AWS DynamoDB Streams
Since Camel 3.1
Only consumer is supported
The AWS2 DynamoDB Stream component supports receiving messages from Amazon DynamoDB Stream service.
Prerequisites
You must have a valid Amazon Web Services developer account, and be signed up to use Amazon DynamoDB Streams. More information are available at AWS DynamoDB
URI Format
aws2-ddbstream://table-name[?options]
The stream needs to be created prior to it being used.
You can append query options to the URI in the following format,
?options=value&option2=value&…
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 AWS DynamoDB Streams component supports 16 options, which are listed below.
Name | Description | Default | Type |
---|---|---|---|
Autowired Amazon DynamoDB client to use for all requests for this endpoint. |
DynamoDbStreamsClient |
||
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 |
|
The component configuration. |
Ddb2StreamConfiguration |
||
Maximum number of records that will be fetched in each poll. |
int |
||
Set the need for overidding the endpoint. This option needs to be used in combination with uriEndpointOverride option. |
false |
boolean |
|
To define a proxy host when instantiating the DDBStreams client. |
String |
||
To define a proxy port when instantiating the DDBStreams client. |
Integer |
||
To define a proxy protocol when instantiating the DDBStreams client. Enum values:
|
HTTPS |
Protocol |
|
The region in which DDBStreams client needs to work. |
String |
||
Defines where in the DynamoDB stream to start getting records. Note that using FROM_START can cause a significant delay before the stream has caught up to real-time. Enum values:
|
FROM_LATEST |
StreamIteratorType |
|
If we want to trust all certificates in case of overriding the endpoint. |
false |
boolean |
|
Set the overriding uri endpoint. This option needs to be used in combination with overrideEndpoint option. |
String |
||
Set whether the DynamoDB Streams client should expect to load credentials through a default credentials provider or to expect static credentials to be passed in. |
false |
boolean |
|
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 |
|
Amazon AWS Access Key. |
String |
||
Amazon AWS Secret Key. |
String |
Endpoint Options
The AWS DynamoDB Streams endpoint is configured using URI syntax:
aws2-ddbstream:tableName
with the following path and query parameters:
Query Parameters (32 parameters)
Name | Description | Default | Type |
---|---|---|---|
Autowired Amazon DynamoDB client to use for all requests for this endpoint. |
DynamoDbStreamsClient |
||
Maximum number of records that will be fetched in each poll. |
int |
||
Set the need for overidding the endpoint. This option needs to be used in combination with uriEndpointOverride option. |
false |
boolean |
|
To define a proxy host when instantiating the DDBStreams client. |
String |
||
To define a proxy port when instantiating the DDBStreams client. |
Integer |
||
To define a proxy protocol when instantiating the DDBStreams client. Enum values:
|
HTTPS |
Protocol |
|
The region in which DDBStreams client needs to work. |
String |
||
If the polling consumer did not poll any files, you can enable this option to send an empty message (no body) instead. |
false |
boolean |
|
Defines where in the DynamoDB stream to start getting records. Note that using FROM_START can cause a significant delay before the stream has caught up to real-time. Enum values:
|
FROM_LATEST |
StreamIteratorType |
|
If we want to trust all certificates in case of overriding the endpoint. |
false |
boolean |
|
Set the overriding uri endpoint. This option needs to be used in combination with overrideEndpoint option. |
String |
||
Set whether the DynamoDB Streams client should expect to load credentials through a default credentials provider or to expect static credentials to be passed in. |
false |
boolean |
|
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 |
|
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 |
||
Sets the exchange pattern when the consumer creates an exchange. Enum values:
|
ExchangePattern |
||
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 |
||
The number of subsequent error polls (failed due some error) that should happen before the backoffMultipler should kick-in. |
int |
||
The number of subsequent idle polls that should happen before the backoffMultipler should kick-in. |
int |
||
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 |
||
Milliseconds before the next poll. |
500 |
long |
|
If greedy is enabled, then the ScheduledPollConsumer will run immediately again, if the previous run polled 1 or more messages. |
false |
boolean |
|
Milliseconds before the first poll starts. |
1000 |
long |
|
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 |
|
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 |
LoggingLevel |
|
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 |
||
To use a cron scheduler from either camel-spring or camel-quartz component. Use value spring or quartz for built in scheduler. |
none |
Object |
|
To configure additional properties when using a custom scheduler or any of the Quartz, Spring based scheduler. |
Map |
||
Whether the scheduler should be auto started. |
true |
boolean |
|
Time unit for initialDelay and delay options. Enum values:
|
MILLISECONDS |
TimeUnit |
|
Controls if fixed delay or fixed rate is used. See ScheduledExecutorService in JDK for details. |
true |
boolean |
|
Amazon AWS Access Key. |
String |
||
Amazon AWS Secret Key. |
String |
Required DynamoDBStream component options
You have to provide the DynamoDbStreamsClient in the Registry with proxies and relevant credentials configured.
Sequence Numbers
You can provide a literal string as the sequence number or provide a bean in the registry. An example of using the bean would be to save your current position in the change feed and restore it on Camel startup.
It is an error to provide a sequence number that is greater than the largest sequence number in the describe-streams result, as this will lead to the AWS call returning an HTTP 400.
Usage
Static credentials vs Default Credential Provider
You have the possibility of avoiding the usage of explicit static credentials, by specifying the useDefaultCredentialsProvider option and set it to true.
-
Java system properties - aws.accessKeyId and aws.secretKey
-
Environment variables - AWS_ACCESS_KEY_ID and AWS_SECRET_ACCESS_KEY.
-
Web Identity Token from AWS STS.
-
The shared credentials and config files.
-
Amazon ECS container credentials - loaded from the Amazon ECS if the environment variable AWS_CONTAINER_CREDENTIALS_RELATIVE_URI is set.
-
Amazon EC2 Instance profile credentials.
For more information about this you can look at AWS credentials documentation
Coping with Downtime
AWS DynamoDB Streams outage of less than 24 hours
The consumer will resume from the last seen sequence number (as implemented for CAMEL-9515), so you should receive a flood of events in quick succession, as long as the outage did not also include DynamoDB itself.
AWS DynamoDB Streams outage of more than 24 hours
Given that AWS only retain 24 hours worth of changes, you will have missed change events no matter what mitigations are in place.
Message Body
The Message body is instance of "software.amazon.awssdk.services.dynamodb.model.Record", for more information about it, have a look at the related javadoc
Dependencies
Maven users will need to add the following dependency to their pom.xml.
pom.xml
<dependency>
<groupId>org.apache.camel</groupId>
<artifactId>camel-aws2-ddb</artifactId>
<version>${camel-version}</version>
</dependency>
where ${camel-version}
must be replaced by the actual version of Camel.
Spring Boot Auto-Configuration
When using aws2-ddbstream with Spring Boot make sure to use the following Maven dependency to have support for auto configuration:
<dependency>
<groupId>org.apache.camel.springboot</groupId>
<artifactId>camel-aws2-ddb-starter</artifactId>
<version>x.x.x</version>
<!-- use the same version as your Camel core version -->
</dependency>
The component supports 40 options, which are listed below.