diff --git a/rollup.test.js b/rollup.test.js
index 8b2b604d..dca3e47d 100644
--- a/rollup.test.js
+++ b/rollup.test.js
@@ -3,7 +3,7 @@ import commonjs from 'rollup-plugin-commonjs'
 import multiEntry from 'rollup-plugin-multi-entry'
 
 export default {
-  entry: 'test/{encode-decode,red-black-tree}.js',
+  entry: 'test/y-array.tests.js',
   moduleName: 'y-tests',
   format: 'umd',
   plugins: [
diff --git a/src/Binary/Decoder.js b/src/Binary/Decoder.js
index 72c4453b..07d9de37 100644
--- a/src/Binary/Decoder.js
+++ b/src/Binary/Decoder.js
@@ -1,4 +1,6 @@
 import utf8 from 'utf-8'
+import ID from '../Util/ID.js'
+import { default as RootID, RootFakeUserID } from '../Util/RootID.js'
 
 export default class BinaryDecoder {
   constructor (buffer) {
@@ -107,9 +109,11 @@ export default class BinaryDecoder {
    */
   readID () {
     let user = this.readVarUint()
-    if (user === 0xFFFFFF) {
+    if (user === RootFakeUserID) {
       // read property name and type id
-      return new RootID(this.readVarString(), this.readVarUint())
+      const rid = new RootID(this.readVarString(), null)
+      rid.type = this.readVarUint()
+      return rid
     }
     return new ID(user, this.readVarUint())
   }
diff --git a/src/Binary/Encoder.js b/src/Binary/Encoder.js
index dfa62a5f..f080ccaf 100644
--- a/src/Binary/Encoder.js
+++ b/src/Binary/Encoder.js
@@ -1,4 +1,5 @@
 import utf8 from 'utf-8'
+import { RootFakeUserID } from '../Util/RootID.js'
 
 const bits7 = 0b1111111
 const bits8 = 0b11111111
@@ -68,13 +69,14 @@ export default class BinaryEncoder {
     }
   }
 
-  writeOpID (id) {
-    let user = id[0]
+  writeID (id) {
+    const user = id.user
     this.writeVarUint(user)
-    if (user !== 0xFFFFFF) {
-      this.writeVarUint(id[1])
+    if (user !== RootFakeUserID) {
+      this.writeVarUint(id.clock)
     } else {
-      this.writeVarString(id[1])
+      this.writeVarString(id.name)
+      this.writeVarUint(id.type)
     }
   }
 }
diff --git a/src/Connector.js b/src/Connector.js
index c22cea6f..d7ac8f4b 100644
--- a/src/Connector.js
+++ b/src/Connector.js
@@ -41,7 +41,6 @@ export default class AbstractConnector {
 
   reconnect () {
     this.log('reconnecting..')
-    return this.y.db.startGarbageCollector()
   }
 
   disconnect () {
@@ -63,7 +62,7 @@ export default class AbstractConnector {
 
   userLeft (user) {
     if (this.connections.has(user)) {
-      this.log('%s: User left %s', this.userId, user)
+      this.log('%s: User left %s', this.y.userID, user)
       this.connections.delete(user)
       // check if isSynced event can be sent now
       this._setSyncedWith(null)
@@ -83,7 +82,7 @@ export default class AbstractConnector {
     if (this.connections.has(user)) {
       throw new Error('This user already joined!')
     }
-    this.log('%s: User joined %s', this.userId, user)
+    this.log('%s: User joined %s', this.y.userID, user)
     this.connections.set(user, {
       uid: user,
       isSynced: false,
@@ -115,33 +114,32 @@ export default class AbstractConnector {
     }
   }
 
-  _syncWithUser (userid) {
+  _syncWithUser (userID) {
     if (this.role === 'slave') {
       return // "The current sync has not finished or this is controlled by a master!"
     }
-    sendSyncStep1(this, userid)
+    sendSyncStep1(this, userID)
   }
 
   _fireIsSyncedListeners () {
-    new Promise().then(() => {
+    setTimeout(() => {
       if (!this.isSynced) {
         this.isSynced = true
         // It is safer to remove this!
-        // TODO: remove: this.garbageCollectAfterSync()
         // call whensynced listeners
         for (var f of this.whenSyncedListeners) {
           f()
         }
         this.whenSyncedListeners = []
       }
-    })
+    }, 0)
   }
 
   send (uid, buffer) {
     if (!(buffer instanceof ArrayBuffer || buffer instanceof Uint8Array)) {
       throw new Error('Expected Message to be an ArrayBuffer or Uint8Array - don\'t use this method to send custom messages')
     }
-    this.log('%s: Send \'%y\' to %s', this.userId, buffer, uid)
+    this.log('%s: Send \'%y\' to %s', this.y.userID, buffer, uid)
     this.logMessage('Message: %Y', buffer)
   }
 
@@ -149,7 +147,7 @@ export default class AbstractConnector {
     if (!(buffer instanceof ArrayBuffer || buffer instanceof Uint8Array)) {
       throw new Error('Expected Message to be an ArrayBuffer or Uint8Array - don\'t use this method to send custom messages')
     }
-    this.log('%s: Broadcast \'%y\'', this.userId, buffer)
+    this.log('%s: Broadcast \'%y\'', this.y.userID, buffer)
     this.logMessage('Message: %Y', buffer)
   }
 
