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net.md

grpc + folly fibers https://github.com/leftyio/tortuga/search?q=fibers&unscoped_q=fibers

Istio grpc C++ https://github.com/Toeplitz/pwave_cloud/commit/fc5ae5a786fef80ad4afee7a98cb21db94a47ad2#diff-a055b85bab3694cc2083e4ae4a7d2b50 https://github.com/NVIDIA/tensorrt-laboratory/blob/f76e4b445f6a2a63485dbc4d8668159328868fcf/examples/12_FlatBuffers/server.cc#L58

Istio tensorrt-laboratory https://github.com/NVIDIA/tensorrt-laboratory/blob/2916998333aab2492da0d0c004fbd076d858b1ba/examples/90_Kubernetes/istio/README.md

Datadog OpenTracing C++ Client istio

https://github.com/DataDog/dd-opentracing-cpp

Lwan in Performance and Scale @ Istio Service Mesh https://github.com/lpereira/lwan/tree/4bb64e2a7b46992249bff2afc8b582a5ce11b464

falcoAAupdate https://github.com/And03380/falcoAAupdate/search?q=Istio&unscoped_q=Istio

A social network with unidirectional follow relationships, implemented with loosely-coupled microservices, communicating with each other via Thrift RPCs.

https://github.com/delimitrou/DeathStarBench/tree/master/socialNetwork

wrk load generator

https://github.com/delimitrou/DeathStarBench/tree/master/socialNetwork/wrk2

Jaeger C+

https://www.alibabacloud.com/help/doc-detail/90502.htm

cpprest

Boost & 0mq & thrift

https://indico.cern.ch/event/281860/contributions/1629763/attachments/517807/714413/iCSC-2014-Network-Libraries.pdf

thrift

https://vorbrodt.blog/2019/03/10/thrift-or-how-to-rpc/

Seastar

http://www.romange.com/2018/07/12/seastar-asynchronous-c-framework/

boost.Fiber

Wangle

folly/fibers

libcoro coroutines

https://medium.com/software-development-2/coroutines-and-fibers-why-and-when-5798f08464fd

continuable

Obiew C++ & Java

grpc cpp LogIn https://github.com/obieww/Obiew/blob/0ccfeb081f8d32e5c01e261033886ecf6b0cf590/DatabaseServer/obiew-service-impl.cc#L54 & https://github.com/obieww/Obiew/blob/6af58ef4ddce55850dd1c98353adfc4a35395637/LoadBalancer/src/main/java/com/obiew/Controllers/UserController.java#L22

Nakama C++ server

grpc cpp authenticate Google/steam/... https://github.com/heroiclabs/nakama-cpp/blob/889c2b27b19c503506159760df2314832ce456f0/src/RestClient.cpp#L256

istio ws / socketio

TODO: read

Istio HTTPS https://www.reddit.com/r/docker/comments/b2ojr6/istio_enduser_authentication_for_kubernetes_using/

envoy/Istio for JWT verification

TODO:

https://github.com/FairwindsOps/advanced-kubernetes-workshop/blob/master/docs/lab_guide.pdf & https://github.com/FairwindsOps/advanced-kubernetes-workshop/blob/3c2624031bd5eb735086d214a387c5dad44ae7be/lb/rate-limit-frontend.yaml

Istio rate limit (requestcountquota)

Envoy rate limit

http_filters:
          - name: envoy.rate_limit # enable the Rate Limit filter

https://venilnoronha.io/envoy-grpc-and-rate-limiting

Istio load balance

https://github.com/GoogleCloudPlatform/istio-samples/tree/master/internal-load-balancer

WxLogin auth server grpc C++

pitaya

https://github.com/topfreegames/libpitaya-cluster/tree/master/cpp-lib

A login demo using grpc.

https://github.com/cs-jeason/grpc-cj-login

foobar-social - grpc - Colossus - Example Microservices

https://github.com/mattpaletta/foobar-social/blob/9bf9e32f6c2853d7681c36bacc2dfab3c6056b77/news_feed/include/main.cpp#L22

grpc

C++ google cloud

C++ k8s

Continuously build, test, and deploy.

