2019-10-15 Afternoon essay

逃离我推掉我的手 2023-06-08 02:37 6阅读 0赞

## AfterNoon ##

## Node Red ##

*  a programming tool for wiring together hardware devices, APIs and online services in new and interesting ways.
 *  browser-based flow editing  
    ![avatar][]
 *  based node.js
 *  stored using JSON

### Install ###

*  node.js [https://nodejs.org/en/][https_nodejs.org_en]
 *  Installing with npm

npm install -g --unsafe-perm node-red

*  Installing with docker

docker run -it -p 1880:1880 --name mynodered nodered/node-red

*  Installing with snap

sudo snap install node-red

### Running ###

$ node-red

then open the browser at [http://localhost:1880][http_localhost_1880]

*  command-line usage

<table> 
 <thead> 
  <tr> 
   <th>option</th> 
   <th>description</th> 
  </tr> 
 </thead> 
 <tbody> 
  <tr> 
   <td>-p,–port PORT</td> 
   <td>set the TCP port,default 1880</td> 
  </tr> 
  <tr> 
   <td>–safe</td> 
   <td>start node red without startting flows</td> 
  </tr> 
  <tr> 
   <td>–s,–settings File</td> 
   <td>setting the settings file ,default settings.js in userDir.</td> 
  </tr> 
  <tr> 
   <td>-title TITLE</td> 
   <td>set process window title</td> 
  </tr> 
  <tr> 
   <td>-u,–userDir Dir</td> 
   <td>set the user directory to user,default ~/.node-red</td> 
  </tr> 
  <tr> 
   <td>-v</td> 
   <td>enables verbose output</td> 
  </tr> 
  <tr> 
   <td>-?,–help</td> 
   <td>shows command-line usage help and exists</td> 
  </tr> 
 </tbody> 
</table>

default flows file flows\_.json

*  update

npm install -g --unsafe-perm node-red

## hello world ##

*  Access the editor  
    [http://localhost:1880][http_localhost_1880]  
    or  
    [http://<ip-address>:1880][http_ip-address_1880]
 *  Add an Inject node
 *  Add a Debug node
 *  Wire the two together
 *  Deploy  
    Click the Deploy button.
 *  Add a Function node  
    write JavaScript code.

# InfluxDB #

*  a time series database
 *  supports high write and query loads
 *  SQL-like query
 *  supports HTTP API

## Install ##

[https://www.influxdata.com/get-influxdb/][https_www.influxdata.com_get-influxdb]

## Compare with MySQL ##

<table> 
 <thead> 
  <tr> 
   <th>InfluxDB</th> 
   <th>MySQL</th> 
  </tr> 
 </thead> 
 <tbody> 
  <tr> 
   <td>database</td> 
   <td>database</td> 
  </tr> 
  <tr> 
   <td>measurement(auto create)</td> 
   <td>table</td> 
  </tr> 
  <tr> 
   <td>points</td> 
   <td>line</td> 
  </tr> 
  <tr> 
   <td>key</td> 
   <td>field</td> 
  </tr> 
  <tr> 
   <td>value</td> 
   <td>value</td> 
  </tr> 
 </tbody> 
</table>

## Running ##

$ influx -precision rfc3339
    Connected to http://localhost:8086 version 1.7.x
    InfluxDB shell 1.7.x
    >

*  create database

CREATE DATABASE mydb

*  show databases

SHOW DATABASES

*  user database  
    before write and read,please use

USE <db-name>

to select the databse,for example

USER mydb

*  insert data  
    insert measurement, key=value…

INSERT cpu,host=serverA,region=us_west value=0.64

*  select data  
    select field from measurement

SELECT "host", "region", "value" FROM "cpu"

## HTTP API ##

status code:

2xx: request success
    4xx: send wrong data
    5xx: server error

--------------------

*  create database

curl -i -XPOST http://localhost:8086/query --data-urlencode "q=CREATE DATABASE mydb"

*  insert data

curl -i -XPOST 'http://localhost:8086/write?db=mydb' --data-binary 'cpu,host=server01,region=us-west value=0.64 1434055562000000000'

*  select data

curl -G 'http://localhost:8086/query?pretty=true' --data-urlencode "db=mydb" --data-urlencode "q=SELECT \"value\" FROM \"cpu_load_short\" WHERE \"region\"='us-west'"

[avatar]: /images/20230601/f215216304e847e09666e7ef16b39f54.png
[https_nodejs.org_en]: https://nodejs.org/en/
[http_localhost_1880]: http://localhost:1880
[http_ip-address_1880]: http://%3Cip-address%3E:1880
[https_www.influxdata.com_get-influxdb]: https://www.influxdata.com/get-influxdb/