Transparent References and Garbage Collection for …...Transparent References and Garbage...
Transcript of Transparent References and Garbage Collection for …...Transparent References and Garbage...
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Transparent Referencesand Garbage Collectionfor Project Darkstar– making it easier to write applications on Project Darkstar Server
Esko LuontolaProgrammer, UI Designerwww.orfjackal.net
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Agenda• How Darkstar's persistence model is
currently?• How transparent references and garbage
collection change the persistence model?• Future directions
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Agenda• How Darkstar's persistence model is
currently?• How transparent references and garbage
collection change the persistence model?• Future directions
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Darkstar requires special handling for ManagedObjects
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What happens under the hood when the following is executed?
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Database
Memory
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Database
Memory
Transaction
BEGIN TRANSACTION
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Database
Memory
Transaction
Personname = “Donald Duck”
Person donald = new Person("Donald Duck");
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Database
Memory
Transaction
Personname = “Donald Duck”
Addresscity = “Duckburg”
street = “Duck Street 313”
address
donald.setAddress(new Address("Duckburg", "Duck Street 313"));
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Database
Memory
Transaction
Personname = “Donald Duck”
Addresscity = “Duckburg”
street = “Duck Street 313”
address
Personname = “Mickey Mouse”
Person mickey = new Person("Mickey Mouse");
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Database
Memory
Transaction
Personname = “Donald Duck”
Addresscity = “Duckburg”
street = “Duck Street 313”
address
Personname = “Mickey Mouse”
addr
ess
mickey.setAddress(donald.getAddress());
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Database
Memory
Transaction
Personname = “Donald Duck”
Addresscity = “Duckburg”
street = “Duck Street 313”
address
Personname = “Mickey Mouse”
addr
essManagedReference
id = 1
id = 1
id = 1
mickey.setRoommate(donald);mickey.roommate = AppContext.getDataManager().createReference(donald);
roommate
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Database
Memory
Transaction
Personname = “Donald Duck”
Addresscity = “Duckburg”
street = “Duck Street 313”
address
Personname = “Mickey Mouse”
addr
essManagedReference
id = 1
ManagedReferenceid = 2
roomm
ate
id = 2
id = 1
id = 1id = 2
donald.setRoommate(mickey);donald.roommate = AppContext.getDataManager().createReference(mickey);
roommate
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Database
Memory
Transaction
Personname = “Donald Duck”
Addresscity = “Duckburg”
street = “Duck Street 313”
address
Personname = “Mickey Mouse”
addr
essManagedReference
id = 1
ManagedReferenceid = 2
roomm
ate
id = 2
id = 1
id = 1id = 2
“donald” = 1
AppContext.getDataManager().setBinding("donald", donald);
roommate
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Database
Memory
Transaction
Personname = “Donald Duck”
Addresscity = “Duckburg”
street = “Duck Street 313”
address
Personname = “Mickey Mouse”
addr
essManagedReference
id = 1
ManagedReferenceid = 2
roomm
ate
id = 2
id = 1
Personname = “Donald Duck”
Addresscity = “Duckburg”
street = “Duck Street 313”ManagedReference
id = 2
id = 1
Write
id = 2
“donald” = 1
COMMIT TRANSACTION
roommate
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Database
Memory
Transaction
Personname = “Donald Duck”
Addresscity = “Duckburg”
street = “Duck Street 313”