@@ -157,7 +155,11 @@ export default class AbstractConnector {
     Buffer operations, and broadcast them when ready.
   */
   broadcastStruct (struct) {
-    let firstContent = this.broadcastBuffer.length === 0
+    const firstContent = this.broadcastBuffer.length === 0
+    if (firstContent) {
+      this.broadcastBuffer.writeVarString(this.y.room)
+      this.broadcastBuffer.writeVarString('update')
+    }
     struct._toBinary(this.broadcastBuffer)
     if (this.maxBufferLength > 0 && this.broadcastBuffer.length > this.maxBufferLength) {
       // it is necessary to send the buffer now
@@ -172,7 +174,7 @@ export default class AbstractConnector {
       // (or buffer exceeds maxBufferLength)
       setTimeout(() => {
         if (this.broadcastBuffer.length > 0) {
-          this.broadcast(this.broadcastBuffer)
+          this.broadcast(this.broadcastBuffer.createBuffer())
           this.broadcastBuffer = new BinaryEncoder()
         }
       })
@@ -201,7 +203,7 @@ export default class AbstractConnector {
     if (!(buffer instanceof ArrayBuffer || buffer instanceof Uint8Array)) {
       return Promise.reject(new Error('Expected Message to be an ArrayBuffer or Uint8Array!'))
     }
-    if (sender === this.userId) {
+    if (sender === this.y.userID) {
       return Promise.resolve()
     }
     let decoder = new BinaryDecoder(buffer)
@@ -210,7 +212,7 @@ export default class AbstractConnector {
     encoder.writeVarString(roomname)
     let messageType = decoder.readVarString()
     let senderConn = this.connections.get(sender)
-    this.log('%s: Receive \'%s\' from %s', this.userId, messageType, sender)
+    this.log('%s: Receive \'%s\' from %s', this.y.userID, messageType, sender)
     this.logMessage('Message: %Y', buffer)
     if (senderConn == null && !skipAuth) {
       throw new Error('Received message from unknown peer!')
@@ -247,7 +249,7 @@ export default class AbstractConnector {
   computeMessage (messageType, senderConn, decoder, encoder, sender, skipAuth) {
     if (messageType === 'sync step 1' && (senderConn.auth === 'write' || senderConn.auth === 'read')) {
       // cannot wait for sync step 1 to finish, because we may wait for sync step 2 in sync step 1 (->lock)
-      readSyncStep1()(decoder, encoder, this.y, senderConn, sender)
+      readSyncStep1(decoder, encoder, this.y, senderConn, sender)
     } else if (messageType === 'sync step 2' && senderConn.auth === 'write') {
       readSyncStep2(decoder, encoder, this.y, senderConn, sender)
     } else if (messageType === 'update' && (skipAuth || senderConn.auth === 'write')) {
diff --git a/src/MessageHandler/deleteSet.js b/src/MessageHandler/deleteSet.js
index 555183ae..e261639c 100644
--- a/src/MessageHandler/deleteSet.js
+++ b/src/MessageHandler/deleteSet.js
@@ -1,4 +1,4 @@
-import deleteItemRange from 'deleteItemRange'
+import { deleteItemRange } from '../Struct/Delete.js'
 
 export function stringifyDeleteSet (y, decoder, strBuilder) {
   let dsLength = decoder.readUint32()
@@ -48,7 +48,7 @@ export function writeDeleteSet (y, encoder) {
   if (currentUser !== null) { // happens on first iteration
     encoder.setUint32(lastLenPos, currentLength)
   }
-  encoder.writeUint32(laterDSLenPus, numberOfUsers)
+  encoder.setUint32(laterDSLenPus, numberOfUsers)
 }
 
 export function readDeleteSet (y, decoder) {
diff --git a/src/MessageHandler/integrateRemoteStructs.js b/src/MessageHandler/integrateRemoteStructs.js
index b969c737..05bd393a 100644
--- a/src/MessageHandler/integrateRemoteStructs.js
+++ b/src/MessageHandler/integrateRemoteStructs.js
@@ -45,7 +45,7 @@ export function integrateRemoteStructs (decoder, encoder, y) {
     let reference = decoder.readVarUint()
     let Constr = getStruct(reference)
     let struct = new Constr()
-    let missing = struct._fromBinary(decoder)
+    let missing = struct._fromBinary(y, decoder)
     if (missing.length === 0) {
       while (struct != null) {
         _integrateRemoteStructHelper(y, struct)
diff --git a/src/MessageHandler/stateSet.js b/src/MessageHandler/stateSet.js
index 88b5a577..3ec21c99 100644
--- a/src/MessageHandler/stateSet.js
+++ b/src/MessageHandler/stateSet.js
@@ -10,15 +10,14 @@ export function readStateSet (decoder) {
   return ss
 }
 
-export function writeStateSet (encoder) {
+export function writeStateSet (y, encoder) {
   let lenPosition = encoder.pos
   let len = 0
   encoder.writeUint32(0)
-  this.ss.iterate(null, null, function (n) {
-    encoder.writeVarUint(n.id[0])
-    encoder.writeVarUint(n.clock)
+  for (let [user, clock] of y.ss.state) {
+    encoder.writeVarUint(user)
+    encoder.writeVarUint(clock)
     len++
-  })
+  }
   encoder.setUint32(lenPosition, len)
-  return len === 0
 }
diff --git a/src/MessageHandler/syncStep1.js b/src/MessageHandler/syncStep1.js
index a4f53680..632a61ff 100644
--- a/src/MessageHandler/syncStep1.js
+++ b/src/MessageHandler/syncStep1.js
@@ -1,4 +1,7 @@
 import BinaryEncoder from '../Binary/Encoder.js'
+import { readStateSet, writeStateSet } from './stateSet.js'
+import { writeDeleteSet } from './deleteSet.js'
+import ID from '../Util/ID.js'
 
 export function stringifySyncStep1 (decoder, strBuilder) {
   let auth = decoder.readVarString()
@@ -17,14 +20,22 @@ export function stringifySyncStep1 (decoder, strBuilder) {
   }
 }
 
-export function sendSyncStep1 (y, syncUser) {
+export function sendSyncStep1 (connector, syncUser) {
   let encoder = new BinaryEncoder()
-  encoder.writeVarString(y.room)
+  encoder.writeVarString(connector.y.room)
   encoder.writeVarString('sync step 1')
-  encoder.writeVarString(y.connector.authInfo || '')
-  encoder.writeVarUint(y.connector.protocolVersion)
-  y.ss.writeStateSet(encoder)
-  y.connector.send(syncUser, encoder.createBuffer())
+  encoder.writeVarString(connector.authInfo || '')
+  encoder.writeVarUint(connector.protocolVersion)
+  writeStateSet(connector.y, encoder)
+  connector.send(syncUser, encoder.createBuffer())
+}
+
+export default function writeStructs (encoder, decoder, y, ss) {
+  for (let [user, clock] of ss) {
+    y.os.iterate(new ID(user, clock), null, function (struct) {
+      struct._toBinary(encoder)
+    })
+  }
 }
 
 export function readSyncStep1 (decoder, encoder, y, senderConn, sender) {
@@ -32,22 +43,20 @@ export function readSyncStep1 (decoder, encoder, y, senderConn, sender) {
   // check protocol version
   if (protocolVersion !== y.connector.protocolVersion) {
     console.warn(
-      `You tried to sync with a yjs instance that has a different protocol version
+      `You tried to sync with a Yjs instance that has a different protocol version
       (You: ${protocolVersion}, Client: ${protocolVersion}).
-      The sync was stopped. You need to upgrade your dependencies (especially Yjs & the Connector)!
       `)
     y.destroy()
   }
-
-  // send sync step 2
+  // write sync step 2
   encoder.writeVarString('sync step 2')
   encoder.writeVarString(y.connector.authInfo || '')
-  writeDeleteSet(encoder)
-  // reads ss and writes os
-  writeOperations(encoder, decoder)
+  writeDeleteSet(y, encoder)
+  const ss = readStateSet(decoder)
+  writeStructs(encoder, decoder, y, ss)
   y.connector.send(senderConn.uid, encoder.createBuffer())
   senderConn.receivedSyncStep2 = true
   if (y.connector.role === 'slave') {
-    sendSyncStep1(y, sender)
+    sendSyncStep1(y.connector, sender)
   }
 }
diff --git a/src/MessageHandler/syncStep2.js b/src/MessageHandler/syncStep2.js
index 3b0c6b70..13c1642e 100644
--- a/src/MessageHandler/syncStep2.js
+++ b/src/MessageHandler/syncStep2.js
@@ -1,6 +1,6 @@
 import { integrateRemoteStructs } from './integrateRemoteStructs.js'
 import { stringifyUpdate } from './update.js'
-import ID from '../Util/ID.js'
+import { readDeleteSet } from './deleteSet.js'
 
 export function stringifySyncStep2 (decoder, strBuilder) {
   strBuilder.push('     - auth: ' + decoder.readVarString() + '\n')
@@ -22,27 +22,8 @@ export function stringifySyncStep2 (decoder, strBuilder) {
   }
 }
 
