Reactive In-App Billing on Android

Presented at DevFest Greece 2015

Transcript

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2. Reactive In-App Billing
   An In-App Billing API with RxJava
   Edward Dale
   Freeletics GmbH
   

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3. Motivation
   • Our app uses RxJava for async operations
   • Except In-app billing
   • Crashes in IAB code
   

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4. Agenda
   • In-App Billing
   • IabHelper
   • RxJava
   • Going Reactive
   

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5. In-App Billing
   • Google Play service that lets you sell digital
   content from inside your applications
   • Google Play handles all checkout details
   • Any application that you publish through
   Google Play can implement In-app Billing
   • Other stores (Amazon, etc) have similar APIs
   http://developer.android.com/google/play/billing/index.html
   

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6. In-App Billing
   Your
   App
   Google
   Play
   App
   Google
   Play
   Server
   IPC
   Binder
   Magic
   

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7. package com.android.vending.billing;
   interface IInAppBillingService {
   int isBillingSupported(int apiVersion,
   String packageName,
   String type);
   .
   .
   AIDL
   

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8. package com.android.vending.billing;
   interface IInAppBillingService {
   .
   .
   Bundle getSkuDetails(int apiVersion,
   String packageName,
   String type,
   in Bundle skusBundle);
   .
   .
   AIDL
   

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9. package com.android.vending.billing;
   interface IInAppBillingService {
   .
   .
   Bundle getBuyIntent(int apiVersion,
   String packageName,
   String sku,
   String type,
   String developerPayload);
   .
   AIDL
   

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10. package com.android.vending.billing;
    interface IInAppBillingService {
    .
    .
    Bundle getPurchases(int apiVersion,
    String packageName,
    String type,
    String continuationToken);
    .
    .
    AIDL
    

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11. package com.android.vending.billing;
    interface IInAppBillingService {
    .
    .
    int consumePurchase(int apiVersion,
    String packageName,
    String purchaseToken);
    }
    AIDL
    

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12. Interprocess Communication
    • Supports primitives, Parcelables, and some
    Collection classes
    • Parcelables must be available to both
    processes
    • Synchronous
    • Multithreading must be dealt with
    • Exceptions aren’t propogated
    http://developer.android.com/guide/components/aidl.html
    

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13. But who really wants
    to write IPC code?
    

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14. How some people do it
    Your
    App
    Google
    Play
    App
    Google
    Play
    Server
    IPC Magic
    IabHelper
    Java
    

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15. IabHelper
    • “Sample” code from Google
    • Not versioned or part of a library
    • ~1,000 lines of code
    • Big API
    • 20 public methods
    • 5 interfaces
    • Buggy
    

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16. public Inventory queryInventory(boolean querySkuDetails,
    List moreSkus) throws IabException
    public Inventory queryInventory(boolean querySkuDetails,
    List moreItemSkus, List moreSubsSkus)
    throws IabException
    public void queryInventoryAsync(boolean querySkuDetails,
    List moreSkus, 

    QueryInventoryFinishedListener listener)
    public void
    queryInventoryAsync(QueryInventoryFinishedListener
    listener)
    public void queryInventoryAsync(boolean querySkuDetails,

    QueryInventoryFinishedListener listener)
    Query
    

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17. public Inventory queryInventory(

    boolean querySkuDetails, 

    List moreItemSkus, 

    List moreSubsSkus

    ) throws IabException
    Query
    

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18. public void launchPurchaseFlow(Activity act, String sku,
    int requestCode, OnIabPurchaseFinishedListener listener)
    public void launchPurchaseFlow(Activity act, String sku,
    int requestCode, OnIabPurchaseFinishedListener listener,
    String extraData)
    public void launchSubscriptionPurchaseFlow(Activity act,
    String sku, int requestCode, 

    OnIabPurchaseFinishedListener listener)
    public void launchSubscriptionPurchaseFlow(Activity act,
    String sku, int requestCode, 

    OnIabPurchaseFinishedListener listener, String extraData)
    public void launchPurchaseFlow(Activity act, String sku,
    String itemType, int requestCode,
    OnIabPurchaseFinishedListener listener, String extraData)
    Purchase
    