address
Personname = “Mickey Mouse”
addr
essManagedReference
id = 1
ManagedReferenceid = 2
roomm
ate
id = 2
id = 1
Personname = “Donald Duck”
Addresscity = “Duckburg”
street = “Duck Street 313”ManagedReference
id = 2
id = 1Person
name = “Mickey Mouse”Address
city = “Duckburg”street = “Duck Street 313”
ManagedReferenceid = 1
id = 2
Write
“donald” = 1
COMMIT TRANSACTION
roommate
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Database
Memory
Personname = “Donald Duck”
Addresscity = “Duckburg”
street = “Duck Street 313”
address
Personname = “Mickey Mouse”
addr
essManagedReference
id = 1
ManagedReferenceid = 2
roomm
ate
Personname = “Donald Duck”
Addresscity = “Duckburg”
street = “Duck Street 313”ManagedReference
id = 2
id = 1Person
name = “Mickey Mouse”Address
city = “Duckburg”street = “Duck Street 313”
ManagedReferenceid = 1
id = 2
“donald” = 1
roommate
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Database
Memory
Personname = “Donald Duck”
Addresscity = “Duckburg”
street = “Duck Street 313”ManagedReference
id = 2
id = 1Person
name = “Mickey Mouse”Address
city = “Duckburg”street = “Duck Street 313”
ManagedReferenceid = 1
id = 2
“donald” = 1
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Database
Memory
Personname = “Donald Duck”
Addresscity = “Duckburg”
street = “Duck Street 313”ManagedReference
id = 2
id = 1Person
name = “Mickey Mouse”Address
city = “Duckburg”street = “Duck Street 313”
ManagedReferenceid = 1
id = 2
“donald” = 1
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What happens under the hood when the following is executed?
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Database
Memory
Personname = “Donald Duck”
Addresscity = “Duckburg”
street = “Duck Street 313”ManagedReference
id = 2
id = 1Person
name = “Mickey Mouse”Address
city = “Duckburg”street = “Duck Street 313”
ManagedReferenceid = 1
id = 2
“donald” = 1
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Database
Memory
Personname = “Donald Duck”
Addresscity = “Duckburg”
street = “Duck Street 313”ManagedReference
id = 2
id = 1Person
name = “Mickey Mouse”Address
city = “Duckburg”street = “Duck Street 313”
ManagedReferenceid = 1
id = 2
“donald” = 1
Transaction
BEGIN TRANSACTION
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Database
Memory
Personname = “Donald Duck”
Addresscity = “Duckburg”
street = “Duck Street 313”ManagedReference
id = 2
id = 1Person
name = “Mickey Mouse”Address
city = “Duckburg”street = “Duck Street 313”
ManagedReferenceid = 1
id = 2
“donald” = 1
Transaction
Person donald = (Person) AppContext.getDataManager().getBinding("donald");
Personname = “Donald Duck”
Addresscity = “Duckburg”
street = “Duck Street 313”address
ManagedReferenceid = 2
roomm
ate
id = 1
Load
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Database
Memory
Personname = “Donald Duck”
Addresscity = “Duckburg”
street = “Duck Street 313”ManagedReference
id = 2
id = 1Person
name = “Mickey Mouse”Address
city = “Duckburg”street = “Duck Street 313”
ManagedReferenceid = 1
id = 2
“donald” = 1
Transaction
Person mickey = donald.getRoommate();Person mickey = donald.roommate.get();
Personname = “Donald Duck”
Addresscity = “Duckburg”
street = “Duck Street 313”address
ManagedReferenceid = 2
roomm
ate
id = 1
Addresscity = “Duckburg”
street = “Duck Street 313”
Personname = “Mickey Mouse”
addr
ess
ManagedReferenceid = 1
roommateid = 2
Load
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Database
Memory
Personname = “Donald Duck”
Addresscity = “Duckburg”
street = “Duck Street 313”ManagedReference
id = 2
id = 1Person
name = “Mickey Mouse”Address
city = “Duckburg”street = “Duck Street 313”
ManagedReferenceid = 1
id = 2
“donald” = 1
Transaction
System.out.println(mickey.getName() + " lives in " + mickey.getAddress().getCity());
Personname = “Donald Duck”