Cloud Bigtable

Istio

https://redhat-developer-demos.github.io/istio-tutorial/istio-tutorial/1.1.x/4advanced-routerules.html#loadbalancer
https://github.com/instana/robot-shop/blob/b5f98f625d73b67180b896b99642642a5a0cf387/K8s/README.md#istio
https://github.com/GoogleCloudPlatform/istio-samples
https://www.bogotobogo.com/DevOps/Docker/Docker_Kubernetes_Deploying_ASP_Net_Core_App_with_ISTIO_Configured_on_Kubernetes_Engine.php & https://www.bogotobogo.com/DevOps/Docker/Docker_Kubernetes_Deploying_ASP_Net_Core_App_with_ISTIO_Configured_on_Kubernetes_Engine_Part_2_More_On_ISTIO.php
https://github.com/GoogleCloudPlatform/microservices-demo
https://supergiant.io/blog/introduction-to-istio-service-mesh-for-kubernetes/
Service Mesh: Moving from bare-bones Envoy to Istio https://hackernoon.com/service-mesh-moving-from-bare-bones-envoy-to-istio-e0fef88fc1e3
https://programmaticponderings.com/2017/12/22/deploying-and-configuring-istio-on-google-kubernetes-engine-gke/
Automatic load balancing for various protocols like HTTP, gRPC, WebSocket, and TCP https://github.com/linux-on-ibm-z/docs/wiki/Building-Istio-with-Kubernetes Sample Book Review Application
https://velotio.com/blog/2018/5/how-to-set-up-istio-using-google-kubernetes-engine
https://meteatamel.wordpress.com/2018/04/24/istio-101-with-minikube/
NOTE: Istio has plans to support additional protocols such as AMQP in the future but for now, the idea of moving from a message based approach to an HTTP centric approach with Istio seems a bit premature. https://www.linkedin.com/pulse/kubernetes-exploring-istio-event-driven-architectures-todd-kaplinger
https://github.com/blockspacer/webrtc-datachannels/blob/3622f145d426f755b33c63bd91fca6d6f874c13d/todo.txt#L173
https://dev.to/sendilkumarn/easy-microservices-with-kubernetes-and-istio-3nl3
https://developer.okta.com/blog/2019/04/01/spring-boot-microservices-with-kubernetes
https://kublr.com/blog/implementing-a-service-mesh-with-istio-to-simplify-microservices-communication/
https://istio.io/blog/2018/egress-tcp/
https://dzone.com/articles/istio-service-mesh-the-step-by-step-guide-part-2-t
https://docs.microsoft.com/en-us/azure/aks/istio-scenario-routing
https://www.lynda.com/Developer-tutorials/Introduction-service-mesh-Istio/802854/5038257-4.html
https://morganpeat.github.io/microservices/2018/08/30/cryptotracker-d.html
https://github.com/EdwinVW/pitstop/wiki/Run%20the%20application%20using%20a%20Service%20Mesh
https://github.com/CodepediaOrg/bookmarks/blob/362140a613b8e86cd1ead2db9914ddd36b194ba6/tagged/istio.md

Refactoring to microservices

https://developer.ibm.com/tutorials/refactor-existing-monolithic-applications-to-microservices-one-bite-at-a-time-part-5/

Best practices for using Cloud Spanner as a gaming database

https://cloud.google.com/solutions/best-practices-cloud-spanner-gaming-database

docker

https://docs.docker.com/develop/develop-images/multistage-build/

minikube

agones

gcloud compute firewall-rules allow udp

https://demo.newingtech.co.uk/2018/10/15/agones-gcp-%E5%9F%BA%E6%9C%AC%E8%A8%AD%E5%AE%9A/

