LEAP Conference – day 3

A summary of day 3 of the LEAP conference in Redmond, Seattle

Sync: Why, what and how

With Lev Novik

Why Sync?

• Facilitates rich clients
• Faster response, richer UX
• Legacy applications can be migrated to use the Cloud as a data storage by using Sync
• …

General Sync Challenges

• Granularity of changes
• Change (non-) Reflection
• Using a timestamp. Use locking until synchronization is finished?
• Conflicts
• Not detecting conflicts will result in data loss
• Complex algorithms for conflics detection exists, which don’t require storing the history of all changes
• Loops
• Multiple devices synchronizing data to multiple servers at the same time
• Can result in duplicated data
• Hierarchical data
• The order of synchronization is important
• Eg. one endpoints adds an item to a folder, while another endpoint deletes the entire folder
• Item filtering
• Optimization by syncing parts of the data more frequently
• “Column” filtering
• Select parts of the data
• Challenge: Can’t do conflicts detection, since one of the endpoints don’t have the complete version of the data
• Errors and interruptions
• Not all conflicts can be solved automatically
• Doing so will result in loss of data
• Must wait for a human to resolve them

Microsoft Sync Framework

• What does MS Sync Framework do?
• Makes it easy to sync participating endpoints
• Build in endpoints for
• V1: File system, relational databases
• V2: SQL Data Services, Live Mesh, ++
• The Sync Session
• Data stores implements a Sync Provider
• The Sync application has a Sync Orchestrator which communicates with the endpoints’ sync providers
• Synch Framework Runtime
• Metadata
• Versioning
• Runtime
• Algorithms to solve sync problems
• Metadata Store
• For those who can’t store the metadata themselves
• Simple Provider Framework
• Makes writing providers easy

How do customers use the sync framework?

• Write sync applications
• Implement synch orchestration
• Write sync providers in order to support sync
• Declare an object identifier
• Declare versioning
• Enumerate changes

Sync Participants

• Sync endpoints
• Stores metadata
• Can be many kinds of devices, and the sync logic should not be implemented for each of them
• Sync providers
• Does most of the sync work
• Operates on the endpoints’ meta data
• Sync application
• Has the Synch Orchestrator

The sync logic can be placed in different locations (eg. on the client or in a web service) for differenc scenarios.

Sync Framework on MSDN: http://msdn.microsoft.com/sync/

Visual Studio Team System: ALM as we do it at Microsoft

With Stephanie Cuthbertson

Some facts about Microsoft Development

• TFS usage at MS
• VS 2008
• 13 000 users
• 2 570 000 work items
• 40 100 000 source file

Planning and tracking

• Feature planning and prioritizing in the development of VSTS 2010
• Value props prioritizing
• Voting and weighting/prioritizing of features in an Excel sheet
• Work items are then imported to TFS
• Generate MS Project GANTT from TFS

VS 2010 demo

• Simple task editing integration with Excel and MS Project
• Improved forecasting statistics and status reports
• User requirement tracking
• Can edit requirements through a web interface
• Requires a separate (new) licence
• Can link requirements to test cases

Branching

• In the development of VSTS 2010, branching per feature is used
• Feature must pass “Quality Gates” before merging into active branch
• Feature complete
• Test complete
• All bugs fixed
• Static code analysis
• Localization testing
• etc

Tracking and reporting in VSTS 2010

• Better SharePoint integration
• Web dashboard
• Extensive statistics and analytics possibilities

Always Responsive Apps in a World of Public Safety

With Mario Szpuszta

A case study for a system for ship tracking and tracing delivered to Frequentis.

Who is Frequentis AG?