Addresscity = “Duckburg”
street = “Duck Street 313”address
ManagedReferenceid = 2
roomm
ate
id = 1
Addresscity = “Duckburg”
street = “Duck Street 313”
Personname = “Mickey Mouse”
addr
ess
ManagedReferenceid = 1
roommateid = 2
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Database
Memory
Personname = “Donald Duck”
Addresscity = “Duckburg”
street = “Duck Street 313”ManagedReference
id = 2
id = 1Person
name = “Mickey Mouse”Address
city = “Duckburg”street = “Duck Street 313”
ManagedReferenceid = 1
id = 2
“donald” = 1
Transaction
donald.setRoommate(null);
Personname = “Donald Duck”
Addresscity = “Duckburg”
street = “Duck Street 313”address
ManagedReferenceid = 2
id = 1
Addresscity = “Duckburg”
street = “Duck Street 313”
Personname = “Mickey Mouse”
addr
ess
ManagedReferenceid = 1
roommateid = 2
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Database
Memory
Personname = “Donald Duck”
Addresscity = “Duckburg”
street = “Duck Street 313”ManagedReference
id = 2
id = 1Person
name = “Mickey Mouse”Address
city = “Duckburg”street = “Duck Street 313”
ManagedReferenceid = 1
id = 2
“donald” = 1
Transaction
AppContext.getDataManager().removeObject(mickey);
Personname = “Donald Duck”
Addresscity = “Duckburg”
street = “Duck Street 313”address
ManagedReferenceid = 2
id = 1
Addresscity = “Duckburg”
street = “Duck Street 313”
Personname = “Mickey Mouse”
addr
ess
ManagedReferenceid = 1
roommate
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Database
Memory
Personname = “Donald Duck”
Addresscity = “Duckburg”
street = “Duck Street 313”
id = 1Person
name = “Mickey Mouse”Address
city = “Duckburg”street = “Duck Street 313”
ManagedReferenceid = 1
id = 2
“donald” = 1
Transaction
COMMIT TRANSACTION
Personname = “Donald Duck”
Addresscity = “Duckburg”
street = “Duck Street 313”address
ManagedReferenceid = 2
id = 1
Addresscity = “Duckburg”
street = “Duck Street 313”
Personname = “Mickey Mouse”
addr
ess
ManagedReferenceid = 1
roommate
Write
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Database
Memory
Personname = “Donald Duck”
Addresscity = “Duckburg”
street = “Duck Street 313”
id = 1
“donald” = 1
Transaction
COMMIT TRANSACTION
Personname = “Donald Duck”
Addresscity = “Duckburg”
street = “Duck Street 313”address
ManagedReferenceid = 2
id = 1
Addresscity = “Duckburg”
street = “Duck Street 313”
Personname = “Mickey Mouse”
addr
ess
ManagedReferenceid = 1
roommate
Delete
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Database
Memory
Personname = “Donald Duck”
Addresscity = “Duckburg”
street = “Duck Street 313”
id = 1
“donald” = 1
Personname = “Donald Duck”
Addresscity = “Duckburg”
street = “Duck Street 313”address
ManagedReferenceid = 2
Addresscity = “Duckburg”
street = “Duck Street 313”
Personname = “Mickey Mouse”
addr
ess
ManagedReferenceid = 1
roommate
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Database
Memory
Personname = “Donald Duck”
Addresscity = “Duckburg”
street = “Duck Street 313”
id = 1
“donald” = 1
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Database
Memory
Personname = “Donald Duck”
Addresscity = “Duckburg”
street = “Duck Street 313”
id = 1
“donald” = 1
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What is the problem?
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Too much work for the programmer!Mixed responsibilities! Leaking abstractions! Tight coupling!
. . .
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Solution• Make Darkstar itself responsible for taking
care of the technical details of ManagedObjects referring to each other
• Code using an object should not know the implementation details of that object – whether it is a ManagedObject or not
• Refer to ManagedObjects through proxies> Allows lazy loading> Separates object graphs during serialization> And the code using the object will never know it!
