MC 402 Overview of MobiLink Synchronization

1
MC 402Overview of MobiLink Synchronization
Russ Chamberlain Team Leader MobiLink
Engineering Russ.Chamberlain_at_sybase.com
2
MobiLink Synchronization

• What is MobiLink?
• How MobiLink works
• MobiLink scripting
• Scalability
• Deployment Issues
• Brief comparison to SQL Remote
• Futures

3
What is MobiLink?

• A two-way synchronization technology for large
  scale mobile database deployment
• remote database (mobile, embedded, or workgroup
  server database)
• consolidated database (enterprise, workgroup, or
  desktop database)
• A server that processes synchronization requests
  from remote databases

4
What is MobiLink?
5
MobiLink Design Goals

• Heterogeneous consolidated database
• Scalable and robust (tens of thousands)
• Manageable in large deployments
• Support handheld and wireless devices
• Flexible

6
MobiLink Consolidated Databases

• Oracle8
• Microsoft SQL Server
• IBM DB2 UDB
• Adaptive Server Enterprise (ASE)
• Adaptive Server Anywhere (ASA)
• ODBC

7
MobiLink Remote Databases

• Adaptive Server Anywhere (ASA)
• Windows 2000/NT/98/95
• Windows CE
• Linux and Unix
• UltraLite
• Palm Computing Platform
• Windows CE
• Java

8
How Synchronization Works

• 1. Upload
• ASA or UltraLite keep track of all changes since
  previous synchronization
• All changes are sent in a single upload stream
• MobiLink applies changes in a single transaction
• 2. Download
• Scripts in the consolidated database determine
  changes that need to be downloaded
• All changes are sent in a single download stream
• 3. Acknowledge download

9
ASA Synchronization
10
UltraLite Synchronization
11
MobiLink Scripts

• Scripts define actions performed in the
  consolidated database at each stage or event
  during synchronization
• Some scripts return result sets (cursor scripts)
• Some scripts are just procedural (event scripts)
• Native language of consolidated database
• Stored in tables in the consolidated database
• Defined using Sybase Central

12
MobiLink Scripts

• begin_connection
• for each synchronization
• begin_synchronization
• receive and apply upload stream
• prepare and send download stream
• end_synchronization
• end_connection

13
The upload_cursor Script

• The upload_cursor script is used to insert,
  update, or delete rows in the consolidated
  database
• This is the primary script for uploading changes
• Example

SELECT emp_id, emp_fname, emp_lname FROM
employee WHERE emp_id ?
14
Applying the Upload Stream

• begin_upload
• for each table
• begin_upload_rows
• process each insert or update using upload_cursor
• end_upload_rows
• for each table (reverse order)
• begin_upload_deletes
• process each delete using upload_cursor
• end_upload_deletes
• end_upload

15
Download Cursor Scripts

• The download_cursor script is used to insert or
  update rows in the remote database

SELECT emp_id, emp_fname, emp_lname FROM
employee WHERE last_modified gt _at_LastDownload

• The download_deletes_cursor script is used to
  delete rows from the remote database

SELECT emp_id FROM employee WHERE last_modified
gt _at_LastDownload AND status INACTIVE
16
Preparing the Download Stream

• begin_download
• for each table
• begin_download_deletes
• SELECT using download_deletes_cursor
• end_download_deletes
• begin_download_rows
• SELECT using download_cursor
• end_download_rows
• end_download

17
MobiLink Synchronization

• begin_connection
• for each synchronization
• begin_synchronization
• receive and apply upload stream
• prepare and send download stream
• end_synchronization
• end_connection

18
MobiLink Synchronization
19
Performance Scalability

• Worker threads
• Connection pooling
• No contention in MobiLink
• Extensive testing
• White paper

20
Deployment Scalability

• Straight forward backup and recovery scenarios
• Multiple consolidated databases
• switch to warm backup of consolidated database
• roaming users can use closest consolidated
  database
• ASA or UltraLite database can be re-populated
  through normal synchronization
• Monitoring
• detection and reporting of potential problems
• measuring usage and response time

21
Errors and Conflicts

• Applying changes to consolidated database
• automated conflict detection and resolution
  (scripts)
• automated error handling and reporting (scripts)
• Applying changes to remote ASA or UltraLite
• downloaded rows are UPSERTED
• enforce referential integrity after a download

22
Deploying New Versions

• Remote sends a script version as part of its
  upload stream
• A script version is just a name
• eg. SalesTrack
• script version ? set of synchronization scripts
• On upgrade, new remotes each use a new script
  version
• eg SalesTrack 2
• The consolidated database can hold many different
  script versions
• One MobiLink server can use many different script
  versions (one per synchronization)

23
MobiLink Design Goals

• Heterogeneous consolidated database
• Scalable and robust (tens of thousands)
• Manageable in large deployments
• Support handheld and wireless devices
• Flexible

24
SQL Remote Comparison

• Heterogeneous consolidated database
• Scalability limited only by the enterprise
  database
• More manageable in larger deployments
• UltraLite remote databases
• More flexible (eg. different schemas)
• Session based

25
SQL Remote Future

• SQL Remote will continue to be important
• Easier to use in following situation
• ASE or ASA consolidated
• Remote schema is same as (or subset of) the
  consolidated schema
• Deployment issues are not a problem
• Message-based communication is sometimes more
  suitable than session-based
• SQL Remote is a mature product with a proven
  track record for success
• SQL Remote replicates transactions in exact order

26
Services Available

• Other TechWave sessions
• Public newsgroups
• Sybase Developer Network (SDN)
• Award-winning technical support
• Training and assistance during the initial phase
  of your synchronization projects

27
7.0.1 New MobiLink Features

• Performance
• User authentication
• Better dbmlsync concurrency with applications
• New HotSync conduit
• Progress indicator

28
MobiLink Futures

• Integrated scripting language
• Application distribution
• Thin-client wireless applications

29
MC 402Overview of MobiLink Synchronization
Russ Chamberlain Team Leader MobiLink
Engineering Russ.Chamberlain_at_sybase.com