User Language

User Language is the internal language of the Model 204 DBMS, a product of Rocket Software. It's is a 4th Generation Language (4GL), which means it was designed to be a "high level" language, with a good deal of abstraction and power embedded in relatively simple programming directives.

User Language is characterized by its very easy, English-like syntax and its tight integration with the Model 204 DBMS. Programs begin with a "BEGIN" statement and end with "END".

BEGIN
PRINT 'HELLO WORLD'
END

Because it is tightly integrated into Model 204, User Language contains native instructions for manipulating data held in Model 204 files. Records in a file are selected using variations on the FIND statement and can be looped over using a variety of structures, the main one being the FOR EACH RECORD loop.

BEGIN
X: IN FILE INVENTORY FIND ALL RECORDS FOR WHICH ITEMTYPE = 'BOOK'
   END FIND
   FOR EACH RECORD IN X
      PRINT TITLE AND AUTHOR AND PUBLISHER AND PRICE
   END FOR
END

In User Language, variables begin with the percent sign (%) and native "functions" -- which implement many complex features of the language -- begin with a dollar sign ($) or a pound-sign in England, or Yen sign in Japan.

BEGIN
  %X IS FLOAT
  FOR %X FROM 1 TO 10
     IF $MOD(%X,2) THEN
        PRINT %X WITH ' IS ODD'
     ELSE
        PRINT %X WITH ' IS EVEN'
     END IF
  END FOR
END

A wide variety of variations are possible with the language, allowing novice coders to start using the language quickly, and expert users to learn the shortcuts and abbreviations.

Model 204 provides its own terminal services, and User Language procedures are typically stored in Model 204 database files, so User Language programmers usually work directly inside the database environment, opening database files at the command level, editing User Language with Model 204's internal editor, and running programs with the "GO" directive from inside the editor.

It is also possible to access Model 204 from external programs using Host Language Interfaces or Model 204's SQL capability but, because User Language is so highly optimized, the majority of Model 204 applications are written in User Language.

Sirius Software extensions to User Language

Any Model 204 site with the Sirius Mods linked in, gains a number of enhancements to User Language, the most obvious one being mixed-case User Language:

Begin
print 'Hello World'
End

Sirius has a host of Object-Oriented additions to User Language that let you write sophisticated applications using a range of classes, some provided by Sirius and others that can be written locally. The Object-Oriented additions to User Language are contained in the Janus SOAP User Language Interface.

For a non-exhaustive list of User Language enhancements, some available throughout the Sirius Mods and some exclusive to the Janus SOAP User Language Interface, see "Other User Language enhancements".

Sirius also provides a large set of User Language $functions. At present, Sirius is not developing new functions, as its emphasis has evolved to the development of classes. The $functions and classes provided by Sirius range from simple functions useful in the language ($Parse and $ParseX) to complex structures and constructs like Stringlists and Daemons that open up new ways of programming and new possibilities for managing complex, in-memory data manipulation.

In addition, many of the Sirius extensions to User Language are in support of the Janus product set, which provides access to Model 204 via HTTP, sockets, Sybase Omni servers, FTP clients, and more.

References

• Model 204 documentation, including the User Language Reference Manual: http://www.cca-int.com/custsupp/documentation/catalog.html
• Additional Sirius Software User Language extensions: "Other User Language enhancements"