C++ Continuous Integration

Sanitizer

https://github.com/cjdb/project_template/tree/master/cmake

Reflection & Serialization

Plugin management library with static and dynamic plugins

The dynamic reflection API can be used to load APIs from external libraries at runtime in a straightforward way + https://github.com/Manu343726/siplasplas
https://github.com/iboB/dynamix/blob/master/doc/07_advanced.dox.template#L285 & https://www.codeproject.com/Articles/1229971/The-Interface-to-Component-Pattern-and-DynaMix & https://accu.org/index.php/journals/2487
The lecture even consists of a demo showcasing loading and/or hotswapping a plugin at runtime and enriching the functionality of the program. https://www.youtube.com/watch?v=-s0zYXGCfJk reloadable .dll plugins (with the help of dynamix) - even with the ability to change the layout of types at runtime! (by serializing object state, recreating the instances and then deserializing the old state) https://github.com/onqtam/game/search?q=dynamix&unscoped_q=dynamix
https://ibob.github.io/dynamix/examples.html#multi_dll
http://onqtam.com/programming/2017-09-02-simple-cpp-reflection-with-cmake/
https://www.reddit.com/r/cpp/comments/9c9kqz/do_cpp_users_wantneed_a_cross_platform_framework/
https://www.boost.org/doc/libs/1_68_0/doc/html/boost_dll/tutorial.html#boost_dll.tutorial.searching_for_a_symbol_in_multiple_plugins & https://www.boost.org/doc/libs/1_64_0/doc/html/boost_dll/missuses.html
https://github.com/jiwaharlal/cpp_experience/commit/ce3107487648c849712d3df777583e3cbc48da7a
https://github.com/anttijuu/PluginDllDemo
sourcey: Building a Simple C++ Cross-platform Plugin System https://sourcey.com/articles/building-a-simple-cpp-cross-platform-plugin-system
sourcey pluga (LGPL sourcey/pluga#1): https://github.com/sourcey/pluga & + https://sourcey.com/pluga/ & https://github.com/jeremydumais/JedConsole/blob/master/libs/PluginBase/src/IPlugin.h
static/dynamic + Signal/slot https://github.com/mosra/corrade & https://doc.magnum.graphics/corrade/plugin-management.html & https://doc.magnum.graphics/magnum/plugins.html & https://github.com/nuclearwhales/push-the-box/blob/master/src/Application.cpp#L23

Load testing

googleforgames/agones#412

Statistics

googleforgames/agones#144

TODO:

PowerfulSeal adds chaos to your Kubernetes clusters, so that you can detect problems in your systems as early as possible. It kills targeted pods and takes VMs up and down. https://bcouetil.gitlab.io/academy/BP-kubernetes.html#powerfulseal

TODO:

TODO

https://medium.com/@andreybronin

Author

blockspacer commented Jan 16, 2020 •

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https://www.theseus.fi/bitstream/handle/10024/73386/Artem_Moskalev_thesis.pdf;sequence=1
https://www.macs.hw.ac.uk/~hwloidl/publications/MScThesis_Bond.pdf
https://pdfs.semanticscholar.org/bbb7/9a87c7adab24d43c75f3bc3d815446778212.pdf
https://pdfs.semanticscholar.org/a654/dd5ccb210e2db99efec180d9eb73b047002a.pdf
https://www.academia.edu/37257029/Fault_Tolerance_For_Main-Memory_Applications_In_The_Cloud
https://www.niap-ccevs.org/MMO/Product/st_10831-agd2.pdf
https://pdfs.semanticscholar.org/2707/3c4bb344cd223b9aade02728f1bc323d1753.pdf
http://libres.uncg.edu/ir/uncc/f/Parker_uncc_0694D_10520.pdf
https://www.collectionscanada.gc.ca/obj/s4/f2/dsk3/QMM/TC-QMM-18200.pdf
http://dl.booktolearn.com/ebooks2/computer/gamedevelopment/9781138035454_Game_Engine_Architecture_Third_Edition_6dfa.pdf
https://www.contrib.andrew.cmu.edu/~ayahyavi/files/Yahyavi-CSUR13-P2PMMOG.pdf

Author

blockspacer commented Jan 16, 2020

https://www.gamedev.net/forums/topic/682814-mmog-optimizations/

Author

blockspacer commented Jan 16, 2020

http://onemanmmo.com/index.php?cmd=newsitem&comment=news.1.11.0

Author

blockspacer commented Jan 16, 2020

https://github.com/gpascualg/Shinzui/blob/time-transform/src/physics/sat_collisions.hpp

Author

blockspacer commented Jan 16, 2020

having a monster in an MMO game remember which players have tried to attack it before so it can be hostile when it sees them again.
https://blog.demofox.org/2015/02/08/estimating-set-membership-with-a-bloom-filter/

Author

blockspacer commented Jan 16, 2020

http://index-of.co.uk/Tutorials/Networking%20And%20Online%20Games.pdf
https://www.gamedev.net/forums/topic/682814-mmog-optimizations/
https://www.gamasutra.com/blogs/AlessandroAlinone/20131127/205705/Optimizing_Multiplayer_3D_Game_Synchronization_Over_the_Web.php

Author

blockspacer commented Jan 16, 2020

Nebula Graph database based on the relations between different vertices
https://github.com/vesoft-inc/nebula/blob/master/docs/manual-EN/1.overview/2.quick-start/1.get-started.md

