SDK Mobile Integration Guide

This README provides technical guidance on the integration of the Halo.SDK with a host Android application.

The Halo Dot SDK is an Isolating MPoC SDK payment processing MPOC Software with Attestation & Monitoring Capabilities.

The Architecture of this isolating MPoC Payment Software, is described in the diagram below. The below diagram also showcases the SDK boundary and the interaction between the SDK its integrating channels, and the 3rd party payment gateway. It also describes the boundary of the SDK and how it interacts with integrators and the third party payments. It also includes details of how the data is communicated sent in-between the boundary.

SDK Boundry

The Halo.SDK is an isolated system development kit with A&M functionality. It operates in an isolated memory space, which provides sufficient separation of data processing between the SDK and other software (including the integrating app).

1. Remote Attestation of Application by Halo Server

In accordance with prescribed security requirements, the Halo server performs remote attestation of the application using the Google SafetyNet attestation framework.

Since Halo is an Android Application Resource (AAR), while the target of the SafetyNet attestation is the entire Android Package (APK), the Halo server needs to be configured with details of any new APK prior to release, otherwise that APK will fail remote attestation during SDK initialization, and not be used to transact.

APK Values Required by Halo Server for Remote Attestation

The following attestation payload field must be configured in the Halo server with each release so that they can be checked by the server during remote attestation.

field	description
apkPackageName	fully qualified APK name, e.g. za.co.synthesis.halo.halo_mpos_new
apkCertificateDigestSha256	base64 encoded, SHA-256 hash of the certifi cate used to sign requesting app
applicationVersion	version number of application of host application

2. Requirements on the Mobile Back-End

JWT

All calls were made to the Halo.SDK requires a valid JWT. The mobile application server is expected to supply the mobile app with a JWT that can be used to authenticate with the Halo Kernel Server. The SDK requires a callback function, onRequestJWT(callback: (String) -> Unit), that it will use whenever a JWT is required.

An asymmetric key is used so that the JWT can be issued (signed) by one system (mobile application server), and independently verified by another (Halo server).

JWT LifeTime

Since the JWT essentially authorizes payment acceptance for a given merchant user, it is essential that the JWT lifetime be kept as short as possible, in order to limit the amount of time an attacker has to crack the key itself and then to limit the scope of damage in the event of a key compromise.

A lifetime of 15 minutes is recommended.

JWT Signing Public Key Format

The JWT public key should be published as a certificate, in a text-friendly format, e.g. B64 encoded PEM (.crt, .pem).

JWT Serialization Format

The compact serialization format is expected, i.e:

urlencodedB64(header) + '.' + urlencodedB64(payload) + '.' + urlencodedB64(signature)

For example:

eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJsb2dnZWRJbkFzIjoiYWRtaW4iLCJpYXQiOjE0MjI3Nzk2Mzh9.gzSraSYS8EXBxLN_oWnFSRgCzcmJmMjLiuyu5CSpyH

JWT Claims

The JWT must make a number of claims - all of them standard except for aud_fingerprints (Audience Fingerprints):

field	type	Note
alg	String	The signing algorithm is RSA signed SHA-256 hash, aliased as RS256. An asymmetric encryption(signing) scheme is required to allow the Kernel Server to be able to validate the token without being able to generate it. If symmetric key encryption was used to sign the auth token (e.g., using the HMAC algorithm), then non-repudiation would be lost.
sub	String	The Payment Processor Merchant-User ID, or Application ID
iss	String	This is a unique (from the perspective of Halo server) identifier for the JWT issuer, agreed upon by the JWT issuer and Synthesis, and configured in advance by Synthesis in the Halo server, e.g. authserver.haloplus.io
aud	String	URL of Halo server TLS endpoint, e.g. 'kernelserver.qa.haloplus.io'. This value should be obtained from Synthesis (different per environment) e.g. for QA it would be 'kernelserver.qa.haloplus.io' and for DEV 'kernelserver.za.dev.haloplus.io'
usr	String	The details of the user performing the transaction, typically the username used to sign into the Integrators application.
iat	NumericDate	The UTC timestamp of when the JWT was generated.
exp	NumericDate	The UTC time of expiration of the JWT.
aud_fingerprints	String	a CSV list of expected SHA-256 fingerprints for the Kernel Server TLS endpoint. This list may contain multiple values to support certificate rotation. In the QA environment, the expected value as of writting this would be: "sha256/zc6c97JhKPZUa+rIrVqjknDE1lDcDK77G41sDo+1ay0="

All these values can be validated by making a POST request to "https://kernelserver.qa.haloplus.io/<sdk-version>/tokens/checkjwt". Your JWT should be added as header (Bearer Auth).