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Agenda• How Darkstar's persistence model is
currently?• How transparent references and garbage
collection change the persistence model?• Future directions
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ProxyType.CLASS- generated proxy extends target class- all fields must be private- all methods must be non-final- the class must be non-final(- an accessible default constructor is not needed, as the constructor will not be called)
ProxyType.INTERFACE- generated proxy implements the same interfaces as the target class- instances of the class must always be used through their interfaces
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What happens under the hood when the following is executed?
– with transparent references and garbage collection
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Database
Memory
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Database
Memory
Transaction
BEGIN TRANSACTION
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Database
Memory
Transaction
Personname = “Donald Duck”
Person donald = new Person("Donald Duck");
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Database
Memory
Transaction
Personname = “Donald Duck”
Addresscity = “Duckburg”
street = “Duck Street 313”
address
donald.setAddress(new Address("Duckburg", "Duck Street 313"));
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Database
Memory
Transaction
Personname = “Donald Duck”
Addresscity = “Duckburg”
street = “Duck Street 313”
address
Personname = “Mickey Mouse”
Person mickey = new Person("Mickey Mouse");
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Database
Memory
Transaction
Personname = “Donald Duck”
Addresscity = “Duckburg”
street = “Duck Street 313”
address
Personname = “Mickey Mouse”
addr
ess
mickey.setAddress(donald.getAddress());
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Database
Memory
Transaction
Personname = “Donald Duck”
Addresscity = “Duckburg”
street = “Duck Street 313”
address
Personname = “Mickey Mouse”
addr
ess
mickey.setRoommate(donald);
roommate
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Database
Memory
Transaction
Personname = “Donald Duck”
Addresscity = “Duckburg”
street = “Duck Street 313”
address
Personname = “Mickey Mouse”
addr
ess
donald.setRoommate(mickey);
roommateroommate
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Database
Memory
Transaction
Personname = “Donald Duck”
Addresscity = “Duckburg”
street = “Duck Street 313”
address
Personname = “Mickey Mouse”
addr
ess
id = 1
id = 1
“donald” = 1
AppContext.getDataManager().setBinding("donald", donald);
roommateroommate
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Database
Memory
Transaction
Personname = “Donald Duck”
Addresscity = “Duckburg”
street = “Duck Street 313”
address
Personname = “Mickey Mouse”
addr
ess
id = 1
id = 1
“donald” = 1
COMMIT TRANSACTION
roommateroommate
!
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Database
Memory
Transaction
Personname = “Donald Duck”
Addresscity = “Duckburg”
street = “Duck Street 313”
address
Personname = “Mickey Mouse”
addr
ess
ManagedReferenceid = 2
id = 2
id = 1
Personname = “Donald Duck”
Addresscity = “Duckburg”
street = “Duck Street 313”
ManagedReferenceid = 2
id = 1 id = 2
“donald” = 1
COMMIT TRANSACTION
roommatePerson Proxy
roomm
ate
Person Proxy
Write
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Database
Memory
Transaction
Personname = “Donald Duck”
Addresscity = “Duckburg”
street = “Duck Street 313”
address
Personname = “Mickey Mouse”
addr
ess
ManagedReferenceid = 2
id = 2
id = 1
Personname = “Donald Duck”
Addresscity = “Duckburg”
street = “Duck Street 313”
ManagedReferenceid = 2
id = 1 id = 2
“donald” = 1
COMMIT TRANSACTION
roommatePerson Proxy
roomm
ate
Person Proxy
!
