Some Useful.NET Techniques Blair Schneider McKay Clareos, Inc. blairschneidermckay/ email:...

Some Useful .NET Techniques

Blair Schneider McKayBlair Schneider McKay

Clareos, Inc.Clareos, Inc.

http://home.comcast.net/~blairschneidermckay/http://home.comcast.net/~blairschneidermckay/

email: [email protected]

Presented to Upsilon Pi Epsilon Presented to Upsilon Pi Epsilon

at The University of Michigan – Dearbornat The University of Michigan – Dearborn

November 10November 10thth, 2004, 2004

Blair Schneider McKay

.NET techniques – Slide 2 Nov. 10, 2004

Agenda

Safe Resource ManagementSafe Resource Management• Leaks, Locks, and Garbage CollectionLeaks, Locks, and Garbage Collection• Exception SafetyException Safety• Dispose/DestructDispose/Destruct

XML SerializationXML Serialization• .NET Facilities.NET Facilities• Uses of SerializationUses of Serialization

What To Do About OutsourcingWhat To Do About Outsourcing



Agenda






What is a Resource?

file handlesfile handles database database connectionsconnections

network portsnetwork ports shared memoryshared memoryi/o streamsi/o streams global objectsglobal objectsweb-server sessionsweb-server sessions sql transactionssql transactionsweb-service sessionsweb-service sessions worker threadsworker threadshardware portshardware ports PLC registersPLC registersetc., etc., etc. . . etc., etc., etc. . .

. . . and, of course, “memory”.. . . and, of course, “memory”.



Agenda






What is a Leak?

Many operating systems automatically reclaim Many operating systems automatically reclaim resources when an application terminates, but…resources when an application terminates, but…

• Code which depends on this is Code which depends on this is less portableless portable..• Leaks hamper performance and cause crashes in Leaks hamper performance and cause crashes in

all but very simple and short-lived apps.all but very simple and short-lived apps.• It’s embarassing.It’s embarassing.

When an application loses all references to a When an application loses all references to a resource and thus can no longer clean it up.resource and thus can no longer clean it up.



ANSI C codeANSI C code::

void void leaky_converter(leaky_converter(unsigned int unsigned int input)input){{

char* char* buf = malloc(11);buf = malloc(11);itoa( input, buf, 2 ); itoa( input, buf, 2 ); // display as // display as

base-2base-2printf( "Int to text: %s\n", ret );printf( "Int to text: %s\n", ret );

}}

Where Is the Leak?



Where Is the Leak?

Standard C++ codeStandard C++ code::

Widget* Widget* unsafe_factory( )unsafe_factory( ){{

Widget* ret =Widget* ret = new new Widget( );Widget( );preProcessWidget ( ret );preProcessWidget ( ret );return return ret;ret;

}}



What Is a Lock?

classclass Lock Lock

{{

public:public:

Lock( Resource& r ) : r_( r ) { acquire ( r ); }Lock( Resource& r ) : r_( r ) { acquire ( r ); }

~Lock() { free( r_ ); }~Lock() { free( r_ ); }

private:private:

Resource& r_;Resource& r_;

};};



Demo – Using Locks

UPE4_lock0UPE4_lock0



Garbage Collection

Fundamental part of .NET framework.Fundamental part of .NET framework. ““Managed Code” == Garbage Collection.Managed Code” == Garbage Collection. Critical for “always on” or long-run apps.Critical for “always on” or long-run apps.

C# codeC# code::

void void safe_function( )safe_function( ){{

Widget w =Widget w = new new Widget( );Widget( );doSomething( w );doSomething( w );returnreturn;;

}}



When GC Isn’t Sufficient

You don’t know when GC will happen. You don’t know when GC will happen. (“Non-deterministic termination.”)(“Non-deterministic termination.”)

You sometimes can force GC to run, but You sometimes can force GC to run, but that’s incredibly wasteful.that’s incredibly wasteful.

GC is typically designed as a “one-size-fits-GC is typically designed as a “one-size-fits-all” system, and it often biased towards all” system, and it often biased towards memory management.memory management.

Remember those “other” resources?Remember those “other” resources?



Demo – Ill-behaved Stream Classes

FileGen0FileGen0



Agenda






Demo – Finally (and beyond?)

FileGen1 FileGen1 FileGen2FileGen2 FileGen3FileGen3



Agenda






Demo – Dispose and Dispose/Destruct

FileGen4 FileGen4 FileGen5FileGen5 FileGen6FileGen6



Agenda






Serialization/Deserialization

Object in memoryObject in memory

Object in memoryObject in memory

……binary or character stream…binary or character stream…



Agenda






.NET Serialization Facilities – 1

Take an extremely simple C# classTake an extremely simple C# class::

public class public class InitialConfigurationInitialConfiguration

{{

public enumpublic enum Difficulty {hard, medium, easy}; Difficulty {hard, medium, easy};

publicpublic InitialConfiguration() { } InitialConfiguration() { }

publicpublic Difficulty starting = Difficulty.medium; Difficulty starting = Difficulty.medium;

}}




Use .NET library functions to serialize itUse .NET library functions to serialize it::