3. SDK Binary

HaloSDK is written in Kotlin and packaged as an AAR (Android Archive Library). For security reasons, the compiled binary has been obfuscated.

See the Getting Started Guide for a detailed guide on accessing and getting started with the SDK.

4. Application Manifest

The AndroidManifest.xml application manifest file of the mobile application must include the following user permissions:

• android.permission.INTERNET - call out to the backend over the internet

• android.permission.NFC- use the NFC module

In addition, in order to indicate to the Play store that this is an NFC-enabled app, the android.hardware.nfc the feature needs to be specifi ed, with required=false . If required is set to true then the mobile app itself will not be allowed to be installed on devices that don't support NFC, which is presumed to not be the desired behavior.

Android Gradle Plugin > 3.4.2

Due to a limitation with the TEE library that is used, if the Android Gradle Plugin (classpath 'com.android.tools.build:gradle') is greater than 3.4.2, the following attribute needs to be added to the application element inside the Android Manifest application

android:extractNativeLibs="true"

5. Life-Cycle Methods

In order for the SDK to properly handle the Android application life cycle, the host app needs to add hooks into the following Android lifecycle methods on the MAIN activity.

⚠️ do not hook up to a SUB activity or a fragment as this will cause problems

List of Android lifecycle methods:

• onCreate(Bundle savedInstanceState)

• onStart()

• onResume()

• onPause()

• onStop()

• onSaveInstanceState(Bundle outState, PersistableBundle outPersistentState)

• onSaveInstanceState(Bundle outState)

• onDestroy()

Halo.SDK has corresponding static methods with matching method signatures for each of the Android lifecycle methods.

This can all be wired up as follows:

public class MainActivity extends AppCompatActivity {
    @Override
    public void onCreate(Bundle savedInstanceState, PersistableBundle persistentState) {
        super.onCreate(savedInstanceState, persistentState);
        // your mobile app code here
        HaloSDK.onCreate(this , this, savedInstanceState, persistentState);
    }

    @Override
    protected void onStart() {
        super.onStart();
        // your mobile app code here
        HaloSDK.onStart();
    }

    @Override
    protected void onResume() {
        super.onResume();
        // your mobile app code here
        HaloSDK.onResume();
    }

    @Override
    protected void onPause() {
        super.onPause();
        // your mobile app code here
        HaloSDK.onPause();
    }

    @Override
    protected void onStop() {
        super.onStop();
        // your mobile app code here
        HaloSDK.onStop();
    }

    @Override
    public void onSaveInstanceState(@NonNull Bundle outState, @NonNull PersistableBundle outPersistentState) {
        super.onSaveInstanceState(outState, outPersistentState);
        // your mobile app code here
        HaloSDK.onSaveInstanceState(outState, outPersistentState);
    }

    @Override
    protected void onSaveInstanceState(@NonNull Bundle outState) {
        super.onSaveInstanceState(outState);
        // your mobile app code here
        HaloSDK.onSaveInstanceState(outState);
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        // your mobile app code here
        HaloSDK.onDestroy();
    }
}

6. Initialization of the SDK

Separate from the lifecycle hooks, the SDK must be initialized before transacting by calling the static initialize method on the SDK, passing it a HaloInitializationParameters object.

The SDK will attempt to perform the following sequence of actions:

• the Perform runtime checks (the device is not rooted, running in debug mode, or under instrumentation)

• Confirm that the software (Android version) and hardware platform (NFC device) is sufficient

• Connect to the server, passing on the JWT for verification

• Confirm that the device has been enrolled, and is not blocked - re-enrolling if necessary

• Perform device-local Google SafetyNet key attestation actions, and submit results to the server for remote verification

• Retrieve terminal configuration from the server

• Initialize the SDK to a state where it will accept transactions

The result will be communicated, typically asynchronously (depending on exactly what happens and when), to the host application via invoking the callback registered in IHaloCallbacks.onInitializationResult and passing a HaloInitializationResult.