Author

blockspacer commented Jan 16, 2020 •

edited

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Build network priority system:

Closer to camera
Within camera frustum
Custom object importance (grenade, vehicle, etc)
Is entity visible or behind solid object. If an entity is in our sight, but behind a mountain, I can possibly ignore it.
the most distant entity will receive updates less frequently

Author

blockspacer commented Jan 20, 2020 •

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Investigate: YugabyteDB on Kubernetes
https://blog.yugabyte.com/understanding-how-yugabyte-db-runs-on-kubernetes/
https://blog.yugabyte.com/why-we-changed-yugabyte-db-licensing-to-100-open-source/
https://docs.yugabyte.com/v1.2/develop/learn/sql-nosql/
YugabyteDB on Istio
yugabyte/yugabyte-db#2158
JSONB indexes?
https://stackoverflow.com/questions/56610522/does-yugabyte-s-sql-support-index-attributes-inside-a-jsonb-column
https://blog.yugabyte.com/a-quick-guide-to-secondary-indexes-in-yugabyte-db-database/
yugabyte/yugabyte-db#741
YugabyteDB vs CockroachDB
https://www.yugabyte.com/yugabyte-db-vs-cockroachdb/
YugabyteDB C++ quick start
https://docs.yugabyte.com/latest/quick-start/build-apps/cpp/ysql/

Author

blockspacer commented Jan 21, 2020 •

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# see https://www.jfrog.com/confluence/display/JFROG/Installing+Artifactory
sudo mkdir -p /data/artifactory
sudo chmod 0755 /data/artifactory
# Artifactory runs as user 1030:1030 by default. When passing a volume to the Artifactory container, this directory (on the host) must be writable by the Artifactory user.
sudo touch /data/artifactory/etc//system.yaml
sudo chown -R 1030:1030 /data/artifactory
#  artifactory-cpp-ce - JFrog Artifactory Community Edition for C/C++, a completely free of charge server for Conan repositories. 
sudo docker pull docker.bintray.io/jfrog/artifactory-cpp-ce
 
#    -e EXTRA_JAVA_OPTIONS='-Xms1024m -Xmx2g -Xss256k -XX:+UseG1GC' \
sudo docker run -d --restart=always --name artifactory \
    -v /data/artifactory:/var/opt/jfrog/artifactory \
    -p 8081:8081 -p 8082:8082 \
    --memory="2048m" \
    -e EXTRA_JAVA_OPTIONS='-server -Xms512m -Xmx4g -Xss256k -XX:+UseG1GC' \
    docker.bintray.io/jfrog/artifactory-cpp-ce
docker logs -f artifactory

visit http://localhost:8081 to open configuration wizard User:admin. Password:password
NOTE: you can skip Configure a Proxy Server step, read https://www.jfrog.com/confluence/display/RTF6X/Configuring+a+Reverse+Proxy
turn off anonymous access in the Admin> Security Configuration page http://localhost:8081/artifactory/webapp/#/admin/security/general
open http://localhost:8081/artifactory/webapp/#/artifacts/browse/tree/General/conan and click the Set Me Up button as in https://www.jfrog.com/confluence/display/RTF/Using+Artifactory#UsingArtifactory-SetMeUp

export CONAN_REVISIONS_ENABLED=1
conan remote add conan-local http://localhost:8081/artifactory/api/conan/conan False
conan remote list
# NOTE: change password
conan user -p password -r conan-local admin
# --all                 Upload both package recipe and packages, see https://docs.conan.io/en/latest/reference/commands/creator/upload.html
# conan upload libhello/stable --all -r=conan-local -c --retry 3 --retry-wait 10
# conan search -r conan-local libhello

Follows
http://chu-studio.com/posts/2019/%E4%BB%8E%E9%9B%B6%E5%BC%80%E5%A7%8B%E7%9A%84C++%E5%8C%85%E7%AE%A1%E7%90%86%E5%99%A8CONAN%E4%B8%8A%E6%89%8B%E6%8C%87%E5%8D%97
https://qiita.com/navitime_tech/items/c1c878b6d22e911f7fb6
https://www.cnblogs.com/rongfengliang/p/9229462.html
https://www.cnblogs.com/xl2432/p/11896466.html
https://www.baeldung.com/java-ee-oauth2-implementation
https://medium.com/@robert.broeckelmann/openid-connect-authorization-code-flow-with-red-hat-sso-d141dde4ed3f

