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You can write an SCF function to handle a scheduled task (which can be triggered in seconds). The timer will automatically trigger the function at the specified time. Timer triggers have the following characteristics:

• Push model: the timer directly calls the Invoke API of the function to trigger it at the specified time. The event source mapping is retained in the SCF function.
• Async invocation: a timer trigger always invokes a function asynchronously, and the result is not returned to the invoker. For more information on invocation types, please see Invocation Types.

Timer Trigger Attributes

• Timer name (required): it can contain up to 60 characters out of a-z, A-Z, 0-9, -, and _ and must begin with a letter and be unique under the same function.
• Triggering cycle (required): this is the specified function triggering time. You can use the default value in the console or customize a standard cron expression to decide when to trigger the function. For more information on cron expressions, please see below.
• Input parameter (optional): it can be a string of up to 4 KB, which can be obtained from the event parameter of the entry function.

Cron Expression

When creating a timer trigger, you can customize the triggering time by using a standard cron expression. Timer triggers can trigger functions in a matter of seconds. In order to be compatible with legacy timer triggers, cron expressions can be written in two ways:

Cron expression syntax 1 (recommended)

A cron expression has seven required fields, separated by spaces.

Each field has a corresponding value range:

Cron expression syntax 2 (not recommended)

A cron expression has five required fields, separated by spaces.

Each field has a corresponding value range:

Wildcards

Precautions

When both the "Day" and "Week" fields in a cron expression are specified, they are in an "or" relationship, i.e., the conditions of both are effective separately.

Sample

Below are some examples of cron expressions and their meanings:

Input Parameters of Timer Triggers

When a timer trigger triggers a function, the following data structures will be encapsulated in event and passed to the function. In addition, you can specify to pass the message for a timer trigger, which is empty by default.

{
   "Type":"Timer",
   "TriggerName":"EveryDay",
   "Time":"2019-02-21T11:49:00Z",
   "Message":"user define msg body"
}