The HaloInitializationResult.resultType field indicates whether or not the initialization was successful or not. A value Initialized indicates success, all other values indicate some kind of failure.

In the case of failure, the errorCode field may hold more information, whereas in the case of success, the SDK is now ready to accept a transaction.

HaloInitializationParameters

import za.co.synthesis.halo.sdk.model.HaloInitializationParameters

public class HaloInitializationParameters {
    public IHaloCallbacks haloCallBacks;
    public Long cardTimeTimeoutMS;
    public String applicationName;
    public String applicationVersion;
}

Long cardTimeTimeoutMS - Timeout value, in milliseconds, that the SDK will wait for a card tap after startTransaction has been called, before returning with a timeout error.

String applicationName - The fully qualified package name of the calling application.

String applicationVersion - The version number of the calling application.

IHaloCallbacks haloCallBacks - See below discussion on the IHaloCallbacks interface.

IHaloCallbacks

import za.co.synthesis.halo.sdk.model.IHaloCallbacks

public interface IHaloCallbacks {
    void onInitializationResult(HaloInitializationResult result);
    void onHaloUIMessage(HaloUIMessage message);
    void onHaloTransactionResult(HaloTransactionResult result);
    void onRequestJWT(Function1<? super String, Unit> function1);
    void onAttestationError(HaloAttesationHealthResult result);
    void onCameraControlLost();
}

The IHaloCallbacks interface encapsulates the call-back methods that the HaloSDK will use to asynchronously communicate back to the host application at relevant junctures:

1. The outcome of the initialization process (onInitializationResult)

2. Interim transaction progress (onHaloUIMessage)

3. Final outcome of a transaction (onHaloTransactionResult)

4. Issues with intermittent attestation checks (onAttestationError)

HaloInitializationResult

import za.co.synthesis.halo.sdk.model.HaloInitializationResult

public class HaloInitializationResult {
    public HaloInitializationResultType resultType;
    public Currency terminalCurrency;
    public List<String> terminalLanguageCodes;
    public String terminalCountryCode;
    public String message;
}

Notes on HaloInitializationResult:

1. HaloInitializationResultType

   Here is a list of possible values for HaloInitializationResultType

   Value	Meaning
   Initialized	Success
   AuthenticationError	Error occurred during authentication
   NetworkError	Network socket error during connection to server
   UnsupportedOperatingSystemVersion	Android OS too low
   RootedDevice	Device rooting detected
   InstrumentedDevice	Runtime instrumentation detected
   DebuggedDevice	Debug mode detected
   GeneralError	General failure
   RemoteAttestationFailure	Device failed remote leg of Android SafetyNet attestation
   NFCDisabledError	NFC either absent, turned off, or NFC permission not granted

2. Terminal Localisation Information Returned in HaloInitializationResult

   As part of initialization, the SDK will fetch its pre-defined terminal configuration from the Halo server - and this includes localization data which should be checked by the host application to ensure that the terminal is transacting in the expected currency, which is required for the limit checks done as part of kernel processing to be performed in the correct matching currency. In addition, these values should be used to determine the correct currency symbol and a number of decimal points to use when displaying the transaction amount to the cardholder.

3. terminalLanguageCodes

   The EMV terminal specification dictates that the terminal be configured with a list of language preferences (ISO 639-1 alpha2 language code), ordered from highest to lowest priority. The mobile app should ideally use this list to determine which language to use for display purposes.

4. terminalCurrency

   The terminal has a single supported currency. This is the currency in which card risk limits are configured, and the transaction must be conducted. It is also the currency that must be used when displaying amounts. The mobile app should determine the correct currency symbol and a number of decimal places from this. If this value is not as expected, then the mobile app should not allow transactions.

5. terminalCountryCode

   The terminal is configured with a country code that indicates the domestic country. The returned value is formatted as an ISO 3166-1 numeric 3 country code left padded with zeros to length 4, e.g. 0710 = South Africa.

7. Transaction Flow

This section describes the Transaction flow of the SDK in more detail.

HaloSDK.startTransaction

Once the SDK has been successfully initialized, as indicated by a HaloInitializationResultType of Success, a transaction may be initiated by calling HaloSDK.startTransaction.

public final fun startTransaction(
    transactionAmount: java.math.BigDecimal,
    merchantTransactionReference: kotlin.String
): za.co.synthesis.halo.sdk.model.HaloStartTransactionResult

Let's take a closer look at startTransaction parameters:

• transactionAmount - The purchase amount, stated in the terminalCurrency as returned in HaloInitializationResult.terminalCurrency.