• Provides systems for
• Air traffic
• Ship tracking & tracing
• Coordination systems for police offices

Terms

• MCS- Maritime Communication System
• Ship – Ship, Ship – Land, Land – Land
• Usually hardware interface
• CAD – Computer Aided Dispatching
• Collaborative Incident Management
• This is the kind of software made in this case study
• TnT – Tracking and Tracing
• CAD and MCS Solution from Frequentis

Tracking & Tracing Architecture

• GUI in WPF
• Several modules
• Complex requirements
• Lots of information and operations available for the users
• Could not use CAB, Prism or similar frameworks since the GUI would then run in one process and one app domain. The entire system should not go down if one module crashes.
• Each GUI module runs in a separate process. A separate shell was created in order to achieve this.
• Communication with Maritime Communication System with .NET remoting
• GUI communicate with the services through a message bus
• Server
• WCF service modules
• Windows 2008 and SQL Server 2005

The Service Bus

• Complex communication
• Everyone communicate with everyone
• Failure of one system may not affect others
• Challenges
• Not every harbour can pay for the required infrastructure, like huge server farms
• Failure of single entity may not affect others
• Classic architecture
• Keep it simple
• Lightweight
• Reliable
• Loosely couples
• Many-to-many communication
• Solution
• Created custom Message Subscription Database
• Use WCF Peer-to-Peer channel for communication
• Issue: Max. 700 msg/sec limitation due to slow serialization
• No Duplex-bindings, no MSMQ
• Just leverage NetTcp-bindings
• Tech-hints for WCF
• NetDataContractSerializer will include assembly info – serialization will fail if endpoints have different assembly versions, even though the contracts are compatible
• DataContractSerializer enables loosely coupling

Creating a responsive user interface

• The application may never hang at any time
• Encapsulate logic in “autonomous” tasks
• Set of jobs executed based on commands
• Core rule: Everything executed asynchronously
• Thread pool with queue and queue manager
• Commands, Jobs and Queues
• Business logic encapsulated into Jobs (and ONLY there)
• Commands executed autonomously without side effects
• Results from Async Jobs
• Modules implements INotify interface
• Passed into the constructor of a job
• Job calls back to module through INotify
• Communication with other systems
• Create yet another job
• Job talks to IConnectionPoint
• Tasks, Jobs – Tech Hint
• CCR (Concurrency Coordination Runtime, originally from The Robotics Studio)
• Simplified execution of concurrent tasks
• Has now been released as a separate toolkit separated from Robotics

WPF-based client

• Why WPF?
• Huge amount of information needed to be presented
• Frequentis hired a separate UX-research team
• Different alternative UX-stories were investigated
• Advanced requirements for alternative visualizations of data
• Presentation Model Pattern
• Separate UI from code

Green Computing through Sharing

With Pat Helland

Introduction

• In 2006, 1,5% of the electricity in US was consumed by Data Centers
• This is more than what is consumed by TVs
• Projected to double every fifth year
• Sharing resources vs. dedicated resources
• Shared resources may not be available when you need them
• Dedicated resources are expensive and have less utilization
• Sharing through
• Virtual machines
• Cloud computing

The evolving landscape of data centers

• Power Usage Effectiveness (PUE)
• PUE = Total Facility Power / IT Equipment Power
• Typical factor is 1.7
• Power and cooling is expensive
• Infrastructure and energy cost are both more expensive than the server cost
• Redundancy
• Represents more than 20% of the data center cost
• All servers require
• Dual power paths
• Dual network
• “Chicago Data Center”
• Highly efficient data center with PUE = 1,2
• Servers are located in isolated steel containers, each containing 2 000+ servers
• Individual servers are never maintained

Over-Provisioning versus Over-Booking of Power

• Power Provisioning
• Total power consumption for a server is typically 200W
• Power consumption typically peaks at about 90% for a data center
• Theoretical max power consumption is seldom used, eg. because disk usage prevents 100% CPU utilization
• This means that it is possible to add more servers than the theoretical max limit in order to utilize the available power

Services and Incentives

• Amazon’s Server Oriented Architecture
• One page request typically use over 150 services
• Service Level Agreements (SLAs)
• Example: 300ms response for 99.9% of requests with 500 requests per sec

What does this mean for developers?

• Factories are more efficient than hand-crafted manufacturing

Etiketter: LEAP, WCF