We call custom develop apps those applications that a user develops to meet their needs; these can be developed in C, Python, Javascript... among others.

How to build an application

In this section we'll look at how to create an application in the first place.

An overview of what we're going to do:

• Create a sample application locally on our computer
• Compress the application
• Install the application using the Syrus 4 Management Tool Apps Manager
• Create an instance of the application and run it on the Syrus 4
• View the logs in the Syrus 4

To get started you'll need to create a package.json file, similar to how you would for a JS/Node project, as well as an init.sh file.

package.json

Assuming we create an application called MyApp from scratch locally on our computer.

$ mkdir MyApp
$ cd MyApp/

We can use npm init to create the package.json file with the default values.

$ npm init

package name: (myapp) 
version: (1.0.0) 
description: My first app
entry point: (index.js) 
test command: 
git repository: 
keywords: syrus4
author: DCT
license: (ISC) 
About to write to /Projects/dct/apps/MyApp/package.json:

{
  "name": "myapp",
  "version": "1.0.0",
  "description": "My first app",
  "main": "index.js",
  "scripts": {
	"test": "echo \"Error: no test specified\" && exit 1"
  },
  "keywords": [
	"syrus4"
  ],
  "author": "[email protected]",
  "license": "ISC"
}

Is this OK? (yes) yes

A valid package.json for Syrus 4 must contain the "name", "version", "description", "main", and "minApexVersion" fields.

Example package.json file:

{
	"name": "myapp",
	"version": "1.0.0",
	"description": "My first app",
	"main": "index.js",
	"icon": "https://image.flaticon.com/icons/svg/2948/2948003.svg",
	"minApexVersion": "20.25.00",
	"repository": "https://www.github.com/path/to/app/",
	"scripts": {
		"test": "echo \"Error: no test specified\" && exit 1"
	},
	"keywords": [
		"syrus4" 
	],
	"author": "[email protected]",
	"license": "ISC",
	"dependencies": {}
}

Please note that the name of the application cannot be longer than 50 characters

index.js

Once you have your package.json specified, you can create your main file index.js and start adding packages and consuming the API.

An example using request

$ npm install request

Create a new file index.js and use this sample code

const request = require("request");
var options = {
	'method': 'GET',
	'url': 'http://localhost:8080/gps/position'
};
request(options, function (error, response) {
	if (error) throw new Error(error);
	payload = JSON.parse(response.body);
	console.log(payload)
});

init.sh

The init.sh file is a script which indicates the starting point for your application. It's executed anytime that syrus-apps-manager starts your application. Make sure this file is executable (chmod +x init.sh):

Example init.sh file:

node index.js

Zipping

At this point in your directory you should have

MyApp/
├── index.js
├── init.sh
├── node_modules/
├── package-lock.json
└── package.json

You can now zip your files into a folder and add it using the Syrus 4 Application Manager.

🚧

Zipping Contents

Make sure that you zip the files into a folder instead of zipping the folder

Incorrectly Zipped

$ zipinfo MyBrokenApp.zip| grep -v "/."  
Archive:  MyBrokenApp.zip  
Zip file size: 1568567 bytes, number of entries: 1408  
drwx------  2.0 unx        0 bx stor 23-Nov-08 23:42 MyBrokenApp/
1408 files, 4106784 bytes uncompressed, 1218827 bytes compressed:  70.3%

Correctly Zipped

$ zipinfo MyApp | grep -v "/."
Archive:  MyApp.zip
Zip file size: 1308204 bytes, number of entries: 705
-rw-r--r--  2.0 unx    11916 bX defN 21-Apr-21 09:50 package-lock.json
-rw-r--r--  2.0 unx      444 bX defN 21-Apr-21 09:50 package.json
-rw-r--r--  2.0 unx      265 bX defN 21-Apr-21 09:25 index.js
-rwxr-xr-x  2.0 unx       14 bX defN 21-Apr-21 09:26 init.sh
drwxr-xr-x  2.0 unx        0 bx stor 21-Apr-21 09:50 node_modules/
705 files, 3983889 bytes uncompressed, 1150036 bytes compressed:  71.1%

📘

Zip tool in Mac

If you are using Mac you may want to use the zip tool to manually remove unnecessary files from the zipped results

Shell

# view zip info
zipinfo MyApp.zip

# delete a single file from zip 
zip -d MyApp.zip file_to_delete.txt

# remove all files under __MACOSX* directory
zip -d MyApp.zip '__MACOSX*'

How to install an Application

Once you have a .zip file with your application, you can install it via Management Tool like this:

1. Go to application section and upload your application.

   

2. Install your application.

   

   
   

3. Click on your app and create an instance.

   

   
   

   

4. Start your instance.

   

   
   

5. Once you click start you can check the logs:

syrus4g@syrus-867698040012345:$ cat /data/logs/myapplication-out.log

{
  coords: {
	latitude: 25.783675,
	longitude: -80.293561,
	speed: 0.046388926000000004,
	accuracy: 2.9499999999999997,
	altitude: 12.207,
	bearing: 346.74,
	altitudeAccuracy: 4.95
  },
  timestamp: 1619013443,
  extras: {
	hdop: 0.59,
	vdop: 0.99,
	pdop: 1.16,
	fix: 3,
	satsActive: 18,
	criteria: 'signal'
  }
}

Click here to view the project on Github and download the example.

Versioning

You can have different versions of your application which allow users to view Your application can manage different
Automatic versioning can be achieved in two steps.

1. specify in the package.json a key called repository with a link to your application's repo.

	"repository": "https://www.github.com/path/to/app/",

2. In the repository create a file with the name: version.json, with the contents being a key called stable and the version is stable.

From there on, the Syrus 4 UI App Manager will display a button for users to click to update to that version, if it detects a newer version than the current one installed on the Syrus, then it will show button with an available upgrade.

{
	"stable": "1.22.0"
}

User Input / JSON Schema

The schema is an optional object that you can include in the package.json file which will produce forms for your application, allowing you to automatically expose input fields and information via a graphical UI for users to input rather than having them edit any json configuration file.

An example schema is:

{
	...
	"schema": {
		"type": "object",
		"required": [
			"api_token"
		],
		"properties": {
			"account": {
				"label": "User Account Name",
				"description": "Name for the account used in application",
				"type": "string",
				"minLength": 3,
				"maxLength": 50
			},
			"api_token": {
				"label": "Token",
				"description": "Application token",
				"type": "string",
				"fullWidth": true
			}
		}
	}
}

For more information visit JSON Schema Format