Downloaded 18 times
![Code (Simplified)
methodDoRequest{
methodurl {type ""} {value ""}} {
for {setrs0} {$rs< 5} {incrrs} {
settok [http::geturl $url
-method $method
-type $type -query $value]
try {
if{[http::ncode $tok] > 399} {
# ERROR
setmsg [myExtractError $tok]
return -code error $msg
} elseif {[http::ncode $tok] > 299
||[http::ncode $tok]==201} {
# REDIRECT
try {
setlocation [dictget
[http::meta $tok] Location]
} on error {} {
error"missing location!"
}
myOnRedirect $tok $location
} else{
# SUCCESS
return[http::data $tok]
}
} finally {
http::cleanup $tok
}
}
error"too many redirections!"
}
methodGETargs {
return [myDoRequest GET
$base/[join $args"/"]]
}
12](https://image.slidesharecdn.com/adventuresintcloo2010-130928134943-phpapp01/75/Adventures-in-TclOO-12-2048.jpg)
![Usage
oo::class create Service {
superclass REST
# … etc …
methodstatus {{status""}} {
if {$statuseq""} {
return[my GET status]
}
my PUT status text/plain $status
return
}
}
13](https://image.slidesharecdn.com/adventuresintcloo2010-130928134943-phpapp01/75/Adventures-in-TclOO-13-2048.jpg)
![Example of Use
# Connect to Database with TDBC
setconn [tdbc::sqlite3::connection new"mydb.sqlite3"]
# Create all the classes holding the mapping
ORM::Databasecreatedb $conn
# Illustrate use by printing out all orders
db table order foreachordr {
puts"Order #[$ordr id]"
puts"Customer: [[$ordr customer] firstname]
[[$ordr customer] surname]"
puts"Address: [[$ordr dispatch] house]
[[$ordr dispatch] street]"
puts"Address: [[$ordr dispatch] city],
[[$ordr dispatch] state]"
puts"Description:nt[$ordr description]"
puts""
}
20](https://image.slidesharecdn.com/adventuresintcloo2010-130928134943-phpapp01/75/Adventures-in-TclOO-20-2048.jpg)
![Annotation Syntax
@SomeAnnotation -foo bar
oo::class createExample {
@AnotherAnnotation
variablex
@GuessWhatThisIs
constructor {} { … }
@HowAboutThis?
@More…
methodxyzzy {xy} { … }
}
# To read the annotations…
puts [infoclassannotation Example]
23](https://image.slidesharecdn.com/adventuresintcloo2010-130928134943-phpapp01/75/Adventures-in-TclOO-23-2048.jpg)
![Declaring an Annotation
oo::class createAnnotation.Argument {
superclassAnnotation.Describe
variableannotationmethod
argument
# Save what argument this applies to
constructor{type argNameargs} {
setargument $argName
next $type {*}$args
}
# How an annotation is introspected
methoddescribe{v {n""} {an""}} {
upvar 1 $vresult
if {[llength [infolevel 0]] == 3} {
lappendresult $method
return
}
if{$method ne $n} {
return
}
if{[llength [infolevel 0]] == 4} {
lappendresult $argument
return
} elseif {$argumenteq$a} {
setresult [join $annotation]
return -code break
}
}
}
25](https://image.slidesharecdn.com/adventuresintcloo2010-130928134943-phpapp01/75/Adventures-in-TclOO-25-2048.jpg)
![Under the Hood
Every Class has List of Annotations Applied to it
Attaching to Classes
Uses Standard Unknown Handler
Rewrites oo::class Command
Attaching to Declarations
Rewrites Whole TclOO Declaration System
Change Declaration
Local Unknown Handler
Adding Introspection
Extra commands in [info class] via ensemble
26](https://image.slidesharecdn.com/adventuresintcloo2010-130928134943-phpapp01/75/Adventures-in-TclOO-26-2048.jpg)
![Under the Hood
TclOO Package Annotation Package
oo::class
oo::define
[info class]
interceptor
interceptors
extensions
Annotation
Class
Annotation
Store
Meddleswithinternals
27](https://image.slidesharecdn.com/adventuresintcloo2010-130928134943-phpapp01/75/Adventures-in-TclOO-27-2048.jpg)
Uploaded byDonal Fellows
Adventures in TclOO
The document discusses advancements in TclOO, highlighting support for RESTful web services and the wrapping of TDBC with object-relational mapping (ORM). It covers the functionality and structure of the TclOO object system, including metadata annotations and future plans for enhancements in REST and ORM integration. Additionally, it describes usage examples and operational methods for handling web resources and database interactions.