• merchantTransactionReference - It is recommended to use a random GUID for this purpose.

The merchantTransactionReference is a unique-per-merchant transaction reference generated and supplied by the mobile application. Halo will generate and maintain its own internal ID for the transaction (haloTransactionReference), but from the perspective of the mobile application merchantTransactionReference together with the value Payment Processor Merchant-User ID specified in the JWT sub field can be used to uniquely identify a merchant transaction.

This value needs to be unique per merchant transaction, i.e. different merchants could use the same merchantTransactionReference for two different transactions, but the value would need to be unique per transaction for a given merchant. In the event that the same merchantTransactionReference is supplied for two different transactions for the same merchant, the second transaction will be rejected by the Halo server, and the final transaction result type returned for the second transaction will be HaloTransactionResultType.DuplicateMerchantTransactionReferenceSupplied.

In the event of the final transaction result type being HaloTransactionResultType.Indeterminate , then it is the merchantTransactionReference that should be used to look up and potentially resolve the final transaction outcome - potentially through a manual reversal by the merchant via the web portal.

The return type of startTransaction is HaloStartTransactionResult and is defined as:

import za.co.synthesis.halo.sdk.model.HaloTransactionResult
    public class HaloStartTransactionResult {
        public HaloStartTransactionResultType resultType;
        public String message;
    }

where HaloStartTransactionResultType is:

import za.co.synthesis.halo.sdk.model.HaloTransactionResultType
    public enum HaloStartTransactionResultType {
        Started,
        NotInitialized,
        GeneralError,
        NFCDisabledError;
    }

Start Transaction Flow

As part of starting a transaction, the SDK will check:

• NFC is present and turned on

• SDK itself has been successfully initialized

• Platform runtime (root/debug/instrumentation)

HaloSDK.startTransaction will always synchronously return a HaloStartTransactionResultType, only a value of Started indicates that the SDK is satisfied to actually start a new transaction, all other values indicate a failure of some kind.

In the event of a failure, the return of the startTransaction method signals the end of the transaction and Halo.SDK will invoke no further callbacks, and this outcome should be regarded as the final outcome of this transaction, and full control returns to the mobile application.

If the SDK is able to start the transaction, startTransaction will return a HaloStartTransactionResultType of Started.

From this point onwards, Halo.SDK will communicate interim transaction progress back to the mobile application by means of invoking the IHaloCallback.onHaloUIMessagecallback function, and the final transaction outcome by invoking the IHaloCallback.onHaloTransactionResult.

Informing the Merchant of a Tamper Event

If HaloSDK.startTransaction returns a result type of RootedDevice, InstrumentedDevice or DebuggedDevice, then the EMV specification dictates that it is mandatory for the host application to immediately inform the merchant on screen that their device has been tampered with.

Communication of Interim Status

Before the final transaction outcome is communicated via IHaloCallbacks.onHaloTransactionResult, interim transaction progress will typically be communicated to the mobile app via invoking IHaloCallbacks.onHaloUIMessage:

void onHaloUIMessage(HaloUIMessage message);

It is expected that the mobile app will use these message events as triggers for communicating interim transaction status information or action prompts such as present card, remove card, present card again to the card holder.

Let's have a closer look at HaloUIMessage:

import za.co.synthesis.halo.sdk.model.HaloUIMessage

public class HaloUIMessage {
    public HaloUIMessageID msgID;
    public int holdTimeMS;
    public List<String> languagePreference;
    public HaloCurrencyValue offlineBalance;
    public HaloCurrencyValue transactionAmount;
}

And the parameters of HaloUIMessage:

1. HaloUIMessageID msgID

   The msgID field indicates the interim transaction status, which should be communicated to the user. The following are the types that msgID can be:

   Enum	Text	Description
   PresentCard	Present Card	Initial message, accompanied by transaction amount
   Processing	Processing...	May occur between PresentCard and CardReadOK_RemoveCard
   CardReadOK_RemoveCard	Card Read OK, Remove Card	Card reading has been completed and user should remove card
   SeePhoneForInstructions_ThenTapAgain	See Phone for Instructions, then Tap Again	Authorise transaction on payment device, then tap again
   AuthorisingWait	Authorising, Please Wait...	Attempting online authorization
   TryAgain	Try Again	Initial card read failed, cardholder to present card again - transaction still in progress
   TryAnotherCard	Try Another Card	Transaction failed, start a new transaction with a different card

2. int holdTimeMS

   The EMV terminal specification dictates that when multiple messages are received in quick succession for the same transaction, each message must be displayed for a minimum amount of time (the message hold time), before proceeeding to display the next message. This is intended to allow the user enough time to read eachmessage, and typically results in queue-based implementations.

   holdTimeMS refl ect the message hold time, in units of milliseconds.

