Question

every once in a while i read/hear about AWS and now i tried reading the docs.
But such docs seem to be written for people who already know which AWS they need to use and only search for how it can be used.

So, for myself, to understand AWS better i try to sketch a hypothetical Webapplication with a few questions.

The apps purpose is to modify content like videos or images. So a user has some kind of webinterface where he can upload his files, do some settings and a server grabs the file and modifies it (e.g. reencoding). The Service also extracts the audio track of a video and trys to index the spoken words so the customer can search within his videos. (well its just hypothetical)

So my questions:

• given my own domain ‘oneofmydomains.com’ is it possible to host the complete webinterface on AWS? i thought about using GWT to create the interface and just deliver the JS/images via AWS, but which one, simple storage? what about some kind of index.html, is there an EC2 instance needed to host a webserver which has to run 24/7 causing costs?
• now the user has the interface with a login form, is it possible to manage logins with an AWS? here i also think about an EC2 instance hosting a database, but it would also cause costs and im not sure if there is a better way?
• the user has logged in and uploads a file. which storage solution could be used to save the customers original and modified content?
• now the user wants to browse the status of his uploads, this means i need some kind of ACL, so that the customer only sees his own files. do i need to use a database (e.g. EC2) for this, or does amazon provide some kind of ACL, so the GWT webinterface will be secure without any EC2?
• the customers files are reencoded and the audio track is indexed. so he wants to search for a video. Which service could be used to create and maintain the index for each customer?

hope someone can give a few answers so i understand AWS better on how one could use it

thx!

Answer 1

Amazon AWS offers a whole ecosystem of services which should cover all aspects of a given architecture, from hosting to data storage, or messaging, etc. Whether they’re the best fit for purpose will have to be decided on a case by case basis. Seeing as your question is quite broad I’ll just cover some of the basics of what AWS has to offer and what the different types of services are for:

EC2 (Elastic Cloud Computing)

Amazon’s cloud solution, which is basically the same as older virtual machine technology but the ‘cloud’ offers additional knots and bots such as automated provisioning, scaling, billing etc.

• you pay for what your use (by hour), for the basic (single CPU, 1.7GB ram) would prob cost you just under $3 a day if you run it 24/7 (on a windows instance that is)
• there’s a number of different OS to choose from including linux and windows, linux instances are cheaper to run without the license cost associated with windows
• once you’re set up the server to be the way you want, including any server updates/patches, you can create your own AMI (Amazon machine image) which you can then use to bring up another identical instance
• however, if all your html are baked into the image it’ll make updates difficult, so normal approach is to include a service (windows service for instance) which will pull the latest deployment package from a storage (see S3 later) service and update the site at start up and at intervals
• there’s the Elastic Load Balancer (which has its own cost but only one is needed in most cases) which you can put in front of all your web servers
• there’s also the Cloud Watch (again, extra cost) service which you can enable on a per instance basis to help you monitor the CPU, network in/out, etc. of your running instance
• you can set up AutoScalers which can automatically bring up or terminate instances based on some metric, e.g. terminate 1 instance at a time if average CPU utilization is less than 50% for 5 mins, bring up 1 instance at a time if average CPU goes beyond 70% for 5 mins
• you can use the instances as web servers, use them to run a DB, or a Memcache cluster, etc. choice is yours
• typically, I wouldn’t recommend having Amazon instances talk to a DB outside of Amazon because of the round trip is much longer, the usual approach is to use SimpleDB (see below) as the database
• the AmazonSDK contains enough classes to help you write some custom monitor/scaling service if you ever need to, but the AWS console allows you to do most of your configuration anyway

SimpleDB

Amazon’s non-relational, key-value data store, compared to a traditional database you tend to pay a penalty on per query performance but get high scalability without having to do any extra work.

• you pay for usage, i.e. how much work it takes to execute your query
• extremely scalable by default, Amazon scales up SimpleDB instances based on traffic without you having to do anything, AND any control for that matter
• data are partitioned in to ‘domains’ (equivalent to a table in normal SQL DB)
• data are non-relational, if you need a relational model then check out Amazon RDB, I don’t have any experience with it so not the best person to comment on it..
• you can execute SQL like query against the database still, usually through some plugin or tool, Amazon doesn’t provide a front end for this at the moment
• be aware of ‘eventual consistency’, data are duplicated on multiple instances after Amazon scales up your database, and synchronization is not guaranteed when you do an update so it’s possible (though highly unlikely) to update some data then read it back straight away and get the old data back
• there’s ‘Consistent Read’ and ‘Conditional Update’ mechanisms available to guard against the eventual consistency problem, if you’re developing in .Net, I suggest using SimpleSavant client to talk to SimpleDB

S3 (Simple Storage Service)

Amazon’s storage service, again, extremely scalable, and safe too – when you save a file on S3 it’s replicated across multiple nodes so you get some DR ability straight away.

• you only pay for data transfer
• files are stored against a key
• you create ‘buckets’ to hold your files, and each bucket has a unique url (unique across all of Amazon, and therefore S3 accounts)
• CloudBerry S3 Explorer is the best UI client I’ve used in Windows
• using the AmazonSDK you can write your own repository layer which utilizes S3

Sorry if this is a bit long winded, but that’s the 3 most popular web services that Amazon provides and should cover all the requirements you’ve mentioned. We’ve been using Amazon AWS for some time now and there’s still some kinks and bugs there but it’s generally moving forward and pretty stable.

One downside to using something like aws is being vendor locked-in, whilst you could run your services outside of amazon and in your own datacenter or moving files out of S3 (at a cost though), getting out of SimpleDB will likely to represent the bulk of the work during migration.