diff --git a/swh/objstorage/api/server.py b/swh/objstorage/api/server.py
--- a/swh/objstorage/api/server.py
+++ b/swh/objstorage/api/server.py
@@ -3,50 +3,48 @@
 # License: GNU General Public License version 3, or any later version
 # See top-level LICENSE file for more information
 
-import asyncio
-import aiohttp.web
 import os
 
+import aiohttp.web
+
 from swh.core.config import read as config_read
-from swh.core.api_async import (SWHRemoteAPI, decode_request,
-                                encode_data_server as encode_data)
+from swh.core.api.asynchronous import (SWHRemoteAPI, decode_request,
+                                       encode_data_server as encode_data)
+
+
+from swh.core.api.serializers import msgpack_loads, SWHJSONDecoder
+
 from swh.model import hashutil
 from swh.objstorage import get_objstorage
 from swh.objstorage.exc import ObjNotFoundError
 
 
-@asyncio.coroutine
-def index(request):
+async def index(request):
     return aiohttp.web.Response(body="SWH Objstorage API server")
 
 
-@asyncio.coroutine
-def check_config(request):
-    req = yield from decode_request(request)
+async def check_config(request):
+    req = await decode_request(request)
     return encode_data(request.app['objstorage'].check_config(**req))
 
 
-@asyncio.coroutine
-def contains(request):
-    req = yield from decode_request(request)
+async def contains(request):
+    req = await decode_request(request)
     return encode_data(request.app['objstorage'].__contains__(**req))
 
 
-@asyncio.coroutine
-def add_bytes(request):
-    req = yield from decode_request(request)
+async def add_bytes(request):
+    req = await decode_request(request)
     return encode_data(request.app['objstorage'].add(**req))
 
 
-@asyncio.coroutine
-def add_batch(request):
-    req = yield from decode_request(request)
+async def add_batch(request):
+    req = await decode_request(request)
     return encode_data(request.app['objstorage'].add_batch(**req))
 
 
-@asyncio.coroutine
-def get_bytes(request):
-    req = yield from decode_request(request)
+async def get_bytes(request):
+    req = await decode_request(request)
     try:
         ret = request.app['objstorage'].get(**req)
     except ObjNotFoundError:
@@ -59,36 +57,31 @@
         return encode_data(ret)
 
 
-@asyncio.coroutine
-def get_batch(request):
-    req = yield from decode_request(request)
+async def get_batch(request):
+    req = await decode_request(request)
     return encode_data(request.app['objstorage'].get_batch(**req))
 
 
-@asyncio.coroutine
-def check(request):
-    req = yield from decode_request(request)
+async def check(request):
+    req = await decode_request(request)
     return encode_data(request.app['objstorage'].check(**req))
 
 
-@asyncio.coroutine
-def delete(request):
-    req = yield from decode_request(request)
+async def delete(request):
+    req = await decode_request(request)
     return encode_data(request.app['objstorage'].delete(**req))
 
 
 # Management methods
 
-@asyncio.coroutine
-def get_random_contents(request):
-    req = yield from decode_request(request)
+async def get_random_contents(request):
+    req = await decode_request(request)
     return encode_data(request.app['objstorage'].get_random(**req))
 
 
 # Streaming methods
 
-@asyncio.coroutine
-def add_stream(request):
+async def add_stream(request):
     hex_id = request.match_info['hex_id']
     obj_id = hashutil.hash_to_bytes(hex_id)
     check_pres = (request.query.get('check_presence', '').lower() == 'true')
@@ -97,24 +90,38 @@
     if check_pres and obj_id in objstorage:
         return encode_data(obj_id)
 
+    # XXX this really should go in a decode_stream_request coroutine in
+    # swh.core, but since py35 does not support async generators, it cannot
+    # easily be made for now
+    content_type = request.headers.get('Content-Type')
+    if content_type == 'application/x-msgpack':
+        decode = msgpack_loads
+    elif content_type == 'application/json':
+        decode = lambda x: json.loads(x, cls=SWHJSONDecoder)  # noqa
+    else:
+        raise ValueError('Wrong content type `%s` for API request'
+                         % content_type)
+
+    buffer = b''
     with objstorage.chunk_writer(obj_id) as write:
-        # XXX (3.5): use 'async for chunk in request.content.iter_any()'
         while not request.content.at_eof():
-            chunk = yield from request.content.readany()
-            write(chunk)
+            data, eot = await request.content.readchunk()
+            buffer += data
+            if eot:
+                write(decode(buffer))
+                buffer = b''
 
     return encode_data(obj_id)
 
 
-@asyncio.coroutine
-def get_stream(request):
+async def get_stream(request):
     hex_id = request.match_info['hex_id']
     obj_id = hashutil.hash_to_bytes(hex_id)
     response = aiohttp.web.StreamResponse()
-    yield from response.prepare(request)
+    await response.prepare(request)
     for chunk in request.app['objstorage'].get_stream(obj_id, 2 << 20):
         response.write(chunk)
-        yield from response.drain()
+        await response.drain()
     return response