![Page 51: Transparent References and Garbage Collection for …...Transparent References and Garbage Collection for Project Darkstar – making it easier to write applications on Project Darkstar](https://reader033.fdocuments.net/reader033/viewer/2022060215/5f05e3f97e708231d4153b63/html5/thumbnails/51.jpg)
Database
Memory
Transaction
Personname = “Donald Duck”
Addresscity = “Duckburg”
street = “Duck Street 313”
address
Personname = “Mickey Mouse”
addr
ess
ManagedReferenceid = 1
ManagedReferenceid = 2
id = 2
id = 1
Personname = “Donald Duck”
Addresscity = “Duckburg”
street = “Duck Street 313”
ManagedReferenceid = 2
id = 1 Personname = “Mickey Mouse”
Addresscity = “Duckburg”
street = “Duck Street 313”
ManagedReferenceid = 1
id = 2
Write
“donald” = 1
COMMIT TRANSACTION
Person Proxyroommate
Person Proxy
roomm
ate
Person ProxyPerson Proxy
![Page 52: Transparent References and Garbage Collection for …...Transparent References and Garbage Collection for Project Darkstar – making it easier to write applications on Project Darkstar](https://reader033.fdocuments.net/reader033/viewer/2022060215/5f05e3f97e708231d4153b63/html5/thumbnails/52.jpg)
Database
Memory
Personname = “Donald Duck”
Addresscity = “Duckburg”
street = “Duck Street 313”
address
Personname = “Mickey Mouse”
addr
ess
ManagedReferenceid = 1
ManagedReferenceid = 2
Personname = “Donald Duck”
Addresscity = “Duckburg”
street = “Duck Street 313”
ManagedReferenceid = 2
id = 1 Personname = “Mickey Mouse”
Addresscity = “Duckburg”
street = “Duck Street 313”
ManagedReferenceid = 1
id = 2
“donald” = 1
Person Proxyroommate
Person Proxy
roomm
ate
Person ProxyPerson Proxy
![Page 53: Transparent References and Garbage Collection for …...Transparent References and Garbage Collection for Project Darkstar – making it easier to write applications on Project Darkstar](https://reader033.fdocuments.net/reader033/viewer/2022060215/5f05e3f97e708231d4153b63/html5/thumbnails/53.jpg)
Database
Memory
Personname = “Donald Duck”
Addresscity = “Duckburg”
street = “Duck Street 313”
ManagedReferenceid = 2
id = 1 Personname = “Mickey Mouse”
Addresscity = “Duckburg”
street = “Duck Street 313”
ManagedReferenceid = 1
id = 2
“donald” = 1 Person ProxyPerson Proxy
![Page 54: Transparent References and Garbage Collection for …...Transparent References and Garbage Collection for Project Darkstar – making it easier to write applications on Project Darkstar](https://reader033.fdocuments.net/reader033/viewer/2022060215/5f05e3f97e708231d4153b63/html5/thumbnails/54.jpg)
Database
Memory
Personname = “Donald Duck”
Addresscity = “Duckburg”
street = “Duck Street 313”
ManagedReferenceid = 2
id = 1 Personname = “Mickey Mouse”
Addresscity = “Duckburg”
street = “Duck Street 313”
ManagedReferenceid = 1
id = 2
“donald” = 1 Person ProxyPerson Proxy
![Page 55: Transparent References and Garbage Collection for …...Transparent References and Garbage Collection for Project Darkstar – making it easier to write applications on Project Darkstar](https://reader033.fdocuments.net/reader033/viewer/2022060215/5f05e3f97e708231d4153b63/html5/thumbnails/55.jpg)
What happens under the hood when the following is executed?
