# PyCon TW 2017 Collaborative Talk Notes <br> Day 1 - R1

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### 10:40-11:10 <br> Talk: [PyOT - The Merge Between Python and the Internet of Things Concept](https://tw.pycon.org/2017/events/talk/337602843466793058/)
- Slider:
- Speaker: Renaldi Gondosubroto

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### 11:45-12:30 <br> Talk: [after VOEZ launch - how to resolve problems of mobile game server development and service maintenance](https://tw.pycon.org/2017/en-us/events/talk/319314010958725199/)
- Slider: https://hackmd.io/p/SkuoAv2lZ#/
- Speaker: 郭學聰
- 共筆：

#### 作者所用的語言
* Python
* Ruby
* Golang
* C#

#### VOEZ Current Status
- Profile, save data, achievement, leaderboard
- Based on GCP
- 曾經想過用AWS
- [Teaser](https://www.youtube.com/watch?v=Bh6gQyJHbxI)

#### HTTP protocol
Request

Response

#### Genuine & Purchase verification

##### leaderboard -> fake score
* verify request: send request & attach signature
* RSA

##### game play -> pirated app & server
* server授權：RSA request hash 增加 nonce (random number)

#### Stability
* transaction

##### publish order and request order (Racer condition)
* request order
* client read game info A, then B, then C
* publish order
* publish game info C, then B, then A
* remove game info A, then B, then C

##### database cache mechanism
* database in HDD and SSD: slow
* Redis and mem in memory: fast, as cache

##### reliable inter-server request
* 由於server之間的溝通導致玩家扣錢失敗
* A: Game server B: 金流伺服器
* 扣款失敗：rollback
* 嘗試三次，失敗後要求client重新連線
* 可以讓玩家排隊沒關係！資料庫不能掛！

#### Performance
* Python is so SLOW
* "skip Python code execution if you can" - HT Kuo 06, 09, 2017
* 支援百萬人上線需要的反應時間: nanosec
* 用Google BigQuery取得公開資料,並把結果存成靜態檔案放流,迴避Python執行
* 使用CDN
* 全球的玩家連線到各地的CDN
* 節省流量及運算資源
* asset files
* 每次都用不同URL
* 可以準確在換日的時候讓 cache expired
* service downtime: 503
* service update: 舊的版本丟410

#### Timezone
* 為了準確地在本地換日時間(ex:3 a.m.)更新活動
* TZ = "Asia/Taipei"
* 用UTC去計算會碰到日光節約時間的問題

>Q: Why not use AWS?
AWS跟中華電信間連線超慢

>Q: 應對百萬使用者的方式?
設定動態開設資源

>Q: Header content type為空?
手動刪除的XD

>Q: 阿里雲和GCP共通方式？
可以做data sync但中國比較偏向自己有伺服器但是Code共通

>Q:歌曲放上CDN是否會被竊取?
歌曲資料有經過加密

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### 14:55-15:40 <br> Talk: [Building Microservices in Python 個案分享](https://tw.pycon.org/2017/events/talk/348376501365768328/)
- Slider: https://www.slideshare.net/jonascheng3/building-microservices-in-python-pycon2017
- Speaker: Jonas Cheng

自我介紹：從趨勢獨立成立的子公司 soocii

平台提供給手遊玩家的價值
- 直播群聊
- 社群分享
- 即時資訊(攻略)

費時<1年
backend工程師*5

推薦大師：Martin Fowler、Sam Newmer

## 使用 microservice 的好處：

- 解決傳統monolithic架構的問題
傳統架構：
（負載平衡）＋（各種認證，註冊，通知等服務...）＋（ＤＢ）
改完後=>user用的版本跟後端不相容=>破壞ＵＸ

- 革新的設計
- 富有彈性(能夠應對PM的變更需求)
- Small Codebase
- 相對容易測試與維護
- Easy to Scale
- plugin可以隨時抽出或加入，容易擴充
- Easy to Deploy
- 部分佈署
- System Resilience
- 部分元件異常還是可以正常運作

