SqueakSave

lundi 31 août 2009 

SqueakSave 

An Automatic Object-Relational Mapping Framework 

Thomas Kowark 

Robert Hirschfeld 

Michael Haupt 

Software Architecture Group 

Hasso-Plattner-Institut Potsdam 

www.hpi.uni-potsdam.de/swa

SqueakSave: An Automatic Object-Relational Mapping Framework 

• motivation 

• basic usage 

• framework architecture 

• performance 

• summary & outlook 

Outline 

Thomas Kowark, Robert Hirschfeld, Michael Haupt (www.hpi.uni-potsdam.de/swa) 2009 


2


Available Persistence Approaches 

• image storing 

• object databases 

• (object-)relational persistence 



3


SqueakSave – Project Goals 

• automatic mapping deduction 

• simplistic API 

• seamless integration into existing applications 



4


al Paradigm for UML Community Edition [not for commercial use] 

User 

-email : string 

-username : string 

-password : string 

Author 

Admin 

Guiding Example 



0..* +followers 

1 

1 

1..* 

+blog 

+administeredBlogs 

1 

0..* 

Blog 

-title : string 

-lastUpdate : dateTime 

1 

0..* 

BlogPost 


-text : string 

1 

0..* 

Comment 

-author : string 


-text : string 

+blogPosts 

+comments 

5


API – Configuration 

• configuration based on naming conventions 

SqsConfig subclass: #BlogExampleSqsConfig 

instanceVariableNames: '' 

classVariableNames: '' 

poolDictionaries: '' 

category: 'BlogExample' 

BlogExampleSqsConfig 

class>>#connectionSpecification 

^ SqsMySQLConnectionSpecification 

user: 'admin' 

password: 'password' 

database: 'blog_example_db' 

Thomas Kowark, Robert Hirschfeld, Michael Haupt (www.hpi.uni-potsdam.de/swa) 2009 6 

lundi 31 août 2009


author := Author new 

password: 'password'; 

username: 'testuser'; 

email: 'user@example.org'. 

author blog: (Blog new title: 'My Blog'). 

author save. 

... 

author destroy. 

API – Basic Operations 


lundi 31 août 2009


API – Queries 



(SqsSearch for: User) detect: [:aUser | 

aUser username = 'testuser'] 

(SqsSearch for: Author) select: [:anAuthor | 

anAuthor blog blogPosts size > 10 ] 

(SqsSearch for: Blog) anySatisfy: [:aBlog | 

aBlog blogPosts noneSatisfy: [:aBlogPost | 

aBlogPost comments isEmpty ] ] 

(SqsSearch for: Blog) findByTitle: 'testblog' 

(SqsSearch for: Comment) 

findByAuthor: 'author' andTitle: 'comment'. 

8

commercial use] 


er 

1 

Class 

SqsBase 0..* 

SqsConnection 

ctureHandler 

SqsDescriptionHandler 

1 

class 

1 

+classInfo 

1 

+session 

1 

SqsProxy 

SqsClassInfo 

SqsSession 

SqsTableStructureHandler 

currentClass 

1 

SqueakSave – Architecture 

instVarValue 

1 

1 

 

SqsConnectionManager 

dbAdapter 

re 4.1: Overview of SqueakSave System Classes. 

SqsDatabaseAdapter 

SqsDatabaseConnection 


0..1 

1 

0..* 

 

connection 

e into the separate sub words and connects them with an underscore. A 

e’, for example, is thereby converted to the column name ‘user name’. 

