diff --git a/Makefile b/Makefile
index 9a5aaab76..a04366033 100644
--- a/Makefile
+++ b/Makefile
@@ -6,20 +6,20 @@ PROJECT_VERSION = 3.0
 
 DEPS = jsx gproc gen_rpc ekka esockd cowboy clique
 
-dep_jsx     = git https://github.com/talentdeficit/jsx 2.9.0
-dep_gproc   = git https://github.com/uwiger/gproc 0.8.0
-dep_gen_rpc = git https://github.com/emqx/gen_rpc 2.3.0
-dep_esockd  = git https://github.com/emqx/esockd v5.4.2
-dep_ekka    = git https://github.com/emqx/ekka v0.5.1
-dep_cowboy  = git https://github.com/ninenines/cowboy 2.4.0
-dep_clique  = git https://github.com/emqx/clique develop
+dep_jsx     = hex-emqx 2.9.0
+dep_gproc   = hex-emqx 0.8.0
+dep_gen_rpc = git-emqx https://github.com/emqx/gen_rpc 2.3.0
+dep_esockd  = git-emqx https://github.com/emqx/esockd v5.4.2
+dep_ekka    = git-emqx https://github.com/emqx/ekka v0.5.1
+dep_cowboy  = hex-emqx 2.4.0
+dep_clique  = git-emqx https://github.com/emqx/clique develop
 
 NO_AUTOPATCH = cuttlefish
 
 ERLC_OPTS += +debug_info -DAPPLICATION=emqx
 
 BUILD_DEPS = cuttlefish
-dep_cuttlefish = git https://github.com/emqx/cuttlefish v2.1.1
+dep_cuttlefish = git-emqx https://github.com/emqx/cuttlefish v2.1.1
 
 #TEST_DEPS = emqx_ct_helplers
 #dep_emqx_ct_helplers = git git@github.com:emqx/emqx-ct-helpers
@@ -47,6 +47,20 @@ PLT_APPS = sasl asn1 ssl syntax_tools runtime_tools crypto xmerl os_mon inets pu
 DIALYZER_DIRS := ebin/
 DIALYZER_OPTS := --verbose --statistics -Werror_handling -Wrace_conditions #-Wunmatched_returns
 
+define dep_fetch_git-emqx
+	git clone -q --depth 1 -b $(call dep_commit,$(1)) -- $(call dep_repo,$(1)) $(DEPS_DIR)/$(call dep_name,$(1)) > /dev/null 2>&1; \
+	cd $(DEPS_DIR)/$(call dep_name,$(1));
+endef
+
+core_http_get-emqx = curl -Lf$(if $(filter-out 0,$(V)),,s)o $(call core_native_path,$1) $2
+
+define dep_fetch_hex-emqx
+	mkdir -p $(ERLANG_MK_TMP)/hex $(DEPS_DIR)/$1; \
+	$(call core_http_get-emqx,$(ERLANG_MK_TMP)/hex/$1.tar,\
+		https://repo.hex.pm/tarballs/$1-$(strip $(word 2,$(dep_$1))).tar); \
+	tar -xOf $(ERLANG_MK_TMP)/hex/$1.tar contents.tar.gz | tar -C $(DEPS_DIR)/$1 -xzf -;
+endef
+
 include erlang.mk
 
 clean:: gen-clean rebar-clean
@@ -119,7 +133,7 @@ comma = ,
 quote = \"
 curly_l = "{"
 curly_r = "}"
-dep-versions = [$(foreach dep,$(DEPS) $(BUILD_DEPS),$(curly_l)$(dep),$(quote)$(word 3,$(dep_$(dep)))$(quote)$(curly_r)$(comma))[]]
+dep-versions = [$(foreach dep,$(DEPS) $(BUILD_DEPS),$(curly_l)$(dep),$(quote)$(word $(words $(dep_$(dep))),$(dep_$(dep)))$(quote)$(curly_r)$(comma))[]]
 
 .PHONY: dep-vsn-check
 dep-vsn-check:
diff --git a/README.md b/README.md
index f8872e8a0..8d03df8dd 100644
--- a/README.md
+++ b/README.md
@@ -63,6 +63,15 @@ You can reach the EMQ community and developers via the following channels:
 
 Please submit any bugs, issues, and feature requests to [emqx/emqx](https://github.com/emqx/emqx/issues).
 
