Explo-IT Research XCC eXtensible Computation Context Antonio Capani Explo-IT Research

Explo-IT Research What is XCC? The eXtensible Computation Context consists of –a methodology for developing open and collaborative systems for doing computations –an extensible language (XCL) for development and maintenance of computation languages –a set of tools which act as integration technology (or middleware) between mathematical systems and non- mathematical systems

Explo-IT Research Extensibility of Languages Some High level languages like C, C++, Java, Smaltalk, Pascal, are designed to be concise and possibly near to human language and standard notations In almost all cases the syntax of the language cannot be extended, for example, by adding new primitive types On the contrary, during the development of a mathematical system, may arise the need for extending syntax and semantics Moreover different (mathematical) systems could benefit from a standardization of their languages

Explo-IT Research Syntactic Sugar When trying to extend a language quite often happens that, even if the semantical extension is clear, the designer of the language have difficulties in finding a suitable syntax For example: what could be the syntax for adding “set” to the C language as primitive types? The candidate delimitators of the set should be “{“ and “}” but they are already taken as delimitators of blocks of commands

Explo-IT Research The XCL Intermediate Language XCL stays for eXtensible Computation Language The syntax of XCL is based on the XML (meta)language. High Level languages may mapped to XCL (are seen as user friendly representations of XCL programs) The semantics of XCL is given in a declarative way and is "plugged" to each XCL program during its execution. XCC offers a basic XCL language which contains lots of standard functionalities like: –primitive types (e.g.: int,string,list,record,matrix) –standard operators to build expressions –standard commands (e.g.: assignment,for,while) –definition of new commands and packages

Explo-IT Research Usage of XCL XCL is at a low level but it is human readable (because it is based on XML). So it is possible to extend the XCL syntax and apply semantics to it even before designing a high level language. For example it is useful for mathematical teams because they focus on the mathematical library and on mathematical research rather than the computer science aspects.

Explo-IT Research Example of XCL program <!DOCTYPE xcl PUBLIC "-//EXPLOIT//DTD XCL-Basic//EN" "

Explo-IT Research Example of plugged semantics # commands (from XML tagname to Java classname) assign = com.ExploIT.coco.xcl.XCLCommandAssign write = com.ExploIT.coco.xcl.XCLCommandWrite if = com.ExploIT.coco.xcl.XCLCommandIf for = com.ExploIT.coco.xcl.XCLCommandFor while = com.ExploIT.coco.xcl.XCLCommandWhile # expressions (note the difference between expressions and values) var = com.ExploIT.coco.xcl.XCLExprVar and = com.ExploIT.coco.xcl.XCLExprBool or = com.ExploIT.coco.xcl.XCLExprBool not = com.ExploIT.coco.xcl.XCLExprBool make-list = com.ExploIT.coco.xcl.XCLExprList # values list = com.ExploIT.coco.xcl.XCLValueList true = com.ExploIT.coco.xcl.XCLValueBool false = com.ExploIT.coco.xcl.XCLValueBool

Explo-IT Research XCC Platform An XCC platform offers means for: –execution of XCL programs (XCL Engine) –XCL-devices (devices which write or read XCL data) –Session Management Framework (multiuser, multisession generic tool for XCL queries) –connection to other XCC enabled tools, for the remote execution of XCL programs –connection to non XCC-enabled tools export of computation results in OpenMath or MathML format visualization of results in browsers

Explo-IT Research XCC Platform XCC Platforms XCL Engine Main XCL Devices Session Management Framework Low Level Library XCL Semantics XCC Platform non-XCC

Explo-IT Research Standard Mathematical Protocols The XCL language may be used as a standard way for representing data and programs, but multiple protocols may be used. Currently we are collaborating with the OpenMath Society in order to: –define a formal specification of XCC –integrate the XCC methodology with the OpenMath and MathML

Explo-IT Research Conclusions and Future Directions An application of XCC (called CoCo, Computation Context) is in progress for the new major release of the CoCoA System in collaboration with the CoCoA Team ( leaded by Prof. Lorenzo Robbiano of the University of Genova. It is under study the implementation "active documents", that is documents containing formulas which may be executed within the document itself.