EM401 Overview of MobiLink Synchronization

Jim GrahamDirector of EngineeringiAnywhere Solutionsjim.graham@ianywhere.com

MobiLink Synchronization

• What is MobiLink?

• How MobiLink works

• MobiLink scripting

• Scalability

• Deployment Issues

• Brief comparison to SQL Remote

• Futures

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

What is MobiLink?

C onsolidatedD atabase

C om m unication Infrastructure( In ternet / D ia l-up / W ire less )

Data Data

DataData

Data

M obiL ink

Data

Data

M obile or R em ote D atabases

MobiLink Design Goals

• Heterogeneous consolidated database

• Scalable and robust (tens of thousands)

• Manageable in large deployments

• Support handheld and wireless devices

• Flexible

MobiLink Consolidated Databases

• Oracle8

• Microsoft SQL Server

• IBM DB2 UDB

• Adaptive Server Enterprise (ASE)

• Adaptive Server Anywhere (ASA)

• ODBC

MobiLink Remote Databases

• Adaptive Server Anywhere (ASA)• Windows 2000/NT/Me/98/95

• Windows CE

• Linux and Unix

• UltraLite• Palm Computing Platform

• Windows CE

• Java

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

ASA Synchronization

C onsolidatedD B

M obiL ink

R em ote ASAD atabase

O D BC

dbm lsync

1. U pload

2. D ow nload

3. Ack D ow nload

UltraLite Synchronization

C onsolidatedD B

M obiL ink U ltraLiteD atabase

O D BC

1. U pload

2. D ow nload

3. Ack D ow nload

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

MobiLink Scripts

• begin_connection

• for each synchronization:• begin_synchronization

• receive and apply upload stream

• prepare and send download stream

• end_synchronization

• end_connection

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 = ?

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

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 > @LastDownload

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

SELECT emp_id FROM employee WHERE last_modified > @LastDownload AND status = ‘INACTIVE’

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

MobiLink Synchronization

• begin_connection

• for each synchronization:• begin_synchronization

• receive and apply upload stream

• prepare and send download stream

• end_synchronization

• end_connection

MobiLink Synchronization

C onsolidatedD B

M obiL ink

R em ote ASAD atabase

O D BC

dbm lsync

1. U pload

2. D ow nload

3. Ack D ow nload

Performance Scalability

• Worker threads

• Connection pooling

• No contention in MobiLink

• Extensive testing

• White paper

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

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

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)

MobiLink Design Goals

• Heterogeneous consolidated database

• Scalable and robust (tens of thousands)

• Manageable in large deployments

• Support handheld and wireless devices

• Flexible

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

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 more mature product with a proven track record for success

• SQL Remote replicates transactions in exact order

8.0 New Feature Highlights

• Performance and Usability• Statement-based uploads

• Integrated last download timestamp

• Optional download ack

• Select uploads (priority synchronization)

• Java synchronization logic

• Better remote ASA terminology

• Improved reporting

MobiLink Futures

• Message-based communication

• Java synchronization logic to non-relational enterprise application servers

• MobiLink monitor console

Resources Available

• other TechWave sessions

• MySybase: Mobile & Wireless Developer• newsgroups, white papers, technotes, FAQs

• samples, patches

• award winning technical support

• training and assistance during the initial phases of your synchronization projects