Cluster support is one of the big thing in slacker 0.6.x. Cluster enables high-availability and load balancing on slacker client and server.
Slacker cluster has a centralized registry, a zookeeper node, stores information of all the namespaces and servers instances in the cluster. Once a client declared remote functions, by calling `defn-remote` or `use-remote`, it reads all available servers offering that namespace from the registry and create connection to each of them. We the user issues a request, the client randomly pick up a connection from them. So the load is eventually distributed to every instance of slacker servers. And thanks to zookeeper’s notification feature, the client watches certain znode. It will be notified when 1. a connected server goes offline 2. a new server serving required namespace added into the cluster. Thus you don’t have to change client code or restart client when server changes.
To start a slacker server and add it to a cluster, you have to provide cluster information using the new :cluster option:
On the client side, it’s important to use APIs from `slacker.client.cluster` instead of `slacker.client`:
If all servers provide ‘slacker.example.api go offline, slacker client will raise a “not-found” exception.
Slacker cluster is also designed with simple and clean in mind. You don’t have to change you business code to make it remote or cluster. Everything is transparent and non-invasive. Enjoy it.
After 98 commits in about one month, I’m glad to announce [slacker "0.6.1"].
One thing in slacker 0.6.x is you can expose multiple namespaces from a single server.
Suppose you have two namespaces `redday.stats` and `redday.api`, both contains functions you want to expose.
This will expose `redday.stats` and `redday.api` on port 6565.
On the client side, we have a new `use-remote` behaviors like clojure’s use. Instead of local one, it imports functions from a remote namespace to your current namespace.
If you need to configure callback to a particular function, you can still use `defn-remote` to specify the callback function. In slacker 0.6.0, a `:remote-ns` is required when you define such a remote function.
The complete code example (both server and client) can be found here.
In next post, I will explain another big new feature of 0.6.x, cluster support.
今天是2月1号，本人决定从今天开始到月底的每个工作日中午去爬山锻炼身体，以摆脱目前体重极速增长的困局。口说无凭，立此为据。
利用春节的假期写了一个Android应用，可以在ClojureDocs.org上搜索clojure API，浏览文档、源代码和社区贡献的代码实例。ClojureDocs在我学习Clojure的过程中起了很大的作用，所以我想这个网站应该对很多人有用。
无暇去学习Android平台上繁琐的知识，不过好在有Phonegap这样的框架，可以把网页应用转化为本地应用，并且提供访问本地设备的API。通过Phonegap开发的程序还可以直接移植到iphone平台上。ClojureDocs Android就是运行在Phonegap中。
首页：
搜索界面
API函数界面
你可以从github获得代码和签名过的apk：https://github.com/sunng87/clojuredocs-android
Known Issue，phonegap程序在屏幕旋转时会崩溃，已经在2.3和3.2上重现，目前还不清楚具体的原因。(Edit 20120127: Fixed in 1.0.4)
欢迎任何的pull request。