– with transparent references and garbage collection
![Page 56: Transparent References and Garbage Collection for …...Transparent References and Garbage Collection for Project Darkstar – making it easier to write applications on Project Darkstar](https://reader033.fdocuments.net/reader033/viewer/2022060215/5f05e3f97e708231d4153b63/html5/thumbnails/56.jpg)
Database
Memory
Personname = “Donald Duck”
Addresscity = “Duckburg”
street = “Duck Street 313”
ManagedReferenceid = 2
id = 1 Personname = “Mickey Mouse”
Addresscity = “Duckburg”
street = “Duck Street 313”
ManagedReferenceid = 1
id = 2
“donald” = 1 Person ProxyPerson Proxy
![Page 57: Transparent References and Garbage Collection for …...Transparent References and Garbage Collection for Project Darkstar – making it easier to write applications on Project Darkstar](https://reader033.fdocuments.net/reader033/viewer/2022060215/5f05e3f97e708231d4153b63/html5/thumbnails/57.jpg)
Database
Memory
Transaction
Personname = “Donald Duck”
Addresscity = “Duckburg”
street = “Duck Street 313”
ManagedReferenceid = 2
id = 1 Personname = “Mickey Mouse”
Addresscity = “Duckburg”
street = “Duck Street 313”
ManagedReferenceid = 1
id = 2
“donald” = 1
BEGIN TRANSACTION
Person ProxyPerson Proxy
![Page 58: Transparent References and Garbage Collection for …...Transparent References and Garbage Collection for Project Darkstar – making it easier to write applications on Project Darkstar](https://reader033.fdocuments.net/reader033/viewer/2022060215/5f05e3f97e708231d4153b63/html5/thumbnails/58.jpg)
Database
Memory
Transaction
Personname = “Donald Duck”
Addresscity = “Duckburg”
street = “Duck Street 313”address
ManagedReferenceid = 2
id = 1
Personname = “Donald Duck”
Addresscity = “Duckburg”
street = “Duck Street 313”
ManagedReferenceid = 2
id = 1 Personname = “Mickey Mouse”
Addresscity = “Duckburg”
street = “Duck Street 313”
ManagedReferenceid = 1
id = 2
“donald” = 1
Person donald = (Person) AppContext.getDataManager().getBinding("donald");
Person Proxy
roomm
ate
Person ProxyPerson Proxy
Load
![Page 59: Transparent References and Garbage Collection for …...Transparent References and Garbage Collection for Project Darkstar – making it easier to write applications on Project Darkstar](https://reader033.fdocuments.net/reader033/viewer/2022060215/5f05e3f97e708231d4153b63/html5/thumbnails/59.jpg)
Database
Memory
Transaction
Personname = “Donald Duck”
Addresscity = “Duckburg”
street = “Duck Street 313”address
ManagedReferenceid = 2
id = 1
Personname = “Donald Duck”
Addresscity = “Duckburg”
street = “Duck Street 313”
ManagedReferenceid = 2
id = 1 Personname = “Mickey Mouse”
Addresscity = “Duckburg”
street = “Duck Street 313”
ManagedReferenceid = 1
id = 2
“donald” = 1
Person mickey = donald.getRoommate();
Person Proxy
roomm
ate
Person ProxyPerson Proxy
![Page 60: Transparent References and Garbage Collection for …...Transparent References and Garbage Collection for Project Darkstar – making it easier to write applications on Project Darkstar](https://reader033.fdocuments.net/reader033/viewer/2022060215/5f05e3f97e708231d4153b63/html5/thumbnails/60.jpg)
Database
Memory
Transaction
Personname = “Donald Duck”
Addresscity = “Duckburg”
street = “Duck Street 313”address
Personname = “Mickey Mouse”
addr
ess
ManagedReferenceid = 1
ManagedReferenceid = 2
id = 2
id = 1
Personname = “Donald Duck”
Addresscity = “Duckburg”
street = “Duck Street 313”
ManagedReferenceid = 2
id = 1 Personname = “Mickey Mouse”
Addresscity = “Duckburg”
street = “Duck Street 313”
ManagedReferenceid = 1
id = 2
“donald” = 1
System.out.println(mickey.getName() + " lives in " + mickey.getAddress().getCity());
Person Proxyroommate
Person Proxy
roomm
