1. Introduction

The client side provides the frontend for our dApp and all the pieces of sofware required for the execution of the complete application flow. It relies heavily on Cardano PAB Client, a library we developed for general purpose frontend Cardano/Plutus development.

The PAB Client library provides all the functionality to connect to the server side services such as the PAB and the Budget service. Moreover, it provides a full-featured general purpose Cardano balancer, that can be used to balance transactions built in any possible way, not only with the PAB. It also includes additional Cardano utilities, such as a wallet wrapper that provides typing and additional functionality to the basic API defined in CIP 30.

In the following sections we describe how to use the different PAB Client modules using the escrow example as a reference. We choose to structure the presentantion following the logical order that requires performing a dApp operation, as illustrated in the following diagram:

The flow starts with the connection to the PAB, that can be either done with the low level module PAB API (section 2), or with the high level module ContractEndpoints built on top of it (section 3). As the PAB yields an unbalanced transaction, next step is to balance it using the Balancer (section 4). Finally, singing and submission of the final transaction is done using the wallet. The complete flow is put together in the escrow frontend (section 5), where the User Interface calls the main Escrow module that provides the full dApp functionality.