Dealing with Enterprise Level Data

dealing with enterprise level data

webdev@rgu

posh term for ‘lots of’

Today we are looking at:•Tier architecture and cloud computing •Moving from 3-tier to n-tier •Scaling services up for use in Enterprise web

•Caches •Proxies •Load Balancing •Queueing

tier architecture and cloud computing

Presentation Logic

Business LogicData Access

LogicDatabase

1 tier architecture

• All 3 layers are kept on the same machine • Presentation, logic, and data are highly connected

• Bad for scalability (single processor being used • Bad for portability • Bad for maintenance (change one thing…change them all)

Presentation Logic


LogicDatabase

2 tier architectureClient Server

• Database runs on server • Easy if you want to switch to a new database

• Presentation and logic still tightly connected • Bad for server load • Bad if you want to make changes

Presentation Logic


LogicDatabase


• Every layer can be on a different machine • Presentation, logic, and data are all disconnected

DB Server

Presentation Logic


LogicDatabase


• Provides the user interface • Handles interaction with the user • Should not contain any business logic

DB Server

Presentation Logic


LogicDatabase


• Contains rules for processing information • Should not contain any presentation information • Can accommodate many users

DB Server

Presentation Logic


LogicDatabase


• Data storage layer • Manages access to information

DB Server

Presentation Logic


LogicDatabase

3 tier architectureClient Server DB Server

HTML CSS JAVASCRIPT

PHP ASP.NET JAVA javascript(ish)

SQL MONGODB

http://ASP.NET

Easier to maintain

Components are reusable

Faster division of work Web Designer does presentation Software Engineer does logic DB Man does DB things…

moving from 3-tier to n-tier

Availability

Performance

Reliability

Scalability

Managability

Cost

Availability

Performance

Reliability

Scalability

Managability

Cost

Services must be available all the time, no matter what

Availability

Performance

Reliability

Scalability

Managability

Cost

Services must be super fast, no lag time for users

Availability

Performance

Reliability

Scalability

Managability

Cost

Services must be reliable. The data that is returned must be the same every time it is called on

Availability

Performance

Reliability

Scalability

Managability

Cost

Services must be easily upgradable to make space for additional content

Availability

Performance

Reliability

Scalability

Managability

Cost

Services must be easy to manage, and should not break anytime someone touches it

Availability

Performance

Reliability

Scalability

Managability

Cost

Services should be cost efficient, in terms of the money to create it and also the time that it takes to create

As good as this is…it wont work for a big web system

Server Storage

Upload ImageFiles written

to storage

Request Image

Client Computer

Image Located

Image Sent

Server Storage


to storage

Request Image

Client Computer

Image Located

Image Sent

make functions to separate services in order to aid in scalability

Image Write

Service

Storage


to storage

Request Image

Client Computer

Image Located

Image Sent

Image retrieval

service

Image Write

Service

Storage


to storage

Request Image

Client Computer

Image Located

Image Sent

Image retrieval

service

build in redundancy to safeguard data

Image Write

Service

Storage


to storage

Request Image

Client Computer

Image Located

Image Sent

Image retrieval

service

Backup Storage

Located in another

geographical location

Image Write

Service

Storage


to storage

Request Image

Client Computer

Image Located

Image Sent

Image retrieval

service

Backup Storage

Located in another


Think about options to deal with extra large data sets

Image Write

Service

Storage


to storage

Request Image

Client Computer

Image Located

Image Sent

Image retrieval

service

Backup Storage

Located in another


horizontal and vertical scaling

Horizontal

VerticalAdds more storage / processing power etc. to the same server

Adds more nodes/shards (this is the preferred option for big web services)

Image Write Service

StorageUpload Image Files written

to storage

Request Image

Client Computer

Image Located

Image Sent

Image retrieval

service

Backup Storage

Located in another


Image Write Service

StorageBackup Storage

Image retrieval

service

Services Separate key web services into different logic nodes

Redundancy Make sure that there is backup of all data

Partitions Split everything into different partitions/shards to deal with increasing data usage