ate
Person ProxyPerson Proxy
Load
Addresscity = “Duckburg”
street = “Duck Street 313”
![Page 61: Transparent References and Garbage Collection for …...Transparent References and Garbage Collection for Project Darkstar – making it easier to write applications on Project Darkstar](https://reader033.fdocuments.net/reader033/viewer/2022060215/5f05e3f97e708231d4153b63/html5/thumbnails/61.jpg)
Database
Memory
Transaction
Personname = “Donald Duck”
Addresscity = “Duckburg”
street = “Duck Street 313”address
Personname = “Mickey Mouse”
addr
ess
ManagedReferenceid = 1
ManagedReferenceid = 2
id = 2
id = 1
Personname = “Donald Duck”
Addresscity = “Duckburg”
street = “Duck Street 313”
ManagedReferenceid = 2
id = 1 Personname = “Mickey Mouse”
Addresscity = “Duckburg”
street = “Duck Street 313”
ManagedReferenceid = 1
id = 2
“donald” = 1
donald.setRoommate(null);
Person Proxyroommate
Person Proxy
Person ProxyPerson Proxy
Addresscity = “Duckburg”
street = “Duck Street 313”
![Page 62: Transparent References and Garbage Collection for …...Transparent References and Garbage Collection for Project Darkstar – making it easier to write applications on Project Darkstar](https://reader033.fdocuments.net/reader033/viewer/2022060215/5f05e3f97e708231d4153b63/html5/thumbnails/62.jpg)
Database
Memory
Transaction
Personname = “Donald Duck”
Addresscity = “Duckburg”
street = “Duck Street 313”address
Personname = “Mickey Mouse”
addr
ess
ManagedReferenceid = 1
ManagedReferenceid = 2
id = 2
id = 1
Personname = “Donald Duck”
Addresscity = “Duckburg”
street = “Duck Street 313”
id = 1 Personname = “Mickey Mouse”
Addresscity = “Duckburg”
street = “Duck Street 313”
ManagedReferenceid = 1
id = 2
“donald” = 1
COMMIT TRANSACTION
Person Proxyroommate
Person Proxy
Person Proxy
Addresscity = “Duckburg”
street = “Duck Street 313”
Write
![Page 63: Transparent References and Garbage Collection for …...Transparent References and Garbage Collection for Project Darkstar – making it easier to write applications on Project Darkstar](https://reader033.fdocuments.net/reader033/viewer/2022060215/5f05e3f97e708231d4153b63/html5/thumbnails/63.jpg)
Database
Memory
Transaction
Personname = “Donald Duck”
Addresscity = “Duckburg”
street = “Duck Street 313”address
Personname = “Mickey Mouse”
addr
ess
ManagedReferenceid = 1
ManagedReferenceid = 2
id = 2
id = 1
Personname = “Donald Duck”
Addresscity = “Duckburg”
street = “Duck Street 313”
id = 1 Personname = “Mickey Mouse”
Addresscity = “Duckburg”
street = “Duck Street 313”
ManagedReferenceid = 1
id = 2
“donald” = 1
COMMIT TRANSACTION
Person Proxyroommate
Person Proxy
Person Proxy
Addresscity = “Duckburg”
street = “Duck Street 313”
Not Modified
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Database
Memory
Personname = “Donald Duck”
Addresscity = “Duckburg”
street = “Duck Street 313”address
Personname = “Mickey Mouse”
addr
ess
ManagedReferenceid = 1
ManagedReferenceid = 2
Personname = “Donald Duck”
Addresscity = “Duckburg”
street = “Duck Street 313”
id = 1 Personname = “Mickey Mouse”
Addresscity = “Duckburg”
street = “Duck Street 313”
ManagedReferenceid = 1
id = 2
“donald” = 1
Person Proxyroommate
Person Proxy
Person Proxy
Addresscity = “Duckburg”
street = “Duck Street 313”
![Page 65: Transparent References and Garbage Collection for …...Transparent References and Garbage Collection for Project Darkstar – making it easier to write applications on Project Darkstar](https://reader033.fdocuments.net/reader033/viewer/2022060215/5f05e3f97e708231d4153b63/html5/thumbnails/65.jpg)
Database
Memory
Personname = “Donald Duck”
Addresscity = “Duckburg”
street = “Duck Street 313”
id = 1 Personname = “Mickey Mouse”
Addresscity = “Duckburg”