#### 曾經面對的挑戰

系統配置
混合雲：AWS + GCP (因為AWS在tokyo，速度不夠快)
使用技術：Python + C

micro service 問題：開發環境的準備
- 外部相依性 & 內部相依性
- 全部在本地
- 只有microservice跟business logic在本地
- 只有microservice在本地
- 都在雲端開發

- soocii 採用混合方案
- 本地環境：docker-compose, mock data, 假認證
- 整合環境：docker-compose

參考：Development environments for microservices (https://www.datawire.io/guide/deployment/development-environments-microservices/)

- 跨服務的溝通
- 程式溝通方式
- RESTful
- 希望達到零溝通，但基本上沒看過
- micro service 要能時刻提供服務，不會影響主要功能
- 理想上：不應該存在部分元件異常導致全部損毀（如：Redis 異常，應該要可以再存取 RDB）
- 實際上：很難，像是 Auth 是全部共用模組，難以取代，不過另外一個想法是也不容易壞掉

- 自動化測試（ＣＩ）
- 理想：修補後可以馬上上線
- 測試種類：（測越多信心越高）
- unit test: functions logics（最快）
- service test: classes + mock class
- requests.mock, mock.patch
- UI test: 整合性測試（最慢）
- consumer-driven contract (CDC)
- 非同步測試：
- celery: task_always_eager
- event-driven (good to have)
- sleep (bad)

- 自動化部署（ＣＤ）
- 盡可能延後
- 多版本ＡＰＩ同時並存（透過blueprint找到對應版本）
-

#### 導入 microservice 的關鍵

- 所有成員要有DevOps mindset
- 至少要有CI（自動）/CD（到處都可部署）的雛形
- 每個service有獨立的CI
- 監控機制

Q. Instance實際溝通的行為，開發中如何處理？
AWS: (application load balancer)
每個docker註冊在ALB後面 => 確保服務活著，但不清楚是跟哪個docker溝通

Q. 跨伺服器溝通如果逼不得已要交換資料，怎麼處理？
只可能盡量避免。

Q. 為什麼要做混合雲？發生什麼事情？
直播的frame rate掉太多，內部做profiling本地端最快，最後才採用本地端。

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### 16:10-16:55 <br> Talk: [Understanding Serverless Architecture](https://tw.pycon.org/2017/events/talk/332303505006002268/)
- Slide: https://speakerdeck.com/dawny33/understanding-serverless-architectures
- Speaker: Jalem Raj Rohit

- what is serverless?
function as a service, no servers
AWS: Lambda > functions > ...

- function container
- function executed in container
- We are not running or maintaining servers
- advantages
- less time maintaining server
- lots of server cost saved
- e.g. deep learning
- dis(ad-)vantages
- allow to run in limit time (AWS: timout setting)
- no control over containers
- monitoring is very very very difficult
- especially, scale out as distributed
- lessons learned and pitfalls
- limit running time problem
- Ansiable to rescue
- help provisioning workers
- running Ansible in `nohup` mode
- no control over container problem
- for security
- monitoring distributed system is difficult
- logging (?)

- How to scale?

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### 17:20-17:50 <br> Talk: [Python module in Rust](https://tw.pycon.org/2017/events/talk/325227434406314071/)
- Slider: [Python module in Rust](https://docs.google.com/presentation/d/1mTw-4buKDTqPNzJS03s2I0apBMal-SaeKk1dHDSE6fk/pub?start=false&loop=false&delayms=3000&slide=id.g22c75fc6c3_0_6)
- Speaker: 許邱翔 (Chiu-Hsiang Hsu) (dv)

- Rust community love Python most
- Rust cares memory safety without GC ; Rust is high performance like C
[benchmark](http://benchmarksgame.alioth.debian.org/)
- [PyPI of Rust](https://doc.crates.io/)
- pyvenv + pip -> Cargo
- PEP of Rust -> RFC

Q: why the Rust source code need something like "Extend C"
A: that is for avoiding default behavior "name mangling" like C++

Q: Rust can share memory buffer with Python?
A: yes