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Building Server Applications Using ObjectiveC And GNUstep
 

Building Server Applications Using ObjectiveC And GNUstep

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By Nicholas Roard

By Nicholas Roard

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    Building Server Applications Using ObjectiveC And GNUstep Building Server Applications Using ObjectiveC And GNUstep Presentation Transcript

    •  
    • Server Applications
        “Server Applications” = programs with no GUI In GNUstep, server applications are based on GNUstep-base. GNUstep-base is the most complete and extensively polished and tested part of GNUstep ... … but is little known to the public.
          • People often identify GNUstep only with the GUI framework/development environment.
    • Objective-C
      • it is a programming language
      • it is a strict superset of C
          • it is C with some new additional constructs
          • C code compiles as Objective-C code
          • C libraries can be linked and used natively from Objective-C
      • it adds Object-Oriented features to C
          • Defining classes
          • Implementing methods
          • Instantiating classes and objects
          • Invoking class and object methods
          • Protocols, categories, selectors, forwarding
    • Why is Objective-C so special ?
      • It is compatible with C libraries
      • Is is a simple extension of C
      • It is a hybrid between C and Smalltalk
          • It can be as fast as raw C if you avoid the object-oriented extensions
          • It can be as high-level and flexible as Smalltalk if you use the object-oriented extensions
          • It allows experienced programmers to mix different programming styles in the same program
      • It is extremely flexible
      • Powerful “ Foundation ” class library
    • Why use Objective-C for Server Applications ?
      • Very fast. You can freely mix it with C and even assembler if you need.
      • High-level language. Organize your server code using high-level, object-orientated design patterns.
      • Powerful Foundation library (GNUstep-base). The API originates from OpenStep and the implementation has been polished for 13+ years.
    • OpenStep API - Foundation Kit (1994)
        Foundation Kit Non-graphical classes
        • Root classes : NSObject, NSProxy
        • Basic data classes : NSString, NSNumber, NSData, NSNull
        • Collection classes : NSArray, NSDictionary, NSSet
        • Execution control classes : NSRunLoop, NSTimer, NSThread, NSLock
        • I/O classes : NSTask, NSFileHandle
        • Notification classes: NSNotification, NSDistributedNotification
        • Serialization classes: NSArchiver, NSCoder
        • Resource management classes: NSBundle, NSUserDefaults
        • Distributed Objects Classes: NSConnection, NSPort
        • And many more...
      Application Foundation Kit Application Kit Operating System OS Graphical System Objective-C Runtime
    • GNUstep-base Application GNUstep Base GNUstep GUI Operating System (Any!) Graphical System (Any!) GNU Objective-C Runtime GNUstep Back
    • Server Applications – what do you need ?
        gcc-objc
          • Objective-C compiler
          • Objective-C runtime
        gnustep-make
          • Official GNUstep Building System
          • Makefile library that automatically takes care of configuring and building on different platforms
        gnustep-base
          • OpenStep Foundation Kit implementation
          • Provides “core” non-graphical Objective-C classes
    • Important dependencies
        libffi
          • Required by gnustep-base
          • You may need to download it and install it from www.gnustep.org
        libxml
          • Required by gnustep-base
          • Install it from your GNU/Linux distribution
        gnutls or openssl
          • Allow gnustep-base to support https://
          • Install it from your GNU/Linux distribution
    • Typical Quick Installation (Ubuntu) apt-get libgnustep-base-dev
    • Typical Manual Installation (RedHat) yum install gcc-objc libxml-devel openssl-devel wget ftp://sourceware.org/pub/libffi/libffi-3.0.1.tar.gz tar xfvz libffi-3.0.1.tar.gz cd libffi-3.0.1 ./configure make su -c 'make install' <edit /etc/ld.so.conf adding /usr/local/lib, then run ldconfig as root> wget ftp://ftp.gnustep.org/pub/gnustep/core/gnustep-make-2.0.8.tar.gz tar xfvz gnustep-make-2.0.8.tar.gz cd gnustep-make-2.0.8.tar.gz ./configure make su -c 'make install' . /usr/GNUstep/System/Library/Makefiles/GNUstep.sh wget ftp://ftp.gnustep.org/pub/gnustep/core/gnustep-base-1.18.0.tar.gz tar xfvz gnustep-base-1.18.0.tar.gz cd gnustep-base-1.18.0 ./configure –enable-openssl make su -c 'make install'
    • “Hello World!” Program
        “Hello World” using Objective-C / GNUstep-base hello.m
      #import <Foundation/Foundation.h> int main (void) { NSLog (@“Hello world!”); return 0; }
    • “Hello World!” Program
        “Hello World” using Objective-C / GNUstep-base GNUmakefile
      include $(GNUSTEP_MAKEFILES)/common.make TOOL_NAME = hello hello_OBJC_FILES = hello.m include $(GNUSTEP_MAKEFILES)/tool.make
    • “Hello World!” Program
        “Hello World” using Objective-C / GNUstep-base Usual compilation commands
      make make clean make distclean make install make messages=yes make install messages=yes
    • “Hello World!” Program
        “Hello World” using Objective-C / GNUstep-base Compilation results are in ./obj Let's try it out: Tutorial Compilation Session
    • GNUstep-base coding: where to start
        GNUstep Mini Tutorials (Introduction): http://www.gnustep.it/nicola/Tutorials/index.html GNUstep Base Documentation (API Reference): http://www.gnustep.org/resources/documentation/Developer/Base/Reference/index.html
    • GNUstep-base coding: basic classes
        Class cluster Design
          • Transparent way of optimizing classes without changing the public API
          • When you create a NSString or NSArray you actually get an instance of a subclass optimized to perform best in your situation
          • Method dispatch is dynamic, so that works
