SDL Forum Society Back to Basic SDL Engineering

SDL Forum Society Back to Basic SDL Engineering background Reason for complexity Defining basic SDL Rick Reed TSE Ltd Chairman SDL Forum Society 17. 09. 2020 Languages Workshop - Back to Basic SDL - Geneva Nov 2002 1

System viewpoints Engineering Background engineer with view enterprise view Reason for Complexity Defining Basic SDL System technology design 17. 09. 2020 information computational Languages Workshop - Back to Basic SDL - Geneva Nov 2002 2

ITU-T Formal Languages for Software Engineering Background Reason for Complexity Defining Basic SDL 17. 09. 2020 o ASN. 1 data to encode/decode o MSC interaction sequences o SDL stimulus/response behaviour o TTCN behaviour validation other issues o requirements modelling o deployment Languages Workshop - Back to Basic SDL - Geneva Nov 2002 3

UML, URN? ? Methodology of Z. 100 Supplement 1 UML, URN? ? ASN. 1 MSC+SDL Engineering Background Reason for Complexity TTCN ? ? ? Defining Basic SDL C, C++, ? ? ? 17. 09. 2020 Languages Workshop - Back to Basic SDL - Geneva Nov 2002 4

Growing complexity: addition of concepts Engineering Background o 1976 - simple state machine models Reason for Complexity o 1992 - TYPE, remote procedure … Defining Basic SDL 17. 09. 2020 o 1984 - data, macro, partitioning … o 2000 - agent, interface, exception … Users (and tool makers) complaining the language is too large! Languages Workshop - Back to Basic SDL - Geneva Nov 2002 5

Typical extended finite state machine: Bit. Stuff Engineering Background 2(3) Reason for Complexity Defining Basic SDL bits_in If. Raw_ Payload to_line If. Lne_ Bits /* INTERFACES If. Raw. Payload If. Line. Bits defined elsewhere */ 17. 09. 2020 Languages Workshop - Back to Basic SDL - Geneva Nov 2002 6

Informative elements UML style class models: Associations Engineering Background Reason for Complexity Defining Basic SDL payload_0, payload_1 bits_in <<STATE>> Send_Bit line_0, line_1 to_line_0, line_1 <<STATE>> Receive_Bit from_line payload_0, payload_1 bits_out transmission 17. 09. 2020 Languages Workshop - Back to Basic SDL - Geneva Nov 2002 7

Key required features Engineering Background Reason for Complexity Defining Basic SDL o Data types, value names, variables o Signals, Gates and Channels o Finite State machine types with • Start, Input, Transitions • Timers (start, stop, cause event) • Assignments, Decisions, Output • Procedures o Finite State machine instance (sets) Priority? None? Continuous Signal? Save? ? 17. 09. 2020 Languages Workshop - Back to Basic SDL - Geneva Nov 2002 8

use if_pack Basic SDL elements sys: s Structure Engineering Background Reason for Complexity system type S x [if_in] b: Blocktype gatea gateb [if_out] [interface_i 1] channelc [interface_i 2] gatep 1(1) Blocktype Processtype p: Processtype Defining Basic SDL Action [interface_i 1] gatep [interface_i 2] process type �� 1(1) Processtype Process_ Type: A state type A state 1 i(v) v else 0 o(v) state 1 17. 09. 2020 A Languages Workshop - Back to Basic SDL - Geneva Nov 2002 state 2 9

Data types: ASN. 1 and SDL-2000 Engineering Background Reason for Complexity Defining Basic SDL o ASN. 1 includes BOOLEAN, INTEGER, BIT STRING, OCTET STRING, ENUMERATED , SEQUENCE (OF), SET (OF), CHOICE o SDL can use ASN. 1 types and adds operations for actions, variables, inheritance, OBJECT and pid types o ASN. 1 has encoding rules SDL (currently) does not 17. 09. 2020 Languages Workshop - Back to Basic SDL - Geneva Nov 2002 10

Language usage enterprise Engineering Background Reason for Complexity Defining Basic SDL URN, UML information technology SDL MSC ASN. 1, SDL design 17. 09. 2020 computational Languages Workshop - Back to Basic SDL - Geneva Nov 2002 11

The way forward o SDL as a design/programming language o Separation of short hands and “advanced” features o Further “simplification” o Further features!!? o Basic core SDL (Z. 100 revised)+Z. 101. . . o Is SDL environment concept adequate o Unification - costs/benefits? 17. 09. 2020 Languages Workshop - Back to Basic SDL - Geneva Nov 2002 12