3. List languagePreference The EMV specification dictates that cards may include a list of language preferences. If the card does contain such a list, it will be specified in HaloUIMessage as languagePreference, which is a list of ISO 639-1 alpha2 language codes, in order of language.

   The mobile application can then choose to display the UI message texts in a preferred language, or if not specifi ed, in its default language.

IHaloCallbacks.onHaloTransactionResult

Once it has completed processing, Halo.SDK communicates the final transaction outcome to the mobile application via invoking the IHaloCallbacks.onHaloTransactionResult callback, and passing it a HaloTransactionResult object. Once the mobile application receives a HaloTransactionResult, it can regard the transaction as concluded, and assume full control again.

Here is a closer look at HaloTransactionResult:

public class HaloTransactionResult {
    public HaloTransactionResultType resultType;
    public String merchantTransactionReference;
    public String haloTransactionReference;
    public String paymentProviderReference;
    public String message;
    public HaloTransactionReceipt receipt;
    public Map<String, String> customTags;
}

And the parameters of HaloTransactionResult:

1. HaloTransactionResultType resultType

   The HaloTransactionResultType resultType field indicates the final transaction status to the host application.

   Value	Description
   Approved	Transaction successfully approved online
   Declined	Transaction declined, either offl ine by terminal or card, or onliny by issuer
   CardTapTimeOutExpired	Timed out waiting for a card tap
   NetworkError	Network socket communication error
   ProcessingError	An error occurred during EMV card processing
   Cancelled	Transaction called by host application
   TryAnotherCard	Transaction failed with this card, but may succeeed with another card
   NFCDisabledError	NFC on the device is turned off
   NotAuthenticated	Invalid JWT token provided
   Indeterminate	Unknown transaction status, inform merchant to manually query transaction status via merchant portal before giving goods
   DuplicateMerchantTransactionReferenceSupplied	Transaction rejected by server due to use of duplicate merchant transaction reference. attempt again with a new reference
   HealthError	An error occurred while checking the status of the Kernel Server
   InvalidJWT	An error occurred while parsing the JWT

   Only if a HaloTransactionResultType of Approved is received should the merchant be instructed that the transaction has been successful. If a result of type Indeterminate is returned, then the merchant MUST be instructed to query the Payment Processor as to the final transaction outcome - BEFORE giving goods/services. This will typically be done either through the host application itself, or via the payment processor's merchant management portal. All other values should be regarded as conclusively indicating that the transaction has failed.

2. Transaction References

   Reference	Source
   merchantTransactionReference	HaloSDK.startTransaction.merchantTransactionReference
   haloTransactionReference	Halo server
   paymentProviderReference	Payment Provider

3. HaloTransactionReceipt

   EMV receipt information is specified in HaloTransactionResult.receipt. Approved transactions will always contain receipt information, whereas this is not guaranteed in the case of declined transactions.

   Field	Description
   transactionDate	Transaction Date, YYMMDD
   transactionTime	Transaction Time, HHMMSS
   aid	Application ID, 16 hex chars
   applicationLabel	Application Label, 16 chars
   applicationPreferredName	Application Preferred Name, 16 chars
   tvr	Terminal Verification Results, 10 hex chars
   cvr	Card Verification Results, hex
   cryptogramType	Application Cryptogram type: AAC, TC, ARQC
   cryptogram	Application Cryptogram, 16 hex chars
   maskedPAN	Card PAN masked according to PCI, 16 chars
   authorizationCode	The final authorization code returned by the issuer in the online response, 12 chars
   ISOResponseCode	Authorisation Response Code returned by the issuer in the online response
   association	Card scheme: MasterCard, Visa, AMEX
   expiryDate	Card application expiry date

8. SDK Async Behaviour after startTransaction Returns

Assuming that startTransaction returns a synchronous result type of Started , the SDK will continue with async transaction processing.