Setting up Jenkins and Artifactory in the CI machine

https://dzone.com/articles/dockerizing-jenkins-part-2-deployment-with-maven-a

docker pull conanio/conan_server

OR

# from https://www.jfrog.com/confluence/display/RTF/Installing+with+Docker
docker pull docker.bintray.io/jfrog/artifactory-cpp-ce
docker run --name artifactory -d -p 8081:8081 -p 8082:8082 --memory="512m" docker.bintray.io/jfrog/artifactory-cpp-ce:latest

https://blog.conan.io/2018/04/25/Continuous-integration-for-C-C++embedded-devices-with-jenkins-docker-and-conan.html
https://docs.conan.io/en/latest/howtos/generic_ci_artifactory.html
https://www.reddit.com/r/devops/comments/8eunov/continuous_integration_for_cc_embedded_devices/
https://cloud.google.com/blog/products/application-development/integrating-google-cloud-build-with-jfrog-artifactory
https://jfrog.com/blog/use-conan-to-simplfy-your-c-containerized-application-build-and-deployment-experience/
https://jfrog.com/blog/container-optimized-workflow-for-coreos-now-red-hat-tectonic/
https://devops.com/devops-challenges-c-c-projects/
https://www.slideshare.net/openstackil/kubernetes-is-hard-lessons-learned-taking-our-apps-to-kubernetes-eldad-assis-jfrog-cloud-native-day-tel-aviv-2018

Author

blockspacer commented Jan 22, 2020 •

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minikube addons enable registry

kubernetes pull image from private repo
https://developers.redhat.com/blog/2019/07/11/deploying-an-internal-container-registry-with-minikube-add-ons/
https://redhat-developer-demos.github.io/knative-tutorial/knative-tutorial-basics/0.7.x/01-setup.html
https://www.digitalocean.com/community/tutorials/how-to-set-up-a-private-docker-registry-on-top-of-digitalocean-spaces-and-use-it-with-digitalocean-kubernetes
https://www.docker.com/blog/building-certified-kubernetes-cluster-on-premises-with-docker/
https://www.mimiz.fr/docker-registry-kubernetes.html
https://kubernetes.io/docs/tasks/configure-pod-container/pull-image-private-registry/
https://www.nearform.com/blog/how-to-run-a-public-docker-registry-in-kubernetes/
https://stackoverflow.com/a/49903820
https://minikube.sigs.k8s.io/docs/tasks/docker_registry/

OR: Create a docker registry on minikube (reusing the Docker daemon)
https://blog.hasura.io/sharing-a-local-registry-for-minikube-37c7240d0615/

Author

blockspacer commented Jan 22, 2020

Continuous Delivery to Kubernetes with Jenkins and Helm
https://www.slideshare.net/davidcurrie/continuous-delivery-to-kubernetes-with-jenkins-and-helm

Author

blockspacer commented Jan 23, 2020 •

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Kubernites ResourceQuotas
https://cloud.google.com/blog/products/gcp/kubernetes-best-practices-resource-requests-and-limits

Kubernetes Failure Stories
https://k8s.af/

grpc timeouts
https://about.sourcegraph.com/go/grpc-in-production-alan-shreve

grpc memory arena allocation
https://developers.google.com/protocol-buffers/docs/reference/arenas

gRPC Compression
https://github.com/grpc/grpc/blob/master/doc/compression.md

SSL in gRPC and performance
https://github.com/grpc/grpc/blob/master/doc/ssl-performance.md

Optimize gRPC
One way to speed up programs is to make sure the CPU is not idling. To do this, we issue work concurrently.
https://grpc.io/blog/optimizing-grpc-part-1/
We need some way of allowing multiple operations to happen safely at the same time. Otherwise, the program can’t take advantage of all the available processors.
https://grpc.io/blog/optimizing-grpc-part-2/

Author

blockspacer commented Jan 23, 2020

What is the difference between a Kubernetes cluster using 100x n1-standard-1 (1 vCPU) VMs VS having 1x n1-standard-96 (vCPU 96), or 6x n1-standard-16 VMs (vCPU 16)?
https://dev.to/gajus/mistake-that-cost-thousands-kubernetes-gke-46ij

Author

blockspacer commented Jan 23, 2020

Preemptible VMs are up to 80% cheaper than regular instances. Pricing is fixed so you will always get low cost and financial predictability, without taking the risk of gambling on variable market pricing.

