Cassandra Day Chicago 2015: 0 to App Faster with Node.js and Ruby

0 to App faster with NodeJS and Ruby
Rebecca Mills @RebccaMills
Patrick McFadin @PatrickMcFadin

The situation
• REST interface to Cassandra data
• Support CRUD operations
• It’s Friday and…
2
Umm yeah, and I’m going to
need that by Monday morning.

Choose your language
• Support for all Cassandra features
• Easy to work with
• Performant
3

DataStax NodeJS driver
• Works with current OSS Cassandra
• Apache Licensed
7
https://github.com/datastax/nodejs-driver
Based on node-cassandra-cql
by Jorge Bay

Get it!
8
> npm install cassandra-driver

DataStax Ruby driver
9
https://github.com/datastax/ruby-driver
• Works with current OSS Cassandra
• Apache Licensed
Based on cql-rb
by Theo Hultberg (@iconara)

Get it!
10
> gem install cassandra-driver

DataStax Cassandra Drivers
• Load Balancing Policies
• Retry Policies
• Asynchronous
• Prepared statements
• Connection and cluster management
11
A Cassandra Driver should have…

On to the code!
• RESTful web server
• Need a few helpers
12
+ +

REST methods
• Operates on the “USERS” table in Cassandra
13
POST Insert a user
GET Select a user
PUT Update a user
DELETE Delete a user
CREATE TABLE users (
firstname text,
lastname text,
age int,
email text,
city text,
PRIMARY KEY (lastname)
);

Connection for NodeJS
• Express as the web server
• body-parser to get POST data
15
var client = new cassandra.Client({ 
contactPoints: ['127.0.0.1'], 
keyspace: 'demo', 
policies: { 
retry: new cassandra.policies.retry.RetryPolicy(), 
loadBalancing: new cassandra.policies.loadBalancing.DCAwareRoundRobinPolicy('datacenter1') 
} 
} 
);
var express = require('express') 
var bodyParser = require('body-parser'); 
var cassandra = require('cassandra-driver');

policies: { 
} 
} 
);
16

policies: { 
} 
} 
);
17

policies: { 
} 
} 
);
18

Load balancing
19
Client 10.0.0.1
00-25
10.0.0.4
76-100
10.0.0.2
26-50
10.0.0.3
51-75
SELECT firstName
FROM users
WHERE lastname = ‘mills’;
datacenter1
datacenter1
Node Primary Replica Replica
10.0.0.1 00-25 76-100 51-75
10.0.0.2 26-50 00-25 76-100
10.0.0.3 51-75 26-50 00-25
10.0.0.4 76-100 51-75 26-50
loadBalancing: new DCAwareRoundRobinPolicy('datacenter1')

Insert a user with a POST
20
app.post('/users', function (req, res) { 
var lastname = req.body.lastname; 
var age = req.body.age; 
var city = req.body.city; 
var email = req.body.email; 
var firstname = req.body.firstname; 
 
 
var query = "INSERT INTO users (lastname, age, city, email, firstname) VALUES ( ?,?,?,?,?)"; 
var params = [lastname, age, city, email, firstname]; 
 
client.execute(query, params, {prepare: true}, function (err, result) { 
if (!err) { 
res.send("Inserted"); 
} else { 
res.sendStatus(404) 
} 
}) 
})

21
 
 
 
if (!err) { 
} else { 
} 
}) 
})

22
 
 
 
if (!err) { 
} else { 
} 
}) 
})

23
 
 
 
if (!err) { 
} else { 
} 
}) 
})

Select user with GET
24
app.get('/users/:lastname',function (req, res) { 
 
var query = "SELECT lastname, age, city, email, firstname FROM users WHERE lastname= ?"; 
var params = [req.params.lastname]; 
if (!err){ 
if ( result.rows.length > 0 ) { 
var user = result.rows[0]; 
console.log("name = %s, age = %d", user.firstname, user.age); 
res.send(user) 
} else { 
res.sendStatus(404); 
} 
} 
}); 
})

25
 
if (!err){ 
res.send(user) 
} else { 
} 
} 
}); 
})

26
 
if (!err){ 
res.send(user) 
} else { 
} 
} 
}); 
})

27
 
if (!err){ 
res.send(user) 
} else { 
} 
} 
}); 
})

28
 
if (!err){ 
res.send(user) 
} else { 
} 
} 
}); 
})