          • You can implement your own subclasses for performance
        Mutable and non-mutable Classes
          • NSString vs NSMutableString
          • NSString is for constant strings that never change
          • NSMutableString is for strings that might change
          • Allows a lot of optimizations inside the library
    • GNUstep-base coding: basic classes
        NSString, NSMutableString
          • String class
          • Full Unicode support
          • Class cluster implementation means ASCII strings are still extremely fast
          • Static strings
        • NSString *string = @”This is a test string”;
    • GNUstep-base coding: basic classes
      • NSArray, NSMutableArray
          • Array class
          • NSMutableArray provides arrays that grow dynamically
      • NSDictionary, NSMutableDictionary
          • Hashtable/associative array class
          • NSMutableDictionary provides associative arrays that grow dynamically
        • {
          • Name = “Gorm.app”;
          • Description = “GNUstep GUI Builder Application”;
          • }
        • (“one”, “two”, “three”);
    • GNUstep-base: Runloops and threads
        NSRunLoop
        • NSRunLoop
        • Event-based model
        • NSFileHandle
        • NSTimer
        Threads
        • NSThread
        • NSLock
    • GNUstep-base: Notifications
      • GNUstep-base supports notifications and observers
          • Flexible way to connect objects
      • NSNotificationCenter
      • Objects can “observe” a notification and specify which method
      • they want invoked when that notification is posted
      • Anything can “post” a notification
      • The notification is delivered to all “observer”
        • See NSNotificationCenter documentation for more information
    • GNUstep-base: Delegates
      • Objective-C and GNUstep-base encourage using delegates
      • A delegate allows you to extend a class without subclassing it
      • Subclassing can be heavy, and not that flexible
      • Delegates are more flexible – you can delegate part of the code to
      • an object of any class
      • -setDelegate: (NSObject *)delegate;
      • -delegate;
    • GNUstep-base: Distributed Objects
      • Remote method invocation
      • High-level
      • You can expose objects in one process to other processes
      • Other processes can then contact the object and invoke methods
      • of the objects, as if they were local objects
      • Very natural to use
      • Excellent for building networks of processes that work cooperatively
      • See http://www.gnustep.it/nicola/Tutorials/ for a tutorial on Distributed Objects.
    • A look at some useful libraries
      • You can use any C library you want
      • Objective-C libraries provided by GNUstep
          • check the dev-libs module in subversion
      • Objective-C libraries provided by other parties
          • SOPE (opengroupware.org)
          • Apple Cocoa non-GUI frameworks can sometime be used
    • GNUstep Database Libraries
      • You can use your own preferite C library
      • GNUstep Database Libraries
          • SQLClient
          • GDL2
      • SOPE
          • The best choice if you use the SOPE application server
          • Not so interesting if you're not
    • GNUstep Database Libraries
        SQLClient
          SQL Layer (low-level)
          • Standard SQL layer to execute SQL queries/commands
          • “Backend bundles” (plugins) for the different databases (standard bundles: PostgreSQL, MySQL, SQLite, Oracle)
          High-performance features
          • Connection pooling
          • Advanced transaction support
          • Query caching
          • Update Batching
    • GNUstep Database Libraries
        GDL2
          • (GNUstep Database Library v2)
        • High-level features
          • SQL layer with EOAdaptors (plugins) for different database (standard bundles: PostgreSQL, SQLite)
          • Object-to-relationship mapping
          • Extensive use of KVC
          • Supports and encourages MVC patterns
        • Rapid development/integration support
          • EOInterface
          • DBModeler (GUI program)
    • GNUstep Database Libraries
        SQLClient
          • SQL only
          • You have to write your SQL code
          • Performance-oriented
          • Excellent for very high-performance servers where you write and tune each and every single SQL command
        GDL2
          • High-level framework
          • You works with models and objects – you do not need to write SQL
          • Can be a bit hard to get into, but people love it once they get used to it
          • Excellent for large and properly structured OO projects
          • Performance is generally good
    • GNUstep WebServer Library
        WebServer Library
          • A library to implement quickly http/https server applications
          • Appropriate to develop efficient APIs for your system
          • Could be used for web pages but that is not the focus
          • Provides a full web server
          • Usually used with Apache in front as a reverse-proxy
    • Jigs: GNUstep Java Interface
        • What is it
          • Allows you to use Objective-C libraries or objects from Java
          • And allows you to use Java libraries or objects from Objective-C
          • Objects and classes in Objective-C are mapped to objects and
          • classes in Java and vice versa
        • Pros
          • Is very cool
        • Cons
          • Can be slow, use it with moderation
          • Problems can be hard to debug
          • Limited support for cross-language subclassing
          • Not easy to port to other platforms
    • SOPE
      • An extensive set of frameworks
      • A complete “Web application server” environment
      • Apple WebObjects compatible app server extended with Zope concepts
      • XML processing (SAX2, DOM, XML-RPC)
      • MIME/IMAP4 processing
      • LDAP connectivity
      • RDBMS connectivity
      • iCalendar parsing
        • http://sope.opengroupware.org
    • Questions ?
    • Thank you For more information
        www.gnustep.org