Pre-Processing

The SDK will first perform transaction pre-processing as per the EMV specification. The transaction can be declined during pre-processing (typically due to terminal limits). In this case, the SDK will communicate this by calling IHaloCallbacks.onHaloTransactionResult with HaloTransactionResult.resultType as Declined, then terminate, sending no UI messages.

Enablement of NFC Field

Assuming that pre-processing succeeds, the SDK will attempt to turn the NFC field on. If it is not able to do so (typically because NFC has not been enabled within phone settings), then the SDK will abandon the transaction, and return HaloTransactionResult.resultType as NFCDisabledError.

Confirmation of Transaction Amount

Assuming that the NFC field could be enabled, the SDK will then send a PresentCard HaloUIMessageID, with the transaction amount specified in the transactionAmount field. No action is required by the user to confirm the amount, the message is displayed only for information purposes.

Wait for Tap or Timeout

At this point, the SDK will wait for either a tag to be tapped, or for the card tap timeout to expire. If the timeout occurs, then the SDK will abandon the transaction,and return HaloTransactionResult.resultType as CardTapTimeOutExpired.

On Tap

Assuming the card is tapped in time, the SDK will engage with the card. At this point, 1 of 2 things can happen:

1. A processing error occurs during the card interaction. HaloTransactionResult.resultType of ProcessingError is returned, and the SDK abandons transaction.

2. The card interaction completes successfully. In this case, the SDK will send a CardReadOK_RemoveCard UI message, and continue with async transaction processing.

Potential for Offline Decline

Under some situations, the attempted online transaction may be declined offline by the card, in this case, the SDK will return a HaloTransactionResult.resultType of Declined, and abandon the transaction.

PIN

If the transaction amount exceeds the CVM limit and the card supports online PIN, the SDK will request a PIN for the transaction. This is handled transparently by the SDK using a Trusted User Interface, which will briefly assume control of the mobile device screen to capture a PIN.

Once the PIN has been captured, control will return to the calling application.

Online Processing

Assuming that the card interaction was successful, no processing errors were encountered, and that the card did not decline the transaction outright, then the SDK will attempt to prepare, submit and process an online transaction authorization request.

The SDK will send a OnlineProcessing UI message to indicate that is begun online processing.

General Error During Online Processing

If there is a general error during the preparation of the online request, the SDK will return a HaloTransactionResult.resultType of ProcessingError, and abandon the transaction.

Could Not go Online

If the SDK is unable to submit the online authorization request due to network connectivity issues, it will return a HaloTransactionResult.resultType of NetworkError, and abandon the transaction.

Ambiguous Transaction Outcome

In the event that the SDK was able to connect and submit an online authorization request, but did not receive a response, it will return a HaloTransactionResult.resultType of Indeterminate, and abandon the transaction.

In this case, the user must be instructed to consult the transaction back-end in order to determine the final transaction outcome before handing over the goods/services.

Final Transaction Outcome

Once the SDK has received and processed the online response, it will communicate the fi nal transaction outcome, which at this point should be one of Approved, Declined or NotAuthenticated. A result of NotAuthenticated typically means that the JWT supplied has expired, and that the transaction should be restarted with a fresh JWT. The SDK will then terminate.

Try Another Card

In some cases the SDK will determine that the transaction cannot be completed with the current card/device, in this case it will return a TryAnotherCard result, and the mobile app should instruct the user to attempt the transaction with a different card. From the perspective of the SDK, this will be a new transaction.

Try Again Flow

In some unusual cases, the SDK will require the user to present the same card/device again, in order to complete the transaction. In these cases, the SDK will retain control, but will require the mobile application to communicate instructions to the user via ui messages during the transaction. These instructions will either be to tap the same card/device again ( TryAgain ), or to first consult their device for instructions, then tap the device again ( SeePhoneForInstructions_ThenTapAgain ). It is only when the transaction has been finally concluded that the SDK will communicate a final transaction result as per normal, then terminate.

9. Conclusion

That concludes the guide to integrate the Halo.SDK into your application. For any questions, please do not hesitate to reach out to the Halo Dot Team.

Not what you were looking for? If you are looking for the Intent Integration guide, it is over here