Creating an Event Subscription

Prerequisites

• (Optional) You have created an event source.
• You have set an event target.

Procedure

1. Log in to the EG console.
2. In the navigation pane, choose Event Subscriptions.
3. Click Create Event Subscription.
4. Click next to the default subscription name.
5. Enter a new subscription name and description, and click OK.
6. Configure an event source.
   1. Click Event Source, as shown in Figure 1.
      Figure 1 Configuring an event source
      
   2. Select an event source provider.
      • Huawei Cloud: Huawei Cloud service event source
      • Custom: custom event source
   3. Set event source parameters.
      When selecting Huawei Cloud, set the parameters listed in Table 1.

      Table 1 Cloud service event source parameters

      Parameter	Description
      Event Source	Select a cloud service event source.
      Event Type	(Optional) Select a predefined event type.
      Filter Rule	Enter an event filter rule. Only events that match these filter rules will be routed to the associated targets. For more information about filter rules, see Filter Rule Parameters and Example Filter Rules.

      Figure 2 Configuring a cloud service event source
      

      If Event Source is set to OBS Application Service, refer to Table 2.

      Table 2 OBS application event source parameters

      Parameter	Description
      Source	Select an event source.
      Bucket	Select an OBS bucket.
      Event Type	Select event types to filter.
      Object Name Prefix	Enter an object name prefix.
      Object Name Suffix	Enter an object name suffix.
      Object Name Encoding	Whether to encode object names of OBS events.
      Filter Rule	Enter an event filter rule. Only events that match these filter rules will be routed to the associated targets. For more information about filter rules, see Filter Rule Parameters and Example Filter Rules.

      When selecting Custom, set the parameters listed in Table 3.

      Table 3 Custom event source parameters

      Parameter	Description
      Channel
      Type	Two types are available: Existing: Select an existing custom event channel. New: Create an event channel.
      Channel	If Type is set to Existing, select an existing custom event channel, for example, channel. If Type is set to New, enter a channel name.
      Description	Set this parameter only when Type is set to New. Describe the custom event channel.
      Event Source
      Type	Two types are available: Existing: Select an existing custom event source. New: Create an event source.
      Event Source	If Type is set to Existing, select a custom event source associated with the custom event channel you specify, for example, channel. If Type is set to New, enter a source name.
      Description	Set this parameter only when Type is set to New. Describe the custom event source.
      Filter Rule	Enter an event filter rule. Only events that match these filter rules will be routed to the associated targets. For more information about filter rules, see Filter Rule Parameters and Example Filter Rules.

      Figure 3 Configuring a custom event source
      

   4. Click OK.

7. Configure an event target.
   

   A subscription can be bound with up to five targets.

   1. Click Event Target, as shown in Figure 4.
      Figure 4 Configuring an event target
      
   2. Select an event target provider.
      • Huawei Cloud: Huawei Cloud service event target
      • Custom: custom event target
   3. Set event target parameters.
      When selecting Huawei Cloud, set the following parameters.

      • Event Target: Select an event target.

        If you set Event Target to FunctionGraph (function computing):

        • Function: Select the function to trigger. If no function is available, create one by referring to section "Creating a Function".
        • Version/Alias: Choose to specify a version or alias.
        • Version: Select a version of the function. By default, latest is selected.
        • Alias: Select an alias of the function.
        • Execute: Select Asynchronously or Synchronously.
          

          Function invocation mode. Default: Asynchronously.

          Asynchronously: Immediate responses of function invocation are not required.

          Synchronously: Immediate responses of function invocation are required.

        • Agency: Select an agency. If no agency is available, click Create Agency to generate one named EG_TARGET_AGENCY.
          1. Only agencies with EG as the delegated cloud service are displayed.
          2. Select an agency with the permission functiongraph:function:invoke*.

        If you set Event Target to Distributed Message Service (DMS) for Kafka:

        • Connection: Select a DMS for Kafka connection.
        • Topic: Select a message topic.
        • Enable: Whether to enable the message key function.
        • Transform Type: Defines how message keys are used. There are two options:
          • Variables: Keys are variable values from CloudEvents-compliant events.
          • Constants: Keys are specified constants. All messages will be sent to the same partition.