ide simple compatibility with most other O/R mappers for dynamic 

lundi 31 août 2009



er 

1 

Class 

SqsBase 0..* 

SqsConnection 

ctureHandler 


1 

class 

1 

+classInfo 

1 

+session 

1 

SqsProxy 

SqsClassInfo 

SqsSession 


currentClass 

1 


instVarValue 

anObject save 

1 

1 

 


dbAdapter 





0..1 

1 

0..* 

 

connection 




lundi 31 août 2009



er 

1 

Class 

SqsBase 0..* 

SqsConnection 

ctureHandler 


1 

class 

1 

+classInfo 

1 

+session 

1 

SqsProxy 

SqsClassInfo 

SqsSession 1 

Creation or fetching of 


currentClass 

1 


instVarValue 

1 

unique SqsStorage 

wrapper instance 

 


dbAdapter 





0..1 

1 

0..* 

 

connection 




lundi 31 août 2009



er 

1 

Class 

SqsBase 0..* 

SqsConnection 

ctureHandler 


1 

class 

1 

+classInfo 

1 

+session 

1 

SqsProxy 

SqsClassInfo 

SqsSession 


currentClass 

1 


instVarValue 

1 

1 

 


dbAdapter 





0..1 

1 

0..* 

 

connection 

Creation or update of 

mapping descriptions 




lundi 31 août 2009



er 

1 

Class 

SqsBase 0..* 

SqsConnection 

ctureHandler 


1 

class 

1 

+classInfo 

1 

+session 

1 

SqsProxy 

SqsClassInfo 

SqsSession 


1 

instVarValue 

1 

1 

 

currentClass 


dbAdapter 


Calculation of changes to 




0..1 

1 

0..* 

 

connection 

e intothe the relational separatedatabase sub words and connects them with an underscore. A 

schema 




lundi 31 août 2009



er 

1 

Class 

SqsBase 0..* 

SqsConnection 

ctureHandler 


1 

class 

1 

+classInfo 

1 

+session 

1 

SqsProxy 

SqsClassInfo 

SqsSession 


1 

instVarValue 

1 

1 

 

currentClass 


dbAdapter 





0..1 

1 

0..* 

 

connection 






Connection pooling



er 

1 

Class 

SqsBase 0..* 

SqsConnection 

ctureHandler 


1 

class 

1 

+classInfo 

1 

+session 

1 

SqsProxy 

SqsClassInfo 

SqsSession 


1 

instVarValue 

1 

1 

 

currentClass 


dbAdapter 





0..1 

1 

0..* 

 

connection 






Schema update and 

object insertion or update


Query Analysis 

• SQL statement generation through block execution 

with placeholder objects 

• one placeholder class per ‘simple type’, 

SqsQueryObject and SqsQueryCollection for 

complex cases 





10







complex cases 

queryObject := SqsQueryObject new 

depictedClass: User. 

result := aBlock value: queryObject. 





10







complex cases 

The query object does not know what #username 

does, but generates the SQL to scope to the 

respective column. 





10







complex cases 

WHERE users.username 





10







complex cases 





The result of the first call is an SqsQueryString. 

It knows how to map the #= to SQL properly. 

10







complex cases 

WHERE users.username = 





10







complex cases 

WHERE users.username = ‘testuser’ 





10


Evaluation 



• evaluation based on OO7 benchmark 

– CAD application data structure 

– complex object model with many cyclic dependencies 

• set of queries with increasing complexity 

• number of traversals of an object graph 

• comparison with GLORP 

11


Evaluation – Query Performance 

• approx. 20% slower than GLORP 

• two exceptions 

– caching mechanism (10x slower) 

(SqsSearch for: SqsAtomicPart) detect: 

[:ap | ap oid = id]. 

– query creation with joins (1/3x faster) 

(SqsSearch for: SqsBaseAssembly) select: [:ba | 

ba unsharedParts anySatisfy: [:part | 

part document = id ]]. 


lundi 31 août 2009


Traversal 1 

SqueakSave GLORP 

Traversal 2b 

– missing eager loading 

(n+1 queries problem) 


Evaluation – Traversal Performance 

6s 

5s 

3s 

2s 

0s 

24s 

18s 

12s 

6s 

0s 

Traversal 2a 


Traversal 2c 

– minimal intrusion into object 

models (only collection proxies) 



lundi 31 août 2009


Summary and Outlook 

• simple usage & setup 

– integration into existing applications almost seamless 

• automatic deduction of database structures 



14


Summary and Outlook 

• simple usage & setup 

– integration into existing applications almost seamless 

• automatic deduction of database structures 

• possible extensions 

– SqueakDBX usage 

– eager loading 

– performance optimizations 



14

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