https://cloud.google.com/preemptible-vms/

Author

blockspacer commented Jan 23, 2020

Continuous Delivery to Kubernetes with Jenkins and Helm
https://static.rainfocus.com/oracle/oow18/sess/1525962270220001tFmN/PF/DEV5364%20-%20Continuous%20Delivery%20to%20Kubernetes%20with%20Jenkins%20and%20Helm_1540478658099001JxtG.pdf

Author

blockspacer commented Jan 24, 2020

Speed up docker build with cache in Kubernetes environment
https://medium.com/swlh/fast-docker-build-in-kubernetes-f52088854f45

Author

blockspacer commented Jan 24, 2020 •

edited

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Microservices blog series

===

Go Microservices blog series, part 13 - data consistency, gorm and CockroachDB.
https://callistaenterprise.se/blogg/teknik/2018/02/14/go-blog-series-part13/

Create Versatile Microservices in Golang — Part 4 (Authentication With JWT)
https://dzone.com/articles/create-versatile-microservices-in-golang-part-4-au

Nodejs rest JWT
https://crosp.net/blog/software-development/web/nodejs/secure-rest-api-using-nodejs-part-2-express-jwt-mongoose/

Author

blockspacer commented Jan 24, 2020 •

edited

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TODO: time series database ???

InfluxDB open source time series database, purpose-built by InfluxData for monitoring metrics and events, provides real-time visibility into stacks, sensors, and ...
https://habr.com/ru/post/449028/

Author

blockspacer commented Jan 24, 2020

TODO: HashiCorp Nomad ??? Why it's simpler than Kubernetes???

Author

blockspacer commented Jan 24, 2020 •

edited

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HOT roblox Microservices
https://portworx.com/architects-corner-roblox-runs-platform-70-million-gamers-hashicorp-nomad/

In my previous job at another company, the biggest issue we had was that we didn’t want to use a storage layer because we felt that per-node storage or local volumes were the best because of cost and flexibility. The truth is, you can probably make it work, but if I have a database that I need to make sure never fails, it just seems way too risky to run it like that. The cost-saving and flexibility you think you are going to get evaporate in the extra management time you have to put in.

Portworx Enterprise is the Kubernetes storage platform trusted in production by the world’s leading enterprises.

Author

blockspacer commented Jan 31, 2020

https://www.mindcontrol.org/~hplus/authentication.html

Author

blockspacer commented Jan 31, 2020

https://github.com/sourabhsahay/gameserver

Game Server 

Creating a Game Server is challenging on many levels.Services are stateful (different than conventional E-commerce model), scale is high and write:read ratio may be as much as 3:1.
Also there are issues of network latency which may require not only a faster protocol, but also data compression.

While part of scalability can be achieved through horizontal scaling, it is not as simple as scaling many servers. Inter-server communication between services will increase latency, so that also has to be kept in mind. 
 :
This document is divided in two parts : -
Game Server Architecture and implementation (As per problem)
Scalability and Future Scope

Game Server Architecture And Implementation:

Networking : 
       Since Game requires fast transport between different services, conventional TCP may not be able to perform at the frame rate required. For this, UDP has been used for the implementation for most of the game fast exchanges with server. For conventional services like Login, TCP or WebSocket is fine. For sending chats to game, the data needs to be consistent (chats need to appear in Sequence in which they arrive, so that has been handled in TCP/Websocket). For full duplex communication, Websocket is preferable to conventional HTTP. 

Data Marshalling/UnMarshalling:
It is important to marshall/unmarshall the data for communication over the network for maximum efficiency. Sometimes, the packets do not arrive at one go and are collated together, so marshalling scheme will help packing as much data as possible. For illustration purpose, in the solution Json format has been used. But it can be readily replaced by binary formats : 
For Flash based clients, AMF protocol can be used.
Unity based clients can be made to work with protobuf. The implementation contains import of protostuff library which helps in annotation driven protobuff generation.

To that effect in the codebase, two servers are implemented.
com.junglee.task.server.impl.TCPServer (Used for Login and Chat Server)
com.junglee.task.server.impl.UDPServer (Used for game session communication)

Database Handling:
Database can be decided depending upon storage and access pattern and consistency/availability guarantees. Stats are past data for user which can be stored in NoSQL solution like MongoDB. State/Session for user can be stored in fast distributed caches like Redis or Mem-cache. Both the game data and chat tend to be write-heavy, so Nosql wins in this regard over conventional DB. Nosql these days come with eventual consistency guarantees 
And implementation contains (LSM tree instead of conventional B Trees) which results in high throughput. 
Chat :The difference is that chat requires data to be highly consistent which can be achieved with a bit of latency (All chats connected to one channel can be partitioned in one partition, so latency becomes an issue). Using read replicas and write master, chats can be taken care of.Writes can be written to majority of nodes and masters keeps track of which nodes have this value. Failure and recovery can be managed by another machine with master which takes over if master fails.

