1. Simple-Spring-Memcached

2. Bio Nelz Carpentier Sr. Software Engineer at Widgetbox, Inc
10+ Years as a Software Engineer
lz9999
n/nelz9999

3. Target Audience Technical Folks Familiar with Spring
May be interested in adding Memcached
Understand the basics of Caching
Understand the basics of Distributed Caching

4. Motivation Broke New Ground? Share My Learnings Self-Evident Concept
Not Too Smart
Willing to do the work

5. Cross-Cutting Concern
Similar to Logging
Similar to Authorization
Main Code Flow doesn't need to know about it
AOP to the Rescue!

6. Target Code / Infrastructure
Java
Spring
Serializable / Externalizable Objects
High-Read, Low-Write
Control / Wrap the Operations being AOP'd
DB (or expensive data source) Backed
Operational Ability to Support Memcached

7. SSM's Niche

8. Shoulders of Giants Build Maven Cobertura Test TestNG EasyMock Mirror
Runtime
Spy Memcached
Spring / AspectJ
Log4J

9. Configure the ApplicationContext
<import resource="simplesm-context.xml" />
<bean id="memcachedConnectionBean" class=
"net.nelz.simplesm.config.MemcachedConnectionBean">
<property name="consistentHashing" value="true" />
<property name="nodeList" value=" : :11311" />
</bean>
<aop:aspectj-autoproxy />

10. Pseudocode of Read Through Scenario
$key = calculateValueCacheName()
if cacheHasKey($key), return getFromCache($key)
$value = doExpensiveRequestForValue()
storeInCache($key, $value)
return $value
[PS: Pertinent Negative Null]

11. RTA - Example @ReadThroughAssignCache( assignedKey = "InTheWindow",
namespace = "DOG",
expiration = 300)
Dog getDogInWindow() {
... }

12. Generating Keys 255 Characters
Key + Namespace + Other Characters (~16)
No Spaces
Default: toString()
Preferred: @CacheKeyMethod

13. Why Namespaces? Avoid Collisions Example: Auto-Increment Primary Keys
Vet:123 vs Pet:123

14. RTS – Example 1 @ReadThroughSingleCache( keyIndex = 0,
namespace = "VETS",
expiration = 300)
Vet getVet(Long id) {
... }

15. RTS – Example 2 @ReadThroughSingleCache( keyIndex = 1,
namespace = "VETS",
expiration = 300)
Vet getVet(Credentials cred, Long id) {
... }

16. Cardinality Options 1-to-1, Invariant “KEY” → Y @*AssignCache
1-to-1, 1-to-Many
Key → Value
Key → List<Value>
@*SingleCache
Many-to-Many
List<Key> → List<Value>
@*MultiCache

17. List → List Contract Requires: Agree in Length Agree in Sequence
Other Collections not (yet?) supported
Subset Fall-Through

18. RTM - Example @ReadThroughMultiCache( keyIndex = 0,
namespace = "VETS",
expiration = 300)
List<Vet> getVet(List<Long> ids) {
... }

19. Pseudocode of Invalidate Scenario
$key = calculateValueCacheName()
doUnderlyingOperations()
deleteFromCache($key)

20. IAC – Example @InvalidateAssignCache( assignedKey = "InTheWindow",
namespace = "DOG")
void removeFromWindow(Dog dog) {
... }

21. ISC – Example @InvalidateSingleCache( keyIndex = 0,
namespace = "FISH")
void died(Fish fish) {
... }

22. IMC – Example @InvalidateMultiCache( keyIndex = 1, namespace = "DOG")
void sellLitter(Buyer to, List<Dog> dogs) {
... }

23. Pseudocode for Update Scenario
doUnderlyingOperations()
$key = calculateValueCacheName()
$value = harnessValueToStore()
storeInCache($key, $value)

24. UAC - Example @UpdateAssignCache( assignedKey = "InTheWindow",
dataIndex = -1,
namespace = "DOG",
expiration = 300)
Dog chooseDogForWindow() {
... }

25. USC - Example @UpdateSingleCache( keyIndex = 0, dataIndex = 0,
namespace = "FISH",
expiration = 300)
void addToInventory(Fish fish) {
... }

26. UMC - Example @UpdateMultiCache( keyIndex = 2, dataIndex = -1,
namespace = "DOG",
expiration = 300)
List<Dog> newLitter(Dog mom, Dog dad, List<Long> ids) {
... }

27. DEMO
DEMO...
Demo...
Demo.

28. Protection from Exceptions
Exceptions from (your) underlying code should flow as normal
Exceptions within the caching code should be invisible to user, other than via log
Commons-logging / Log4J

29. Best Practices Externalizable (!!!) Up to 8x faster!?!
Single Canonical Representation
How to do aggregate collections
Invalidates on Delete
Updates on Save

30. What SSM Doesn't Do Stampede Protection or Soft Locks
Namespace Invalidation
Multi-Invalidation / Method
Multi-Parameter Keys

31. Possible Future Features
Multiple Logical Memcacheds
Cache Observers
Second-level cache

32. Version 2.0 Changes Package Structure
Remove Index Params, Adopt Annotations -1 0+
Key Calculation
Spring Bean Nameable
@ReturnValueKeyProvider(
keyProviderBeanName = “myBeanName” )

33. Other Projects to Know About
Statsproxy - Monitoring
Supported by Gear6
Brutis - Benchmarking
Also by Gear6
Xmemcached
Young
Whalin
Old, Stable
Not Maintained?

35. Presentation and Demo Files
Blog Post:
On Project Page:
Presentation
Demo Code
Also on SlideShare
Gliffy.com

36. Photo Credits http://www.flickr.com/photos/adulau/3086751588/

37. Questions
Questions?