450c6df9bf
Apply suggestions from code review Co-authored-by: roldanbob <broldan@redhat.com> Apply suggestions from code review Co-authored-by: roldanbob <broldan@redhat.com> Apply suggestions from code review Co-authored-by: roldanbob <broldan@redhat.com> Apply suggestions from code review Co-authored-by: roldanbob <broldan@redhat.com>
263 lines
8.2 KiB
Plaintext
263 lines
8.2 KiB
Plaintext
// Category: debezium-using
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// Type: assembly
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[id="debezium-notification"]
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= {prodname} notifications
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ifdef::community[]
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:toc:
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:toc-placement: macro
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:linkattrs:
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:icons: font
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:source-highlighter: highlight.js
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toc::[]
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== Overview
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endif::community[]
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{prodname} notifications provide a mechanism to obtain status information about the connector.
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Notifications can be sent to the following channels:
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SinkNotificationChannel:: Notifications are sent through the Connect API to a configured topic.
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LogNotificationChannel:: Notification are appended to the log.
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Custom:: Notifications are sent to a xref:debezium-notification-custom-channel[custom channel] that you implement.
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// Type: concept
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[id="debezium-notification-format"]
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== Debezium notification format
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Notification messages contain the following information:
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|===
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|Property |Description
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|id
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|A unique identifier that is assigned to the notification. For incremental snapshot notifications, the `id` is the same sent with the `execute-snapshot` signal.
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|aggregate_type
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|The data type of the aggregate root to which a notification is related.
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In domain-driven design, exported events should always refer to an aggregate.
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|type
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|Provides status information about the event specified in the `aggregate_type` field.
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|additional_data
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|A Map<String,String> with detailed information about the notification.
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For an example, see xref:debezium-notifications-about-the-progress-of-incremental-snapshots[{prodname} notifications about the progress of incremental snapshots].
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|===
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// Type: concept
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[id="debezium-available-notifications"]
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=== Available notifications
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{prodname} notifications deliver information about the progress of xref:debezium-notifications-about-the-status-of-an-initial-snapshot[initial snapshots] or xref:debezium-notifications-about-the-progress-of-incremental-snapshot[incremental snapshots].
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==== Status of an initial snapshot
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The following example shows a typical notification that provides the status of an initial snapshot:
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[source, json]
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----
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{
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"id": "5563ae14-49f8-4579-9641-c1bbc2d76f99",
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"aggregate_type": "Initial Snapshot",
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"type": "COMPLETED" <1>
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}
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----
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<1> The type field can contain one of the following values:
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* `COMPLETED`
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* `ABORTED`
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* `SKIPPED`
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[id="debezium-notifications-about-the-progress-of-incremental-snapshots"]
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==== {prodname} notifications about the progress of incremental snapshots
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The following table shows examples of the different payloads that might be present in notifications that report the status of incremental snapshots:
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|Status|Payload
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|Start
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a|[source, json]
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----
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{
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"id":"ff81ba59-15ea-42ae-b5d0-4d74f1f4038f",
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"aggregate_type":"Incremental Snapshot",
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"type":"STARTED",
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"additional_data":{
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"connector_name":"my-connector",
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"data_collections":"table1, table2"
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}
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}
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----
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|Paused
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a|[source, json]
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----
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{
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"id":"068d07a5-d16b-4c4a-b95f-8ad061a69d51",
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"aggregate_type":"Incremental Snapshot",
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"type":"PAUSED",
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"additional_data":{
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"connector_name":"my-connector",
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"data_collections":"table1, table2"
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}
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}
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----
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|Resumed
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a|[source, json]
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----
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{
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"id":"a9468204-769d-430f-96d2-b0933d4839f3",
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"aggregate_type":"Incremental Snapshot",
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"type":"RESUMED",
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"additional_data":{
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"connector_name":"my-connector",
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"data_collections":"table1, table2"
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}
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}
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----
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|Stopped
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a|[source, json]
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----
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{
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"id":"83fb3d6c-190b-4e40-96eb-f8f427bf482c",
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"aggregate_type":"Incremental Snapshot",
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"type":"ABORTED",
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"additional_data":{
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"connector_name":"my-connector"
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}
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}
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----
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|Processing chunk
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a|[source, json]
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----
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{
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"id":"d02047d6-377f-4a21-a4e9-cb6e817cf744",
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"aggregate_type":"Incremental Snapshot",
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"type":"IN_PROGRESS",
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"additional_data":{
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"connector_name":"my-connector",
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"data_collections":"table1, table2",
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"current_collection_in_progress":"table1",
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"maximum_key":"100",
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"last_processed_key":"50"
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}
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}
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----
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|Snapshot completed for a table
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a|[source, json]
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----
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{
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"id":"6d82a3ec-ba86-4b36-9168-7423b0dd5c1d",
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"aggregate_type":"Incremental Snapshot",
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"type":"TABLE_SCAN_COMPLETED",
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"additional_data":{
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"connector_name":"my-connector",
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"data_collection":"table1",
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"total_rows_scanned":"100"
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}
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}
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----
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|Completed
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a|[source, json]
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----
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{
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"id":"6d82a3ec-ba86-4b36-9168-7423b0dd5c1d",
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"aggregate_type":"Incremental Snapshot",
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"type":"COMPLETED",
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"additional_data":{
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"connector_name":"my-connector"
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}
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}
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----
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|===
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// Type: procedure
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[id="enabling-debezium-notifications"]
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=== Enabling {prodname} notifications
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To enable Debezium to emit notifications, specify a list of notification channels by setting the `notification.enabled.channels` configuration property.