Game session writes : This needs to be highly available with eventual consistency. Also failure and recovery can be taken care by consistent hashing.

In Memory storage of data : Kyro can be used for storing the data in memory. This gives a very high compression compared to conventional Java.

Thread Management : Since a game server maintains state and has high write requirement at the same time, it makes sense to not block one thread for each incoming connection. Using Java NIO Channel  and event loops helps in this regard. Netty has been used in the project for building up things.
Moreover, the internal communication between services is asynchronous and event-driven which scales better than conventional threading scheme. This has been proven time and again in nginx and new systems like AKKA.
That said, there are places for thread synchronization (creating new tables, adding new players to Table) which have been handled in (PokerTable and PokerTableManager).

Event Dispatcher : com.junglee.task.event.impl.ExecutorEventDispatcher is used for handling events. For good scalability, as mentioned in the previous point, it is necessary that communication is asynchronous in nature and event dispatcher helps in that. Also, as mentioned in the problem document, it helps in keeping the services loosely coupled.
 For example, 
 Incoming packets are regarded as events for which handlers are used for processing. Even the game logic is contained in an eventHandler.
For pushing data for Stats, event handler is used.
For chat processing, event handler is used.
The communication between TableManager(PokerTableManager) and PokerTable(at which a particular game instance is being played) is through event Dispatcher.
In this manner the same Event Dispatcher  pool can be used across multiple services.

Authentication, Player Creation and Player Management :  Authentication is done in TCPUpStreamHandler. Currently the DBLookUpServiceImpl is used for user and gameChannel(explaned later). Chats are contained in ChatServiceImpl. For illustration purposes, in-memory Java HashMap is used, but it can be readily replaced by DB.

Game Table Management/Player Management/Game Logic.
This will require a bit explanation
Game state is managed by GameStateManagerService (get or Set State, serialize/deserialize game states etc)
For maintaining user actions  for a game, PlayerSession is used. A Player can play mutiple games together and has a set of sessions for each of these games.
A player session is linked to a GameChannel where multiple players collaborate. For instance, 
A poker table could be one game channel, a chessboard can be another.
Game Logic is handled in a “handler” in PokerTable (which extends GameChannel).

So for a game Channel, A Player Session is proxy for remote client. 
A SessionManager  is used for maintaining Session. First incoming request is Login, upon which PlaySession is created and linked to a PokerTable instance. Also SessionManager stores
<remoteAddress, PlaySession> key-value pair which can be subsequently used.

Data Flow : - Incoming Message (Session events)
Network => PlayerSession => PlayerSession Handler(attached in Poker Table) => Game Channel( Or Poker Table) => PokerSessionHandler



Outgoing event (NetworkEvent) : Used for broad-cast and sending individually
For sending individually, PlayerSession is directly used, which uses TCP/UDPSender to send.
For broadcast, PokerTable is used, which calls event dispatcher, but all PlayerSession(s) are registered, so they get the event. Exactly in the reverse order

Sessions can be stored in a key-value store like RIAK or cached in Redis/Memcached.

GAME LOGIC : Game Logic is contained in PokerSessionHandler. As it is event driven, it is handled whenever there is an input from player. This is in continuation of even-driven design given in problem statement.


Project Setup :
All different parts are wired together using spring DI framework. Starting point is GameServer.


Extensibility:
Any other game can be developed extending GameChannelSession and developing custom-logic. At Server level, new/custom protocol can be registered by implementing com.junglee.task.server.Server.
As the various services are wired through interfaces, the implementation can be changed.

Not covered : If all players leave, destroy the table. (Made it more consistent with if everyone moves, return to pool, like in case of game over, though other can be implemented easily).

Future Scope :
EventsDispatcher can be extended to make sure that it is more cognizant of sending events not only based on events +sessions.
The event handling is based on handler and source/handlers are separated. There maybe cases where callbacks are required. Akka frame work provides this along with consistent hashing routing, so can be used to scale this further.