street = “Duck Street 313”
ManagedReferenceid = 1
id = 2
“donald” = 1 Person Proxy
![Page 66: Transparent References and Garbage Collection for …...Transparent References and Garbage Collection for Project Darkstar – making it easier to write applications on Project Darkstar](https://reader033.fdocuments.net/reader033/viewer/2022060215/5f05e3f97e708231d4153b63/html5/thumbnails/66.jpg)
Database
Memory
Personname = “Donald Duck”
Addresscity = “Duckburg”
street = “Duck Street 313”
id = 1 Personname = “Mickey Mouse”
Addresscity = “Duckburg”
street = “Duck Street 313”
ManagedReferenceid = 1
id = 2
“donald” = 1 Person Proxy
![Page 67: Transparent References and Garbage Collection for …...Transparent References and Garbage Collection for Project Darkstar – making it easier to write applications on Project Darkstar](https://reader033.fdocuments.net/reader033/viewer/2022060215/5f05e3f97e708231d4153b63/html5/thumbnails/67.jpg)
Database
Memory
Personname = “Donald Duck”
Addresscity = “Duckburg”
street = “Duck Street 313”
id = 1 Personname = “Mickey Mouse”
Addresscity = “Duckburg”
street = “Duck Street 313”
ManagedReferenceid = 1
id = 2
“donald” = 1 Person Proxy
![Page 68: Transparent References and Garbage Collection for …...Transparent References and Garbage Collection for Project Darkstar – making it easier to write applications on Project Darkstar](https://reader033.fdocuments.net/reader033/viewer/2022060215/5f05e3f97e708231d4153b63/html5/thumbnails/68.jpg)
Database
Memory
Personname = “Donald Duck”
Addresscity = “Duckburg”
street = “Duck Street 313”
id = 1
“donald” = 1
![Page 69: Transparent References and Garbage Collection for …...Transparent References and Garbage Collection for Project Darkstar – making it easier to write applications on Project Darkstar](https://reader033.fdocuments.net/reader033/viewer/2022060215/5f05e3f97e708231d4153b63/html5/thumbnails/69.jpg)
Database
Memory
Personname = “Donald Duck”
Addresscity = “Duckburg”
street = “Duck Street 313”
id = 1
“donald” = 1
![Page 70: Transparent References and Garbage Collection for …...Transparent References and Garbage Collection for Project Darkstar – making it easier to write applications on Project Darkstar](https://reader033.fdocuments.net/reader033/viewer/2022060215/5f05e3f97e708231d4153b63/html5/thumbnails/70.jpg)
Agenda• How Darkstar's persistence model is
currently?• How transparent references and garbage
collection change the persistence model?• Future directions
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Future directions• Include transparent references in the official
Project Darkstar Server distribution• Areas which need more work
> Scalability of the multi-node version> Improved garbage collector, multi-node support,
alternative algorithms, reference counting vs. tracing collectors
> Refactoring serialized data, rolling upgrades> Indexing and querying the database> ...
• It's all open source!
![Page 72: Transparent References and Garbage Collection for …...Transparent References and Garbage Collection for Project Darkstar – making it easier to write applications on Project Darkstar](https://reader033.fdocuments.net/reader033/viewer/2022060215/5f05e3f97e708231d4153b63/html5/thumbnails/72.jpg)
Questions?Project Darkstar Community– official web site, discussion forumshttp://www.projectdarkstar.com/
Darkstar EXP– unofficial distribution of Darkstar Server with experimental features, includes transparent references and garbage collectorhttp://code.google.com/p/darkstar-exp/
Dimdwarf Application Server– same transparent reference implementation, alternative server implementation, primarily designed for embedded standalone modehttp://dimdwarf.sourceforge.net/