Band of brothers, building scalable social web apps on windows azure with asp.net mvc3, mongo db, rabbitmq

Band of Brothers, building scalable social web apps on Windows Azure

with ASP.NET MVC3, MongoDB, RabbitMQ

Marjan NikolovskiCo-Owner, Senior Software Engineer at EmitKnowledgeSenior Software Engineer at Seavus

Contact:emitknowledge.com/@[email protected]

Agenda

• Social web architecture• Intro to MongoDB• Data modeling for MongoDB• Intro to RabbitMQ• Preparing your guns for pub/sub with RabbitMQ• Data painting with MVC3• Hosting and scaling strategies on Windows Azure

Social web architecture

• By definition a social web must provide connectivity between the users for a common good

• From functional aspect a social web must provide:• Connectivity (Relationships)• Privacy• Private messaging• Notifications and events (both real-time and offline)• Recommendations


• Connectivity, how users are socializing• Directional or bidirectional relations ?• How are users going to socialize ?

• Post Sharing• Groups• Private messaging• Gamification


• Privacy• Beware of details• Who, When and What

UserA User B User C

Who can access my data ? Y N

When can my data be accessed ? After publish Delay with 1 day

What kind of data could be accessed ? Posts and events Posts


• Private messaging aka Conversations• Define messaging types:

• One to One• Group messaging

• Define messaging strategy• When a new conversation starts ?• Until when does it last ?

• Spam detection and prevention• Mark as spam strategy• Spam filtering strategy• Both ?


• Notifications and events (both real-time and offline)• When to notify ?• Frequency of notifications• To stream or to aggregate?• To filter or display all ?


• Recommendations• Define recommendation method:

• Friends method• Recommends the friends of my friends• Ease to implement• Big miss factor• Recommends people that we possibly know• Not very practical

• Sharing interests method• Recommend me a friend that we have a starting point to talk about• Efficient for connectivity• Needs initial user input for building the analytics


• From technical aspect must respect:• Stateless• Pluggability• Async execution• Load distribution• Intensive logging and auditing• Content delivery strategy


• Stateless• Azure instance load balancing is your enemy

• We don’t know on which instance the request will end (cloud load balancing)

• So, forget about using server side session or tempdata• Yes we can store it in DB, but performance per request ?


mysocialapp.cloudapp.net

mysocialapp.cloudapp.net


• Pluggability• Enable the platform to go down partially• Develop your functionalities as plugins• Enable real-time plugin load/unload (hotplug)• Partial deployment



• Async execution• Sequential processing only at the minimum, everything else

delegate to background services• User registration use case• User reset password use case• User notification use case

• Time and data intensive operations must execute as background services jobs


Web server Messaging infrastructure

Send create user request

Worker services

User created response

Send confirmation email message

Notify for new user registration message


• Load distribution• We hit the processing limit per machine. Now what ?

• Develop your data and time intensive functionalities with job distribution in mind

• Event based Producer – consumer jobs• Each functionality requires

• Job orchestrator• Job processor


MESSAGING INFRASTRUCTURENew user postNotify all of my friends Notify from 1 – 100

Notify from 101 – 123

Notify all of my friends




• Intensive logging and auditing• You will always want to know what your users are up to• Analytics can’t help !• Put your intensive logging and auditing so you can playback later• Log and audit everything you can get• Build your own analytics system


{ "Username" : "some_username", "IsAuthenticated" : false, "RawUri" : "/Account/Login", "BaseUri" : "/Account/Login", "HttpMethod" : "POST", "IpAddress" : "127.0.0.1", "Refferer" : "http://localhost:42378/", "UserAgent" : "mozilla/5.0 (windows nt 6.1) applewebkit/535.12 (khtml, like gecko) maxthon/3.3.4.4000 chrome/18.0.966.0 safari/535.12", "IsCrawler" : false, "IsSecureResource" : false, "Action" : "Emit.Knowledge.Controllers.RequestLogging.UserRequestLoggingController.VerifyUserCredentials(String username, String password, User& verifiedUser)", "Data" : { "username" : "test333" }, "IsFaulted" : false, "CreatedOn" : { "UtcDateTime" : new Date("3/10/2012 01:40:52") }}


• Content delivery strategy• Reference your scripts with build number

• .js?ver=1.0.1 to propagate script changes with ease• Minify as many js scripts into one• Group page images into sprites and add build number

• .png?ver=1.0.1• Reference user images to the CDN • Analyze the average change of user profile image to determine

the image caching period

Intro to MongoDB

• Document store• Fast, scalable and available• JSon – used for data hydratation• Dynamic• Stores data structured as documents instead of row as seen in

RDBMS• Uses Query, Insert, Update and Remove for data manipulation• Used for adding data at high rates without “choking” the system

Intro to MongoDB

• Documents in MongoDB• Each document can be of size max to 16mb• Each document you insert into MongoDB will be assigned an id

consisted of: • This is a 12-byte value consisting of 4 parts:

timestamp (4 bytes)• machine identifier (3 bytes)• process id (2 bytes)• increment (3 bytes)

• in MongoDB, each document will contain not only the values, but the key names (~"column names" in relational db-speak) too. So if you have keys: “Username" and “Password", then those alone will add 16 bytes to each document.

