Google Mail Stream

Since Camel 2.22

Only consumer is supported

The Google Mail component provides access to Gmail via the Google Mail Web APIs. This component provides the streaming feature for Messages.

Google Mail uses the OAuth 2.0 protocol for authenticating a Google account and authorizing access to user data. Before you can use this component, you will need to create an account and generate OAuth credentials. Credentials comprise of a clientId, clientSecret, and a refreshToken. A handy resource for generating a long-lived refreshToken is the OAuth playground.

In the case of a service account, credentials comprise of a JSON-file (serviceAccountKey). You can also use delegation domain-wide authority (delegate) and one, several, or all possible GMail API Auth Scopes (scopes).

Maven users will need to add the following dependency to their pom.xml for this component:

<dependency>
    <groupId>org.apache.camel</groupId>
    <artifactId>camel-google-mail</artifactId>
    <!-- use the same version as your Camel core version -->
    <version>x.y.z</version>
</dependency>

URI Format

The GoogleMail Component uses the following URI format:

google-mail-stream://index?[options]

Configuring Options

Camel components are configured on two separate levels:

  • component level

  • endpoint level

Configuring Component Options

The component level is the highest level which holds general and common configurations that are inherited by the endpoints. For example a component may have security settings, credentials for authentication, urls for network connection and so forth.

Some components only have a few options, and others may have many. Because components typically have pre configured defaults that are commonly used, then you may often only need to configure a few options on a component; or none at all.

Configuring components can be done with the Component DSL, in a configuration file (application.properties|yaml), or directly with Java code.

Configuring Endpoint Options

Where you find yourself configuring the most is on endpoints, as endpoints often have many options, which allows you to configure what you need the endpoint to do. The options are also categorized into whether the endpoint is used as consumer (from) or as a producer (to), or used for both.

Configuring endpoints is most often done directly in the endpoint URI as path and query parameters. You can also use the Endpoint DSL and DataFormat DSL as a type safe way of configuring endpoints and data formats in Java.

A good practice when configuring options is to use Property Placeholders, which allows to not hardcode urls, port numbers, sensitive information, and other settings. In other words placeholders allows to externalize the configuration from your code, and gives more flexibility and reuse.

The following two sections lists all the options, firstly for the component followed by the endpoint.

Component Options

The Google Mail Stream component supports 19 options, which are listed below.

Name Description Default Type

applicationName (consumer)

Google mail application name. Example would be camel-google-mail/1.0.

String

bridgeErrorHandler (consumer)

Allows for bridging the consumer to the Camel routing Error Handler, which mean any exceptions (if possible) occurred while the Camel consumer is trying to pickup incoming messages, or the likes, will now be processed as a message and handled by the routing Error Handler. Important: This is only possible if the 3rd party component allows Camel to be alerted if an exception was thrown. Some components handle this internally only, and therefore bridgeErrorHandler is not possible. In other situations we may improve the Camel component to hook into the 3rd party component and make this possible for future releases. 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

clientId (consumer)

Client ID of the mail application.

String

delegate (consumer)

Delegate for wide-domain service account.

String

labels (consumer)

Comma separated list of labels to take into account.

String

markAsRead (consumer)

Mark the message as read once it has been consumed.

true

boolean

maxResults (consumer)

Max results to be returned.

10

long

query (consumer)

The query to execute on gmail box.

is:unread

String

raw (consumer)

Whether to store the entire email message in an RFC 2822 formatted and base64url encoded string (in JSon format), in the Camel message body.

false

boolean

scopes (consumer)

GMail scopes.

List

autowiredEnabled (advanced)

Whether autowiring is enabled. This is used for automatic autowiring options (the option must be marked as autowired) by looking up in the registry to find if there is a single instance of matching type, which then gets configured on the component. This can be used for automatic configuring JDBC data sources, JMS connection factories, AWS Clients, etc.

true

boolean

clientFactory (advanced)

The client Factory.

GoogleMailClientFactory

configuration (advanced)

The configuration.

GoogleMailStreamConfiguration

healthCheckConsumerEnabled (health)

Used for enabling or disabling all consumer based health checks from this component.

true

boolean

healthCheckProducerEnabled (health)

Used for enabling or disabling all producer based health checks from this component. Notice: Camel has by default disabled all producer based health-checks. You can turn on producer checks globally by setting camel.health.producersEnabled=true.

true

boolean

accessToken (security)

OAuth 2 access token. This typically expires after an hour so refreshToken is recommended for long term usage.