-export function writeSyncStep2 () {
-  // TODO
-}
-
-export default function writeStructs (encoder, decoder, y, ss) {
-  let lenPos = encoder.pos
-  let len = 0
-  encoder.writeUint32(0)
-  for (let [user, clock] of ss) {
-    y.os.iterate(new ID(user, clock), null, function (struct) {
-      struct._toBinary(y, encoder)
-      len++
-    })
-  }
-  encoder.setUint32(lenPos, len)
-}
-
 export function readSyncStep2 (decoder, encoder, y, senderConn, sender) {
-  // apply operations first
-  applyDeleteSet(decoder)
+  readDeleteSet(y, decoder)
   integrateRemoteStructs(decoder, encoder, y)
-  // then apply ds
   y.connector._setSyncedWith(sender)
 }
diff --git a/src/Persistence.js b/src/Persistence.js
index 1cdb40ce..8582b735 100644
--- a/src/Persistence.js
+++ b/src/Persistence.js
@@ -35,7 +35,6 @@ export default function extendPersistence (Y) {
       }
       if (this.saveOperationsBuffer.length === 0) {
         this.saveOperationsBuffer = ops
-        this.y.db.whenTransactionsFinished().then(saveOperations)
       } else {
         this.saveOperationsBuffer = this.saveOperationsBuffer.concat(ops)
       }
diff --git a/src/Store/DeleteStore.js b/src/Store/DeleteStore.js
index 7477ab54..873126be 100644
--- a/src/Store/DeleteStore.js
+++ b/src/Store/DeleteStore.js
@@ -17,6 +17,18 @@ export default class DeleteStore extends Tree {
     var n = this.ds.findWithUpperBound(id)
     return n != null && n.id[0] === id[0] && id[1] < n.id[1] + n.len
   }
+  applyMissingDeletesOnStruct (struct) {
+    const strID = struct._id
+    // find most right delete
+    let n = this.findWithUpperBound(new ID(strID.user, strID.clock + struct.length - 1))
+    if (n === null || n.id.user !== strID.user || n.id.clock + n.length <= strID.clock) {
+      // struct is not deleted
+      return null
+    }
+    // TODO:
+    // * iterate to the right and apply new Delete's
+    throw new Error('Not implemented!')
+  }
   /*
    * Mark an operation as deleted. returns the deleted node
    */
diff --git a/src/Store/OperationStore.js b/src/Store/OperationStore.js
index a3e03e8a..f6be01f8 100644
--- a/src/Store/OperationStore.js
+++ b/src/Store/OperationStore.js
@@ -3,83 +3,61 @@ import RootID from '../Util/ID.js'
 import { getStruct } from '../Util/structReferences.js'
 
 export default class OperationStore extends Tree {
+  constructor (y) {
+    super()
+    this.y = y
+  }
   get (id) {
     let struct = this.find(id)
     if (struct === null && id instanceof RootID) {
       let Constr = getStruct(id.type)
       struct = new Constr()
       struct._id = id
+      struct._parent = this.y
       this.put(struct)
     }
     return struct
   }
+  // Use getItem for structs with _length > 1
   getItem (id) {
     var item = this.findWithUpperBound(id)
-    if (item == null) {
+    if (item === null) {
       return null
     }
-    var len = item.content != null ? item.content.length : 1 // in case of opContent
-    if (id[0] === item.id[0] && id[1] < item.id[1] + len) {
+    const itemID = item._id
+    if (id.user === itemID.user && id.clock < itemID.clock + item._length) {
       return item
     } else {
       return null
     }
-
   }
   // Return an insertion such that id is the first element of content
-  // This function manipulates an operation, if necessary
-  getInsertionCleanStart (id) {
-    var ins = this.getInsertion(id)
-    if (ins != null) {
-      if (ins.id[1] === id[1]) {
-        return ins
-      } else {
-        var left = Y.utils.copyObject(ins)
-        ins.content = left.content.splice(id[1] - ins.id[1])
-        ins.id = id
-        var leftLid = Y.utils.getLastId(left)
-        ins.origin = leftLid
-        left.originOf = [ins.id]
-        left.right = ins.id
-        ins.left = leftLid
-        // debugger // check
-        this.setOperation(left)
-        this.setOperation(ins)
-        if (left.gc) {
-          this.store.queueGarbageCollector(ins.id)
-        }
-        return ins
-      }
+  // This function manipulates an item, if necessary
+  getItemCleanStart (id) {
+    var ins = this.getItem(id)
+    if (ins === null || ins._length === 1) {
+      return ins
+    }
+    const insID = ins._id
+    if (insID.clock === id.clock) {
+      return ins
     } else {
-      return null
+      return ins._splitAt(this.y, id.clock - insID.clock)
     }
   }
   // Return an insertion such that id is the last element of content
   // This function manipulates an operation, if necessary
-  getInsertionCleanEnd (id) {
-    var ins = this.getInsertion(id)
-    if (ins != null) {
-      if (ins.content == null || (ins.id[1] + ins.content.length - 1 === id[1])) {
-        return ins
-      } else {
-        var right = Y.utils.copyObject(ins)
-        right.content = ins.content.splice(id[1] - ins.id[1] + 1) // cut off remainder
-        right.id = [id[0], id[1] + 1]
-        var insLid = Y.utils.getLastId(ins)
-        right.origin = insLid
-        ins.originOf = [right.id]
-        ins.right = right.id
-        right.left = insLid
-        // debugger // check
-        this.setOperation(right)
-        this.setOperation(ins)
-        if (ins.gc) {
-          this.store.queueGarbageCollector(right.id)
-        }
-        return ins
-      }
+  getItemCleanEnd (id) {
+    var ins = this.getItem(id)
+    if (ins === null || ins._length === 1) {
+      return ins
+    }
+    const insID = ins._id
+    if (insID.clock + ins._length - 1 === id.clock) {
+      return ins
     } else {
-      return null
+      ins._splitAt(this.y, id.clock - insID.clock + 1)
+      return ins
     }
   }
 }
diff --git a/src/Struct/Delete.js b/src/Struct/Delete.js
index 4b9bd850..e195b1c2 100644
--- a/src/Struct/Delete.js
+++ b/src/Struct/Delete.js
@@ -1,26 +1,44 @@
-import StructManager from '../Util/StructManager.js'
+import { getReference } from '../Util/structReferences.js'
 
