81.What is GWT RPC?

• RPC, Remote Procedure Call is the mechansim used by GWT in which client code can directly executes the server side methods.
• GWT RPC is servlet based.
• GWT RPC is asynchronous and client is never blocked during communication.
• Using GWT RPC Java objects can be sent directly between the client and the server whichareautomaticallyserializedbytheGWTframework.
• Server-side servlet is termed as service.
• Remote procedure call that is calling methods of server side servlets from client side code is referred to as invoking a service.

82.What are the core components of GWT RPC?

Following are the three components used in GWT RPC communication mechanism:

• A remote service server − sideservlet that runs on the server.
• Client code to invoke that service.
• Java data objects which will be passed between client and server.
• GWT client and server both serialize and deserialize data automatically so developers are not required to serialize/deserialize objects and data objects can travel over HTTP.

83.Which interface a java data object should implement so that it can be transferred over the wire in GWT RPC?

A java data object should implement isSerializable interface so that it can be transferred over the wire in GWT RPC.

84.What is internationalization?

Internationalization is a way to show locale specific information on a website. For example, display content of a website in English language in United States and in Danish in France.

85.What are the ways using which you can internationalize a GWT application?

GWT provides three ways to internationalize a GWT application −

• Static String Internationalization.
• Dynamic String Internationalization.
• Localizable Interface.

86.What is Static String Internationalization technique in GWT?

This technique is most prevalent and requires very little overhead at runtime; is a very efficient technique for translating both constant and parameterized strings;simplest to implement. Static string internationalization uses standard Java properties files to store translated strings and parameterized messages, and strongly-typed Java interfaces are created to retrieve their values.

87.What is Dynamic String Internationalization technique in GWT?

This technique is very flexible but slower than static string internationalization. Host page contains the localized strings therefore, applications are not required to be recompiled when we add a new locale. If GWT application is to be integrated with an existing server-side localization system, then this technique is to be used.

88.What is Localizable Interface internationalization technique in GWT?

This technique is the most powerful among the three techniques. Implementing Localizable allows us to create localized versions of custom types. It's an advanced internationalization technique.

89.Which tag of *.gwt.xml is used to support internationalization in GWT application?

extend-property tag with attribute name set as locale and values as language specific locale, say de for german locale.

90.How to enable history support in GWT application?

In order to use GWT History support, we must first embed following iframe into our host HTML page.

91.What is GWT logging framework?

The logging framework emulates java.util.logging, so it uses the same syntax and has the same behavior as server side logging code.
GWT logging is configured using .gwt.xml files.
We can configure logging to be enabled/disabled; we can enable/disable particular handlers, and change the default logging level.

92.What is SystemLogHandler in GWT?

SystemLogHandler logs to stdout and these messages can only be seen in Development Mode in the DevMode window.

93.What is DevelopmentModeLogHandler in GWT?

DevelopmentModeLogHandler logs by calling method GWT.log. These messages can only be seen in Development Mode in the DevMode window.

94.What is ConsoleLogHandler in GWT?

ConsoleLogHandler logs to the javascript console, which is used by Firebug Lite forIE, Safari and Chrome.

95.What is FirebugLogHandler in GWT?

FirebugLogHandler logs to Firebug console.

96.What is PopupLogHandler in GWT?

PopupLogHandler logs to the popup which resides in the upper left hand corner of application when this handler is enabled.

97.What is SimpleRemoteLogHandler in GWT?

This handler sends log messages to the server, where they will be logged using the server side logging mechanism.

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