Tuesday, August 17, 2010

Erlang, RabbitMQ and Spring

Erlang was selected for use as the development language for RabbitMQ because of its excellent threading and multicore capabilities. SpringSource acquired RabbitMQ in April 2010 for incorporation into Spring Integration.

After installing Erlang, save the following code in a file named 'math1.erl': 

-module(math1).
-export([factorial/1]).

factorial(0) -> 1;
factorial(N) -> N * factorial(N-1).
Start the Erlang console, compile the module and run the function: 
[greg:erlang] erl
1> c(math1.erl).                  
{ok,math1}
2> math1:factorial(25).
15511210043330985984000000
3>

Setup RabbitMQ

Once Erlang works, you can run RabbitMQ. After downloading and extracting the archive, I created 'log', 'mnesia' and 'config' folders in my rabbitmq_server folder and then set these environment variables. 
export RABBIT=/bin/rabbitmq_server-1.8.1
export RABBITMQ_MNESIA_BASE=$RABBIT/mnesia
export RABBITMQ_LOG_BASE=$RABBIT/log
export RABBITMQ_NODENAME=gregs
export RABBITMQ_NODE_IP_ADDRESS=0.0.0.0
export RABBITMQ_NODE_PORT=5672
export RABBITMQ_CLUSTER_CONFIG_FILE=$RABBIT/config/rabbitmq_cluster.config
export RABBITMQ_CONFIG_FILE=$RABBIT/config/rabbitmq

Run RabbitMQ

[greg:rabbitmq_server-1.8.1] ./sbin/rabbitmq-server

Client Code

Examples of Groovy clients using the RabbitMQ server are shown here.

Java client code is explained here.

Running the Included LoanBroker Example

[greg:~] cd spring-integration-2.0.0.M6/samples/loanbroker 
[greg:loan-broker] mvn compile
[greg:loan-broker] mvn test
. . . 
INFO : org.springframework.integration.samples.loanbroker.demo.LoanBrokerSharkDetectorDemo - 
********* Best Quote: 
====== Loan Quote =====
Lender: StubBank-13
Loan amount: $253,664
Quote Date: Wed Aug 18 08:44:37 CDT 2010
Expiration Date: Sat Sep 11 08:44:37 CDT 2010
Term: 19 years
Rate: 5.130192%
=======================

INFO : org.springframework.integration.samples.loanbroker.stubs.CreditBureauStub - Credit Score: 797
INFO : org.springframework.integration.samples.loanbroker.demo.LoanBrokerSharkDetectorDemo - 
********* All Quotes: 
INFO : org.springframework.integration.samples.loanbroker.demo.LoanBrokerSharkDetectorDemo - 
====== Loan Quote =====
Lender: StubBank-0
Loan amount: $272,807
Quote Date: Wed Aug 18 08:44:37 CDT 2010
Expiration Date: Mon Aug 23 08:44:37 CDT 2010
Term: 19 years
Rate: 5.1708126%
=======================
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