+export function deleteItemRange (y, user, clock, range) {
+  let items = y.os.getItems(this._target, this._length)
+  for (let i = items.length - 1; i >= 0; i--) {
+    items[i]._delete(y, false)
+  }
+}
+
+/**
+ * Delete is not a real struct. It will not be saved in OS
+ */
 export default class Delete {
   constructor () {
-    this._target = null
+    this._targetID = null
     this._length = null
   }
   _fromBinary (y, decoder) {
-    this._targetID = decoder.readOpID()
+    this._targetID = decoder.readID()
     this._length = decoder.readVarUint()
   }
-  _toBinary (y, encoder) {
-    encoder.writeUint8(StructManager.getReference(this.constructor))
-    encoder.writeOpID(this._targetID)
+  _toBinary (encoder) {
+    encoder.writeUint8(getReference(this.constructor))
+    encoder.writeID(this._targetID)
     encoder.writeVarUint(this._length)
   }
-  _integrate (y) {
-    let items = y.os.getItems(this._target, this._length)
-    for (let i = items.length - 1; i >= 0; i--) {
-      items[i]._delete()
+  /**
+   * - If created remotely (a remote user deleted something),
+   *   this Delete is applied to all structs in id-range.
+   * - If created lokally (e.g. when y-array deletes a range of elements),
+   *   this struct is broadcasted only (it is already executed)
+   */
+  _integrate (y, locallyCreated = false) {
+    if (!locallyCreated) {
+      // from remote
+      const id = this._targetID
+      deleteItemRange(y, id.user, id.clock, this._length)
+    } else {
+      // from local
+      y.connector.broadcastStruct(this)
     }
-    // TODO: only broadcast if created by local user or if y.connector._forwardAppliedStructs..
-    y.connector.broadcastStruct(this)
     if (y.persistence !== null) {
       y.persistence.saveOperations(this)
     }
diff --git a/src/Struct/Item.js b/src/Struct/Item.js
index 2b1ab0eb..4f7413e4 100644
--- a/src/Struct/Item.js
+++ b/src/Struct/Item.js
@@ -1,3 +1,27 @@
+import { getReference } from '../Util/structReferences.js'
+import ID from '../Util/ID.js'
+import { RootFakeUserID } from '../Util/RootID.js'
+import Delete from './Delete.js'
+
+/**
+ * Helper utility to split an Item (see _splitAt)
+ * - copy all properties from a to b
+ * - connect a to b
+ * - assigns the correct _id
+ * - save b to os
+ */
+export function splitHelper (y, a, b, diff) {
+  const aID = a._id
+  b._id = new ID(aID.user, aID.clock + diff)
+  b._origin = a
+  b._left = a
+  a._right = b
+  a._right_origin = b
+  b._parent = a._parent
+  b._parentSub = a._parentSub
+  b._deleted = a._deleted
+  y.os.put(b)
+}
 
