payload size: $size" }
+	val map = constructor(size)
+
+	for (i in 0 until size) {
+		map[keyReader(this)] = valueReader(this)
+	}
+
+	return map
+}
+
+fun <S : InputStream, K, V> S.readMap(keyReader: S.() -> K, valueReader: S.() -> V): Object2ObjectOpenHashMap<K, V> {
+	return readMap(keyReader, valueReader, ::Object2ObjectOpenHashMap)
+}
+
+fun <S : InputStream, V> S.readKOptional(reader: S.() -> V): KOptional<V> {
+	if (read() == 0) {
+		return KOptional.empty()
+	} else {
+		return KOptional(reader(this))
+	}
+}
+
+fun <S : InputStream, V : Any> S.readOptional(reader: S.() -> V): Optional<V> {
+	if (read() == 0) {
+		return Optional.empty()
+	} else {
+		return Optional.of(reader(this))
+	}
+}
diff --git a/src/main/kotlin/ru/dbotthepony/kommons/io/OutputStreamUtils.kt b/src/main/kotlin/ru/dbotthepony/kommons/io/OutputStreamUtils.kt
index 75df993..1b7eb66 100644
--- a/src/main/kotlin/ru/dbotthepony/kommons/io/OutputStreamUtils.kt
+++ b/src/main/kotlin/ru/dbotthepony/kommons/io/OutputStreamUtils.kt
@@ -19,6 +19,7 @@ import ru.dbotthepony.kommons.util.IStruct4f
 import ru.dbotthepony.kommons.util.IStruct4i
 import ru.dbotthepony.kommons.util.IStruct4l
 import ru.dbotthepony.kommons.util.IStruct4s
+import ru.dbotthepony.kommons.util.KOptional
 import java.io.DataOutput
 import java.io.OutputStream
 import java.io.RandomAccessFile
@@ -257,3 +258,28 @@ fun OutputStream.writeDecimal(value: Decimal) {
 	writeVarInt(bytes.size)
 	write(bytes)
 }
+
+fun <S : OutputStream, K, V> S.writeMap(map: Map<K, V>, keyWriter: S.(K) -> Unit, valueWriter: S.(V) -> Unit) {
+	writeVarInt(map.size)
+
+	for ((k, v) in map.entries) {
+		keyWriter(this, k)
+		valueWriter(this, v)
+	}
+}
+
+fun <S : OutputStream, V> S.writeKOptional(value: KOptional<V>, writer: S.(V) -> Unit) {
+	write(if (value.isPresent) 1 else 0)
+
+	if (value.isPresent) {
+		writer(this, value.value)
+	}
+}
+
+fun <S : OutputStream, V : Any> S.writeOptional(value: Optional<V>, writer: S.(V) -> Unit) {
+	write(if (value.isPresent) 1 else 0)
+
+	if (value.isPresent) {
+		writer(this, value.get())
+	}
+}
diff --git a/src/main/kotlin/ru/dbotthepony/kommons/io/StreamCodec.kt b/src/main/kotlin/ru/dbotthepony/kommons/io/StreamCodec.kt
index bddf2e9..210a1e7 100644
--- a/src/main/kotlin/ru/dbotthepony/kommons/io/StreamCodec.kt
+++ b/src/main/kotlin/ru/dbotthepony/kommons/io/StreamCodec.kt
@@ -150,6 +150,34 @@ interface StreamCodec<V> {
 			}
 		}
 	}
+
+	class KOptional<V>(val codec: StreamCodec<V>) : StreamCodec<ru.dbotthepony.kommons.util.KOptional<V>> {
+		override fun read(stream: DataInputStream): ru.dbotthepony.kommons.util.KOptional<V> {
+			return stream.readKOptional(codec::read)
+		}
+
+		override fun write(stream: DataOutputStream, value: ru.dbotthepony.kommons.util.KOptional<V>) {
+			stream.writeKOptional(value, codec::write)
+		}
+
+		override fun copy(value: ru.dbotthepony.kommons.util.KOptional<V>): ru.dbotthepony.kommons.util.KOptional<V> {
+			return value.map(codec::copy)
+		}
+	}
