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Unformatted text preview: e use of prepared statements and bind variables 22
© 2 0 0 6 e B a y In c . Scaling the Data Tier: Minimize DB Transactions
• Auto-commit for vast majority of DB writes
• Absolutely no client side transactions nc . – Single database transactions managed through anonymous PL/SQL blocks.
– No distributed transactions. ,I • How do we pull it off? ay – Careful ordering of DB operations
– Recovery through
• A s y n c h r o n o u s r e c o v e r y e v e n ts
• R e c o n c ilia tio n b a tc h • Rationale
– eB • F a ilo v e r to a s y n c flo w Avoid deadlocks
Avoid coupling availability
Seamless handling of splits 23
© 2 0 0 6 e B a y In c . eB ay ,I nc . Scaling the Application Tier Scaling the Application Tier – Overview nc – Segmentation by function.
– Horizontal load-balancing within functions. . • Spread the Load • Minimize dependencies eB • Virtualize data access ay ,I – Between applications
– Between functional areas
– From applications to data tier resources 25
© 2 0 0 6 e B a y In c . Scaling the Application Tier – Massively Scaling J2EE • Step 1 - Throw out most of J2EE
– eBay scales on servlets and a rewritten connection pool. nc . • Step 2 – Keep Application Tier Completely Stateless ,I – No session state in application tier
– Transient state maintained in cookie or scratch database • Step 3 – Cache Where Possible eB ay – Cache common metadata across requests, with sophisticated cache refresh
– Cache reload from local storage
– Cache request data in ThreadLocal 26
© 2 0 0 6 e B a y In c . Scaling the Application Tier – Tiered Application Model nc XSL ,I Presentation Tier . • Strictly partition application into tiers
•Integration Command (View) Integration Tier BO/BOF Business Logic DO/DAO Data Access Layer (DAL) eB Business Tier ay AO/AOF (View) XML Model
Building Logic 27
© 2 0 0 6 e B a y In c . Scaling the Application Tier – Data Access Layer (DAL) • W h a t is th e D A L ? ,I nc . – eBay’s i...
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This note was uploaded on 10/11/2012 for the course INFORMATIO IS taught by Professor Various during the Spring '11 term at CSU Northridge.
- Spring '11