diff --git a/client/src/main/kotlin/org/hso/texturesyncclient/controller/net/Connection.kt b/client/src/main/kotlin/org/hso/texturesyncclient/controller/net/Connection.kt
index c646f55..4b878a7 100644
--- a/client/src/main/kotlin/org/hso/texturesyncclient/controller/net/Connection.kt
+++ b/client/src/main/kotlin/org/hso/texturesyncclient/controller/net/Connection.kt
@@ -5,6 +5,7 @@ import javafx.scene.image.Image
 import org.hso.texturesyncclient.model.Sha256
 import org.hso.texturesyncclient.model.Texture
 import java.io.*
+import java.lang.IllegalArgumentException
 import java.lang.RuntimeException
 import java.net.*
 import java.util.*
@@ -214,17 +215,102 @@ class Connection(val address: InetAddress, val port: Int = 10796) : Closeable {
         }
     }
 
+    @Throws(IOException::class, ConnectionException::class, IllegalArgumentException::class)
+    @Synchronized
+    private fun replaceTexture(old: Texture?, new : Texture?, image : ByteArray? ) {
+        val io = getStreams()
+
+        val obj = JsonObject()
+        obj.add("replace_texture", {
+            val inner = JsonObject()
+            if(old != null) {
+                inner.add("old", Gson().toJsonTree(InternalTexture(old), InternalTexture::class.java))
+            } else {
+                inner.add("old", null)
+            }
+            if(new != null) {
+                inner.add("new", Gson().toJsonTree(InternalTexture(new), InternalTexture::class.java))
+            } else {
+                inner.add("new", null)
+            }
+            inner
+        }())
+
+        JsonPackage(obj).write(io.second)
+
+        when (val pkg = Package.read(io.first)) {
+            is JsonPackage -> {
+                if (pkg.content == JsonPrimitive(true)) {
+                    // everthing is fine!
+                    return
+                } else if (image != null) {
+                    // should be  { "get_texture_file": { texture_hash : <Hash> }}
+                    // we don't check, since there is no good way to handle it.
+
+                    BinaryPackage(image).write(io.second)
+                    when (val ipkg = Package.read(io.first)) {
+                        is JsonPackage -> {
+                            if(ipkg.content != JsonPrimitive(true)) {
+                                // Protokoll Assertion failed
+                                throw ConnectionUnexpecedPacketException()
+                            }
+                        }
+                        is BinaryPackage -> throw ConnectionUnexpecedPacketException()
+                        is ErrorPackage -> throw ConnectionErrorException(ipkg)
+                        else -> throw RuntimeException("Unreachable")
+                    }
+                } else {
+                    ErrorPackage(404, "Texture not found!").write(io.second)
+                    close() // gets re-opened on next request.
+                    throw IllegalArgumentException("Image Argument was needed.")
+                }
+            }
+            is BinaryPackage -> throw ConnectionUnexpecedPacketException()
+            is ErrorPackage -> throw ConnectionErrorException(pkg)
+            else -> throw RuntimeException("Unreachable")
+        }
+    }
+
+    @Throws(IOException::class, ConnectionException::class, IllegalArgumentException::class)
+    @Synchronized
+    fun uploadTexture(texture: Texture, image : ByteArray ) {
+        if(texture.textureHash != Sha256(image)) {
+            throw IllegalArgumentException("Sha256 of Image does not Match with Texture.")
+        }
+
+        replaceTexture(null, texture, image)
+    }
+
+    @Throws(IOException::class, ConnectionException::class, IllegalArgumentException::class)
+    @Synchronized
+    fun updateTexture(old: Texture, new : Texture, image : ByteArray ) {
+        if(new.textureHash != Sha256(image)) {
+            throw IllegalArgumentException("Sha256 of Image does not Match with Texture.")
+        }
+
+        replaceTexture(old, new, image)
+    }
+
+    @Throws(IOException::class, ConnectionException::class, IllegalArgumentException::class)
+    @Synchronized
+    fun deleteTexture(texture : Texture) {
+        replaceTexture(texture, null , null)
+    }
+
     @Throws(IOException::class)
     @Synchronized
     override fun close() {
         if (output != null) {
             output!!.close()
+            output = null
         }
         if (input != null) {
             input!!.close()
+            input = null
         }
         if (socket != null) {
             socket!!.close()
+            socket = null
         }
     }
 
diff --git a/client/src/main/kotlin/org/hso/texturesyncclient/model/DataModel.kt b/client/src/main/kotlin/org/hso/texturesyncclient/model/DataModel.kt
index a8036dc..588006d 100644
--- a/client/src/main/kotlin/org/hso/texturesyncclient/model/DataModel.kt
+++ b/client/src/main/kotlin/org/hso/texturesyncclient/model/DataModel.kt
@@ -56,4 +56,19 @@ class Sha256 {
         }
         return s.toString()
     }
+
+    override fun equals(other: Any?): Boolean {
+        if (this === other) return true
+        if (javaClass != other?.javaClass) return false
+
+        other as Sha256
+
+        if (!hashBytes.contentEquals(other.hashBytes)) return false
+
+        return true
+    }
+
+    override fun hashCode(): Int {
+        return hashBytes.contentHashCode()
+    }
 }
\ No newline at end of file