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.
1.3
rcap-rails-generators depends on the following gems
rcap-rails-generators uses the REXML API, included in Ruby, to parse and generate XML.
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’
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The RCAP project page can be found at www.aimred.com/projects/rcap
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The RCAP API docs can be fount at www.aimred.com/projects/rcap/api
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A public git repository can be found at git://github.com/farrel/RCAP.git
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(...
alert = Alert.new( :sender => 'cape_town_disaster_relief@capetown.municipal.za', :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"
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>cape_town_disaster_relief@capetown.municipal.za</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>
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: cape_town_disaster_relief@capetown.municipal.za 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.
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":"cape_town_disaster_relief@capetown.municipal.za", "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."}]}
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.
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 )
An Alert can also be initialised from a JSON string produced by Alert#to_json
alert = RCAP::Alert.from_json( json_string )
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.full_messages.each{ |message| puts "Error: #{ message }" }
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.
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.
Farrel Lifson - farrel.lifson@aimred.com
RCAP is released under the BSD License.
2009-2011 Aimred CC