4.2 Propagate Oracle-Tmm-Tx-Token for multiple REST API calls

When the business logic of your application spawns across multiple API calls to complete a transaction, you must propagate Oracle-Tmm-Tx-Token for multiple REST API calls.

This section explains how the Oracle_Tmm_Tx_Token token is propagated when the business logic of your application spawns across multiple API calls to complete a transaction. If you have set transactionTokenEnabled to true in the YAML file and the business logic of your application spawns across multiple API calls to complete a transaction, you must retrieve the value of Oracle_Tmm_Tx_Token and pass it in the request header for all the subsequent API calls that the user makes.

Skip these steps if the business logic of your application requires only a single API call from a user to complete the entire transaction. To understand how the Oracle_Tmm_Tx_Token token is propagated when the business logic of your application requires only a single API call from a user, see About the Oracle_Tmm_Tx_Token Transaction Token.

Let's consider a trip booking application, which requires two calls from a user. The first call is to initiate a transaction and make a provisional booking. The application requires a second API call from the user to confirm or cancel the booking. In such scenarios, when your application's business logic spawns across multiple API calls from a user to complete a single transaction, you must include Oracle_Tmm_Tx_Token in the request header of the subsequent API call from the user to confirm or cancel the booking.

The following steps describe how MicroTx Distributed Transactions creates the Oracle_Tmm_Tx_Token transaction token and propagates it for the first call and how you need to include Oracle_Tmm_Tx_Token in the subsequent API calls from a user.

1. When a user begins a transaction, the transaction initiator service sends a request to MicroTx Distributed Transactions.
2. MicroTx Distributed Transactions responds to the transaction initiator and returns Oracle_Tmm_Tx_Token in the response header.

   The MicroTx Distributed Transactions library creates this token based on the private-public key pair that you provide. You don't have to create the Oracle_Tmm_Tx_Token transaction token or pass it in the request header.

   MicroTx Distributed Transactions works with multiple headers and token. For the sake of simplicity, we are limiting our discussion to the Oracle_Tmm_Tx_Token transaction token in this section.

3. To secure calls from the participant services to the transaction coordinator, the MicroTx Distributed Transactions library passes Oracle_Tmm_Tx_Token in the request header for all the subsequent calls.
4. MicroTx Distributed Transactions returns Oracle_Tmm_Tx_Token in the response header while responding to the first call from the user. Retrieve the value of Oracle_Tmm_Tx_Token from the response header.
5. In all the subsequent API calls that the user makes, you must manually include the Oracle_Tmm_Tx_Token in the request header. Provide the value that you have retrieved in the previous step.

This ensures that the multiple API calls from a user are linked together and all the calls are considered as part of a single transaction.