ZKLUA: an one-minute introduction for beginners

Zklua is the first(as far as I know) lua binding of apache zookeeper. If you are wondering what is apache zookeeper, please visit the zookeeper official website to get more information about it, hereinafter is an one-sentence description that can inform of you what is apache zookeeper:

ZooKeeper is a high-performance coordination service for distributed applications. It exposes common services - such as naming, configuration management, synchronization, and group services - in a simple interface so you don't have to write them from scratch. You can use it off-the-shelf to implement consensus, group management, leader election, and presence protocols.

Zklua provides a complete API binding of Lua for apache zookeeper(hereinafter referred to as zookeeper), including synchronous and asynchronous interface as well as some useful auxiliary APIs. That is, you may create/delete/get/update(CRUD) a zookeeper node(ZNode) in lua language synchronously and/or asynchronously without any pains.

How to build zklua

Prepare to build zklua

First of all, you have to get zklua source code from github:

$ git clone [email protected]:forhappy/zklua.git

Dependencies

Zklua has no other dependencies except for zookeeper c API implementation, which usually resides in zookeeper-X.Y.Z/src/c, hence you need to install zookeeper c API at first.

Install zklua

all you have to do is just a make to compile zklua:

$ make

If you want to install zklua into your system after you have compiled zklua, you need to make install(as root):

$ make install

Getting started in 5 minutes

Examples

Deleting a ZNode.

Here is a tiny lua example to show you deleting a ZNode from zookeeper server.

require "zklua"
  
function zklua_my_watcher(zh, type, state, path, watcherctx)
    if type == zklua.ZOO_SESSION_EVENT then
        if state == zklua.ZOO_CONNECTED_STATE then
            print("Connected to zookeeper service successfully!\n");
            elseif (state == ZOO_EXPIRED_SESSION_STATE) then
            print("Zookeeper session expired!\n");
        end
    end
end
	
function zklua_my_void_completion(rc, data)
    print("zklua_my_void_completion:\n")
    print("rc: "..rc.."\tdata: "..data)
end
	
zklua.set_log_stream("zklua.log")
	
zh = zklua.init("127.0.0.1:2181,127.0.0.1:2182,127.0.0.1:2183", zklua_my_watcher, 10000)
	
ret = zklua.adelete(zh, "/zklua", -1, zklua_my_void_completion, "zklua adelete.")
print("zklua.adelete ret: "..ret)
	
print("hit any key to continue...")
io.read()

Set watch on a specified path.

Here is a tiny lua example to show you set a watch on a specified path.

require "zklua"
    
function zklua_my_global_watcher(zh, type, state, path, watcherctx)
    if type == zklua.ZOO_SESSION_EVENT then
        if state == zklua.ZOO_CONNECTED_STATE then
            print("Connected to zookeeper service successfully!\n");
         elseif (state == ZOO_EXPIRED_SESSION_STATE) then
            print("Zookeeper session expired!\n");
        end
    end
end

function zklua_my_local_watcher(zh, type, state, path, watcherctx)
    print("zklua_my_local_watcher(".."type: "..type..", state: "..state..", path: "..path..")")
    print("zklua_my_local_watcher(".."watcherctx: "..watcherctx..")")
end
    
function zklua_my_stat_completion(rc, stat, data)
    print("zklua_my_stat_completion:\n")
    print("rc: "..rc.."\tdata: "..data)
end
    
zklua.set_log_stream("zklua.log")
    
zh = zklua.init("127.0.0.1:2181,127.0.0.1:2182,127.0.0.1:2183", zklua_my_global_watcher, 10000)
    
ret = zklua.awexists(zh, "/zklua",
                     zklua_my_local_watcher,"zklua_my_local_watcher",
                     zklua_my_stat_completion, "zklua aexists.")
print("zklua.aexists ret: "..ret)
    
print("hit any key to continue...")
io.read()

API specification

See docs/zklua.lua for more details about zklua's API specification.

License

Licensed to the Apache Software Foundation (ASF) under one or more contributor license agreements. See the NOTICE file distributed with this work for additional information regarding copyright ownership. The ASF licenses this file to you under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

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.