rcap-rails-generators - Generators for the Common Alerting Protocol for Ruby on Rails
Overview
The Common Alerting Protocol is a lightweight standard to facilitate the distribution of alerting data. RCAP is an implementation of the CAP in Ruby. It allows for the creation of RCAP messages from Ruby applications and the parsing of external messages.
RCAP currently supports only CAP Version 1.1 and rcap-rails-generators only supports Rails 3.X.
This gem is a set of generators for creating RCAP ActiveRecord models and migrations.
Version
1.3
Dependencies
rcap-rails-generators depends on the following gems
rcap-rails-generators uses the REXML API, included in Ruby, to parse and generate XML.
Installation
rcap-rails-generators is distributed as a Ruby gem and is available from Gemcutter. If you have Gemcutter set as a source of your gems then rcap-rails-generators can be installed from the command line
gem install rcap-rails-generators
or via Bundler
gem 'rcap-rails-generators'
The gem is also available for download and manual installtion at www.aimred.com/gems .
Once installed you can run:
rails generate rcap:models
and
rails generate rcap:migrations
to create the respective files.
rcap:models also installs a couple of necessary modules in your Rails.root/lib directory. You will need to make sure they are required:
# config/initializers/load_extensions.rb require ‘rcap’ require ‘validations’
Web resources
-
The RCAP project page can be found at www.aimred.com/projects/rcap
-
The RCAP API docs can be fount at www.aimred.com/projects/rcap/api
-
A public git repository can be found at git://github.com/farrel/RCAP.git
Usage
To include RCAP into your application add the following require
require 'rcap'
All RCAP classes reside in the RCAP namespace but including the RCAP module makes the classes available at the top level without the RCAP prefix.
alert = RCAP::Alert.new(...
include RCAP # Include RCAP module into namespace
alert = Alert.new(...
Creating an Alert
alert = Alert.new( :sender => '[email protected]',
:status => Alert::STATUS_ACTUAL,
:msg_type => Alert::MSG_TYPE_ALERT,
:scope => Alert::SCOPE_PUBLIC,
:infos => Info.new( :event => 'Liquid Petroleoum Tanker Fire',
:language => 'en-ZA',
:categories => [ Info::CATEGORY_TRANSPORT, Info::CATEGORY_FIRE ],
:urgency => Info::URGENCY_IMMEDIATE,
:severity => Info::SEVERITY_SEVERE,
:certainty => Info::CERTAINTY_OBSERVED,
:headline => 'LIQUID PETROLEOUM TANKER FIRE ON N2 INCOMING FREEWAY',
:description => 'A liquid petroleoum tanker has caught fire on the N2 incoming freeway 1km
after the R300 interchange. Municipal fire fighting crews have been dispatched.
Traffic control officers are on the scene and have diverted traffic onto
alternate routes.' ))
# Accessing attributes
puts alert.status # Print out "Actual"
puts alert.infos[0].language # Print out "en-ZA"
puts alert.infos[0].categories.join( ' ' ) # Print out "Transport Fire"
Exporting an Alert
To XML
Using the alert message created above
puts alert.to_xml # Print out CAP XML message
Will print the following CAP XML
<?xml version='1.0'?>
<alert xmlns='urn:oasis:names:tc:emergency:cap:1.1'>
<identifier>494207a7-f86b-4060-8318-a4b2a3ce565e</identifier>
<sender>[email protected]</sender>
<sent>2009-10-26T21:04:51+02:00</sent>
<status>Actual</status>
<msgType>Alert</msgType>
<scope>Public</scope>
<info>
<language>en-ZA</language>
<category>Transport</category>
<category>Fire</category>
<event>Liquid Petroleoum Tanker Fire</event>
<urgency>Immediate</urgency>
<severity>Severe</severity>
<certainty>Observed</certainty>
<headline>LIQUID PETROLEOUM TANKER FIRE ON N2 INCOMING FREEWAY</headline>
<description>
A liquid petroleoum tanker has caught fire on the N2 incoming freeway 1km
after the R300 interchange. Municipal fire fighting crews have been
dispatched. Traffic control officers are on the scene and have diverted
traffic onto alternate routes.