 export default class Item {
   constructor () {
@@ -13,22 +37,30 @@ export default class Item {
   get _length () {
     return 1
   }
-  _getDistanceToOrigin () {
-    if (this.left == null) {
-      return 0
-    } else {
-      var d = 0
-      var o = this.left
-      while (o !== null && !this.origin.equals(o.id)) {
-        d++
-        o = o.left
-      }
-      return d
+  /**
+   * Splits this struct so that another struct can be inserted in-between.
+   * This must be overwritten if _length > 1
+   * Returns right part after split
+   * - diff === 0 => this
+   * - diff === length => this._right
+   * - otherwise => split _content and return right part of split
+   * (see ItemJSON/ItemString for implementation)
+   */
+  _splitAt (y, diff) {
+    if (diff === 0) {
+      return this
     }
+    return this._right
   }
-  _delete (y) {
+  _delete (y, createDelete = true) {
     this._deleted = true
     y.ds.markDeleted(this._id, this._length)
+    if (createDelete) {
+      let del = new Delete()
+      del._targetID = this._id
+      del._length = this._length
+      del._integrate(y, true)
+    }
   }
   /*
    * - Integrate the struct so that other types/structs can see it
@@ -36,8 +68,12 @@ export default class Item {
    * - Check if this is struct deleted
    */
   _integrate (y) {
-    if (this._id === null) {
+    const selfID = this._id
+    if (selfID === null) {
       this._id = y.ss.getNextID(this._length)
+    } else if (selfID.clock < y.ss.getState(selfID.user)) {
+      // already applied..
+      return []
     }
     /*
     # $this has to find a unique position between origin and the next known character
@@ -71,86 +107,145 @@ export default class Item {
     // Note that conflictingItems is a subset of itemsBeforeOrigin
     while (o !== null && o !== this._right) {
       itemsBeforeOrigin.add(o)
-      if (this.origin === o.origin) {
+      if (this._origin === o._origin) {
         // case 1
         if (o._id.user < this._id.user) {
-          this.left = o
+          this._left = o
           conflictingItems = new Set()
         }
       } else if (itemsBeforeOrigin.has(o)) {
         // case 2
         if (conflictingItems.has(o)) {
-          this.left = o
+          this._left = o
           conflictingItems = new Set()
         }
       } else {
         break
       }
-      o = o.right
+      o = o._right
     }
-    y.os.set(this)
-    y.ds.checkIfDeleted(this)
-    if (y.connector._forwardAppliedStructs || this._id.user === y.userID) {
-      y.connector.broadcastStruct(this)
+    if (this._left === null) {
+      if (this._parentSub !== null) {
+        this._parent._map.set(this._parentSub, this)
+      } else {
+        this._parent._start = this
+      }
     }
-    if (y.persistence !== null) {
-      y.persistence.saveOperations(this)
+    y.os.put(this)
+    if (this._id.user !== RootFakeUserID) {
+      if (y.connector._forwardAppliedStructs || this._id.user === y.userID) {
+        y.connector.broadcastStruct(this)
+      }
+      if (y.persistence !== null) {
+        y.persistence.saveOperations(this)
+      }
+      y.ds.applyMissingDeletesOnStruct(this)
     }
   }
-  _toBinary (y, encoder) {
-    encoder.writeUint8(StructManager.getReference(this.constructor))
-    encoder.writeOpID(this._id)
-    encoder.writeOpID(this._parent._id)
-    encoder.writeVarString(this.parentSub === null ? '' : JSON.stringify(this.parentSub))
-    encoder.writeOpID(this._left === null ? null : this._left._id)
-    encoder.writeOpID(this._right_origin === null ? null : this._right_origin._id)
-    encoder.writeOpID(this._origin === null ? null : this._origin._id)
+  _toBinary (encoder) {
+    encoder.writeUint8(getReference(this.constructor))
+    let info = 0
+    if (this._origin !== null) {
+      info += 0b1 // origin is defined
+    }
+    if (this._left !== this._origin) {
+      info += 0b10 // do not copy origin to left
+    }
+    if (this._right_origin !== null) {
+      info += 0b100
+    }
+    if (this._parentSub !== null) {
+      info += 0b1000
+    }
+    encoder.writeUint8(info)
+    encoder.writeID(this._id)
+    if (info & 0b1) {
+      encoder.writeID(this._origin._id)
+    }
+    if (info & 0b10) {
+      encoder.writeID(this._left._id)
+    }
+    if (info & 0b100) {
+      encoder.writeID(this._right_origin._id)
+    }
+    if (~info & 0b101) {
+      // neither origin nor right is defined
+      encoder.writeID(this._parent._id)
+    }
+    if (info & 0b1000) {
+      encoder.writeVarString(JSON.stringify(this._parentSub))
+    }
   }
   _fromBinary (y, decoder) {
     let missing = []
-    this._id = decoder.readOpID()
-    let parent = decoder.readOpID()
-    let parentSub = decoder.readVarString()
-    if (parentSub.length > 0) {
-      this._parentSub = JSON.parse(parentSub)
-    }
-    let left = decoder.readOpID()
-    let right = decoder.readOpId()
-    let origin = decoder.readOpID()
-    if (parent !== null && this._parent === null) {
-      let _parent = y.os.get(parent)
-      if (_parent === null) {
-        missing.push(parent)
-      } else {
-        this._parent = _parent
+    const info = decoder.readUint8()
+    this._id = decoder.readID()
+    // read origin
+    if (info & 0b1) {
+      // origin != null
+      const originID = decoder.readID()
+      if (this._origin === null) {
+        const origin = y.os.getItemCleanEnd(originID)
+        if (origin === null) {
+          missing.push(originID)
+        } else {
+          this._origin = origin
+        }
       }
     }
-    if (origin !== null && this._origin === null) {
-      let _origin = y.os.getCleanStart(origin)
-      if (_origin === null) {
-        missing.push(origin)
-      } else {
-        this._origin = _origin
+    // read left
+    if (info & 0b10) {
+      // left !== origin
+      const leftID = decoder.readID()
+      if (this._left === null) {
+        const left = y.os.getItemCleanEnd(leftID)
+        if (left === null) {
+          // use origin instead
+          this._left = this._origin
+        } else {
+          this._left = left
+        }
+      }
+    } else {
+      this._left = this._origin
+    }
+    // read right
+    if (info & 0b100) {
+      // right != null
+      const rightID = decoder.readID()
+      if (this._right_origin === null) {
+        const right = y.os.getCleanStart(rightID)
+        if (right === null) {
+          missing.push(right)
+        } else {
+          this._right = right
+          this._right_origin = right
+        }
       }
     }
-    if (left !== null && this._left === null) {
-      let _left = y.os.getCleanEnd(left)
-      if (_left === null) {
-        // use origin instead
-        this._left = this._origin
-      } else {
-        this._left = _left
+    // read parent
+    if (~info & 0b101) {
+      // neither origin nor right is defined
+      const parentID = decoder.readID()
+      if (this._parent === null) {
+        const parent = y.os.get(parentID)
+        if (parent === null) {
+          missing.push(parent)
+        } else {
+          this._parent = parent
+        }
+      }
+    } else if (this._parent === null) {
+      if (this._origin !== null) {
+        this._parent = this._origin._parent
+      } else if (this._right_origin !== null) {
+        this._parent = this._origin._parent
       }
     }
-    if (right !== null && this._right_origin === null) {
-      let _right = y.os.getCleanStart(right)
-      if (_right === null) {
-        missing.push(right)
-      } else {
-        this._right = _right
-        this._right_origin = _right
-      }
+    if (info & 0b1000) {
+      this._parentSub = decoder.readVarString()
     }
+    return missing
   }
   _logString () {
     return `left: ${this._left}, origin: ${this._origin}, right: ${this._right}, parent: ${this._parent}, parentSub: ${this._parentSub}`
diff --git a/src/Struct/ItemJSON.js b/src/Struct/ItemJSON.js
index 91fe1f86..25f00cf6 100644
--- a/src/Struct/ItemJSON.js
+++ b/src/Struct/ItemJSON.js
@@ -1,4 +1,4 @@
-import Item from './Item.js'
+import { splitHelper, default as Item } from './Item.js'
 
 export default class ItemJSON extends Item {
   constructor () {
@@ -17,8 +17,8 @@ export default class ItemJSON extends Item {
     }
     return missing
   }
-  _toBinary (y, encoder) {
-    super._toBinary(y, encoder)
+  _toBinary (encoder) {
+    super._toBinary(encoder)
     let len = this._content.length
     encoder.writeVarUint(len)
     for (let i = 0; i < len; i++) {
@@ -29,4 +29,15 @@ export default class ItemJSON extends Item {
     let s = super._logString()
     return 'ItemJSON: ' + s
   }
+  _splitAt (y, diff) {
+    if (diff === 0) {
+      return this
+    } else if (diff >= this._length) {
+      return this._right
+    }
+    let item = new ItemJSON()
+    item._content = this._content.splice(diff)
+    splitHelper(y, this, item, diff)
+    return item
+  }
 }
diff --git a/src/Struct/ItemString.js b/src/Struct/ItemString.js
index cfe5c2a5..bef915b6 100644
--- a/src/Struct/ItemString.js
+++ b/src/Struct/ItemString.js
@@ -1,4 +1,4 @@
-import Item from './Item.js'
+import { splitHelper, default as Item } from './Item.js'
 
 export default class ItemString extends Item {
   constructor () {
@@ -13,12 +13,24 @@ export default class ItemString extends Item {
     this._content = decoder.readVarString()
     return missing
   }
-  _toBinary (y, encoder) {
-    super._toBinary(y, encoder)
+  _toBinary (encoder) {
+    super._toBinary(encoder)
     encoder.writeVarString(this._content)
   }
   _logString () {
     let s = super._logString()
     return 'ItemString: ' + s
   }
+  _splitAt (y, diff) {
+    if (diff === 0) {
+      return this
+    } else if (diff >= this._length) {
+      return this._right
+    }
+    let item = new ItemString()
+    item._content = this._content.slice(diff)
+    this._content = this._content.slice(0, diff)
+    splitHelper(y, this, item, diff)
+    return item
+  }
 }
diff --git a/src/Struct/Type.js b/src/Struct/Type.js
index bd498bf1..e595d0ae 100644
--- a/src/Struct/Type.js
+++ b/src/Struct/Type.js
@@ -5,6 +5,11 @@ export default class Type extends Item {
     super()
     this._map = new Map()
     this._start = null
+    this._y = null
+  }
+  _integrate (y) {
+    super._integrate(y)
+    this._y = y
   }
   _delete (y) {
     super._delete(y)
diff --git a/src/Type/YArray.js b/src/Type/YArray.js
index 11f07d25..3c24ba25 100644
--- a/src/Type/YArray.js
+++ b/src/Type/YArray.js
@@ -2,21 +2,50 @@ import Type from '../Struct/Type.js'
 import ItemJSON from '../Struct/ItemJSON.js'
 
