@PDC09 – Day 2 – Developing Advanced Applications with Windows Azure

                                                                   (Rough notes from the session)
By Steve Marx, Technical Strategist, Microsoft Corporation

LB –> Web Role + Worker Role

Official shipping version of the Table Storage SDK is available now

What we’ll Build – Search application using IIS + SMTP  + Web and Worker Roles

• Three role architecture
  • Web UI (ASP.net MVC)
  • SMTP Server (TCPListener)
  • Search (Lucene.NET)
• New Features we’ll take advantage of
  • Inter-role communication
  • Non-HTTP endpoints
  • Role instance lifecycle
  • VM sizes
  • Local storage

HOW TO: Model your application

• Draw the boxes and arrows
• Each box is a role
  • Which receive traffic from the internet
  • Which need IIS?
  • Which receive internal communication?

Receiving Traffic. Input Endpoints

• Different ports on the same domain
• Always load balanced
• Declared in ServiceDefinition.csdef
• Handled by IIS in web roles
• Handled by your code in worker roles
• API to find

The instance could should always be atleast 2 or else SLA isn’t valid.
Azure Storage Explorer in codeplex

Input Endpoints Demo :  Set the configurations in the xml file
As an Aside about Email

• Spammers will use Windows Azure. (sending email should not be done via azure as the IP is not trusted)

Asynchronous work without a Queue

• Queues deliver messages to one worker
• We need every worker to see the messages
• Use a table instead
  • build your own secondary index
  • order references
  • (Beware of clock drift!!)

HOW TI: DO Initialization

• don’t want traffic until we are listening
• role instance lifecycle lets us prepare
  • both web roles and worker roles
  • OnStart() - “busy” state, initialization
  • Run() – do work
  • OnStop() – traffic stops, graceful shutdown

HOW TO: Internal Endpoints

• Declare endpoints in servicedefinition.csdef
• API to find out what port to listen on:
  RoleEnvironment.CurrentRoleInstance.InstanceEndpoints[“”]

For internal endpoints always rely on the API to provide the port number, do not assign any port number.
HOW TO: Get more RAM

• RAMDirectory puts everything in memory
• If we have lots of data, we need lots of RAM
• Choose among four VM sizes:
  • Small
  • Medium
  • Large
  • Extra Large
• Simple edit to servicedefinition.csdef
  <WorkerRole  vmsize=”ExraLarge” />

HOW TO: Save the Index

• Lucene.NET writes files to the local system
• Preserve those across reboots/upgrades : 
  <LocalStorage cleanOnRoleRecycle=”false” />
• Consider writing state on OnStop()
  (this is the to write I was on record XX and save the last state)

Using In-Place Upgrade

• Rolling Upgrade
• Specify which roles to upgrade
• Keep local storage intact
• Great for stateful roles

Call of Action:

• Any instance can talk to any other
• Don’t need IIS to listen for traffic
• Use the role instance lifecycle
• Choose different VM sizes
• In-Place upgrades