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19. public void launchPurchaseFlow(
    Activity act, 

    String sku, 

    String itemType, 

    int requestCode,

    OnIabPurchaseFinishedListener listener,

    String extraData
    )
    Purchase
    

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20. void consume(Purchase itemInfo) throws IabException
    public void consumeAsync(Purchase purchase,
    OnConsumeFinishedListener listener)
    public void consumeAsync(List purchases,
    OnConsumeMultiFinishedListener listener)
    Consume
    

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21. public boolean handleActivityResult(int requestCode, 

    int resultCode, Intent data)
    public void enableDebugLogging(boolean enable, String tag)
    public void enableDebugLogging(boolean enable)
    public void startSetup(OnIabSetupFinishedListener listener)
    public void dispose()
    Misc
    

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22. The Ideal Billing API
    • query(…)
    • purchase(…)
    • consume(…)
    • Not too much else
    

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23. RxJava
    • A library for composing asynchronous and
    event-based programs by using observable
    sequences
    • Parameterized concurrency
    • Uniform, composable interface
    https://github.com/ReactiveX/RxJava
    

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24. “observable sequences”
    http://rxmarbles.com/#map
    

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25. “composable”
    http://rxmarbles.com/#filter
    

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26. “parameterized concurrency”
    http://reactivex.io/documentation/operators/observeon.html
    

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27. Let’s create a Billing
    API with Rx
    

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28. Going Reactive
    • Remember “The ideal Billing API”?
    • query(…)
    • purchase(…)
    • consume(…)
    • (Not much else)
    

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29. Observable queryInventory(

    boolean querySkuDetails, 

    List moreItemSkus, 

    List moreSubsSkus)
    Observable consume(List toConsume)
    Observable launchPurchaseFlow(

    Activity activity,

    SkuDetails sku,

    int requestCode,

    String extraData)
    Going Reactive
    

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30. Observable consume(List toConsume)
    • sync/async versions of the method
    • Listener to be notified of the result
    • Checked exceptions
    • Single/multiple product consumption
    What’s Missing?
    

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31. final Observable consumeObs = billingService.consume(purchases);
    consumeObs.subscribe(new Action1() {
    @Override
    public void call(Purchase purchase) {
    // Successful consume
    }
    }, new Action1() {
    @Override
    public void call(Throwable throwable) {
    // Show error message
    }
    });
    Using the API
    

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32. final Observable consumeObs
    = billingService.consume(purchases)
    .subscribeOn(io())
    .observeOn(mainThread());
    consumeObs.subscribe(new Action1() {
    @Override
    public void call(Purchase purchase) {
    // Successful consume
    }
    });
    Using the API
    

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33. final Observable> consumeObs
    = billingService.consume(purchases).toList()
    consumeObs.subscribe(new Action1>() {
    @Override
    public void call(List purchases) {
    // Successful consume
    }
    });
    Using the API
    

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34. billingService.queryInventory(true)
    .flatMap(inventory -> just(getPurchases())
    .flatMap(purchases -> billingService.consume(purchases))
    .subscribe()
    Using the API (Advanced)
    

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35. Additional Benefits
    Your
    App
    Google
    Play
    App
    Google
    Play
    Server
    IPC Magic
    Play
    Billing
    Service
    RxJava
    Amazon
    Billing
    Service
    Amazon
    Server
    Magic
    Billing
    Service
    Polymorphism
    

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36. Additional Benefits
    Your
    App
    Mock
    Billing
    Service
    RxJava
    Testability
    Billing
    Service
    

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37. Observable queryInventory(

    boolean querySkuDetails, 

    List moreItemSkus, 

    List moreSubsSkus)
    Observable consume(List toConsume)
    Observable launchPurchaseFlow(

    Activity activity,

    SkuDetails sku,

    int requestCode,

    String extraData)
    Reactive In-App Billing
    Coming soon

    as Open Source
    library
    

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38. Questions?
    Edward Dale

    edward@freeletics.com
    @scompt
    Now hiring Android,
    iOS, Ruby backend,
    DevOps in Germany
    

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