</description>
</info>
</alert>
To YAML
YAML is a plain text serialization format designed to be easily readable and editable by both human and machine. RCAP has custom YAML generation and parsing methods to produce a YAML document that is as human friednly as possible. The following code
alert.to_yaml
will produce the following YAML document
---
Identifier: 2a1ba96d-16e4-4f52-85ea-0258c1440bd5
Sender: [email protected]
Sent: 2009-11-19T02:41:29+02:00
Status: Actual
Message Type: Alert
Scope: Public
Information:
- Language: en-ZA
Categories: [Transport, Fire]
Event: Liquid Petroleoum Tanker Fire
Urgency: Immediate
Severity: Severe
Certainty: Observed
Headline: LIQUID PETROLEOUM TANKER FIRE ON N2 INCOMING FREEWAY
Description: |-
A liquid petroleoum tanker has caught fire on the N2 incoming freeway 1km
after the R300 interchange. Municipal fire fighting crews have been dispatched.
Traffic control officers are on the scene and have diverted traffic onto
alternate routes.
Note: If you use Ruby 1.8 the order of the attributes is jumbled due to hashes being unorderd (Ruby 1.9 implements ordered hashes). This does not affect the ability to parse documents generated from RCAP::Alert#to_yaml, it just makes things the output slightly messy.
To JSON
JSON(JavaScript Object Notation) is a text serialization format that can be easily loaded in a JavaScript environment.
alert.to_json
will produce the following JSON string
{"identifier":"0eb97e40-195b-437b-9a01-55fe89691def",
"sender":"[email protected]",
"sent":"2011-03-04T15:58:01+02:00",
"status":"Actual",
"msg_type":"Alert",
"scope":"Public",
"infos":[
{"language":"en-ZA",
"categories":["Transport","Fire"],
"event":"Liquid Petroleoum Tanker Fire",
"urgency":"Immediate",
"severity":"Severe",
"certainty":"Observed",
"headline":"LIQUID PETROLEOUM TANKER FIRE ON N2 INCOMING FREEWAY",
"description":"A liquid petroleoum tanker has caught fire on the N2 incoming freeway 1km
after the R300 interchange. Municipal fire fighting crews have been dispatched.
Traffic control officers are on the scene and have diverted traffic onto \nalternate routes."}]}
Parsing an Alert From An External Source
From XML
RCAP allows for the parsing of a CAP XML string
alert = RCAP::Alert.from_xml( xml_string )
Currently RCAP only supports version 1.1 of the CAP standard and the parser is as strict as possible when parsing data.
From YAML
Alert messgaes can be read in from text files containing data formatted in YAML as generated by Alert#to_yaml.
alert = RCAP::Alert.from_yaml( yaml_string )
From JSON
An Alert can also be initialised from a JSON string produced by Alert#to_json
alert = RCAP::Alert.from_json( json_string )
Validating an alert
The RCAP API aims to codify as many of the rules of the CAP XML format into validation rules that can be checked using the Assistance API. The following Info object has two attributes (‘severity’ and ‘certainty’) set to incorrect values.
info = Info.new( :event => 'Liquid Petroleoum Tanker Fire',
:language => 'en-ZA',
:categories => [ Info::CATEGORY_TRANSPORT, Info::CATEGORY_FIRE ],
:urgency => Info::URGENCY_IMMEDIATE,
:severity => nil, # Severity is not assigned
:certainty => 'Unknown Certainty' ) # Certainty is assigned in incorrect value
puts "Is info valid: #{ info.valid? }"
info.errors..each{ || puts "Error: #{ }" }
Will produce the folling output:
Is info valid: false
Error: severity is not present
Error: certainty can only be assigned the following values: Observed, Likely, Possible, Unlikely, Unknown
All RCAP classes include the Validation module.
A full spec suite using RSpec was used to test the validations and currently numbers over 250 tests.
DateTime and Time
It is highly recommended that when dealing with date and time fields (onset, expires etc) that the DateTime class is used to ensure the correct formatting of dates. The Time class can be used when generating a CAP alert XML message however any CAP alert that is parsed from an external XML source will use DateTime by default.
Authors
Farrel Lifson - [email protected]
License
RCAP is released under the BSD License.
Copyright
2009-2011 Aimred CC