+
+	class Optional<V : Any>(val codec: StreamCodec<V>) : StreamCodec<java.util.Optional<V>> {
+		override fun read(stream: DataInputStream): java.util.Optional<V> {
+			return stream.readOptional(codec::read)
+		}
+
+		override fun write(stream: DataOutputStream, value: java.util.Optional<V>) {
+			stream.writeOptional(value, codec::write)
+		}
+
+		override fun copy(value: java.util.Optional<V>): java.util.Optional<V> {
+			return value.map(codec::copy)
+		}
+	}
 }
 
 val NullValueCodec = StreamCodec.Impl({ _ -> null }, { _, _ -> })
@@ -168,5 +196,35 @@ val VarLongValueCodec = StreamCodec.Impl(DataInputStream::readSignedVarLong, Dat
 val BinaryStringCodec = StreamCodec.Impl(DataInputStream::readBinaryString, DataOutputStream::writeBinaryString)
 val DecimalValueCodec = StreamCodec.Impl(DataInputStream::readDecimal, DataOutputStream::writeDecimal)
 
+val OptionalBooleanValueCodec = StreamCodec.Optional(BooleanValueCodec)
+val OptionalByteValueCodec = StreamCodec.Optional(ByteValueCodec)
+val OptionalShortValueCodec = StreamCodec.Optional(ShortValueCodec)
+val OptionalCharValueCodec = StreamCodec.Optional(CharValueCodec)
+val OptionalIntValueCodec = StreamCodec.Optional(IntValueCodec)
+val OptionalLongValueCodec = StreamCodec.Optional(LongValueCodec)
+val OptionalFloatValueCodec = StreamCodec.Optional(FloatValueCodec)
+val OptionalDoubleValueCodec = StreamCodec.Optional(DoubleValueCodec)
+val OptionalBigDecimalValueCodec = StreamCodec.Optional(BigDecimalValueCodec)
+val OptionalUUIDValueCodec = StreamCodec.Optional(UUIDValueCodec)
+val OptionalVarIntValueCodec = StreamCodec.Optional(VarIntValueCodec)
+val OptionalVarLongValueCodec = StreamCodec.Optional(VarLongValueCodec)
+val OptionalBinaryStringCodec = StreamCodec.Optional(BinaryStringCodec)
+val OptionalDecimalValueCodec = StreamCodec.Optional(DecimalValueCodec)
+
+val KOptionalBooleanValueCodec = StreamCodec.KOptional(BooleanValueCodec)
+val KOptionalByteValueCodec = StreamCodec.KOptional(ByteValueCodec)
+val KOptionalShortValueCodec = StreamCodec.KOptional(ShortValueCodec)
+val KOptionalCharValueCodec = StreamCodec.KOptional(CharValueCodec)
+val KOptionalIntValueCodec = StreamCodec.KOptional(IntValueCodec)
+val KOptionalLongValueCodec = StreamCodec.KOptional(LongValueCodec)
+val KOptionalFloatValueCodec = StreamCodec.KOptional(FloatValueCodec)
+val KOptionalDoubleValueCodec = StreamCodec.KOptional(DoubleValueCodec)
+val KOptionalBigDecimalValueCodec = StreamCodec.KOptional(BigDecimalValueCodec)
+val KOptionalUUIDValueCodec = StreamCodec.KOptional(UUIDValueCodec)
+val KOptionalVarIntValueCodec = StreamCodec.KOptional(VarIntValueCodec)
+val KOptionalVarLongValueCodec = StreamCodec.KOptional(VarLongValueCodec)
+val KOptionalBinaryStringCodec = StreamCodec.KOptional(BinaryStringCodec)
+val KOptionalDecimalValueCodec = StreamCodec.KOptional(DecimalValueCodec)
+
 fun <E : Enum<E>> Class<E>.codec() = StreamCodec.Enum(this)
 fun <E : Enum<E>> KClass<E>.codec() = StreamCodec.Enum(this.java)