Architecture design for a web-based application

We are looking for an architect to create a high-level architectural design for a web application. Mandatory requirement: - Proven software architect experience for web systems/applications - Knowledge of MS Azure - Solid understanding of consumer-grade web-based applications and their architecture Nice-to-have: - Yammer platform experience App requirements (more specifics will be provided once the winner is determined and NDA is signed): 1. Application should be web-based (no client software) 2. Application will need to be able to handle high transaction volume 3. Scalability is a must (the app should be designed in a way that it can be scaled up to significant size) 4. The app needs to be designed for shared environments where multiple users can be hosted together without overlapping 5. The app needs to be designed in a way that it could be hosted (MS Azure services) or implemented/brought in on premise by individual users 6. The best technology package needs to be proposed (framework, database, additional components). The app needs to be modern, smooth, consumer-grade, such as Picasa or Instagram. 7. High-level (not table/field level, but high-level) DB structure 8. The app will need to have strong search capabilities. Detailed description of design of the predictive/intelligent/adaptive search would be needed. 9. Statistical information collection – likes, reads, clicks, reposts, etc. is the must 10. Yammer integration a. How it should be integrated (options, the best option) b. What can be moved back and forth from/to Yammer c. Security with Yammer – can we re-use Yammer’s security mechanisms i. Accounts ii. Groups iii. Emails iv. Other security settings such as network restrictions 11. App should also be able to exist on its own without Yammer 12. Security mechanisms a. Protecting application integrity b. User (individual user) data security c. Secure administration, including multi-level approvals to access user data d. Privacy 13. The system should be flexible enough to allow later expansion into the mobile space – native Android, iOS and Windows apps. Optional Items 1. Design that can allow rapid product prototyping initially and full development later 2. Work effort estimates for the development work necessary to complete each component