diff --git a/benchmark/src/main/java/org/capnproto/benchmark/TestCase.java b/benchmark/src/main/java/org/capnproto/benchmark/TestCase.java
index c1b7980..7fe9aac 100644
--- a/benchmark/src/main/java/org/capnproto/benchmark/TestCase.java
+++ b/benchmark/src/main/java/org/capnproto/benchmark/TestCase.java
@@ -52,10 +52,12 @@ public abstract class TestCase<RequestFactory extends StructFactory<RequestBuild
             ResponseBuilder response = responseMessage.initRoot(responseFactory);
 
             {
-                org.capnproto.ByteBufferWritableByteChannel writer = new org.capnproto.ByteBufferWritableByteChannel(requestBytes);
+                org.capnproto.ArrayOutputStream writer = new org.capnproto.ArrayOutputStream(requestBytes);
                 org.capnproto.Serialize.writeMessage(writer, requestMessage);
             }
 
+            new org.capnproto.ArrayInputStream(requestBytes);
+
             // TODO
             throw new Error("unimplemented");
         }
diff --git a/runtime/src/main/java/org/capnproto/ArrayInputStream.java b/runtime/src/main/java/org/capnproto/ArrayInputStream.java
new file mode 100644
index 0000000..1ac7c68
--- /dev/null
+++ b/runtime/src/main/java/org/capnproto/ArrayInputStream.java
@@ -0,0 +1,38 @@
+package org.capnproto;
+
+import java.io.IOException;
+import java.nio.ByteBuffer;
+import java.nio.channels.ReadableByteChannel;
+
+public final class ArrayInputStream implements BufferedInputStream {
+
+    public final ByteBuffer buf;
+
+    public ArrayInputStream(ByteBuffer buf) {
+        this.buf = buf;
+    }
+
+    public final int read(ByteBuffer dst) throws IOException {
+        int available = this.buf.remaining();
+        int size = dst.remaining();
+
+        ByteBuffer slice = buf.slice();
+        slice.limit(size);
+        dst.put(slice);
+
+        this.buf.position(this.buf.position() + size);
+        return size;
+    }
+
+    public final ByteBuffer getReadBuffer() {
+        return this.buf;
+    }
+
+    public final void close() throws IOException {
+        return;
+    }
+
+    public final boolean isOpen() {
+        return true;
+    }
+}
diff --git a/runtime/src/main/java/org/capnproto/ByteBufferWritableByteChannel.java b/runtime/src/main/java/org/capnproto/ArrayOutputStream.java
similarity index 83%
rename from runtime/src/main/java/org/capnproto/ByteBufferWritableByteChannel.java
rename to runtime/src/main/java/org/capnproto/ArrayOutputStream.java
index 71d03b3..a130212 100644
--- a/runtime/src/main/java/org/capnproto/ByteBufferWritableByteChannel.java
+++ b/runtime/src/main/java/org/capnproto/ArrayOutputStream.java
@@ -4,11 +4,11 @@ import java.io.IOException;
 import java.nio.ByteBuffer;
 import java.nio.channels.WritableByteChannel;
 
-public final class ByteBufferWritableByteChannel implements BufferedWritableByteChannel {
+public final class ArrayOutputStream implements BufferedOutputStream {
 
     public final ByteBuffer buf;
 
-    public ByteBufferWritableByteChannel(ByteBuffer buf) {
+    public ArrayOutputStream(ByteBuffer buf) {
         this.buf = buf;
     }
 
diff --git a/runtime/src/main/java/org/capnproto/BufferedInputStream.java b/runtime/src/main/java/org/capnproto/BufferedInputStream.java
new file mode 100644
index 0000000..9e1b0a3
--- /dev/null
+++ b/runtime/src/main/java/org/capnproto/BufferedInputStream.java
@@ -0,0 +1,8 @@
+package org.capnproto;
+
+import java.nio.ByteBuffer;
+import java.nio.channels.ReadableByteChannel;
+
+public interface BufferedInputStream extends ReadableByteChannel {
+    public ByteBuffer getReadBuffer();
+}
diff --git a/runtime/src/main/java/org/capnproto/BufferedWritableByteChannel.java b/runtime/src/main/java/org/capnproto/BufferedOutputStream.java
similarity index 65%
rename from runtime/src/main/java/org/capnproto/BufferedWritableByteChannel.java
rename to runtime/src/main/java/org/capnproto/BufferedOutputStream.java
index 60aa3aa..45e52d2 100644
--- a/runtime/src/main/java/org/capnproto/BufferedWritableByteChannel.java
+++ b/runtime/src/main/java/org/capnproto/BufferedOutputStream.java
@@ -3,6 +3,6 @@ package org.capnproto;
 import java.nio.ByteBuffer;
 import java.nio.channels.WritableByteChannel;
 
-public interface BufferedWritableByteChannel extends WritableByteChannel {
+public interface BufferedOutputStream extends WritableByteChannel {
     public ByteBuffer getWriteBuffer();
 }
diff --git a/runtime/src/main/java/org/capnproto/BufferedWritableByteChannelWrapper.java b/runtime/src/main/java/org/capnproto/BufferedOutputStreamWrapper.java
similarity index 90%
rename from runtime/src/main/java/org/capnproto/BufferedWritableByteChannelWrapper.java
rename to runtime/src/main/java/org/capnproto/BufferedOutputStreamWrapper.java
index 9f5bd41..23713d1 100644
--- a/runtime/src/main/java/org/capnproto/BufferedWritableByteChannelWrapper.java
+++ b/runtime/src/main/java/org/capnproto/BufferedOutputStreamWrapper.java
@@ -4,12 +4,12 @@ import java.io.IOException;
 import java.nio.ByteBuffer;
 import java.nio.channels.WritableByteChannel;
 
-public final class BufferedWritableByteChannelWrapper implements BufferedWritableByteChannel {
+public final class BufferedOutputStreamWrapper implements BufferedOutputStream {
 
     public final WritableByteChannel inner;
     public final ByteBuffer buf;
 
-    public BufferedWritableByteChannelWrapper(WritableByteChannel w) {
+    public BufferedOutputStreamWrapper(WritableByteChannel w) {
         this.inner = w;
         this.buf = ByteBuffer.allocate(8192);
     }
@@ -34,7 +34,7 @@ public final class BufferedWritableByteChannelWrapper implements BufferedWritabl
                 throw new IOException("failed to write all of the bytes");
             }
 
-            src.position(available);
+            src.position(src.position() + available);
             this.buf.put(src);
         } else {
             //# Writing so much data that we might as well write