tillhub/payment-engine

Android library which combines different payments SDKs into single interface solution

Payment Engine

Android library which combines different payments protocols into single interface solution. So far supported payments are:

• ZVT - Zero Reactive Voltage Transmission is an german abbreviation and stands for Payment Terminal
• OPI - The Open Payment Initiative, or O.P.I. for short

How to setup

Step 1. Add the JitPack repository to your settings.gradle file:

dependencyResolutionManagement {
    repositories {
        ...
        mavenCentral()
        maven { url 'https://jitpack.io' }
    }
}

Step 2. Add the dependency to your app build.gradle:

dependencies {
    implementation 'com.github.tillhub:payment-engine:x.x.x'
}

Usage

There are two ways you can use payment SDK:

• First one would be manually registering activity result contract (callback)
• Second one is via helper class PaymentEngine.kt

1. Register a callback for an activity result

In UI component like Activity or Fragment first register one of Payment contracts:

• PaymentContract - use for new card payment
• PaymentRefundContract - use for refunds
• PaymentReversalContract - use for payment reversal
• TerminalReconciliationContract - use for terminal reconciliation

val getPayment = registerForActivityResult(PaymentContract()) {
    // Handle the returned payment response
}

override fun onCreate(savedInstanceState: Bundle?) {
    // ...

    val paymentButton = findViewById<Button>(R.id.payment_button)

    paymentButton.setOnClickListener {
        // Pass in PaymentRequest as the input
        getPayment.launch(PaymentRequest(...))
    }
}

2. Usage of PaymentEngine

PaymentEngine.kt is singlton helper class which tries to simplify the process of implementation and it gives you access to all library available actions (managers).

• PaymentManager is used to start of a card payment transaction
• RefundManager is used to start of a partial card payment refund
• ReversalManager is used to start of a card payment reversal
• ReconciliationManager is used to start of a terminal reconciliation

It also gives you more flexibility setting up terminal configuration, observing result through singleton Flow and triggering actions with multiple methods.

private val paymentEngine: PaymentEngine by lazy {
    PaymentEngine.getInstance()
}

override fun onCreate(savedInstanceState: Bundle?) {
    // ...

    val paymentManager = paymentEngine.newPaymentManager(this)

    ...

    paymentButton.setOnClickListener {
        // Pass in PaymentRequest as the input
        paymentManager.startPaymentTransaction(...)
    }

    lifecycleScope.launch {
        lifecycle.repeatOnLifecycle(Lifecycle.State.CREATED) {
            paymentManager.observePaymentState()
                .collect {
                    // Handle payment response
                }
        }
    }
}

Here's example of PaymentManager interface and what provides:

interface PaymentManager {
    fun putTerminalConfig(config: Terminal)
    fun observePaymentState(): SharedFlow<TerminalOperationStatus>
    fun startPaymentTransaction(amount: BigDecimal, currency: ISOAlphaCurrency)
    fun startPaymentTransaction(amount: BigDecimal, currency: ISOAlphaCurrency, configName: String)
    fun startPaymentTransaction(amount: BigDecimal, currency: ISOAlphaCurrency, config: Terminal)
}

In case you do not provide terminal configuration default one will be used (ZVT, ip:127.0.0.1, port:40007)

Credits

• Đorđe Hrnjez
• Martin Širok
• Chandrashekar Allam

License

MIT License

Copyright (c) 2024 Tillhub GmbH

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.