Adventures in TclOO
- 1. Adventures in TclOOor, Here’sSome Tricks I’ve Been Up To Donal Fellows University of Manchester / Tcl Core Team
- 2. Outline A QuickTclOO Refresher Support Class for REST Wrapping TDBC with ORM Extending TclOO with Annotations Where to go in the Future 2
- 3.
- 4. TclOO Refresher ObjectSystem Incorporated in 8.6, Package for 8.5 Designed for Keeping Out of Your Way Being Tcl’ish and Dynamic Being Powerful and Extensible Key Features Single-Rooted Inheritance Hierarchy Classes are Objects and May be Extended Object’s Namespace contains Object’s Variables Class (Re-)Definition by Separate Command 4
- 5. The Anatomy Lesson oo::object Namespace Method Table Mixin List Variables NSPath Commands Instance Method Table Mixin List Superclass List oo::class An object has these things… A class also has these, which apply to instances Classes are objects Objects are made by classes You can subclass the class of classes for custom construction 5
- 6.
- 7. REpresentational State Transfer REST is Way of Doing Web Services Popular Easy to Use in Ad Hoc Way Strongly Leverages HTTP Verbs are GET, PUT, DELETE, POST, … Nouns are Resources with URLs View of Resources Determined by Content Negotiation 7
- 8. Example… http://example.org/pizzas isa Pizza Parlor GET http://example.org/pizzas Returns Current List of Pizzas GET http://example.org/pizzas/123 Returns Description of Pizza #123 GET http://example.org/pizzas/123/pepperoni Returns Amount of Pepperoni on Pizza 8
- 9. Example… Updates PUThttp://example.org/pizzas/123/pepperoni Sets Amount of Pepperoni on Pizza #123 Idempotent POST http://example.org/pizzas Makes a New Pizza from Scratch Request document says what to make Redirects to Created Pizza DELETE http://example.org/pizzas/123 Gets Rid of Pizza #123 Idempotent 9
- 10. REST Class TclOOClass Wrapper for http package Models a Base Resource Methods for Each HTTP Verb Designed to be Subclassed! Some Production Use Testing Interface for Very Complex REST Service More than 35 Operations with non-fixed URLs Still Growing… 10
- 11. General Plan oo::object Service InstanceService InstanceService Instance oo::class REST Specific Service 11
- 12. Code (Simplified) methodDoRequest{ methodurl {type""} {value ""}} { for {setrs0} {$rs< 5} {incrrs} { settok [http::geturl $url -method $method -type $type -query $value] try { if{[http::ncode $tok] > 399} { # ERROR setmsg [myExtractError $tok] return -code error $msg } elseif {[http::ncode $tok] > 299 ||[http::ncode $tok]==201} { # REDIRECT try { setlocation [dictget [http::meta $tok] Location] } on error {} { error"missing location!" } myOnRedirect $tok $location } else{ # SUCCESS return[http::data $tok] } } finally { http::cleanup $tok } } error"too many redirections!" } methodGETargs { return [myDoRequest GET $base/[join $args"/"]] } 12
- 13. Usage oo::class create Service{ superclass REST # … etc … methodstatus {{status""}} { if {$statuseq""} { return[my GET status] } my PUT status text/plain $status return } } 13
- 14. Bioscience ServicesBioscience ServicesBioscience Services What I WasUsing This For Workflow Server Web FrontEnd Database Filesystem Heliophysics ServicesHeliophysics ServicesHeliophysics Services Chemistry ServicesChemistry ServicesChemistry Services Workflow Workflow Workflow Taverna 2 Server Taverna Engine Taverna Engine Taverna EngineTesting This Part 14
- 15.
