Language Traits
DASL combines a declarative syntax with a Java-like procedural syntax. The declarative part of the language enables defining applications at a higher level of abstraction than 3rd generation languages such as Java. In DASL, the programmer does not describe inter-process communication between client processes, web servers, application servers, databases, or details of the user interface of the desired application. Rather, the programmer describes the application as a set of related domain objects (including their behavior), and as a set of forms and actions annotated with basic layout properties.
In contrast to highly specialized DSLs, DASL is Turing-complete. The behavior of domain objects can be expressed using a combination of declarative and procedural syntax. For example, constraints on objects and object attributes are expressed declaratively, but the constraint itself can be defined either as a declarative expression or procedurally.
A DASL application has two primary components: A business object specification (BOS) that describes the object domain model, consisting of persistent and transient objects representing the domain of the application, and an application usage specification (AUS) that describes the actions or use cases that may be performed on the domain model. The AUS is essentially the choreography of the domain objects into a series of forms and actions.
The DASL programmer models the graphical user interface of the application by annotating the logical AUS forms and actions with properties that describe the basic layout of the data on the page. Rather than user interface considerations dominating the application specification, in DASL the logical interaction between the user and domain model is central, and the user interface is derived from the logical interaction. It is believed that DASL is unique among other languages in this respect.
Read more about this topic: Distributed Application Specification Language
Famous quotes containing the words language and/or traits:
“To write or even speak English is not a science but an art. There are no reliable words.... Whoever writes English is involved in a struggle that never lets up even for a sentence. He is struggling against vagueness, against obscurity, against the lure of the decorative adjective, against the encroachment of Latin and Greek, and, above all, against the worn-out phrases and dead metaphors with which the language is cluttered up.”
—George Orwell (1903–1950)
“And, beholding in many souls the traits of the divine beauty, and separating in each soul that which is divine from the taint which it has contracted in the world, the lover ascends to the highest beauty, to the love and knowledge of the Divinity, by steps on this ladder of created souls.”
—Ralph Waldo Emerson (1803–1882)