Designing Softwares for Extensibility / 拡張性を備えたソフトウェア設計

Providing solutions to our marketers has been a unique problem, where we have the advantage of having internal customers. However, the requirements are never frozen (and that's always for a good reason). With this, we took the challenge to build a product that can still serve the business while it's being built.
This session tries to cover the challenges we saw and the options we took to build our Engagement Platform. It also covers how product development is different from solution development, and how to strike a balance between extensibility and speed. We will look at examples of a few major use cases while we discuss this.

マーケティング担当者にソリューションを提供することは、社内に顧客がいるという私たちのチームならではの課題でした。また、常に正当な理由があるものの、要件が完全に確定することはありません。そのため私たちは、開発途中でもビジネスに貢献できるプロダクトの開発に取り組みました。
本セッションでは、エンゲージメントプラットフォームを構築するために私たちが直面した課題と、課題解決のために選んだ選択肢について説明します。また、プロダクト開発がソリューション開発とどのように異なるのか、拡張性とスピードのバランスをどのように取るのかについても、いくつかの主要なユースケースの例を紹介しながら議論します。

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Merpay & Mercoin Tech Fest 2023は3日間のオンライン技術カンファレンスです。
IT企業で働くソフトウェアエンジニアおよびメルペイ・メルコインの技術スタックに興味がある方々を対象に2023年8月22日（火）、23日（水）、24日（木）の3日間、開催します。 Merpay & Mercoin Tech Fest は事業との関わりから技術への興味を深め、プロダクトやサービスを支えるエンジニアリングを知ることができるお祭りです。

今年のテーマは「Unleash Fintech」。 メルペイ・メルコインのこれまでの技術的な取り組みはもちろん、メルカリグループのFintech事業における新たな挑戦をお伝えします。 セッションでは事業を支える組織・技術・課題などへの試行錯誤やアプローチなど多面的にご紹介予定です。

メルペイ・メルコインが今後どのようにUnleash（解放）していくのか、ぜひ見に来てください。

■イベント関連情報
- 公式ウェブサイト：https://events.merpay.com/techfest-2023/
- 申し込みページ：https://mercari.connpass.com/event/286670/
- Twitterハッシュタグ： #MerpayMercoinTechFest
■リンク集
- メルカリ・メルペイイベント一覧：https://mercari.connpass.com/
- メルカリキャリアサイト：https://careers.mercari.com/
- メルカリエンジニアリングブログ：https://engineering.mercari.com/blog/
- メルカリエンジニア向けTwitterアカウント：https://twitter.com/mercaridevjp
- 株式会社メルペイ：https://jp.merpay.com/

Transcript

1. Session Title Designing Softwares for Extensibility Rupesh Agrawal Merpay Backend Engineer
2. Rupesh Agrawal / @Rupesh Specializing in Software product development, Rupesh has worked at multinational companies, primarily in the B2B domain. His career has afforded him experience with product development in telecom billing and IT infrastructure management. Rupesh joined Mercari in 2021 as a Backend engineer and later led the development of a marketing platform named Engagement Platform. Merpay Backend Engineer
3. What is Software Extensibility ? https://en.wikipedia.org/wiki/Extensibility 01 Adapt to changes without major refactoring 02 Extensibility ~ Configurability 03 Extensibility ~ Scalability 04
4. Building a product or platform => longer lifetime (decades) 01 The target business domain is vast, current development is not 02 Not all the use cases are known in advance 03 Support integration with 3rd party softwares 04 When Extensibility is needed?
5. Solution vs Products/Platform Solution • Requirements are collected at initial phase • Tailor-made for the requirement • Extensibility is not the prime focus • Best if the time or resources are deciding factor • Short lived Product/Platform • Requirements are groomed continuously • Room to grow and shape • Extensibility is must • Best when having a clear vision of roadmap • Evolves with time
6. But, how do we do it ?
7. Identify the Modules and their responsibilities 01 For each module, Identify the entities and their relationship 02 Define Interfaces with composite types and not primitives 03 Volume projection, it is important to decide inter-service communication mode 04 How ?
8. Case Study: Engagement Platform
9. In house platform, envisioned to serve all the growth needs 01 Started with use case of distributing coupons on user signup in realtime 02 Could have been done with much simpler piece of code 03 The core design was considered to support extension 04 Engagement Platform Provides Brand(Mercari) to users communication for happy and long-lasting retention(growth).
10. Segment Campaign Distribution Hub Points Coupons Notifications
11. Considerations made while desgining Loosely coupled modules 01 Entity Modelling considering possible scenarios. 02 Composite objects in Request and Response 03 04 Defined scope of each of the constituting services and 05 Strategy to communicate between services
12. Data Model - Identifying entities Campaign - Models any kind of communication with customer 01 Segment - Users who qualified certain conditions 02 Incentives - Rewards or discounts to be granted 03 04 Notification - The communication going to the Users
13. Data Model - Entity Relation Campaign - Defines any kind of interaction with custimer 01 Segment - Target Users for the Campaign 02 Incentives - What rewards and incentives 03 04 Notification - The Notifications and messages going to the Users
14. Example: User Onboarding Campaign Welcome user with P1000 on registration 01 Once they have listed an item reward them with a seller coupon 02 They have sold something (utilizing the seller coupon), reward them a Buyer Coupon 03 04 (Each of these steps can have different notification channels)
15. Campaign Segment -1 Segment -2 Segment -5 Incentive Notifications[] Incentive Notifications[] Incentive Notifications[] Registration Listing Selling 1000P Sellers Coupon Buyers Coupon Private Message Push Notifn InApp Msg Push Notifn Private Message Example - Campaign Visualization
16. Event processing strategy All event processing designed to happen asynchronously 01 Events Idempotency made retry & recovery possible in case of failures or duplication due to underlying infrastructure. 02 Event state logging on service level to assure traceability 03 04 Synchronous calls only for campaign configuration
17. How it helped : Enhancements Point distributions along with coupon distributions 01 Number of times a user can be rewarded , 1 or N 02 Max amount a user can be rewarded with 03
18. Supporting Batch Distributions of Incentives Not something we originally planned for !! 01 Change the Segment definition : User events to Query 02 Required to support event bursts, as real-time events are more continious 03 New challenges : flow control, and event prioritization !! 04
19. Supporting Notifications Only distributions Originally Notifications attached to rewards were only supported 01 02 The Campaign model already supported it, with minor adjustments, we could deliver this ! 03 Originally sought for Batch distributions, modular design made it available for real-time campaigns as well ! Originally sought for Batch distributions, modular design made it available for real-time campaigns as well !
20. What it mean to run such software
21. Check Maintain Backward compatibility 01 02 Good user documentation: so that they can onboard themselves 03 Security and controlling data access across user groups 04 Monitoring and continuity : One failure can impact multiple Business Offering