Object Storage Service:Use event notifications to monitor object changes in real time

Prerequisite

Simple Message Queue (SMQ) is activated. You can activate SMQ on the SMQ product page.

Usage notes

• Event notification triggers calls from OSS to SMQ. When an operation in OSS matches an event notification rule, OSS sends a notification message via SMQ. This call can fail. To verify that the message was sent, check the x-oss-event-status value in the response header. The value is Base64-encoded. If the decoded value is {"Result": "Ok"}, the message was sent successfully.

• Using event notification incurs SMQ fees. For more information, see Billing.

• For a list of regions that support event notification configuration for buckets, see Regions and endpoints.

• You can configure a maximum of 10 event notification rules per region. If more rules are required, contact technical support.

• TS and M3U8 objects generated from Real-Time Messaging Protocol (RTMP) streams do not trigger event notification rules. For more information about RTMP streaming, see LiveChannel-related operations.

How it works

After you create an event notification rule, if a request to your OSS bucket triggers the rule, SMQ sends a message about the event to the HTTP server or SMQ queue that you configured. The following figure illustrates this process.

Events

Event notifications

{"events": [
      {
        "eventName": "",  // The event name. 
        "eventSource": "", // The source that triggers the event notification rule. Valid value: acs:oss. 
        "eventTime": "", // The time when the event occurred. The time is a timestamp in the ISO 8601 standard. 
        "eventVersion": "", // The version of the event notification. The current version is 1.0. 
        "oss": {
            "bucket": {
                "arn": "", // The Alibaba Cloud Resource Name (ARN) of the bucket in the following format: acs:oss:region:uid:bucketname. 
                "name": "", // The name of the bucket that contains the objects to which the event notification rule applies. 
                "ownerIdentity": "" // The owner of the bucket. 
            }, 
            "object": {
                "deltaSize": "", // The size difference between the new object and the original object. If an object is created, the value of this parameter indicates the size of the object. If an object is overwritten, the value indicates the difference between the sizes of the new object and the original object. The value may be negative. 
                "eTag": "", // The ETag value of the object. 
                "key": "", // The name of the object. 
                "position": "", // The position from which the AppendObject operation starts. This parameter applies only to the ObjectCreated:AppendObject event. The first AppendObject operation on an object starts from byte 0 of the object. 
                "readFrom": "", // The position from which the GetObject operation starts. This parameter applies only to the ObjectDownloaded:GetObject event. If the GetObject operation is not performed by range, the value of this parameter is 0. Otherwise, the value refers to the position of the byte from which the GetObject operation starts. 
                "readTo": "", // The position at which the GetObject operation ends. This parameter applies only to the ObjectDownloaded:GetObject event. If the GetObject operation is not performed by range, the value of this parameter is the object size. Otherwise, the value refers to the position of the first byte after the byte at which the GetObject operation ends. 
                "size": "" // The size of the object. 
                }, 
        "ossSchemaVersion": "", // The version of the schema. The current value is 1.0. 
        "ruleId": "GetObject", // The ID of the event notification rule that is triggered by the event. 
        "region": "", // The region in which the bucket is located. 
        "requestParameters": {
            "sourceIPAddress": "" // The source IP address from which the request is sent. 
            }, 
        "responseElements": {
            "requestId": "" // The ID of the request. 
            }, 
        "userIdentity": {
            "principalId": "" // The UID of the requester. 
            }, 
        "xVars": {  // The custom parameters of an OSS callback. 
            "x:callback-var1":"value1",
            "x:vallback-var2":"value2"
            }
        }        
     }
  ]
}

