# Web侧高频数据 chart 展示预研说明文档 

Author: 彭玲 	CreatedTime: 2021/5/11 

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## 背景 

目前，光纤光栅、振动连续采集、动应变、GNSS 实时动态解析等的采样频率高达到 1~100Hz（或更高）。针对高频采样，之前接入侧常采用”降低采样频率“”分时段采样（振动）“等处理方式，但存在数据”丢失“的必然结果。

为满足客户对高频数据接入的需求，针对高频数据采集进行了专项处理：平台侧接收原始采集粒度数据、存储于 HDFS 文件系统中，并提供 HDFS 查询服务和可视化 (不限于平台)。



## 功能说明 

Web侧将平台接入的高频数据以图表形式进行展示。

### 输入 

输入为：chart 图片的 Base64 地址 (Data URLs) 

- Data URLs：`data:image/png;base64,<image-data>` 
- Base64 图片来源：平台 PyRpcService (http://10.8.30.22/FS-Anxinyun/trunk/codes/services/PyRpcService) 接口查询服务`high_frequency_chart`(查询 HDFS 存储数据) 

### 输出 

输出为：chart 图片 

必要的查询组件：**结构物**选择器、**起止时间**选择框 

![](E:\WorkSpace\iFS-Backend\高频数据接入\assets\高频数据展示-web-demo.png)



## Postman 请求 

参数说明：

- HDFS 文件地址，包括：结构物 id，HDFS 文件夹 `<年份>`，HDFS 文件夹 `<月份>` 
- 查询起止时间：Unix 时间戳 (ms) 

![](E:\WorkSpace\iFS-Backend\高频数据接入\assets\Postman RPC：high_frequency_chart.png)



## 关键代码 

### web-api 

```js
const request = require('superagent')

module.exports = {
    entry: function (app, router, opts) {

        const RPC_SVR_URL = opts.highFrequencyChartRpcSvrUrl || `http://localhost:15000/api`;

        let fetchHighFrequencyChartData = async function (ctx, next) {
            const params = ctx.request.body;
            try {
                const reqBody = {
                    "jsonrpc": "2.0",
                    "id": "myid",
                    "method": "high_frequency_chart",
                    "params": params,
                    // "params": {
                    //     "url": "/anxinyun/structure_data/structure_854/raw/2021/2/gxwd1-1.csv",
                    //     "gte": 1613810269584,
                    //     "lt": 1613810706956
                    // }
                }
                const proxyReq = request.post(RPC_SVR_URL).send(reqBody)
                const res = await proxyReq

                ctx.status = res.status
                ctx.body = { data: res.body.result }
            } catch (e) {
                let errMsg = `fetch high_frequency_chart data error: ${e}`
                ctx.status = 500;
                ctx.fs.logger.error(errMsg)
                ctx.body = { err: errMsg }
            }
        }

        router.post('/_high_frequency_chart', fetchHighFrequencyChartData)
    }
};

```



### web 

```js
import React, { Component } from 'react'

import { Select, DatePicker } from 'antd'
const Option = Select.Option
const { RangePicker } = DatePicker

const request = require('superagent')

class HighFrequencyChart extends Component {
    constructor(props) {
        super(props)

        this.state = {
            chartData: null
        }
    }

    fetchHighFrequencyChartData = () => {
        let structId = 854
        let hdfsDirYear = '2021',
            hdrsDirMonth = '2'
        let filterBegin = 1613810269584, // 2021-02-20 16:37:49
            fiterEnd = 1613810706956 // 2021-02-20 16:45:06

        const params = {
            // Example: /anxinyun/structure_data/structure_854/raw/2021/2/gxwd1-1.csv 
            "url": `/anxinyun/structure_data/structure_${structId}/raw/${hdfsDirYear}/${hdrsDirMonth}/gxwd1-1.csv`,
            "gte": filterBegin, // begin time for part of the HDFS resource 
            "lt": fiterEnd // end time for part of the HDFS resource 
        }

        request.post('_high_frequency_chart').send(params).end((err, res) => {
            if (!err) {
                let chartData = res.body.data
                this.setState({ chartData })
            } else {
                // handle err msg... 
            }
        })
    }

    componentDidMount() {
        this.fetchHighFrequencyChartData()
    }

    renderStructures = () => {
        return (
            <Select
                showSearch
                style={{ width: 200 }}
                placeholder="Select a structure"
                optionFilterProp="children"
                filterOption={(input, option) => option.props.children.toLowerCase().indexOf(input.toLowerCase()) >= 0}
            >
                <Option value="bridge">桥梁 #1</Option>
                <Option value="slope">边坡 #2</Option>
            </Select>
        )
    }

    renderRangePicker = () => {
        return (
            <RangePicker
                showTime={{ format: 'HH:mm' }}
                format="YYYY-MM-DD HH:mm"
                placeholder={['Start Time', 'End Time']}
            />
        )
    }

    renderHighFrequencyChart = () => {
        let data = this.state.chartData
        if (data) {
            return <img src={data} width='1000' height='500' />
        }
        return null
    }

    render() {
        return (
            <div>
                <section style={{ padding: '32px 0' }}>
                    <span>结构物选择：</span>{this.renderStructures()}
                    <span style={{ paddingLeft: '24px' }}>起止时间选择：</span>{this.renderRangePicker()}
                </section>

                {/* HighFrequencyChart Module */}
                <section>
                    {this.renderHighFrequencyChart()}
                </section>
            </div>
        )
    }
}

export default HighFrequencyChart

```