 export default class YArray extends Type {
+  toJSON () {
+    return this.map(c => {
+      if (c instanceof Type) {
+        if (c.toJSON !== null) {
+          return c.toJSON()
+        } else {
+          return c.toString()
+        }
+      }
+    })
+  }
+  map (f) {
+    const res = []
+    this.forEach((c, i) => {
+      res.push(f(c, i, this))
+    })
+    return res
+  }
   forEach (f) {
     let pos = 0
     let n = this._start
     while (n !== null) {
-      let content = n._getContent()
-      for (let i = 0; i < content.length; i++) {
-        pos++
-        let c = content[i]
-        if (!c._deleted) {
+      if (!n._deleted) {
+        const content = n._content
+        const contentLen = content.length
+        for (let i = 0; i < contentLen; i++) {
+          pos++
           f(content[i], pos, this)
         }
       }
       n = n._right
     }
   }
+  get length () {
+    let length = 0
+    let n = this._start
+    while (n !== null) {
+      if (!n._deleted) {
+        length += n._length
+      }
+      n = n._next
+    }
+    return length
+  }
   [Symbol.iterator] () {
     return {
       next: function () {
@@ -41,15 +70,37 @@ export default class YArray extends Type {
       _count: 0
     }
   }
+  delete (pos, length = 1) {
+    let item = this._start
+    let count = 0
+    while (item !== null && length > 0) {
+      if (count < pos && pos < count + item._length) {
+        const diffDel = pos - count
+        item = item
+          ._splitAt(this._y, diffDel)
+          ._splitAt(this._y, length)
+        length -= item._length
+        item._delete(this._y)
+      }
+      if (!item._deleted) {
+        count += item._length
+      }
+      item = item._right
+    }
+    if (length > 0) {
+      throw new Error('Delete exceeds the range of the YArray')
+    }
+  }
   insert (pos, content) {
     let left = this._start
-    let right
+    let right = null
     let count = 0
-    while (left !== null && !left._deleted) {
-      if (pos < count + left._content.length) {
-        [left, right] = left._splitAt(pos - count)
+    while (left !== null) {
+      if (count <= pos && pos < count + left._content.length) {
+        right = left._splitAt(this.y, pos - count)
         break
       }
+      count += left._length
       left = left.right
     }
     if (pos > count) {
@@ -79,6 +130,9 @@ export default class YArray extends Type {
         prevJsonIns._content.push(c)
       }
     }
+    if (prevJsonIns !== null) {
+      prevJsonIns._integrate(this._y)
+    }
   }
   _logString () {
     let s = super._logString()
diff --git a/src/Type/YMap.js b/src/Type/YMap.js
index 819e9d98..58189352 100644
--- a/src/Type/YMap.js
+++ b/src/Type/YMap.js
@@ -3,6 +3,25 @@ import Item from '../Struct/Item.js'
 import ItemJSON from '../Struct/ItemJSON.js'
 
 export default class YMap extends Type {
+  toJSON () {
+    const map = {}
+    for (let [key, item] of this._map) {
+      if (!item._deleted) {
+        let res
+        if (item instanceof Type) {
+          if (item.toJSON !== undefined) {
+            res = item.toJSON()
+          } else {
+            res = item.toString()
+          }
+        } else {
+          res = item._content[0]
+        }
+        map[key] = res
+      }
+    }
+    return map
+  }
   set (key, value) {
     let old = this._map.get(key)
     let v
diff --git a/src/Type/YXml.js b/src/Type/YXml.js
index 3bf9ac0a..4e0bd83e 100644
--- a/src/Type/YXml.js
+++ b/src/Type/YXml.js
@@ -1,4 +1,10 @@
 import YArray from './YArray.js'
 
 export default class YXml extends YArray {
+  setDomFilter () {
+    // TODO
+  }
+  toString () {
+    return '<nodeName></nodeName>'
+  }
 }
diff --git a/src/Util/ID.js b/src/Util/ID.js
index bfc1b666..3c3e8235 100644
--- a/src/Util/ID.js
+++ b/src/Util/ID.js
@@ -1,6 +1,4 @@
 
-import { getReference } from './structReferences.js'
-
 export default class ID {
   constructor (user, clock) {
     this.user = user
diff --git a/src/Util/RootID.js b/src/Util/RootID.js
index e3498e56..0968dced 100644
--- a/src/Util/RootID.js
+++ b/src/Util/RootID.js
@@ -1,9 +1,12 @@
+import { getReference } from './structReferences.js'
+
+export const RootFakeUserID = 0xFFFFFF
 
