diff --git a/README.md b/README.md
index 960889f..906815b 100644
--- a/README.md
+++ b/README.md
@@ -23,6 +23,21 @@ let g:langserver_executables = {
       \ }
 ```
 
+To start the language server, run the command:
+
+```vim
+:LSPStart
+```
+
+After starting the language server, you should be able to run commands like:
+
+```vim
+:LSPGoto
+:LSPHover
+```
+
+and some more to come.
+
 More configuration to come...
 
 ## Plans
diff --git a/autoload/langserver/api/textDocument.vim b/autoload/langserver/api/textDocument.vim
index 25f5e02..6cf3f09 100644
--- a/autoload/langserver/api/textDocument.vim
+++ b/autoload/langserver/api/textDocument.vim
@@ -7,3 +7,7 @@ function! langserver#api#textDocument#definition(request) abort
         \ {},
         \ )
 endfunction
+
+function! langserver#api#textDocument#completion(request) abort
+
+endfunction
diff --git a/autoload/langserver/client.vim b/autoload/langserver/client.vim
index 020401d..78fd8c1 100644
--- a/autoload/langserver/client.vim
+++ b/autoload/langserver/client.vim
@@ -1,4 +1,4 @@
-let s:lsp_clients = {} " { id, opts, req_seq, on_notifications: { request, on_notification }, stdout: { max_buffer_size, buffer, next_token, current_content_length, current_content_type } }
+let s:lsp_clients = {}
 let s:lsp_token_type_contentlength = 'content-length'
 let s:lsp_token_type_contenttype = 'content-type'
 let s:lsp_token_type_message = 'message'
@@ -14,11 +14,14 @@ function! s:_on_lsp_stdout(id, data, event) abort
         "     \ 'id': l:lsp_client_id,
         "     \ 'opts': a:opts,
         "     \ 'req_seq': 0,
-        "     \ 'on_notifications': {},
+        "     \ 'lock': langserver#lock#semaphore(),
+        "     \ 'request_notifications': {},
         "     \ 'stdout': {
         "         \ 'max_buffer_size': l:max_buffer_size,
         "         \ 'buffer': '',
         "         \ 'next_token': s:lsp_token_type_contentlength,
+        "         \ 'current_content_length': ,
+        "         \ 'current_content_type': ,
         "     \ },
         " \ }
         let l:client = s:lsp_clients[a:id]
@@ -126,6 +129,7 @@ function! s:lsp_start(opts) abort
         \ 'id': l:lsp_client_id,
         \ 'opts': a:opts,
         \ 'req_seq': 0,
+        \ 'lock': langserver#lock#semaphore(),
         \ 'on_notifications': {},
         \ 'stdout': {
             \ 'max_buffer_size': l:max_buffer_size,
diff --git a/autoload/langserver/completion.vim b/autoload/langserver/completion.vim
new file mode 100644
index 0000000..81b0efa
--- /dev/null
+++ b/autoload/langserver/completion.vim
@@ -0,0 +1,38 @@
+function! langserver#completion#callback(id, data, event) abort
+  let l:parsed_data = langserver#callbacks#data(a:id, a:data, a:event)
+  if l:parsed_data == {}
+    return
+  endif
+
+  " {'isIncomplete': bool, 'items': [CompletionItems]}
+  let l:completion_items = l:parsed_data['items']
+
+endfunction
+
+function! langserver#completion#request(...) abort
+  return langserver#client#send(langserver#util#get_lsp_id(), {
+        \ 'method': 'textDocument/completion',
+        \ 'params': langserver#util#get_text_document_position_params(),
+        \ })
+endfunction
+
+let s:CompletionItemKind = {
+      \ 'Text': 1,
+      \ 'Method': 2,
+      \ 'Function': 3,
+      \ 'Constructor': 4,
+      \ 'Field': 5,
+      \ 'Variable': 6,
+      \ 'Class': 7,
+      \ 'Interface': 8,
+      \ 'Module': 9,
+      \ 'Property': 10,
+      \ 'Unit': 11,
+      \ 'Value': 12,
+      \ 'Enum': 13,
+      \ 'Keyword': 14,
+      \ 'Snippet': 15,
+      \ 'Color': 16,
+      \ 'File': 17,
+      \ 'Reference': 18
+      \ }