• MongoDB automatically adds some padding to the documents to allow for documents to grow in size to try and reduce the need for documents to be moved around if they do grow

Data modeling for MongoDB

• Forget what you’ve learned at school and shift your mind• Want to be fast ? – Denormalize data that will be static

(IAuditable – ring any bells ?)• Common pitfalls• To render a post we need the post content and the username• Modeling by the book will get you to model the Content entity to

have Title, Content, UserId • Now we need to fire two queries to display the username

Data modeling for MongoDB

• Beware of your queries• Analyze all of your queries• Set index per query

• But don’t forget the order by in the index • Mongodb has limitation for “OR” queries and sorts (indexing will

not help you here)• Think in map/reduce way maybe ?

Intro to RabbitMQ

• Robust and reliable messaging for apps• Supports many messaging patterns• Publish-subscribe• Topic based PubSub• Point-to-point• Request-reply• Store and forward• …

Publish-subscribe{

Publisher

Topic

Subscriber Subscriber

Consumes the event Consumes the event

Publish an event

Topic based PubSub

Publisher

Topic

Subscriber Subscriber

Consumes the event Consumes the event

Publish an event

SubtopicSubscriber

Consumes the event

{

Point-to-point

Publisher SubscriberQueue

{

Request-reply

Publisher/Subscriber SubscriberTopic

Subscriber

Subscriber

{

Store and forward

Publisher/Subscriber SubscriberTopic

Subscriber

Subscriber

Data

{

Preparing your guns for pub/sub with RabbitMQ

• Establishing pub/sub architecture• Who will listen on what ?• Do we need to intercept messages ?• Do we need to deliver one message to many subscribers ?• Do we need to distribute the message processing ?

• Two levels of messaging• Job coordination and distribution• Server instancing coordination

• Messaging patterns of interests• Pub/Sub• Topic based Pub/Sub

Preparing your guns for pub/sub pub/sub with RabbitMQ

• Persist messages that must be delivered, everything else just flush it through the wire

• Topic subscription is your enemy• Don’t expand your topics tree in depth• Minimize topic root subscriptions

Data painting with MVC3

• Delegate data render to the client with dynamic data instead on server side

• Prepare your static content and the templates in the views (this will help you to reduce the traffic. Dom will be created on fly.)

• Knockout your dynamic data


<script id="notes-template" type="text/html"> {{each notes }} <div class="note-wrap"> <div class="note-title"> <div class="title-text">${GetTitle}</div> <div class="title-date">${LastEditedDate}</div> </div> </div> </div> {{/each}}</script>


<div class="note-wrap"> <div class="note-title"> <div class="title-text">Title 1</div> <div class="title-date">2012-01-01</div> </div> <div class="note-title"> <div class="title-text">Title 2</div> <div class="title-date">2012-01-02</div> </div> <div class="note-title"> <div class="title-text">Title 3</div> <div class="title-date">2012-01-03</div> </div> </div></div>


Template + Ajax Server render

638 bytes - JSON /

2246 bytes - HTML template 22460 bytes - HTML

TOTAL 2884 bytes 22460 bytes – HTML

Hosting and scaling strategies on Windows Azure

• Design deployment and scaling strategy per component:• Web server• Data server• Messaging server• Worker server


• When to scale ?• MongoDB instances

• Indexes are too large to fit in memory• First scale vertically with RAM then shard

• RabbitMQ instances• Message delivery slows down• Scale vertically with CPU then shard

• ASP.NET MVC instances• Number of users goes large• Check what is eating the machine throughtput

• Usually problem with the notifications long pooling• Scale horizontally with more extra small or small instances

• Worker instances• Job processing time goes “large”• Scale horizontally with more extra small or small instances• Round robin processing strategy will help you to relax the job processing


• Two instances per type to meet with the SLA requirements• Use CentOS for MongoDB, Linux has better memory

fragmentation than Windows• For RabbitMQ choose the OS that you are most comfortable

with.• Windows 2K8 OS for the ASP.NET MVC


• Open SSH and MongoDB ports only• Don’t forget to disable anonymous login on the MongoDB and

set u/p combinations for both server and database


• Open SSH/Remote Desktop ports and RabbitMQ communication port

• Disable anonymous connections to the instance and add u/p combinations for connection to the RabbitMQ server

?

Technology

Band of brothers, building scalable social web apps on windows azure with asp.net mvc3, mongo db, rabbitmq