 export default class RootID {
   constructor (name, typeConstructor) {
-    this.user = -1
+    this.user = RootFakeUserID
     this.name = name
-    this.type = StructManager.getReference(typeConstructor)
+    this.type = getReference(typeConstructor)
   }
   equals (id) {
     return id !== null && id.user === this.user && id.name === this.name && id.type === this.type
diff --git a/src/Util/Tree.js b/src/Util/Tree.js
index 0680bf77..9960443e 100644
--- a/src/Util/Tree.js
+++ b/src/Util/Tree.js
@@ -140,11 +140,11 @@ export default class Tree {
       return null
     } else {
       while (true) {
-        if (from === null || (from.lessThan(o.val.id) && o.left !== null)) {
+        if (from === null || (from.lessThan(o.val._id) && o.left !== null)) {
           // o is included in the bound
           // try to find an element that is closer to the bound
           o = o.left
-        } else if (from !== null && o.val.id.lessThan(from)) {
+        } else if (from !== null && o.val._id.lessThan(from)) {
           // o is not within the bound, maybe one of the right elements is..
           if (o.right !== null) {
             o = o.right
@@ -168,11 +168,11 @@ export default class Tree {
       return null
     } else {
       while (true) {
-        if ((to === null || o.val.id.lessThan(to)) && o.right !== null) {
+        if ((to === null || o.val._id.lessThan(to)) && o.right !== null) {
           // o is included in the bound
           // try to find an element that is closer to the bound
           o = o.right
-        } else if (to !== null && to.lessThan(o.val.id)) {
+        } else if (to !== null && to.lessThan(o.val._id)) {
           // o is not within the bound, maybe one of the left elements is..
           if (o.left !== null) {
             o = o.left
@@ -213,8 +213,8 @@ export default class Tree {
       o !== null &&
       (
         to === null || // eslint-disable-line no-unmodified-loop-condition
-        o.val.id.lessThan(to) ||
-        o.val.id.equals(to)
+        o.val._id.lessThan(to) ||
+        o.val._id.equals(to)
       )
     ) {
       f(o.val)
@@ -238,9 +238,9 @@ export default class Tree {
         if (o === null) {
           return null
         }
-        if (id.lessThan(o.val.id)) {
+        if (id.lessThan(o.val._id)) {
           o = o.left
-        } else if (o.val.id.lessThan(id)) {
+        } else if (o.val._id.lessThan(id)) {
           o = o.right
         } else {
           return o
@@ -393,14 +393,14 @@ export default class Tree {
     if (this.root !== null) {
       var p = this.root // p abbrev. parent
       while (true) {
-        if (node.val.id.lessThan(p.val.id)) {
+        if (node.val._id.lessThan(p.val._id)) {
           if (p.left === null) {
             p.left = node
             break
           } else {
             p = p.left
           }
-        } else if (p.val.id.lessThan(node.val.id)) {
+        } else if (p.val._id.lessThan(node.val._id)) {
           if (p.right === null) {
             p.right = node
             break
diff --git a/src/Y.js b/src/Y.js
index 9c33de87..fd013beb 100644
--- a/src/Y.js
+++ b/src/Y.js
@@ -3,6 +3,7 @@ import OperationStore from './Store/OperationStore.js'
 import StateStore from './Store/StateStore.js'
 import { generateUserID } from './Util/generateUserID.js'
 import RootID from './Util/RootID.js'
+import NamedEventHandler from './Util/NamedEventHandler.js'
 
 import { messageToString, messageToRoomname } from './MessageHandler/messageToString.js'
 
@@ -15,8 +16,10 @@ import YXml from './Type/YXml.js'
 
 import debug from 'debug'
 
-export default class Y {
+export default class Y extends NamedEventHandler {
   constructor (opts) {
+    super()
+    this._opts = opts
     this.userID = generateUserID()
     this.ds = new DeleteStore(this)
     this.os = new OperationStore(this)
@@ -30,10 +33,17 @@ export default class Y {
     }
     this.connected = true
     this._missingStructs = new Map()
-    this._readyToIntegrate = new Map()
+    this._readyToIntegrate = []
+  }
+  // fake _start for root properties (y.set('name', type))
+  get _start () {
+    return null
+  }
+  set _start (start) {
+    return null
   }
   get room () {
-    return this.connector.opts.room
+    return this._opts.connector.room
   }
   get (name, TypeConstructor) {
     let id = new RootID(name, TypeConstructor)
@@ -41,6 +51,7 @@ export default class Y {
     if (type === null) {
       type = new TypeConstructor()
       type._id = id
+      type._parent = this
       type._integrate(this)
     }
     return type
@@ -68,9 +79,6 @@ export default class Y {
     } else {
       this.connector.disconnect()
     }
-    this.os.iterate(null, null, function (struct) {
-      struct.destroy()
-    })
     this.os = null
     this.ds = null
     this.ss = null
@@ -88,7 +96,8 @@ Y.extend = function extendYjs () {
   }
 }
 
-Y.Connector = Connector
+// TODO: The following assignments should be moved to yjs-dist
+Y.AbstractConnector = Connector
 Y.Persisence = Persistence
 Y.Array = YArray
 Y.Map = YMap
diff --git a/test/red-black-tree.js b/test/red-black-tree.js
index 299e85f0..63cb6f08 100644
--- a/test/red-black-tree.js
+++ b/test/red-black-tree.js
@@ -55,15 +55,15 @@ function checkRootNodeIsBlack (t, tree) {
 
 test('RedBlack Tree', async function redBlackTree (t) {
   let tree = new RedBlackTree()
-  tree.put({id: new ID(8433, 0)})
-  tree.put({id: new ID(12844, 0)})
-  tree.put({id: new ID(1795, 0)})
-  tree.put({id: new ID(30302, 0)})
-  tree.put({id: new ID(64287)})
+  tree.put({_id: new ID(8433, 0)})
+  tree.put({_id: new ID(12844, 0)})
+  tree.put({_id: new ID(1795, 0)})
+  tree.put({_id: new ID(30302, 0)})
+  tree.put({_id: new ID(64287)})
   tree.delete(new ID(8433, 0))
-  tree.put({id: new ID(28996)})
+  tree.put({_id: new ID(28996)})
   tree.delete(new ID(64287))
-  tree.put({id: new ID(22721)})
+  tree.put({_id: new ID(22721)})
   checkRootNodeIsBlack(t, tree)
   checkBlackHeightOfSubTreesAreEqual(t, tree)
   checkRedNodesDoNotHaveBlackChildren(t, tree)
@@ -83,7 +83,7 @@ test(`random tests (${numberOfRBTreeTests})`, async function random (t) {
           t.assert(false, 'tree and elements contain different results')
         }
         elements.push(obj)
-        tree.put({id: obj})
+        tree.put({_id: obj})
       }
     } else if (elements.length > 0) {
       // ~20% chance to delete an element
@@ -101,7 +101,7 @@ test(`random tests (${numberOfRBTreeTests})`, async function random (t) {
   let allNodesExist = true
   for (let id of elements) {
     let node = tree.find(id)
-    if (!node.id.equals(id)) {
+    if (!node._id.equals(id)) {
       allNodesExist = false
     }
   }
@@ -110,7 +110,7 @@ test(`random tests (${numberOfRBTreeTests})`, async function random (t) {
   let findAllNodesWithLowerBoundSerach = true
   for (let id of elements) {
     let node = tree.findWithLowerBound(id)
-    if (!node.id.equals(id)) {
+    if (!node._id.equals(id)) {
       findAllNodesWithLowerBoundSerach = false
     }
   }
diff --git a/test/y-array.tests.js b/test/y-array.tests.js
index e5bf0561..69c15a11 100644
--- a/test/y-array.tests.js
+++ b/test/y-array.tests.js
@@ -11,11 +11,11 @@ test('basic spec', async function array0 (t) {
 
   let throwInvalidPosition = false
   try {
-    array0.delete(1, 0)
+    array0.delete(1, 1)
   } catch (e) {
     throwInvalidPosition = true
   }
-  t.assert(throwInvalidPosition, 'Throws when deleting zero elements with an invalid position')
+  t.assert(throwInvalidPosition, 'Throws when deleting with an invalid position')
 
   array0.insert(0, ['A'])
   array0.delete(1, 0)
diff --git a/tests-lib/helper.js b/tests-lib/helper.js
index ca4ceb73..f6c87145 100644
--- a/tests-lib/helper.js
+++ b/tests-lib/helper.js
@@ -87,7 +87,7 @@ export async function compareUsers (t, users) {
 
   var userArrayValues = users.map(u => u.get('array', Y.Array).toJSON())
   var userMapValues = users.map(u => u.get('map', Y.Map).toJSON())
-  var userXmlValues = users.map(u => u.get('xml', Y.Xml).getDom().toString())
+  var userXmlValues = users.map(u => u.get('xml', Y.Xml).toString())
 