InitialConfiguration conf = InitialConfiguration conf = newnew InitialConfiguration(); InitialConfiguration();

XmlSerializer ser XmlSerializer ser

= = newnew XmlSerializer( XmlSerializer(typeoftypeof(InitialConfiguration));(InitialConfiguration));

XmlTextWriter writer = XmlTextWriter writer = newnew XmlTextWriter( XmlTextWriter(

streamstream, System.Text.Encoding.UTF8);, System.Text.Encoding.UTF8);

ser.Serialize(writer, conf);ser.Serialize(writer, conf);




Get XMLGet XML::

<?xml version="1.0" encoding=“utf-8"?><?xml version="1.0" encoding=“utf-8"?>

<InitialConfiguration <InitialConfiguration

xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsd="http://www.w3.org/2001/XMLSchema"

xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">

<Starting>medium</starting><Starting>medium</starting>

</InitialConfiguration></InitialConfiguration>



.NET Serialization Facilities – 4You can get fancyYou can get fancy::[XmlType("MyState")][XmlType("MyState")]public class RunningStatepublic class RunningState{{// . . . snip . . .// . . . snip . . .[XmlIgnore][XmlIgnore]public boolpublic bool StateSaved { StateSaved {

getget { { returnreturn m_state_saved; } m_state_saved; }setset { ; } { ; }

}}[XmlElement(ElementName="PowerLevel")][XmlElement(ElementName="PowerLevel")]public doublepublic double EnergyLevel { EnergyLevel {

getget { { returnreturn m_energy_level; } m_energy_level; } setset { m_energy_level = { m_energy_level = valuevalue; }; }

}}// . . . snip . . .// . . . snip . . .

}}



Agenda






Uses of Serialization Save program state for later recall.Save program state for later recall. Parameterize programs.Parameterize programs. Interprocess communication. (Why not?)Interprocess communication. (Why not?) Exchange data across machine, architecture, Exchange data across machine, architecture,

programming language, etc.programming language, etc. Send data and/or objects across networks Send data and/or objects across networks

(SOAP, REST, XML-RPC).(SOAP, REST, XML-RPC). Debug running system.Debug running system. etc .….etc .….



Demo – Initializing and Preserving Program State

UPE4_GameSimulationUPE4_GameSimulation



Agenda






What to Do About Outsourcing – 1

Be good at what you do!Be good at what you do! Study. Study.

(Sometimes you just have to RTFM.)(Sometimes you just have to RTFM.) Practice.Practice.

(Sometimes you just need to mess around.)(Sometimes you just need to mess around.) Do what the gurus do.Do what the gurus do.

(design patterns, best practices, idioms, etc.)(design patterns, best practices, idioms, etc.)

Or, What to Do About a Soft Job MarketOr, What to Do About a Soft Job Market





Learn to Communicate Well.Learn to Communicate Well. If you need, take your time and write your thoughts down.If you need, take your time and write your thoughts down. Ask a co-worker to review your written work.Ask a co-worker to review your written work. Non-technical bosses often have no independent way to Non-technical bosses often have no independent way to

evaluate your work. The quality of your communication evaluate your work. The quality of your communication with them will matter a lot. with them will matter a lot.

History demonstrates that if you can learn to explain History demonstrates that if you can learn to explain complex issues in simple language, you will Go Far.complex issues in simple language, you will Go Far.





Don’t “hide your light.”Don’t “hide your light.” ““It ain’t bragging if you done it.”It ain’t bragging if you done it.”

(Of course, this can easily go too far.)(Of course, this can easily go too far.) The The bestbest way to ensure that you get fair credit for way to ensure that you get fair credit for

your work is to promote your work your work is to promote your work as part ofas part of a a team effort. team effort.

The more generous we are with each other, the The more generous we are with each other, the more successful we all will be.more successful we all will be.



What to Do About Outsourcing - 4

Above all, don’t despair!Above all, don’t despair! People don’t like to work with unhappy co-workers. People don’t like to work with unhappy co-workers.

Bosses don’t like to hire or to promote them.Bosses don’t like to hire or to promote them. This does This does notnot mean that you must smile and just “take it” mean that you must smile and just “take it”

if people or events make you miserable, nor that you if people or events make you miserable, nor that you shouldn’t strive to improve things.shouldn’t strive to improve things.

Bosses Bosses willwill listen to problems and concerns if they are listen to problems and concerns if they are presented calmly and (most especially) if you offer them presented calmly and (most especially) if you offer them solutionssolutions, no matter how tentative or incomplete., no matter how tentative or incomplete.


Nov. 10, 2004

Blair Schneider McKayBlair Schneider McKay

Clareos, Inc.Clareos, Inc.

http://home.comcast.net/~blairschneidermckay/http://home.comcast.net/~blairschneidermckay/

email: [email protected]

Also, please feel free to email me Also, please feel free to email me questions at the address below.questions at the address below.

Questions, Answers, and Cowardly Evasions.

Some Useful.NET Techniques Blair Schneider McKay Clareos, Inc. blairschneidermckay/ email:...

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