diff --git a/autoload/langserver/hover.vim b/autoload/langserver/hover.vim
index 0d357bb..1d1f8d6 100644
--- a/autoload/langserver/hover.vim
+++ b/autoload/langserver/hover.vim
@@ -20,6 +20,9 @@ function! langserver#hover#request() abort
   return langserver#client#send(langserver#util#get_lsp_id(), {
         \ 'method': 'textDocument/hover',
         \ 'params': langserver#util#get_text_document_position_params(),
+        \ 'on_notification': {
+          \ 'callback': function('langserver#hover#callback'),
+          \ },
         \ })
 endfunction
 
@@ -38,7 +41,7 @@ function! langserver#hover#display(range, data) abort
 
   echo l:hover_string
 
-  return timer_start(5000, function('s:delete_highlight'))
+  return timer_start(3000, function('s:delete_highlight'))
 endfunction
 
 function! s:delete_highlight() abort
diff --git a/autoload/langserver/lock.vim b/autoload/langserver/lock.vim
new file mode 100644
index 0000000..3b99682
--- /dev/null
+++ b/autoload/langserver/lock.vim
@@ -0,0 +1,46 @@
+let s:unlocked_id = -1
+
+function! s:dict_lock(job_id) dict
+  if self.locked == v:false
+    let self.locked = v:true
+    let self.id = a:job_id
+    return v:true
+  else
+    return v:false
+  endif
+endfunction
+
+function! s:dict_unlock() dict
+  let self.id = s:unlocked_id
+  let self.locked = v:false
+endfunction
+
+function! s:get_id() dict
+  return self.id
+endfunction
+
+function! s:take_lock(job_id) dict
+  " If we're locked, kill the other job
+  " And set ourselves to be the current job.
+  if self.locked
+    " TODO: Don't actually want to stop the whole server...
+    " I just want to stop the current request. Maybe a send cancel request
+    " would be good enough. We will see.
+    " call langserver#job#stop(self.id)
+    call self.unlock()
+  endif
+
+  call self.lock(a:job_id)
+endfunction
+
+function! langserver#lock#semaphore() abort
+  let l:ret = {
+        \ 'id': s:unlocked_id,
+        \ 'locked': v:false,
+        \ }
+  let l:ret.lock = function('s:dict_lock')
+  let l:ret.unlock = function('s:dict_unlock')
+  let l:ret.get_id = function('s:get_id')
+  let l:ret.take_lock = function('s:take_lock')
+  return l:ret
+endfunction
diff --git a/rplugin/python3/deoplete/langserver.py b/rplugin/python3/deoplete/langserver.py
new file mode 100644
index 0000000..5a282b4
--- /dev/null
+++ b/rplugin/python3/deoplete/langserver.py
@@ -0,0 +1,24 @@
+from .base import  Base
+
+
+class Source(Base):
+    def __init__(self, nvim):
+        super(Source, self).__init__(nvim)
+
+        self.nvim = nvim
+        self.name = 'langserver'
+        self.mark = '[LSP]'
+
+    def on_event(self, context, filename=''):
+        pass
+
+    def gather_candidates(self, context):
+        user_input = context['input']
+        filetype = context.get('filetype', '')
+        complete_str = context['complete_str']
+
+        return [
+            {
+                'word': user_input + '_hello',
+            }
+        ]
diff --git a/tests/test_lock.vader b/tests/test_lock.vader
new file mode 100644
index 0000000..403c256
--- /dev/null
+++ b/tests/test_lock.vader
@@ -0,0 +1,22 @@
+Execute (Test Lock):
+  let my_lock = langserver#lock#semaphore()
+
+  AssertEqual v:false, my_lock.locked
+
+  call my_lock.lock(1)
+  AssertEqual v:true, my_lock.locked
+
+  call my_lock.unlock()
+  AssertEqual v:false, my_lock.locked
+
+  AssertEqual -1, my_lock.get_id()
+
+  call my_lock.lock(1)
+  AssertEqual 1, my_lock.get_id()
+
+  let set_result = my_lock.lock(2)
+  AssertEqual v:false, set_result
+  AssertEqual 1, my_lock.get_id()
+
+  call my_lock.take_lock(2)
+  AssertEqual 2, my_lock.get_id()