A method performed by a computer system of generating an abstract representation for a model representation, the method comprising: receiving information identifying a model representation for an application, the model representation comprising information describing a graphical user interface (118, 124, 128) for the application; generating an abstract representation for the GUI (118, 124, 128) based upon the model representation, the abstract representation being an executable GUI language representation in a form of an XML file, wherein the XGL is a generic, declarative, and executable GUI language, wherein the XGL is used for generating representations of different GUIs and supports connectivity to different application data services, wherein the abstract representation is independent of a runtime environment platform for executing the application; wherein generating the abstract representation comprises using a first set of mapping rules for generating the abstract representation from the model representation; generating a first GUI (118, 124, 128) for a first runtime environment platform using the abstract representation, wherein generating the first GUI (118, 124, 128) comprises using a second set of mapping rules for generating the first GUI (118, 124, 128) from the abstract representation; and generating a second GUI (118, 124, 128) for a second runtime environment platform using the abstract representation, wherein the second runtime environment platform is different from the first runtime environment platform, wherein generating the second GUI (118, 124, 128) comprises using a third set of mapping rules for generating the second GUI (118, 124, 128) from the abstract representation; wherein the application is packaged as a collection of XGL documents with inter-dependencies and deployed to any system supporting XGL implementation; wherein the XGL defines data models including a data model called infoactors representing the different application data services, wherein the infoactors are declared using a system alias rather than an actual system connection, wherein the infoactors are defined in an extension kit and declared using a respective kit namespace; wherein the XGL defines resources including a resource called systems representing a connection to a backend system that provides an access to the different application data services, wherein a system declaration associates a system connection with the system alias, and wherein the system alias used in the infoactor declarations is replaced with the actual system connection during deployment. receiving information identifying a model representation for an application, the model representation comprising information describing a graphical user interface (118, 124, 128) for the application; generating an abstract representation for the GUI (118, 124, 128) based upon the model representation, the abstract representation being an executable GUI language representation in a form of an XML file, wherein the XGL is a generic, declarative, and executable GUI language, wherein the XGL is used for generating representations of different GUIs and supports connectivity to different application data services, wherein the abstract representation is independent of a runtime environment platform for executing the application; wherein generating the abstract representation comprises using a first set of mapping rules for generating the abstract representation from the model representation; generating a first GUI (118, 124, 128) for a first runtime environment platform using the abstract representation, wherein generating the first GUI (118, 124, 128) comprises using a second set of mapping rules for generating the first GUI (118, 124, 128) from the abstract representation; and generating a second GUI (118, 124, 128) for a second runtime environment platform using the abstract representation, wherein the second runtime environment platform is different from the first runtime environment platform, wherein generating the second GUI (118, 124, 128) comprises using a third set of mapping rules for generating the second GUI (118, 124, 128) from the abstract representation; wherein the application is packaged as a collection of XGL documents with inter-dependencies and deployed to any system supporting XGL implementation; wherein the XGL defines data models including a data model called infoactors representing the different application data services, wherein the infoactors are declared using a system alias rather than an actual system connection, wherein the infoactors are defined in an extension kit and declared using a respective kit namespace; wherein the XGL defines resources including a resource called systems representing a connection to a backend system that provides an access to the different application data services, wherein a system declaration associates a system connection with the system alias, and wherein the system alias used in the infoactor declarations is replaced with the actual system connection during deployment.