Calls and callbacks

Calls and callbacks follow this flow:

1. Invoke a method to perform a specific action.

2. The invoked method invokes the synchronization helper method, specifying a parameter to determine which callback should be returned.

3. The synchronization helper method waits until one of the following occurs:

   1. The system returns a callback
   2. A time-out of 20 seconds
   3. An exception.

    

4. if the system returns a callback, the main flow resumes, and the application handles and processes the information returned in the callback.

Callback Parameter Order

The order of parameters is defined in the C library defines the order of parameters but can not enforce it. 

The createTender callback returns a tender object. Use this to execute subsequent actions on a tender. Evaluate other arguments using the provided helper methods.

Error Messages can be used directly in logging or feedback without helper methods.

Actionable vs. Informational Callbacks

Several callbacks occur during the processing of a tender. There are two types of callback: Actionable and Informational.

• Actionable callbacks require action to complete the transaction.
• Informational callbacks can be logged but are not required to complete a transaction.

Actionable callbacks:

• Signature Callback
• AdditionalData Callback
• PrintReceipt Callback

Informational callbacks:

• Progress Event Callback
• DCC Callback