argosy-service

argosy-service

Deprecated

Use argosy instead. This module is no longer maintained as a separate entity.

Easily create micro-services.

Part of the Argosy family.

example

var service = require('argosy-service')(),
    match   = require('argosy-pattern/match'),
    client  = require('argosy-client')

// connect the client to the service
client.pipe(service).pipe(client)

// create the service
service.message({ greet: match.string }).process(function (msg, cb) {
    cb(null, 'Hello ' + msg.greet)
})

// use the service
client.invoke({ greet: 'Jason' }, function (err, result) {
    console.log(result)
})

or with promises...

// create the service
service.message({ greet: match.string }).process(function (msg) {
    return Promise.resolve('Hello ' + msg.greet)
})

// use the service
client.invoke({ greet: 'Jason' }).then(console.log)

api

var argosyService = require('argosy-service')

service = argosyService()

Create a new service object. The service object is a stream intended to be connected (piped) to Argosy clients through any number of intermediary streams.

queue = service.message(pattern)

Create a concurrent-queue that will be pushed messages that match the pattern object provided (see argosy-pattern for details on defining patterns). These messages should be processed and responded to using the process function of the queue. Responses will be sent to the connected/requesting client.

It is advised not to match the key argosy as this is reserved for internal use.

built-in message handlers

{argosy: 'info'}

All services created will respond to messages that match {argosy: 'info'}. The response payload will be:

{
    role: 'service',
    implemented: [
        'encoded argosy pattern 1',
        'encoded argosy pattern 2',
        '...'
    ]
}

The implemented array will contain encoded argosy-pattern's for which the service will respond.

service stream messages

service request

Incoming requests are structured like so:

{
    type: 'request',
    headers: { client: { id: 'uuid', seq: 0 } },
    body: {}
}

Where:

• headers can be anything you want to send, the service will send them back exactly as they were. This is useful for correlating responses with requests. The argosy-client sends a client UUID and a request sequence number in the headers to correlate responses.
• body contains the message that the service will match against

service response

Outbound responses are structured like so:

{
    type: 'response',
    headers: { client: { id: 'uuid', seq: 0 } },
    body: {},
    error: { message: '', stack: '' }
}

Where:

• headers matches whatever headers object was supplied by the client to allow the client to correlate responses with requests on it's end
• body contains the response from the service message implementation
• error will be undefined unless an error occured in which case it will contain an object with the error message and stack

new service message implementation

When a new message pattern for the service is defined, a notify-implemented message object will be emitted from the service stream. This allows connected listers to be made aware of new message implementations. The structure of this message is:

{
    type: 'notify-implemented',
    body: 'encoded argosy pattern'
}

testing

npm test [--dot | --spec] [--grep=pattern]

Specifying --dot or --spec will change the output from the default TAP style. Specifying --grep will only run the test files that match the given pattern.

coverage

npm run coverage [--html]

This will output a textual coverage report. Including --html will also open an HTML coverage report in the default browser.