Using a Subscription Filtering Policy

Scenario

This section describes how to configure a subscription filtering policy when adding a subscription to specify the scope of message publishing. The default filtering policy applies to message attributes. If you have set a filtering policy and message attributes when publishing a message, the system determines whether to push the message to the subscriber based on the filtering policy.

Prerequisites

A topic has been created. For details, see Creating a Topic.

Adding a Subscription

You can add the following subscriptions to the created topic by referring to Adding a Subscription to a Topic.

• If you add a subscription endpoint A to the topic and want to receive notifications every Sunday and Wednesday morning or afternoon, you can configure the following subscription filtering policy when creating subscription A:

  {
      "filter_polices": [
          {
              "name": "week",
              "string_equals": [
                  "sunday",
                  "wednesday"
              ]
          },
          {
              "name": "time",
              "string_equals": [
                  "morning",
                  "afternoon"
              ]
          }
      ]
  }

• If you add a subscription endpoint B to the topic and want to receive notifications at night or late night on Monday, Tuesday, and Wednesday, you can configure the following subscription filtering policy when creating the subscription:

  {
      "filter_polices": [
          {
              "name": "week",
              "string_equals": [
                  "monday",
                  "tuesday",
                  "wednesday"
              ]
          },
          {
              "name": "time",
              "string_equals": [
                  "night",
                  "midnight"
              ]
          }
      ]
  }

Publishing a Message

When you publish messages to a topic, different results will be obtained in different scenarios.

For details about how to publish a message, see Introduction.

• Scenario 1

  The message attribute fields are as follows:

  {
      "name": "week",
      "type": "STRING",
      "value": [
          "sunday"
      ]
  }

  Sending result: The message will only be sent to subscription A because only week is specified, and time is not specified.

• Scenario 2:

  The message attribute fields are as follows:

  [
      {
          "name": "week",
          "type": "STRING",
          "value": [
              "sunday"
          ]
      },
      {
          "name": "time",
          "type": "STRING",
          "value": [
              "night"
          ]
      }
  ]

  Sending result: Neither subscription A nor subscription B will receive the message because this message is intended only for subscribers who receive it on Sunday night.

• Scenario 3:

  The message attribute fields are as follows:

  [
      {
          "name": "week",
          "type": "STRING",
          "value": [
              "monday"
          ]
      },
      {
          "name": "time",
          "type": "STRING",
          "value": [
              "night"
          ]
      }
  ]

  Sending result: This message is only sent to subscription B because this message is intended for subscribers who receive it on Monday night.

• Scenario 4

  The message attribute fields are as follows:

  [
      {
          "name": "week",
          "type": "STRING",
          "value": [
              "sunday"
          ]
      },
      {
          "name": "time",
          "type": "STRING",
          "value": [
              "morning"
          ]
      }
  ]

  Sending result: This message is only sent to subscription A because this message is intended for subscribers who receive it on Sunday morning.

• Scenario 5

  The message attribute fields are as follows:

  [
      {
          "name": "week",
          "type": "STRING_ARRAY",
          "value": [
              "sunday",
              "monday"
          ]
      },
      {
          "name": "time",
          "type": "STRING_ARRAY",
          "value": [
              "morning",
              "night"
          ]
      }
  ]

  Sending result: Both subscription A and subscription B can receive this message because this message is intended for subscribers who receive it in the morning or night on Sunday or Monday.

• Scenario 6

  No subscription filtering policy is configured.

  Sending result: Subscriptions without subscription filtering policies will not receive messages with any attributes.