know is her telephone number。 Translated into programming terms； the telephone acts as an interface to an implementation。 The challenge is connecting to the implementation。 In the case of the telephone； you can discover the telephone number by using the telephone book。 The telephone book contains the names of individuals at specific addresses and their tele phone numbers。 Names and addresses are easy to remember； telephone numbers are a bit more plicated。 Thus； the telephone book serves the purpose of cross…referencing an easy piece of information with a more plicated piece of information。 In programming terms； the cross…referencing is a configuration file that is associated with the application。 Once you have cross…referenced the information； you have the location of the project and can then instantiate the cross…referenced type。 In programming terms； the configuration file gives you the location and name of the type。 Decoupling Using a Convention Architecture Configuration files are useful； but they can bee too plicated。 Some projects have such plicated configuration files that bugs arise due to an improperly configured application。 Convention architecture attempts to simplify plexity by instituting a familiar pattern to the referencing of the type。 Consider a telephone number like 1…800…BIG…CARS。 The 1 and 800 are easy to remember； as is BIG CARS。 This works because of the convention where a digit on the telephone keypad corresponds to three or four letters。 So in the case of BIG…CARS； the number is 244…2277。 Conventions are good things as long as you know what they are。 For example； if you were not familiar with the telephone system； you would wonder how BIG CARS represents a telephone number。 The missing piece of information is the convention of how to convert the letters into the numbers。 …………………………………………………………Page 338…………………………………………………………… 316 CH AP T E R 1 2 ■ L E A R N I N G A B OU T A PP L I CA TI O N CO N F I G U R AT IO N AN D D Y N A M I C L O AD I N G What is useful with convention architecture is that you are not limited to what is defined in the configuration file； as there is a general logic。 When implementing a convention architec ture； you are not discarding configuration； but you are making assumptions for the user and implementation of the code。 You will still probably have a configuration file； but the configuration is for specific functionality。 Regardless of whether you use a configuration architecture or a convention architecture； you will dynamically load assemblies； as demonstrated in this chapter。 Setting Up the Dynamic Loading Projects For this chapter’s examples； four projects are defined： o Definitions： A class library that contains the definition for the interface IDefinition and the class ConfigurationLoader。 The class ConfigurationLoader will contain the functionality to dynamically load the assemblies Implementations1 and Implementations2。 o Implementations1： A class library that contains the class Implementation and implements the interface IDefinition。 The class Implementation is defined in the namespace Implementations1 and is not declared Public。 o Implementations2： A class library that contains the class Implementation and imple ments the interface IDefinition。 The class Implementation is defined in the namespace Implementations2 and is not declared Public。 o CallRuntimeImplementation： A console application that will be referenced throughout the chapter as the user application。 In the Definitions project； the references are to the standard libraries （ System； System。Core； and so on）。 The unique reference that you need to add is to System。configuration。 The System。configuration reference contains the types that you need to read the application configuration file。 Here is the code for IDefinition： Public Interface IDefinition Function TranslateWord（ByVal word As String） As String End Interface The Implementations1 project contains the file Implementation。vb； which is the type Implementation and implements the interface IDefinitions。 The implementation of Implementation is as follows （make sure you add a reference to the Definitions project）： Imports Definitions Class Implementation ： Implements IDefinition Public Function TranslateWord（ByVal word As String） _ As String Implements IDefinition。TranslateWord Return 〃〃 End Function End Class …………………………………………………………Page 339…………………………………………………………… CH AP T E R 1 2 ■ L E AR N IN G AB O U T AP P L I CAT I ON CO N F IG U R AT IO N A N D D Y N A M IC L O AD IN G 317 The class Implementation has a hard reference to IDefinition； so under the References node in the Implementations1 project is a reference to the Definitions project。 Because there is a hard reference to IDefinition； the interface IDefinition is declared as Public； but Implementation is not。 The Implementations2 project has the same implementation and reference to Definitions as Implementations1。 What is special about Implementations2 is its use of a strong name； which makes it unique。 Thus far； all of your assemblies are not unique。 To make them unique； you need to enable signing。 You must also enable signing in the Definitions project。 The next section describes how to enable signing。 The C