          For more information about the transform types, see Event Content Transformation.

        If you set Event Target to EventGrid (EG):

        

        An event can be transmitted three times in an EG channel.

        • Account Type: Select Current or Other. The following table lists the parameters.

          Table 4 Event target parameters

          Current	Other	Description
          Region	Region	CN North-Beijing4, CN East-Shanghai1, CN East-Shanghai2, and CN South-Guangzhou NOTE: Coming soon in more regions.
          Project ID	Project ID	Enter the project ID of the target channel. NOTE: Enter the same project ID as the target channel, or events cannot be published to it. Obtain the project ID on the My Credentials page of the corresponding account.
          Channel	Channel	Enter the target channel ID. NOTE: Current account and same region: Select a channel in the current account. Other account: Specify a channel ID. If you select Current, select a different channel from the subscription. Do not select the default channel. When entering IDs across accounts, do not enter the same channel ID and default channel ID. Otherwise, the event cannot be delivered. If the current channel is not associated with a subscription, messages published to the channel cannot be consumed. Therefore, you need to add a subscription. The event source name of the downstream event subscription must be the same as that of the upstream event subscription, and the downstream event source must be a user-defined event source.
          Agency	Agency	Select an agency. NOTE: If no agency is available, click Create Agency to generate one named EG_TARGET_AGENCY. Only agencies with EG as the delegated cloud service are displayed. Select an agency with the permission eg:channels:putEvents.

          Rule:

        • Transform Type: EG transforms CloudEvents-compliant events for targets.
          • Pass-through: Directly route CloudEvents-compliant events to the target.

          For more information about the transform types, see Event Content Transformation.

        If you set Event Target to Simple Message Notification (SMN):

        • Topic: Select a message topic.
        • Agency: Select an agency. If no agency is available, click Create Agency to generate one named EG_SMN_PUBLISHER_AGENCY.
          • Only agencies with EG as the delegated cloud service are displayed.
          • Select an agency with the permission smn:topic:publish.
        • Message Subject: Configure the subject through constants or variables.
        • Type: Type of the message subject. Two types are available:
          • Constants: The subject does not change from specified. All messages will use the same subject.
          • Variables: The subject in the template is a variable value from CloudEvents-compliant events. Max.: 512 characters.
            

            The Subject parameter is optional.

        Rule:

      • Transform Type: EG transforms CloudEvents-compliant events for targets. The following three types are supported:
        • Pass-through: Directly route CloudEvents-compliant events to the target.
        • Variables: Route variables in CloudEvents-compliant events to the target.
        • Constants: Route constants in events to the target.

        For more information about the transform types, see Event Content Transformation.

      Figure 5 Configuring a Huawei Cloud service event target
      
      When selecting Custom, set the following parameters.

      • URL: Enter the URL of an event target.
      • Connection: Select a custom or the default connection.
      • Headers Parameters
        • Enter a request header.
        • Enter a value.
        • Specify whether to encrypt the header.
          Figure 6 Header parameters
          
          

          • For custom HTTPS events, add authorization configurations for the event target to improve security.
          • If the request header and value are invalid, the encryption option is unavailable.
          • Key: Max. 256 characters starting and ending with a letter. Only letters and hyphen (-) are allowed.
          • Value: Max. 1024 characters, including letters, hyphens (-), underscores (_), spaces, and special characters (~!@#$%^&*()=+|[{}];:'",<.>/?).
      • Transform Type: EG transforms CloudEvents-compliant events for targets. The following three types are supported:
        • Pass-through: Directly route CloudEvents-compliant events to the target.
        • Variables: Route variables in CloudEvents-compliant events to the target.
        • Constants: Route constants in events to the target.

        For more information about the transform types, see Event Content Transformation.

      Figure 7 Configuring a custom event target
      
   4. Click OK.

8. Click Save.

   The subscription is enabled by default once created.