功能演进：

V1:

• 基础http服务器
• 支持中间件
• 支持异步中间件

V1.x:

• JS切换为TS
• request/response装饰增强
• 细化统一异常处理
• 细化流程控制

V2:

• AOP自定义注解拦截
• IOC管理注入@Controller/@Service组件
• @Request标记handler
• @ResponseBody自动处理返回值
• 事务

V2.x:

• 缓存框架
• 权限认证（AOP,策略模式,装饰模式）

V1:

SOS.js

const http = require('http');
const url = require('url');
const EventEmitter = require('events');

const compose = (ctx) => (...funcs) => {
    if (funcs.length === 0) {
        return arg => arg
    }
    let lastIndex = funcs.length - 1;
    return funcs.reduceRight((a, b, index) => b(() => {
        if (index === funcs.length - 1) {
            return Promise.resolve();
        }
        if (lastIndex !== index) {
            return Promise.reject(new Error('can not call next() over once!'))
        }
        lastIndex--;
        try {
            return Promise.resolve(a(ctx));
        } catch (e) {
            return Promise.reject(e);
        }
    }), 1);
};


const applyMiddleware = (middles, ctx) => compose(ctx)(...middles);

class SOS extends EventEmitter {
    constructor() {
        this.middleWares = [];
        this.serve = http.createServer(async (req, res) => {
            const ctx = { req, res };
            const handler = applyMiddleware(this.middleWares, ctx);
            await handler(ctx);
            res.finisn || res.end();
        });
    }

    use(mid) {
        this.middleWares.push(mid);
    }

    listen(...agr) {
        this.serve.listen(...agr);
        console.log('starting');
    }

    onerror(err, ctx) {
        if (err.code === 'ENOENT') {
            ctx.status = 404;
        }
        else {
            ctx.status = 500;
        }
        let msg = err.message || '000 error';
        ctx.res.end(msg);

        this.emit('error', err);
    }
}

test.js

const sos = new SOS();
sos.listen(9009);

sos.use((next) =>async (ctx) => {
    console.log('\npathname::',url.parse(ctx.req.url).pathname);
    ctx.res.write(new Date()+'');
    console.log('before 111');
    ctx.res.write('before 111\n');
    await next();
    console.log('after 111');
    ctx.res.write('after 111\n');
});
sos.use((next) =>async (ctx) => {
    console.log('before 222');
    ctx.res.write('before 222\n');
    await next();
    console.log('after 222');
    ctx.res.write('end test222\n');
    return new Promise((resolve, reject) => {
      setTimeout(() => {
        console.log('timeout 222 ');
        ctx.res.write('timeout 222 \n');
        return resolve();
      }, 3000);
    });
});
sos.use((next) =>async (ctx) => {
    console.log('before 333');
    ctx.res.write('before 333\n');
    await next();
    console.log('after 333');
    ctx.res.write('end test333\n');
});