String

clientSecret (security)

Client secret of the mail application.

String

refreshToken (security)

OAuth 2 refresh token. Using this, the Google Calendar component can obtain a new accessToken whenever the current one expires - a necessity if the application is long-lived.

String

serviceAccountKey (security)

Sets .json file with credentials for Service account.

String

Endpoint Options

The Google Mail Stream endpoint is configured using URI syntax:

google-mail-stream:index

with the following path and query parameters:

Path Parameters (1 parameters)

Name Description Default Type

index (consumer)

Required Currently not in use.

String

Query Parameters (32 parameters)

Name Description Default Type

applicationName (consumer)

Google mail application name. Example would be camel-google-mail/1.0.

String

clientId (consumer)

Client ID of the mail application.

String

delegate (consumer)

Delegate for wide-domain service account.

String

labels (consumer)

Comma separated list of labels to take into account.

String

markAsRead (consumer)

Mark the message as read once it has been consumed.

true

boolean

maxResults (consumer)

Max results to be returned.

10

long

query (consumer)

The query to execute on gmail box.

is:unread

String

raw (consumer)

Whether to store the entire email message in an RFC 2822 formatted and base64url encoded string (in JSon format), in the Camel message body.

false

boolean

scopes (consumer)

GMail scopes.

List

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

bridgeErrorHandler (consumer (advanced))

Allows for bridging the consumer to the Camel routing Error Handler, which mean any exceptions (if possible) occurred while the Camel consumer is trying to pickup incoming messages, or the likes, will now be processed as a message and handled by the routing Error Handler. Important: This is only possible if the 3rd party component allows Camel to be alerted if an exception was thrown. Some components handle this internally only, and therefore bridgeErrorHandler is not possible. In other situations we may improve the Camel component to hook into the 3rd party component and make this possible for future releases. 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

exceptionHandler (consumer (advanced))

To let the consumer use a custom ExceptionHandler. Notice if the option bridgeErrorHandler is enabled then this option 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 (advanced))

Sets the exchange pattern when the consumer creates an exchange.

Enum values:

  • InOnly

  • InOut

ExchangePattern

pollStrategy (consumer (advanced))

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.

PollingConsumerPollStrategy

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.

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.

1000

long

repeatCount (scheduler)

Specifies a maximum limit of number of fires. So if you set it to 1, the scheduler will only fire once. If you set it to 5, it will only fire five times. A value of zero or negative means fire forever.

0

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.

Enum values:

  • TRACE

  • DEBUG

  • INFO

  • WARN

  • ERROR

  • OFF

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.

ScheduledExecutorService

scheduler (scheduler)

To use a cron scheduler from either camel-spring or camel-quartz component. Use value spring or quartz for built in scheduler.

none

Object

schedulerProperties (scheduler)

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

Map

startScheduler (scheduler)

Whether the scheduler should be auto started.

true

boolean

timeUnit (scheduler)

Time unit for initialDelay and delay options.

Enum values:

  • NANOSECONDS

  • MICROSECONDS

  • MILLISECONDS

  • SECONDS

  • MINUTES

  • HOURS

  • DAYS

MILLISECONDS

TimeUnit

useFixedDelay (scheduler)

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

true

boolean

accessToken (security)

OAuth 2 access token. This typically expires after an hour so refreshToken is recommended for long term usage.

String

clientSecret (security)

Client secret of the mail application.

String

refreshToken (security)

OAuth 2 refresh token. Using this, the Google Calendar component can obtain a new accessToken whenever the current one expires - a necessity if the application is long-lived.

String

serviceAccountKey (security)

Sets .json file with credentials for Service account.

String

Message Headers

The Google Mail Stream component supports 6 message header(s), which is/are listed below:

Name Description Default Type

CamelGoogleMailStreamTo (consumer)

Constant: MAIL_TO

The recipient of the message.

String

CamelGoogleMailStreamFrom (consumer)

Constant: MAIL_FROM

The emitter of the message.

String

CamelGoogleMailStreamCc (consumer)

Constant: MAIL_CC

The carbon copy of the message.

String

CamelGoogleMailStreamBcc (consumer)

Constant: MAIL_BCC

The blind carbon cpoy of the message.

String

CamelGoogleMailStreamSubject (consumer)

Constant: MAIL_SUBJECT

The subject of the message.

String

CamelGoogleMailId (consumer)

Constant: MAIL_ID

The ID of the message.

String