diff --git a/moo/kernel/Stream.moo b/moo/kernel/Stream.moo
new file mode 100644
index 0000000..ac37d40
--- /dev/null
+++ b/moo/kernel/Stream.moo
@@ -0,0 +1,289 @@
+class Stream(Object)
+{
+	method(#class) new
+	{
+		## you must use dedicated class methods for instantiation
+		self messageProhibited: #new.
+	}
+
+	method(#class) on: object
+	{
+		^self subclassResponsibility: #on:.
+	}
+
+	method contents
+	{
+		^self subclassResponsibility: #contents.
+	}
+
+	method next
+	{
+		## return the next object in the receiver
+		^self subclassResponsibility: #next.
+	}
+
+	method nextPut: object
+	{
+		## insert an object at the next position in the receiver
+		^self subclassResponsibility: #next.
+	}
+
+	method nextPutAll: collection
+	{
+		collection do: [:elem | self nextPut: elem ].
+		^collection.
+	}
+
+	method atEnd
+	{
+		^self subclassResponsibility: #next.
+	}
+
+	method print: object
+	{
+		object printOn: self.
+	}
+}
+
+class PositionableStream(Stream)
+{
+	var collection.
+	var(#get) position.
+	var readLimit.
+
+	method(#class) on: collection
+	{
+		^self new __on collection.
+	}
+
+	method initialize
+	{
+		super initialize.
+		self.position := 0.
+		self.readLimit := collection size.
+	}
+
+	method __on: collection
+	{
+		self.collection := collection.
+	}
+
+	method contents
+	{
+		^self.collection copyFrom: 0 to: self.readLimit
+	}
+
+	method next: count
+	{
+		| newobj i |
+		newobj := self contents class new: count.
+		while (i < count)
+		{
+			newobj at: i put: self next.
+			i := i + 1.
+		}.
+	}
+
+	method peek
+	{
+	}
+
+	method atEnd
+	{
+		^self.position >= self.readLimit.
+	}
+
+	method isEmpty
+	{
+		^self.position == 0.
+	}
+
+	method position: pos
+	{
+		##if (pos >= 0 and 
+	}
+
+	method reset
+	{
+		self.position := 0.
+	}
+
+	method setToEnd
+	{
+		self.position := self.readLimit.
+	}
+}
+
+class ReadWriteStream(PositionableStream)
+{
+	method next
+	{
+	}
+}
+
+class ExternalStream(ReadWriteStream)
+{
+}
+
+(*
+## mimic java's interface...
+interface ByteStreamable
+{
+	readBytes:
+	writeBytes:
+}
+*)
+
+### TODO: specify interface inside [] 
+(* 
+difficulty: how to ensure that the class implements the defined interface?
+
+1) check when a new instance is created.
+   -> i don't want this runtime overhead.
+
+2) create an empty methods as soon as an interface is encountered.
+   allows the class body or extend to redefine the methods.
+   give a warning that the interface is not fully implemened if
+   it doesn't redefined all inteface methods at the end of the class
+   definition or at the end of the extend defintion.
+   ->
+ 
+3) don't allow 'extend' for the class that implements inteface
+   and do the check at the end of class definition. or allow extend
+   but the inteface methods must stay inside the main class definition
+   -> if i support pooldic definition from within the class, it looks more natural
+   -> i use 'extend' more simply because i want to have some constants defined
+   -> before i use them in the methods. if i support 'const' inside the class
+   -> defintion, it looks also ok.
+
+   interface Shoutable
+   {
+      method shout.
+      method shoutWith: number.
+   }
+   class xxx(Object) [Shoutable]  <---- allow multiple intefaces here
+   {
+       const DEFVAL := 10.
+       method shout {}
+       method shoutWith: number {}
+   }
+
+4) other methods???
+
+Let me think about it..
+*) 
+
+class ByteStream(Object) ### [ByteStreamable, ByteXXX]
+{
+	var bsobj.
+	var inbuf.
+	var inpos.
+	var inlen.
+	var indown.
+
+	method(#class) new
+	{
+		self messageProhibited: #new.
+	}
+
+	method(#class) new: obj
+	{
+		self messageProhibited: #new:.
+	}
+
+	method initialize 
+	{
+		super initialize.
+		self.bsobj := nil.
+		self.inbuf := ByteArray new: 1024.
+		self.inpos := 0.
+		self.inlen := 0.
+		self.indown := false.
+	}
+
+	method(#class) on: bsobj
+	{
+		^super new __on: bsobj.
+	}
+
+	method __on: bsobj
+	{
+		self.bsobj := bsobj.
+	}
+
+	method __fill_inbuf
+	{
+		| v |
+		v := self.bsobj readBytes: self.inbuf.
+		## if the streamable object is not blocking, it may return an 
+		## error object when data is not ready. 
+		if (v isError) { ^v }. 
+		if (v == 0) 
+		{
+			## end of input
+			self.indown := true.
+			^v
+		}.
+
+		self.inlen := v.
+		self.inpos := 0.
+		^v.
+	}
+
+	method next
+	{
+		| v |
+
+		if (self.indown) { ^nil }.
+		if (self.inpos >= self.inlen)
+		{ 
+			v := self __fill_inbuf.
+			if (v isError) { ^v }.
+			if (v <= 0) { ^nil }.
+			####if (self.inpos >= self.inlen) { ^nil }.
+		}.
+		
+		v := self.inbuf at: self.inpos.
+		self.inpos := self.inpos + 1.
+		^v.
+	}
+
+	method nextUint16
+	{
+	}
+
+	method next: count into: byte_array startingAt: pos
+	{
+		## return the count bytes
+		| taken avail needed v |
+
+		if (self.indown) { ^0 }.
+
+		## i assume the given byte array is large enough
+		## to store as many as count bytes starting at the pos position.
+		## if the parameters cannot meet this assumption, you will get
+		## into various system exceptions.
+		needed := count.
+
+		while (needed > 0)
+		{
+			avail := self.inlen - self.inpos.
+			if (avail <= 0)
+			{
+				v := self __fill_inbuf.
+				if (v isError or v <= 0) { break }. ## <<< TODO: change the error handling
+			}.
+
+			taken := if (avail <= needed) { avail } else { needed }.
+			byte_array replaceFrom: pos count: taken with: self.inbuf startingAt: self.inpos. 
+
+			self.inpos := self.inpos + taken.
+			pos := pos + taken.
+			needed := needed - taken.
+		}.
+
+		^count - needed.
+	}
+
+
+}