云原生编程语言ballerina:hello-world

Posted by lyp on Wednesday, January 1, 2020

TOC

前言

Ballerina是一款完全开源的编译时强类型语言,愿景是让云原生时代的程序员轻松编写出想要的的软件.
开源地址:https://github.com/ballerina-platform/ballerina-lang

Example

下载对应平台的包进行安装

https://ballerina.io/downloads/

这里使用的是在ubuntu环境下安装,下载好deb包后,进行安装

lan@lan-machine:~$ sudo dpkg -i ballerina-linux-installer-x64-1.1.0.deb 
[sudo] password for lan: 
Selecting previously unselected package ballerina-1.1.0.
(Reading database ... 187196 files and directories currently installed.)
Preparing to unpack ballerina-linux-installer-x64-1.1.0.deb ...
Unpacking ballerina-1.1.0 (1.1.0) ...
Setting up ballerina-1.1.0 (1.1.0) ...
lan@lan-machine:~$ ballerina version
jBallerina 1.1.0
Language specification 2019R3
Ballerina tool 0.8.0

可以看到安装的ballerina的版本是1.1.0

Hello World Main

  1. 创建ballerina目录以及进入到ballerina目录下,这一步骤不是必须的,但为了文件整理,建议这样处理 lan@lan-machine:/disk/note$ mkdir ballerina && cd ballerina lan@lan-machine:/disk/note/ballerina$
  2. 创建hello-world.bal文件并写入hello-world print对应代码
    lan@lan-machine:/disk/note/ballerina$ touch hello-world.bal import ballerina/io; public function main() { io:println("Hello, World!"); }
  3. 运行hello-world ` lan@lan-machine:/disk/note/ballerina$ ballerina run hello-world.bal Compiling source hello-world.bal

Generating executables Running executables

Hello, World!

可以看到,已经成功输入 Hello World,最简单的一个例子完成了。

### Hello World Service

第二个hello-world的例子是启动一个监听9090端口的http服务器
1. 创建hello-world-service.bal文件并写入对应的代码

``
lan@lan-machine:/disk/note/ballerina$ touch hello-world-service.bal
``

import ballerina/http; import ballerina/log; service hello on new http:Listener(9090) {

resource function sayHello(http:Caller caller, http:Request req) {

    var result = caller->respond("Hello, World!");

    if (result is error) {
        log:printError("Error sending response", result);
    }
}

}

1. 运行hello-world-service.bal

lan@lan-machine:/disk/note/ballerina$ ballerina run hello-world-service.bal Compiling source hello-world-service.bal

Generating executables Running executables

[ballerina/http] started HTTP/WS listener 0.0.0.0:9090

lan@lan-machine:~$ curl http://localhost:9090/hello/sayHello Hello, World!

其中路径的组成是这样的,
1. http:Listener(9090) 构成监听端口9090,也就是localhost:9090
2. service hello 构成第一个路径
3. resource function sayHello 构成第二个路径
   
完整的组成之后就是http://localhost:9090/hello/sayHello

### Hello World Paraller
第三个hello-world的例子是异步任务的执行

1. 创建hello-world-paraller.bal文件并写入对应代码  
``
lan@lan-machine:/disk/note/ballerina$ touch hello-world-paraller.bal
``

import ballerina/io; public function main() { worker w1 { io:println(“Hello, World! #m”); }

worker w2 {
    io:println("Hello, World! #n");
}
worker w3 {
    io:println("Hello, World! #k");
}

}

1. 运行hello-world-paraller.bal 文件

lan@lan-machine:/disk/note/ballerina$ ballerina run hello-world-paraller.bal Compiling source hello-world-paraller.bal

Generating executables Running executables

Hello, World! #m Hello, World! #n Hello, World! #k lan@lan-machine:/disk/note/ballerina$ lan@lan-machine:/disk/note/ballerina$ lan@lan-machine:/disk/note/ballerina$ ballerina run hello-world-paraller.bal Compiling source hello-world-paraller.bal

Generating executables Running executables

Hello, World! #n Hello, World! #m Hello, World! #k

可以看到每次打印的顺序并不是一样的

### Hello World Client
最后一个hello-world的例子是http客户端请求

1. 创建hello-world-client.bar文件并写入对应代码
``
lan@lan-machine:/disk/note/ballerina$ touch hello-world-client.bal
``

import ballerina/http; import ballerina/io; public function main() { http:Client clientEP = new (“http://www.mocky.io");

var resp = clientEP->get("/v2/5ae082123200006b00510c3d/");

if (resp is http:Response) {
    var payload = resp.getTextPayload();
    if (payload is string) {

        io:println(payload);
    } else {

        io:println(payload.detail());
    }
} else {

    io:println(resp.detail());
}

}

2. 运行hello-world-client.bal文件

lan@lan-machine:/disk/note/ballerina$ ballerina run hello-world-client.bal Compiling source hello-world-client.bal

Generating executables Running executables ``` Hello World

例子中是请求 http://www.mocky.io/v2/5ae082123200006b00510c3d/ 并将结果打印出来

更多的example可以在官网找到