Chapter 43. Beanstalk Component

Available as of Camel version 2.15

camel-beanstalk project provides a Camel component for job retrieval and post-processing of Beanstalk jobs.

You can find the detailed explanation of Beanstalk job lifecycle at Beanstalk protocol.

43.1. Dependencies

Maven users need to add the following dependency to their pom.xml

<dependency>
  <groupId>org.apache.camel</groupId>
  <artifactId>camel-beanstalk</artifactId>
  <version>${camel-version}</version>
</dependency>

where ${camel-version} must be replaced by the actual version of Camel (2.15.0 or higher).

43.2. URI format

beanstalk://[host[:port]][/tube][?options]

You may omit either port or both host and port: for the Beanstalk defaults to be used (“localhost” and 11300). If you omit tube, Beanstalk component will use the tube with name “default”.

When listening, you may probably want to watch for jobs from several tubes. Just separate them with plus sign, e.g.

beanstalk://localhost:11300/tube1+tube2

Tube name will be URL decoded, so if your tube names include special characters like + or ?, you need to URL-encode them appropriately, or use the RAW syntax, see more details here.

By the way, you cannot specify several tubes when you are writing jobs into Beanstalk.

43.3. Beanstalk options

The Beanstalk component supports 2 options which are listed below.

NameDescriptionDefaultType

connectionSettings Factory (common)

Custom ConnectionSettingsFactory. Specify which ConnectionSettingsFactory to use to make connections to Beanstalkd. Especially useful for unit testing without beanstalkd daemon (you can mock ConnectionSettings)

 

ConnectionSettings Factory

resolveProperty Placeholders (advanced)

Whether the component should resolve property placeholders on itself when starting. Only properties which are of String type can use property placeholders.

true

boolean

The Beanstalk endpoint is configured using URI syntax:

beanstalk:connectionSettings

with the following path and query parameters:

43.3.1. Path Parameters (1 parameters):

NameDescriptionDefaultType

connectionSettings

Connection settings host:port/tube

 

String

43.3.2. Query Parameters (26 parameters):

NameDescriptionDefaultType

command (common)

put means to put the job into Beanstalk. Job body is specified in the Camel message body. Job ID will be returned in beanstalk.jobId message header. delete, release, touch or bury expect Job ID in the message header beanstalk.jobId. Result of the operation is returned in beanstalk.result message header kick expects the number of jobs to kick in the message body and returns the number of jobs actually kicked out in the message header beanstalk.result.

 

BeanstalkCommand

jobDelay (common)

Job delay in seconds.

0

int

jobPriority (common)

Job priority. (0 is the highest, see Beanstalk protocol)

1000

long

jobTimeToRun (common)

Job time to run in seconds. (when 0, the beanstalkd daemon raises it to 1 automatically, see Beanstalk protocol)

60

int

awaitJob (consumer)

Whether to wait for job to complete before ack the job from beanstalk

true

boolean

bridgeErrorHandler (consumer)

Allows for bridging the consumer to the Camel routing Error Handler, which mean any exceptions occurred while the consumer is trying to pickup incoming messages, or the likes, will now be processed as a message and handled by the routing Error Handler. By default the consumer will use the org.apache.camel.spi.ExceptionHandler to deal with exceptions, that will be logged at WARN or ERROR level and ignored.

false

boolean

onFailure (consumer)

Command to use when processing failed.

 

BeanstalkCommand

sendEmptyMessageWhenIdle (consumer)

If the polling consumer did not poll any files, you can enable this option to send an empty message (no body) instead.

false

boolean

useBlockIO (consumer)

Whether to use blockIO.

true

boolean

exceptionHandler (consumer)

To let the consumer use a custom ExceptionHandler. Notice if the option bridgeErrorHandler is enabled then this options is not in use. By default the consumer will deal with exceptions, that will be logged at WARN or ERROR level and ignored.

 

ExceptionHandler

exchangePattern (consumer)

Sets the exchange pattern when the consumer creates an exchange.

 

ExchangePattern

pollStrategy (consumer)

A pluggable org.apache.camel.PollingConsumerPollingStrategy allowing you to provide your custom implementation to control error handling usually occurred during the poll operation before an Exchange have been created and being routed in Camel.

 

PollingConsumerPoll Strategy

synchronous (advanced)

Sets whether synchronous processing should be strictly used, or Camel is allowed to use asynchronous processing (if supported).

false

boolean

backoffErrorThreshold (scheduler)

The number of subsequent error polls (failed due some error) that should happen before the backoffMultipler should kick-in.

 

int

backoffIdleThreshold (scheduler)

The number of subsequent idle polls that should happen before the backoffMultipler should kick-in.

