CareerCup

here are some basic Idea.
1. there should has many file server, which used to store data from user client.
2. master web server tell user client send the file to which file server. and save the file with encode name, or even data encode.
3. and use the encode name and file server to generate url, user then can use this url to access the text.
4. there should has account service, which used to make sure this user's storage limitation.
5. there should has duplicate logic, which make sure the file is can not access because file server down.

Here is other solution
Assumptions - Only registered users can use this service.
All files are stored in S3 or similar system.
1. When user paste a text generate a hascode of the text, and hashcode can be used as a filename.
2. Generate a user by using username + hash code

Some thoughts with respect to each phase ... please help improve

Requirements:
Pastebin utility or pastebin service
Should paste some text - max. limit of text, only ascii characters or symbols (i.e. Roman characters or any other alphabet)
Location of the destination document in which text is to be pasted, i.e. server, disk etc.

Text should be accessible with the help of a URL - so URL-text relationship, is it one-to-one or one-to-many? How about one-to-none? I.e. URL exists but does not map to any text. Should we use already exisiting URLs? Can new URL be created on fly?
Is there a maintainable URL repository?
Details about invoker(s) of this service
Details about end-users of this service - what happens once a URL-text mapping is established - any persistence happening here? Or notifications being sent to the invoker?

Design:
URL - string (starting with http, https or ftp)
URL repository - memory(list), database, cache, file (application/disk)
URL creation - pre-existing or on-the-fly
URL-Text map repository - database, cache
URL-Text mapping - one-to-one, one-to-many


Architecture:
Namespace: com.gooogle.pastebin

driver - main driver class - PasteBinDriver
processor - PasteBinProcessor
service - PasteBinService
persistence - PasteBinPersistence

Patterns used:
Factory/abstract factory for creating objects in each layer
Singleton for driver class

What was your response to this ? ... Could you please share some design ideas