opifex

Opifex is a node.js module providing base functionality for adapters integrating with the wot.io operating environment.

Usage

opifex = require 'opifex'
opifex 'amqp://user:password@host:port/domain/source', 'amqp://user:password@host:port/domain/destination', () ->
	@foo = (args...) ->
		console.log "Got foo message with args: #{JSON.stringify args}"

Facilities provided by opifex

Accepts a function or module and apply it as a mixin to its message handler.
Initializes and manages the specified source and destination bus connections.
Provides a message-handling method dispatch mechanism. By default, opifex will attempt to interpret JSON arrays as s-expressions and dispatch to the method named in the first array element, if it exists, else to the * method. If the message is an s-expression, the array will be passed as a list of arguments to the dispatched method. If configured for raw mode, opifex will always try to dispatch to *, with the raw message as the only argument.

Properties

log - logger object. See wot-logger for usage.
key - routing key of the current message. Note that this can differ from the configured routing key. See bindings.
headers - headers of the current message.
bindings - an object whose attributes describe the configured channels. The bindings property is an object with the following keys

{
	"domain": "",
	"source": {
		"exchange": "configured source exchange",
		"key": "configured binding pattern",
		"queue": "configured source queue"
	},
	"sink": {
		"exchange": "configured destination exchange",
		"key": "configured routing key"
	}
}

Methods

send(message[, key]) - Sends a message to the configured output exchange. If no key argument, routing key defaults to the configured routing key. If no ouput channel is defined, send logs a warning. To enable sending binary data over the bus, send converts message to a Buffer prior to publishing. Serializable javascript objects will be converted to JSON before being encoded as a Buffer.

Scripts

The bin/opifex wrapper script has been provided as a convenience. It can be called with the function arguments as command-line parameters, in order, or configured with environment variables as below.

Environment

All opifex adapters can be configured via the following common environment variables (default values shown)

Name	Default	Description
`APP`	opifex	Service name override for logging. opifex will use the value of `MODULE` by default, if set, else `'opifex'`. If `MODULE` is set, and it is desirable for the service name to be different in logs, `APP` will override `MODULE`.
`AMQP_QUEUE_DURABLE`	false	Queues declared are transient unless set to true.
`AMQP_QUEUE_AUTODELETE`	true	Queues declared are autodelete unless set to false.
`AMQP_EXCHANGE_DURABLE`	false	Exchanges declared are transient unless set to true.
`AMQP_EXCHANGE_AUTODELETE`	false	Exchanges declared are not autodelete unless set to true.
`DEBUG_LOG_MESSAGE_CONTENT`	false	`send(message)` will debug log the contents of message if true. false is convenient with binary data.
`FORCE_RAW_MESSAGES`	false	Messages will be dispatched to the `*` method with no examination or manipulation if true.

See individual adapter documentation for adapter-specific configuration.

In addition, bin/opifex also respects the following environment variables

Name	Default	Description
`MODULE`		Name of module to load after prepending with "opifex." For example, `MODULE=example` would result in `require 'opifex.example'`
`SOURCE_URI`		Full URI of AMQP source. If undefined, no source channel will be created.
`DEST_URI`		Full URI of AMQP destination. If undefined, no destination channel will be created.
`ARGS`		Whitespace-separated list of additional arguments, e.g. `ARGS='one two three'`
`SOURCE`		Deprecated in favor of `SOURCE_URI`.
`SINK`		Deprecated in favor of `DEST_URI`.

Example

Create a node.js module named opifex.test with an index.coffee something like

module.exports = opifex = () ->
	@hello = (name) -> console.log "Hello, #{name}"
	@

and then run it as the opifex mixin via something like

$ bin/opifex 'amqp://user:password@host:port/account/source', 'amqp://user:password@host:port/account/destination' 'test'

And then send a message like this to the appropriate vhost on the given exchange:

[ "hello", "world" ]

And it will log the obligatory Hello, world message to the console.

Alternatively, a function could be passed directly instead of a module.

BillTheBest / opifex