{"events": [
      {
        "eventName": "ObjectDownloaded:GetObject",
        "eventSource": "acs:oss",
        "eventTime": "2016-07-01T11:17:30.000Z",
        "eventVersion": "1.0",
        "oss": {
            "bucket": {
                "arn": "acs:oss:cn-shenzhen:114895646818****:event-notification-test-shenzhen",
                "name": "event-notification-test-shenzhen",
                "ownerIdentity": "114895646818****"},
            "object": {
                "deltaSize": 0,
                "eTag": "0CC175B9C0F1B6468E1199E269772661",
                "key": "test",
                "readFrom": 0,
                "readTo": 1,
                "size": 1
            },
        "ossSchemaVersion": "1.0",
        "ruleId": "GetObjectRule",
        "region": "cn-shenzhen",
        "requestParameters": {
            "sourceIPAddress": "198.51.100.1"
            },
        "responseElements": {
            "requestId": "5FF16B65F05BC932307A3C3C"
            },
        "userIdentity": {
            "principalId": "114895646818****"
            },
        "xVars": {
            "x:callback-var1":"value1",
            "x:vallback-var2":"value2"
            }
        }        
     }
  ]
}

Procedure

1. Log on to the OSS console.

2. In the left-side navigation pane, click Buckets. On the Buckets page, find and click the desired bucket.

3. In the left-side navigation tree, choose Data Processing > Event Notification.

4. On the Event Notification page, click Create Rule.

5. In the Create Rule panel, configure the parameters that are described in the following table.

   Parameter	Description
   Rule Name	Enter a name for the event notification rule. The name of an event notification rule must be unique in a region within an Alibaba Cloud account. The name must start with a letter and can contain only letters, digits, and hyphens (-). The name cannot exceed 85 characters in length.
   Match Object	Select one or more events from the drop-down list. For example, if you want to receive a notification when a specific object is created or overwritten by copying an object, select CopyObject. You can configure an event notification rule for a specific object and specify multiple events that can trigger the rule. You can also configure multiple event notification rules for an object. When you configure multiple event notification rules, take note of the following items: If multiple event notification rules apply to the same object, the events configured in these rules must be different. For example, if you select CopyObject for Event Type when you create an event notification rule for objects whose names contain the images prefix, you cannot select CopyObject for Event Type when you create another event notification rule that applies to objects whose names contain the same prefix. If multiple event notification rules apply to different objects, the values of this parameter in these rules can be the same or different. For example, if you select PutObject for Event Type when you create an event notification rule for objects whose names contain the images prefix and the .png extension, you can select PutObject or DeleteObject for Event Type when you create another event notification rule for objects whose names contain the log prefix and the .jpg extension. Important If you delete an object from a versioning-enabled bucket without specifying a version ID, the event notification rule for the DeleteObject or DeleteObjects event is not triggered. In this case, no version of the object is deleted. The current version of the object is stored as a previous version and a delete marker is added to the object. For more information about object operations that can trigger events, see Use event notifications to monitor object changes in real time.
   Resource Description	Specify the objects to which you want to apply the event notification rule. Select Full Name to apply the rule to an object whose name is the same as the specified name. To create a rule that applies to an object named exampleobject.txt in the root directory of the bucket, enter exampleobject.txt. To create a rule that applies to an object named myphoto.jpg in the destdir directory within the root directory of the bucket, enter destdir/myphoto.jpg. Select Prefix/Suffix to apply the rule to objects whose names contain a specific prefix and extension. To create a rule that applies to all objects in the bucket, leave Prefix and Suffix empty. To create a rule that applies to all objects in the examplefolder directory within the root directory of the bucket, set Prefix to examplefolder/ and leave Suffix empty. To create a rule that applies to all JPG objects in the bucket, leave Prefix empty and set Suffix to .jpg. To create a rule that applies to all MP3 objects in the examplefolder directory within the root directory of the bucket, set Prefix to examplefolder/ and Suffix to .mp3. To add another Resource Description entry, click Add Condition. You can specify up to five entries in an event notification rule.
   Subscription Endpoint	Specify the endpoint to which event notifications are sent. Valid values include HTTP and Queue.

6. Click OK.

   After you configure an event notification rule, the rule takes effect after approximately 10 minutes.

FAQ

Why do I receive no notifications when I delete objects?

References

• You can configure event notification rules to monitor specific objects in OSS and receive notifications about object changes. For more information, see Tutorial: Use SMQ to send notifications of OSS events.

• If you fail to receive a message body at your HttpEndpoint, the POST method might be the cause. To resolve the issue, see Cannot receive the message body with a PHP HttpEndpoint in Simple Message Queue (formerly MNS)

• Refer to Upload callbacks to implement upload callbacks.