Presentation Logic

Business Logic Database

we can go from this…

Presentation Logic

Business Logic

Business Logic

Database

Database

Database

Database

Database

Database

Database

Database

…to this

scaling services up for use in an enterprise level web

program

4 methods that we are going to look at:

Caching Proxies Load Balancing Queuing


program

Caches

Application Server

Database server

I would like an image of a dog

Application Server

Database server


too many images to physically sort through

Application Server Database

server


• Use a cache to store things that are sorted for most recently

• There’s a good chance that if something is searched for once, it is going to be searched for again

cache

Cache is checked before going to the DB server

Application Server Database

server


• This tiny change makes a big difference to application speed!

• Cache reads are lightning fast • Database server reads are snails pace in comparison

cache

Cache is checked before going to the DB server

Database server

Application Server

cache

Application Server

cache

Application Server

cache

Application Server

cache


Doesn’t always work as expected. Doing things this way can create a cache miss

Distributed cache system

Database server

Application Server

cache

I would like an image of a

dog

Each request that is made passes through a cache, if it has the data it returns it, if not it goes to the database

Global cache system I

Application Server

Application Server

Application Server

This is the most common type of cache system

Database server

Application Server

cache


dog

Application server checks the cache, if it doesn't find what it is after the application server then goes to the database

Global cache system II

Application Server

Application Server

Application Server

Better for large files that may otherwise clog the cache. Also better for static cache files

Want to give it a go?

http://memcached.org/

http://www.phpfastcache.com/(documentation is online)

Caches


program

proxies

Database server


catApplication

Server

Proxy

Database server


cat


cat


cat


cat

Application Server

Application Server

Application Server

Application Server

Proxy

Proxies are good when lots of people

are searching for the same thing

Collapses requests into a single

request, reduces database reads

Bring me the cats!

Database server


black cat


ginger cat


tabby cat


fluffy cat

Application Server

Application Server

Application Server

Application Server

Proxy

Also good if people are searching for close to the same

thing

Bring me the cats!

Database server


black cat


ginger cat


tabby cat


fluffy cat

Application Server

Application Server

Application Server

Application Server

Proxycache

We can use techniques at the same time to make it even faster.

A lot of proxies actually come with a cache built into them


http://www.squid-cache.org/

https://www.varnish-cache.org/(documentation is online)

proxy/cache


program

load balancing

Database server


black cat


ginger cat


tabby cat


fluffy cat

Application Server

Application Server

Application Server

Application Server

Magic Box

!?!?!?!?


black cat

upload a picture of a

ginger cat

I want to change my password

I just really like cats

Application Server

Application Server

Application Server

Application Server

Load Balancer


black cat


ginger cat



Application Server

Application Server

Application Server

Application Server

Load Balancer

Load Balancer B


black cat


ginger cat



Application Server

Application Server

Application Server

Application Server

Load Balancer

Load balancing methods

round robin

Random nodeAs it sounds…just picks a random node

Node with most free processing power Node with access to [x]

Criteria based

Location based

node[x], node[x+1], node[x+2]

Node in Aberdeen Node in Dundee

Problems with load balancing

Managing user session dataYou don’t want to be put to a different server node every time you change a page

Even changing a node every time you visit a site would be a pain! (shopping basket might be deleted)


http://www.haproxy.org/(documentation is online)

load balancing


program

queues

Database server

Application Server

Application Server

Application Server

Application Server

Sends write

Waits for response

Sends write

Sends write

Sends write

Waits for response

Waits for response

Waits for response

this is torture

Queues are good for writing data

caches, proxies and load balancing are all good for reading data

Database server

Application Server

Application Server

Application Server

Application Server

Sends write

Sends write

Sends write

Sends write

queue

writing to the queue gets instant acknowledgment

Sends writes when

database is available


http://zookeeper.apache.org/

http://www.rabbitmq.com/(documentation is online)

queues

Recap•Tier architecture and cloud computing •Moving from 3-tier to n-tier •Scaling services up for use in Enterprise web

•Caches •Proxies •Load Balancing •Queueing

Dealing with Enterprise Level Data

Internet

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