- 16. Object-Relational Mapping Objectsare Natural Way to Model World Well, much of it… Relational Databases are Excellent at Managing Data Build Links between Objects and Databases Many Languages Have Them Java, C#, Ruby, … Wanted to do in Tcl Leverage TclOO and TDBC 16
- 17. Data First orObjects First? Data First Data is already in the database How to introspect database’s structure How to represent naturally as objects Objects First Data is in objects How to construct database to store and restore My ORM Package is Data First Dynamic class construction! 17
- 18. Basic Class Plan oo::objectoo::class Database Table NamedRow AnonRow Instance makes instance subclass 18
- 19. CRM DB Interaction Plan Database Table NamedRow Order DescnCustI D DispID Customer FirstName Surname Dispatch ID House Street City ID ID State crmdb orderorder#42 customer dispatch customer#7 dispatch#9 Introspects DB Columns go to properties Foreign keys make inter-object links Class per table Instance per row 19
- 20. Example of Use #Connect to Database with TDBC setconn [tdbc::sqlite3::connection new"mydb.sqlite3"] # Create all the classes holding the mapping ORM::Databasecreatedb $conn # Illustrate use by printing out all orders db table order foreachordr { puts"Order #[$ordr id]" puts"Customer: [[$ordr customer] firstname] [[$ordr customer] surname]" puts"Address: [[$ordr dispatch] house] [[$ordr dispatch] street]" puts"Address: [[$ordr dispatch] city], [[$ordr dispatch] state]" puts"Description:nt[$ordr description]" puts"" } 20
- 21.
- 22. What is anAnnotation? Additional Arbitrary Metadata Attached to Class or Part of Class User-Defined Purpose Easy way to add information without doing big changes to TclOO’s C implementation Uses from Other Languages Documentation Constraints Coupling to Container Frameworks Persistence, Web Apps, Management, … 22
- 23. Annotation Syntax @SomeAnnotation -foobar oo::class createExample { @AnotherAnnotation variablex @GuessWhatThisIs constructor {} { … } @HowAboutThis? @More… methodxyzzy {xy} { … } } # To read the annotations… puts [infoclassannotation Example] 23
- 24. Types of Annotations Annotations Specify What They Attach To Classes Methods Any declaration… Examples @Description @Argument @Result @SideEffect 24
- 25. Declaring an Annotation oo::classcreateAnnotation.Argument { superclassAnnotation.Describe variableannotationmethod argument # Save what argument this applies to constructor{type argNameargs} { setargument $argName next $type {*}$args } # How an annotation is introspected methoddescribe{v {n""} {an""}} { upvar 1 $vresult if {[llength [infolevel 0]] == 3} { lappendresult $method return } if{$method ne $n} { return } if{[llength [infolevel 0]] == 4} { lappendresult $argument return } elseif {$argumenteq$a} { setresult [join $annotation] return -code break } } } 25
- 26. Under the Hood Every Class has List of Annotations Applied to it Attaching to Classes Uses Standard Unknown Handler Rewrites oo::class Command Attaching to Declarations Rewrites Whole TclOO Declaration System Change Declaration Local Unknown Handler Adding Introspection Extra commands in [info class] via ensemble 26
- 27. Under the Hood TclOOPackage Annotation Package oo::class oo::define [info class] interceptor interceptors extensions Annotation Class Annotation Store Meddleswithinternals 27
- 28. Future? Where to goin the
- 29. Future of RESTClass Contribute to Tcllib Needs More Features First Authentication Support Cookie Handling WADL Parser Well, maybe… 29
- 30. Future of ORM Much Work Needed What is natural way to handle object deletion? What is best way to handle complex keys? What is best way to bring in objects? What sort of cache policy should be used? Support Object-First Style With annotations? 30
- 31. Future of Annotations Too Hard to Declare Far too much work! Introspection Axes Wrong Current code uses very unnatural order Add to TclOO? Depends on issues being resolved Find Cool Things to Do, e.g… Augment ORM? Ways of creating server-side REST bindings 31