Update a user with PUT
29
app.put('/users/:lastname', function (req, res) { 
 
console.log("lastname = " + req.params.lastname + ", age= " + age); 
 
var query = "UPDATE users SET age = ? WHERE lastname = ?"; 
var params = [age, req.params.lastname]; 
 
if (!err) { 
res.send("Updated"); 
} else { 
} 
}); 
})

Remove a user with DELETE
30
app.delete('/users/:lastname', function (req, res) { 
var query = "DELETE FROM users WHERE lastname = ?"; 
 
 
if (!err) { 
res.send("Deleted"); 
} else { 
} 
}); 
})

Connection with Ruby
• Sinatra as the web server
• JSON for returning formatted results
32
cluster = Cassandra.cluster( 
:hosts => ['127.0.01'], 
:load_balancing_policy => Cassandra::LoadBalancing::Policies::RoundRobin.new, 
:retry_policy => Cassandra::Retry::Policies::Default.new, 
logger: log) 
 
keyspace = 'demo' 
session = cluster.connect(keyspace)
require 'sinatra' 
require 'JSON' 
require 'cassandra' 
require 'logger'

33
:hosts => ['127.0.01'], 
logger: log) 
 
require 'JSON' 
require 'logger'

34
:hosts => ['127.0.01'], 
logger: log) 
 
require 'JSON' 
require 'logger'

Retry Policies
• Retry requests on server errors
• Write Timeout
• Read Timeout
• Unavailable
35

36
:hosts => ['127.0.01'], 
logger: log) 
 
require 'JSON' 
require 'logger'

37
post '/users' do 
 
begin 
session.execute(userInsertStatement, :arguments => [params[:firstname], params[:lastname],
params[:age].to_i, params[:city], params[:email]]) 
 
"Inserted" 
 
rescue Exception => e 
log.error 'Error in insert a user' 
log.error(e) 
halt(404) 
end 
 
end
userInsertStatement = session.prepare("INSERT INTO users (firstname, lastname, age, city, email)
VALUES (?,?,?,?,?)")

38
post '/users' do 
 
begin 
 
"Inserted" 
 
log.error(e) 
halt(404) 
end 
 
end
VALUES (?,?,?,?,?)")
…

39
post '/users' do 
 
begin 
 
"Inserted" 
 
log.error(e) 
halt(404) 
end 
 
end
VALUES (?,?,?,?,?)")
…

40
get '/users/:lastname' do 
 
begin 
result = session.execute(userSelectStatement, :arguments => [params[:lastname]]) 
 
if result.size < 1 
halt(404) 
end 
 
result.first.to_json 
log.error 'Error in select a user' 
log.error(e) 
halt(404) 
end 
 
end
userSelectStatement = session.prepare("SELECT firstname,lastname, age, email, city
FROM users where lastname = ?")

41
 
begin 
 
halt(404) 
end 
 
log.error(e) 
halt(404) 
end 
 
end
FROM users where lastname = ?")…

42
 
begin 
 
halt(404) 
end 
 
log.error(e) 
halt(404) 
end 
 
end
…

43
 
begin 
 
halt(404) 
end 
 
log.error(e) 
halt(404) 
end 
 
end
…

Quick note on Async
• Generates a Future
• Non-blocking until get
44
future = session.execute_async(statement) 
 
# register success listener 
future.on_success do |rows| 
rows.each do |row| 
puts "#{row["artist"]}: #{row["title"]} / #{row["album"]}" 
end 
end

Quick note on Async
45
 
end 
end

Quick note on Async
46
 
end 
end

Update a user with PUT
47
put '/users' do 
 
begin 
session.execute(userUpdateStatement, :arguments => [params[:age].to_i, params[:lastname]]) 
 
"Updated" 
 
log.error 'Error in update a user' 
log.error(e) 
halt(404) 
end 
 
end
userUpdateStatement = session.prepare("UPDATE users SET age = ? WHERE lastname = ?")

Remove a user with DELETE
48
delete '/users/:lastname' do 
 
begin 
session.execute(userDeleteStatement, :arguments => [params[:lastname]]) 
 
"Deleted" 
 
log.error 'Error in delete a user' 
log.error(e) 
halt(404) 
end 
 
end
userDeleteStatement = session.prepare("DELETE FROM users WHERE lastname = ?")

Made it!
49
Nice code.
Have a beer.

Get the code! Try yourself!
50
https://github.com/beccam/rest_server_ruby
https://github.com/beccam/rest_server_nodejs
NodeJS Code
Ruby Code

Questions?
Don’t forget to follow us on Twitter for more:
@RebccaMills
@PatrickMcFadin

Cassandra Day Chicago 2015: 0 to App Faster with Node.js and Ruby

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