Micronats

MICRONATS 🚀 - A nats.io micro-service-framework for nodejs.

With this framework you can easily and very quickly create a micro-service for any requirement 🌈

What's inside?

• Publish / Subscribe
• Request / Response
• Fast & simple data storage
• Database-Events

Dependencies

• NATS.io server https://nats.io/download/

Content

• Installing
• Use
• Options
• Service
• $call
• $data
• $storage
• authors
• license

Installing

npm i micronats

Use

• Servicename - name of the service
• Hooks - event callbacks
• Methods - Middleware for the service
• Funcs - local functions
• Data - local data

Subject servicename.methodname, example user-service-example.addUser

const Micronats = require('micronats')
const mn = new Micronats(/* options */)

mn.create({
    servicename : 'user-service-example',
    beforeCreate(){
        console.log('HOOK: before create. No data or storage set')
    },
    created(){
        console.log('HOOK: created')
    },
    mounted(){
        console.log('HOOK: mounted. All done. Service is ready')
    },
    destroyed(){
        console.log('HOOK service destroyed')
    },
    methods : {
    },
    funcs : {
    },
    data(){
        // Local variables
        return {
        }
    }
})

// Start the services
mn.listen()

const Micronats = require('micronats')
const mn = new Micronats(/* options */)

mn.create({
    servicename : 'user-service-example',
    beforeCreate(){
        console.log('HOOK: before create. No data or storage set')
    },
    created(){
        console.log('HOOK: created')
    },
    mounted(){
        // Make some serivce registry here
        // Or get some data from another services
        // Read the storage, ... init some service-components
        // Start some other stuff
        console.log('HOOK: mounted. All done. Service is ready')
   
        // Call local function
        this.$call.setTimestamp()
        
        // Talk to services
        mn.service.publish('user-service-example.addScore', 
            { score : 3 }
        )

        mn.service.publish('dashboard-sevice.scores', 
            { score : this.$data.score }
        )

        mn.service.request('user-service-example.addUser', 
            { name : 'yamigr' }, 
            { max : 1}, 
            function(msg){
                console.log(msg)
        })

        mn.service.request('user-service-example.getAll', 
            {}, 
            { max : 1}, 
            function(msg){
                console.log(msg)
            })

        mn.service.request('user-service-example.delUser',
            {_id: '6oYDedYd'},
            { max : 1},
            function(msg){
                console.log(msg.err)
            })

        // Subscribe database events
        mn.service.subscribe('user-service-example.$storage.>', 
            function(msg, _, subject){
                console.log(subject, msg)
            })
    },
    destroyed(){
        console.log('HOOK service destroyed')
    },
    methods : {
        addUser(req, res){
            // add some service-methods
            // use this.$storage to store some data
            this.$storage.put(req, function(err, doc){
                res({message : 'User added', doc : doc, err : err})
            })
        },
        getAll(req, res){
            this.$storage.find({}, function(err, users){
                res({users : users})
            })
        },
        getUser(req, res){
            this.$storage.findOne(req._id, function(err, user){
                res({user : user})
            })
        },
        delUser(req, res){
            this.$storage.del(req._id, function(err){
                res({err : err})
            })
        },
        addScore(req){
            this.$data.score += req.score
            console.log(this.$data.score)
        }
        /*
            create more methods
        */
    },
    funcs : {
        setTimestamp(){
           // call local-functions with this.$call
           // access local-variables with this.$data
           this.$data.timestamp = Date() 
        }
    },
    data(){
        // Local variables
        return {
            timestamp : Date(),
            score : 42
        }
    }
})

///////////////////////////////////////////
// Listen runs the instances
mn.listen()

///////////////////////////////////////////
// Destroy a service by name
setTimeout(function(){
    mn.destroy('user-service-example')
}, 5000)

///////////////////////////////////////////
// Events
mn.on('err', function(err){
    console.log('error:', err)
})
mn.on('disconnect', function(err){
    console.log('disconnect')
})
mn.on('reconnecting', function(){
    console.log('reconnecting')
})
mn.on('reconnect', function(){
    console.log('reconnect')
})

Options

Important - Keep the json-options.

let options = {
    connection : {
        json : true,
        port : 4222,
        servers : ['nats://nats.io:4222']
    },
    db : {
        path : './db',
        options : {
            valueEncoding: 'json'
        }
    }
}
const mn = new Micronats(options)

Service

Communicate with services.

mn.service.publish('servicename.methodname', {/* data */})

mn.service.subscribe('servicename.$storage.eventname._id', function(msg, _, subject){
        console.log(subject, msg)
})

// Wildcard
mn.service.subscribe('servicename.$storage.eventname.>', function(msg, _, subject){
        console.log(subject, msg)
})

mn.service.request('servicename.methodname', function(msg){
        console.log(msg)
})

mn.service.requestOne('servicename.methodname', function(msg){
        console.log(msg)
})

Methods

Call a method from another service use the subject servicename.methodname and send the json-data.

addUser(req, res){
    // add some service-methods and handle the request and send a response
    this.$storage.put(req, function(err){
        res({message : 'User added'})
    })
}

$call

Call local functions.

funcs : {
    setTimestamp(){
        // call local-functions with this.$call in other methods
        // access the variables in data with this.$data
        this.$data.timestamp = Date() 
    }
}

Access the functions in methods or other functions.

this.$call.setTimestamp()

$data

Create the data object to set some local variables.

data(){
    // Use local variables with this.$data in other methods
    return {
        timestamp : Date()
    }
}

Access the variables in methods or functions.

this.$data.timestamp

$storage

Store data with this.$storage in the methods.

Insert single data

// Object without _id
this.$storage.put({...}, function(err, doc){
})

// Event from storage
mn.service.subscribe('servicename.$storage.put._id', function(msg, _, subject){
        console.log('Database event:', subject, msg)
})

Insert multiple data

// Handles a batch
var ops = [
  { type: 'put',  value: {}},
  { type: 'put',  value: {}},
  { type: 'put',  value: {}},
  { type: 'del',  key: _id},
]

this.$storage.batch( ops, function(err){
})

// Event from storage for each bach-entry
mn.service.subscribe('servicename.$storage.put | del._id', function(msg, _, subject){
        console.log(subject, msg)
})

Update a entry

// Object needs to have the _id-prop
this.$storage.update({ _id : 'T4gbDiXx3', ...}, function(err){
})

// Event from storage
mn.service.subscribe('servicename.$storage.update._id', function(msg, _, subject){
        console.log(subject, msg)
})

Find one entry

this.$storage.findOne(_id, function(err, doc){
    // returns a object
})

Find data

// Mongodb-like find-filter
this.$storage.find({}, function(err, docs){
    // returns a array of docs
})

this.$storage.find( { name: { $in: ['yamigr', 'yanosh'] }}, function(err, docs){
    // returns a array of docs
})

Delete a entry by id

this.$storage.del(_id, function(err){
})

// Event from storage
mn.service.subscribe('servicename.$storage.del._id', function(msg, _, subject){
        console.log(subject, msg)
})

Authors

• Yannick Grund - Initial work - yamigr

License

This project is licensed under the MIT License