What is a geo-grid system? You must be familiar with the words “longitude” and “latitude”. They are used to identify a point on the Eath’s surface. They represent the angle (in degrees) between the point and the Earth’s center. Usually they are shown as float point numbers. To give an rough idea, 1 degree of latitude is roughly 110km (longi...

Recap In the previous post explained the architecture of the courier recommendation prototype and features of Akka. In this post we will explain some of the challenges faced by distributed systems, and how we can solve them. Has it failed? Distributed systems need to exchange data between nodes to ensure data consistency (unless you have a m...

Recap In the previous post we demoed a distributed courier recommendation prototype and introduced the actor systems. In this post we will explain the prototype in some more details. The Prototype The most important idea of the prototype is that everything is an actor. Those include the each courier, each restaurant, as well as each grid ce...

The Problem At Lastmilelink we need to manage a large fleet of couriers to get goods delivered to customers efficiently. On a typical day there are thousands of deliveries, with customers, controllers and couriers constantly sending data to the backend system. Some of the biggest challenges of processing the data related to couriers are: ...

You’ll find this post in your _posts directory. Go ahead and edit it and re-build the site to see your changes. You can rebuild the site in many different ways, but the most common way is to run jekyll serve, which launches a web server and auto-regenerates your site when a file is updated. To add new posts, simply add a file in the _posts dire...

C，C++和C#的关系 C是纯面向过程语言，C++在C的基础上加入了面向对象和库的概念。C#是微软自个儿搞出来的一个语言，和Java类似，算是高级语言，和C、C++没半点关系。 IDE Visual Studio — 只适用于Windows Eclipse — 跨平台多语言编辑器 CLion — JetBrains的新作品。懂Java的同学都知道他们的Intellij吧？ 书籍 C语言程序设计现代方法（第二版） — 经典教科书，但电子版只有220MB的扫描版 C程序设计语言 — C的白皮书 帝国理工的C语言笔记 — 可以作为快速入门手册和语言参考，没有高级应用 课程 Learn C the hard way — 超精简课程，两天就能学完，只不...