 

int

backoffMultiplier (scheduler)

To let the scheduled polling consumer backoff if there has been a number of subsequent idles/errors in a row. The multiplier is then the number of polls that will be skipped before the next actual attempt is happening again. When this option is in use then backoffIdleThreshold and/or backoffErrorThreshold must also be configured.

 

int

delay (scheduler)

Milliseconds before the next poll. You can also specify time values using units, such as 60s (60 seconds), 5m30s (5 minutes and 30 seconds), and 1h (1 hour).

500

long

greedy (scheduler)

If greedy is enabled, then the ScheduledPollConsumer will run immediately again, if the previous run polled 1 or more messages.

false

boolean

initialDelay (scheduler)

Milliseconds before the first poll starts. You can also specify time values using units, such as 60s (60 seconds), 5m30s (5 minutes and 30 seconds), and 1h (1 hour).

1000

long

runLoggingLevel (scheduler)

The consumer logs a start/complete log line when it polls. This option allows you to configure the logging level for that.

TRACE

LoggingLevel

scheduledExecutorService (scheduler)

Allows for configuring a custom/shared thread pool to use for the consumer. By default each consumer has its own single threaded thread pool.

 

ScheduledExecutor Service

scheduler (scheduler)

To use a cron scheduler from either camel-spring or camel-quartz2 component

none

ScheduledPollConsumer Scheduler

schedulerProperties (scheduler)

To configure additional properties when using a custom scheduler or any of the Quartz2, Spring based scheduler.

 

Map

startScheduler (scheduler)

Whether the scheduler should be auto started.

true

boolean

timeUnit (scheduler)

Time unit for initialDelay and delay options.

MILLISECONDS

TimeUnit

useFixedDelay (scheduler)

Controls if fixed delay or fixed rate is used. See ScheduledExecutorService in JDK for details.

true

boolean

Producer behavior is affected by the command parameter which tells what to do with the job, it can be

The consumer may delete the job immediately after reserving it or wait until Camel routes process it. While the first scenario is more like a “message queue”, the second is similar to “job queue”. This behavior is controlled by consumer.awaitJob parameter, which equals true by default (following Beanstalkd nature).

When synchronous, the consumer calls delete on successful job completion and calls bury on failure. You can choose which command to execute in the case of failure by specifying consumer.onFailure parameter in the URI. It can take values of burydelete or release.

There is a boolean parameter consumer.useBlockIO which corresponds to the same parameter in JavaBeanstalkClient library. By default it is true.

Be careful when specifying release, as the failed job will immediately become available in the same tube and your consumer will try to acquire it again. You can release and specify jobDelay though.

The beanstalk consumer is a Scheduled Polling Consumer which means there is more options you can configure, such as how frequent the consumer should poll. For more details see Polling Consumer.

43.4. Consumer Headers

The consumer stores a number of job headers in the Exchange message:

PropertyTypeDescription

beanstalk.jobId

long

Job ID

beanstalk.tube

string

the name of the tube that contains this job

beanstalk.state

string

“ready” or “delayed” or “reserved” or “buried” (must be “reserved”)

beanstalk.priority

long

the priority value set

beanstalk.age

int

the time in seconds since the put command that created this job

beanstalk.time-left

int

the number of seconds left until the server puts this job into the ready queue

beanstalk.timeouts

int

the number of times this job has timed out during a reservation

beanstalk.releases

int

the number of times a client has released this job from a reservation

beanstalk.buries

int

the number of times this job has been buried

beanstalk.kicks

int

the number of times this job has been kicked

43.5. Examples

This Camel component lets you both request the jobs for processing and supply them to Beanstalkd daemon. Our simple demo routes may look like

from("beanstalk:testTube").
   log("Processing job #${property.beanstalk.jobId} with body ${in.body}").
   process(new Processor() {
     @Override
     public void process(Exchange exchange) {
       // try to make integer value out of body
       exchange.getIn().setBody( Integer.valueOf(exchange.getIn().getBody(classOf[String])) );
     }
   }).
   log("Parsed job #${property.beanstalk.jobId} to body ${in.body}");
from("timer:dig?period=30seconds").
   setBody(constant(10)).log("Kick ${in.body} buried/delayed tasks").
   to("beanstalk:testTube?command=kick");

In the first route we are listening for new jobs in tube “testTube”. When they are arriving, we are trying to parse integer value from the message body. If done successful, we log it and this successful exchange completion makes Camel component to delete this job from Beanstalk automatically. Contrary, when we cannot parse the job data, the exchange failed and the Camel component buries it by default, so that it can be processed later or probably we are going to inspect failed jobs manually.

So the second route periodically requests Beanstalk to kick 10 jobs out of buried and/or delayed state to the normal queue.

 

43.6. See Also

  • Configuring Camel
  • Component
  • Endpoint
  • Getting Started