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By default, the following notification channels are available:
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* `sink`
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* `log`
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To use the `sink` notification channel, you must also set the `notification.sink.topic.name` configuration property to the name of the topic where you want {prodname} to send notifications.
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// Type: concept
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[id="debezium-notification-custom-channel"]
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== Custom notification channels
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Notification mechanism has been built to be extensible. You can implement more channels where receive notification in an easy way.
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You need to set up a java project and add {prodname} Core dependency, implement your notification channel and deploy it. Then you just need to enable your custom channel.
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// Type: procedure
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[id="debezium-configuring-custom-notification-channels"]
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=== Configuring custom notification channels
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Custom notification channels are Java classes that implement the `io.debezium.pipeline.notification.channels.NotificationChannel` service provider interface (SPI).
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For example:
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[source,java,indent=0]
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----
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public interface NotificationChannel {
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String name(); // <1>
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void init(CommonConnectorConfig config); // <2>
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void send(Notification notification); // <3>
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void close(); // <4>
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}
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----
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<1> The name of the channel.
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To enable {prodname} to use the channel, specify this name in the connector's `notification.enabled.channels` property.
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<2> Initializes specific configuration, variables, or connections that the channel requires.
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<3> Sends the notification on the channel.
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{prodname} calls this method to report its status.
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<4> Closes all allocated resources.
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{prodname} calls this method when the connector is stopped.
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// Type: concept
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[id="debezium-core-module-dependency"]
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=== {prodname} core module dependencies
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A custom notification channel Java project has compile dependencies on the {prodname} core module.
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You must include these compile dependencies in your project's `pom.xml` file, as shown in the following example:
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[source,xml]
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----
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<dependency>
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<groupId>io.debezium</groupId>
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<artifactId>debezium-core</artifactId>
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<version>${version.debezium}</version> // <1>
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</dependency>
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----
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<1> `${version.debezium}` represents the version of the {prodname} connector.
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Declare your implementation in the `META-INF/services/io.debezium.pipeline.notification.channels.NotificationChannel` file.
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// Type: procedure
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[id="deploying-a-debezium-custom-notification-channel"]
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=== Deploying a custom notification channel
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.Prerequisites
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* You have a custom notification channel Java program.
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.Procedure
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* To use a notification channel with a {prodname} connector, export the Java project to a JAR file, and copy the file to the directory that contains the JAR file for each {prodname} connector that you want to use it with. +
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+
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For example, in a typical deployment, the {prodname} connector files are stored in subdirectories of a Kafka Connect directory (`/kafka/connect`), with each connector JAR in its own subdirectory (`/kafka/connect/debezium-connector-db2`, `/kafka/connect/debezium-connector-mysql`, and so forth).
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To use a signaling channel with a connector, add the converter JAR file to the connector's subdirectory.
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NOTE: To use a custom notification channel with multiple connectors, you must place a copy of the notification channel JAR file in each connector subdirectory.
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// Type: procedure
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[id="configuring-a-connectors-to-use-a-custom-notification-channel"]
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=== Configuring a connector to use a custom notification channel
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Add the name of the custom notification channel to the `notification.enabled.channels` configuration property.
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