Advanced orm

ColdFusion
Advanced ORM

Himavanth Rachamsetty
ColdFusion Engineer

Copyright 2009 Adobe Systems Incorporated. All rights reserved. Adobe confidential. 1

Agenda

 Advanced Mapping
 CF-ORM Internals
 Sessions &Transactions
 Concurrency Control (Optimistic Locking)
 Performance Optimization
 Lazy – Loading
 Caching

 Q&A

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Advanced Mapping

 Collection Mapping
 Embedded Mapping
 Join Mapping
 Inheritance Mapping

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Collection Mapping

 Similar to 1:n relationship
 Useful when target table need not be mapped as persistent CFC
 Just need information from the target table

 Demo

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Embedded Mapping

 One entity with multiple CFC
 Mapping needs to be specified in *.hbmxml

<hibernate-mapping>
<class name="cfc:Employees" entity-name="employee"
table="Employees">
<id name="ID" type="integer" column="EmployeeID">
<generator class="native"/>
</id>
<component name="Name" class="cfc:cname">
<property name="FirstName" type="string" column="FirstName"/>
<property name="LastName" type="string" column="LastName"/>
</component>
<property name="Title" type="string" column="Title"/>
<property name="BirthDate" type="date" column="BirthDate"/>
<property name="HireDate" type="date" column="HireDate"/>
</class>
</hibernate-mapping>
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Join Mapping

 Useful when using one CFC for multiple tables

<cfcomponent persistent="true“ table=“employee”>
<cfproperty name="id">
<cfproperty name="name">
<cfproperty name="city"
table="Address” joincolumn="addressId">
<cfproperty name="country"
table="Address“ joincolumn="addressId">
</cfcomponent>

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Inheritance Mapping

 Three Types
 Table per hierarchy Payment Table

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Inheritance Mapping

 Demo

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Inheritance Mapping

 Three Types

 Table per subclass (without discriminator)

CreidtCardPayment Table

Cheque Payment Table

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Inheritance Mapping

 Demo

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Inheritance Mapping

 Three Types
 Table per subclass (without discriminator)
 Table per subclass (with discriminator)

CreidtCardPayment Table

Cheque Payment Table

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Inheritance Mapping

 Demo

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ORM Internals - Initialization

false

Inspect
true

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ORM Session

 All the ORM operations happen in a session
 Ensures a single instance of an entity.
 Tracks changes made to the objects
 SQLs are executed when session is flushed
 Typically when the transaction is committed or when the request completes
 Can use ORMFlush to force

 Provides First Level Caching
 Automatically managed by CF
 In most cases, you don’t need to worry about it

 A unit of work – a transaction

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ORM Session Management

New Request

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Object States

 Transient
 Persistent
 Detached

EntityNew()/ new()/
CreateObject Session ends

Detached
EntitySave() EnityMerge
EntitySave
Transient Entity

Session
EntityDelete

Persistent Entities EntityLoad
ORMExecuteQuery

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ORM Session Management – Transactions

New Request

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17

Concurrency Control
 Optimistic lock for high concurrency
 Update only if the entity is not modified by other thread or externally.
 optimisticlock attribute on cfc
 All
 All properties are included in where clause of update
Update myTbl set col1= newVal
where col1= oldVal and col2= oldVal2
 Dirty
 Includes only modified fields in the current session
Update myTbl set col1= newVal where col1= oldVal
 Version (default)
 Checks only version or timestamp column
<cfproperty name="lastModified“ fieldtype="timestamp|version“>
 None
 Also available at property level. <cfproperty .. optimisticlock=“true”>
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Fetching Strategy

 Lazy fetching
 Default strategy, lazy=true
 Extra Lazy : lazy = “extra” gets pk of arts and then all art columns from db

 Immediate fetching
 Fetch target relationship in a separate SQL, immediately
<cfproperty name=“artist" fieldtype="one-to-many" cfc=“art"
fkcolumn=“ARTISTID“ lazy="false" fetch="select">

 Eager fetching
 Fetch together in a single SQL, fetch=“join”
 Useful for 1:1 frequently used relationships

 Batch fetching < cfcomponent persistent="true" batchsize="100“ >
 When fetching relationship, get some more that maybe required later
 Get Addr1 for emp101, plus address for emp102, 103 etc depending on batch size

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Caching

 Session Level
 Ensures a single instance for a given ID
 EntityLoad fetches data for the first time
 Data is cached for the session
 Next request in the same session will use cached data
 EntyReload re-fetches

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Secondary Level Cache

 Caches data across sessions
 In-memory/disk/clustered
 Pluggable cache impls
 Default – EHCache

…

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Secondary Level caching ...

 Configuration in Application.cfc
 ormsettings.secondarycacheenabled
 ormsettings.Cacheprovider
 JBossCache, OSCache, SwarmCache, Hashtable, DEFAULT - ehcache

 ormsettings.cacheconfig
 Appropriate config file for cache, e.g. ehcache.xml

 What is being cached
 How (caching strategy)
 3 Things in 4 Ways

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Secondary Level Cache – 3 Things in 4 Ways

 3 Things  4 Ways (cacheuse)
 Component  Read-only
 cfcomponent  Nonrestrict-read-write
 Collection/Association  Read-write
 cfproperty
 Transactional
 Query
 EntityLoad/OrmExecuteQuery

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Caching - examples

 Component
 <cfcomponent persistent="true“
cachename=“foo_region" cacheuse="read-only">

 Relationship/Association/Collection
 Primary Key of the associated object is cached
 The associated object itself is cached if specified as below
<cfproperty name="arts" fieldtype="one-to-many“
cachename="foo_region" cacheuse="read-write">

 Query data
 ORMExecuteQuery("from Art where issold=0", {}, false,
{cacheable=true, cachename=“foo_region"});

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Caching – cacheuse

 Read-only
 Best performance for read only data

 Read-write
 Use if your data needs to be updated
 More overhead

 Nonrestrict-read-write
 Use when data is updated occasionally

 Transactional
 Transactional cache
 Can only be used if the cache provider is transaction aware

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Caching - cleanup

 ORMEvictEntity
ORMEvictEntity("<component_name>", [primarykey])

 ORMEvictCollection
ORMEvictCollection("<component_name>", "<relation_name>",
[primarykey])

 ORMEvictQueries
ORMEvictQueries([cachename])

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Thank You !
- himar@adobe.com


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