+## MQTT Specifications
+
+You can read the mqtt protocol via the following links:
+
+[MQTT Version 3.1.1](https://docs.oasis-open.org/mqtt/mqtt/v3.1.1/os/mqtt-v3.1.1-os.html)
+
+[MQTT Version 5.0](https://docs.oasis-open.org/mqtt/mqtt/v5.0/cs02/mqtt-v5.0-cs02.html)
+
+[MQTT SN](http://mqtt.org/new/wp-content/uploads/2009/06/MQTT-SN_spec_v1.2.pdf)
 
 ## License
 
@@ -74,4 +83,3 @@ Licensed under the Apache License, Version 2.0 (the "License");you may not use t
 
 Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 See the License for the specific language governing permissions and limitations under the License.
-
diff --git a/docs/.placeholder b/docs/.placeholder
deleted file mode 100644
index e69de29bb..000000000
diff --git a/docs/MQTT-SN_spec_v1.2.pdf b/docs/MQTT-SN_spec_v1.2.pdf
deleted file mode 100644
index ee6020d23..000000000
Binary files a/docs/MQTT-SN_spec_v1.2.pdf and /dev/null differ
diff --git a/docs/README b/docs/README
deleted file mode 100644
index 94f96fb12..000000000
--- a/docs/README
+++ /dev/null
@@ -1,11 +0,0 @@
-
-http://emqttd.io/docs/v2/
-
-or
-
-http://docs.emqtt.com/
-
-or
-
-http://emqttd-docs.rtfd.org
-
diff --git a/docs/mqtt-v3.1.1.pdf b/docs/mqtt-v3.1.1.pdf
deleted file mode 100644
index e4095f1b5..000000000
Binary files a/docs/mqtt-v3.1.1.pdf and /dev/null differ
diff --git a/docs/mqtt-v5.0.pdf b/docs/mqtt-v5.0.pdf
deleted file mode 100644
index c3d0c9725..000000000
Binary files a/docs/mqtt-v5.0.pdf and /dev/null differ
diff --git a/rebar.config.script b/rebar.config.script
index 0b18592f1..aed271af8 100644
--- a/rebar.config.script
+++ b/rebar.config.script
@@ -1,13 +1,21 @@
 
+CONFIG0 = case os:getenv("REBAR_GIT_CLONE_OPTIONS") of
+              "--depth 1" ->
+                  CONFIG;
+              _ ->
+                  os:putenv("REBAR_GIT_CLONE_OPTIONS", "--depth 1"),
+                  CONFIG
+          end,
+
 CONFIG1 = case os:getenv("TRAVIS") of
-  "true" ->
-    JobId = os:getenv("TRAVIS_JOB_ID"),
-    [{coveralls_service_job_id, JobId},
-     {coveralls_coverdata, "_build/test/cover/*.coverdata"},
-     {coveralls_service_name , "travis-ci"} | CONFIG];
-  _ ->
-    CONFIG
-end,
+              "true" ->
+                  JobId = os:getenv("TRAVIS_JOB_ID"),
+                  [{coveralls_service_job_id, JobId},
+                   {coveralls_coverdata, "_build/test/cover/*.coverdata"},
+                   {coveralls_service_name , "travis-ci"} | CONFIG];
+              _ ->
+                  CONFIG
+          end,
 
 {_, Deps} = lists:keyfind(deps, 1, CONFIG1),
 {_, OurDeps} = lists:keyfind(github_emqx_deps, 1, CONFIG1),