   // disconnect all except user 0
   await Promise.all(users.slice(1).map(async u =>
@@ -107,28 +107,22 @@ export async function compareUsers (t, users) {
       u.connector.whenSynced(resolve)
     })
   ))
-  var data = users.forEach(u => {
+  var data = users.map(u => {
     var data = {}
     let ops = []
     u.os.iterate(null, null, function (op) {
       if (!op._deleted) {
         ops.push({
+          id: op._id,
           left: op._left,
           right: op._right,
           deleted: op._deleted
         })
       }
     })
-
-    data.os = {}
-    for (let i = 0; i < ops.length; i++) {
-      let op = ops[i]
-      op = Y.Struct[op.struct].encode(op)
-      delete op.origin
-      data.os[JSON.stringify(op.id)] = op
-    }
-    data.ds = getDeleteSet.apply(this)
-    data.ss = getStateSet.apply(this)
+    data.os = ops
+    data.ds = getDeleteSet(u)
+    data.ss = getStateSet(u)
     return data
   })
   for (var i = 0; i < data.length - 1; i++) {
@@ -141,7 +135,7 @@ export async function compareUsers (t, users) {
       t.compare(data[i].ss, data[i + 1].ss, 'ss')
     }, `Compare user${i} with user${i + 1}`)
   }
-  users.map(u => u.close())
+  users.map(u => u.destroy())
 }
 
 export async function initArrays (t, opts) {
@@ -161,6 +155,7 @@ export async function initArrays (t, opts) {
       connector: connOpts
     })
     result.users.push(y)
+    result['array' + i] = y.get('array', Y.Array)
     y.get('xml', Y.Xml).setDomFilter(function (d, attrs) {
       if (d.nodeName === 'HIDDEN') {
         return null
@@ -193,9 +188,6 @@ export async function flushAll (t, users) {
     // use flushAll method specified in Test Connector
     await users[0].connector.testRoom.flushAll(users)
   } else {
-    // flush for any connector
-    await Promise.all(users.map(u => { return u.db.whenTransactionsFinished() }))
-
     var flushCounter = users[0].get('flushHelper', Y.Map).get('0') || 0
     flushCounter++
     await Promise.all(users.map(async (u, i) => {
diff --git a/tests-lib/test-connector.js b/tests-lib/test-connector.js
index 07a7f92b..f20d3654 100644
--- a/tests-lib/test-connector.js
+++ b/tests-lib/test-connector.js
@@ -8,24 +8,21 @@ export class TestRoom {
   constructor (roomname) {
     this.room = roomname
     this.users = new Map()
-    this.nextUserId = 0
   }
   join (connector) {
-    if (connector.userId == null) {
-      connector.setUserId(this.nextUserId++)
-    }
-    this.users.forEach((user, uid) => {
-      if (user.role === 'master' || connector.role === 'master') {
-        this.users.get(uid).userJoined(connector.userId, connector.role)
+    const userID = connector.y.userID
+    this.users.set(userID, connector)
+    for (let [uid, user] of this.users) {
+      if (uid !== userID && (user.role === 'master' || connector.role === 'master')) {
         connector.userJoined(uid, this.users.get(uid).role)
+        this.users.get(uid).userJoined(userID, connector.role)
       }
-    })
-    this.users.set(connector.userId, connector)
+    }
   }
   leave (connector) {
-    this.users.delete(connector.userId)
+    this.users.delete(connector.y.userID)
     this.users.forEach(user => {
-      user.userLeft(connector.userId)
+      user.userLeft(connector.y.userID)
     })
   }
   send (sender, receiver, m) {
@@ -82,7 +79,7 @@ export default function extendTestConnector (Y) {
       return super.disconnect()
     }
     logBufferParsed () {
-      console.log(' === Logging buffer of user ' + this.userId + ' === ')
+      console.log(' === Logging buffer of user ' + this.y.userID + ' === ')
       for (let [user, conn] of this.connections) {
         console.log(` ${user}:`)
         for (let i = 0; i < conn.buffer.length; i++) {
@@ -96,11 +93,11 @@ export default function extendTestConnector (Y) {
     }
     send (uid, message) {
       super.send(uid, message)
-      this.testRoom.send(this.userId, uid, message)
+      this.testRoom.send(this.y.userID, uid, message)
     }
     broadcast (message) {
       super.broadcast(message)
-      this.testRoom.broadcast(this.userId, message)
+      this.testRoom.broadcast(this.y.userID, message)
     }
     async whenSynced (f) {
       var synced = false
@@ -119,7 +116,7 @@ export default function extendTestConnector (Y) {
       })
     }
     receiveMessage (sender, m) {
-      if (this.userId !== sender && this.connections.has(sender)) {
+      if (this.y.userID !== sender && this.connections.has(sender)) {
         var buffer = this.connections.get(sender).buffer
         if (buffer == null) {
           buffer = this.connections.get(sender).buffer = []
@@ -135,30 +132,30 @@ export default function extendTestConnector (Y) {
       }
     }
     async _flushAll (flushUsers) {
-      if (flushUsers.some(u => u.connector.userId === this.userId)) {
+      if (flushUsers.some(u => u.connector.y.userID === this.y.userID)) {
         // this one needs to sync with every other user
         flushUsers = Array.from(this.connections.keys()).map(uid => this.testRoom.users.get(uid).y)
       }
       var finished = []
       for (let i = 0; i < flushUsers.length; i++) {
-        let userId = flushUsers[i].connector.userId
-        if (userId !== this.userId && this.connections.has(userId)) {
-          let buffer = this.connections.get(userId).buffer
+        let userID = flushUsers[i].connector.y.userID
+        if (userID !== this.y.userID && this.connections.has(userID)) {
+          let buffer = this.connections.get(userID).buffer
           if (buffer != null) {
             var messages = buffer.splice(0)
             for (let j = 0; j < messages.length; j++) {
-              let p = super.receiveMessage(userId, messages[j])
+              let p = super.receiveMessage(userID, messages[j])
               finished.push(p)
             }
           }
         }
       }
       await Promise.all(finished)
-      await this.y.db.whenTransactionsFinished()
       return finished.length > 0 ? 'flushing' : 'done'
     }
   }
-  Y.extend('test', TestConnector)
+  // TODO: this should be moved to a separate module (dont work on Y)
+  Y.test = TestConnector
 }
 
 if (typeof Y !== 'undefined') {