1 PROCESS SPECIFICATIONS for DFDs Concepts and Examples

2 Process Specification part of the specifications for a complete –Dataflow Analysis (DFD) –OOAD model –SADT –etc.

3 Process Specification for a DFD specifies process “bubbles” in a DFD –NOT sources and sinks must be consistent with DFD –specification compatible with diagram must be complete with regard to the DFD consists of –process decomposition (diagrams) –process description

4 Process Description (see also IEEE ) name (and aliases) informal description inputs (see DFD & data dictionary) outputs (see DFD & data dictionary) processing (semi-formal) related processes, sources and sinks

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6 Read & Check Query name: read & check query (RCQ) description: Reads query statements from the physician’s terminal interface, brings them into internal format, checks correctness and completeness, and handles error situations. Transaction oriented. Communicates with user interface.

7 Read & Check Query inputs: –Query from: physician terminal (external source)

8 Read & Check Query outputs: –Query + to: process request (system internal process) –Query - to: physician terminal (external source) comment: needs further elaboration

9 Read & Check Query related processes, sources and sinks: –depends on: user interface design for physician terminal –is-part-of (super-ordinate process): Patient Information System

10 Read & Check Query related processes, sources and sinks: –is-decomposed-into (sub-ordinate proc.): read query check query error handling for query

11 (Semi-) Formal Specification? PDL - Program Design Language –see Caine, Farber, and Gordon –“pseudo-code”, structured English –English embedded within programming language syntax –close to flowcharts

12 Specifying Processes in DFDs Structured English Decision Trees Decision Tables => see the example SRS on the course webpage/library => see the information about structured decisions in course folder in the library => read A.Davis’ book (see syllabus)

13 STOP HERE We will come back at design level!

14 (Semi-) Formal Specification? PDL - Program Design Language –see Caine, Farber, and Gordon –“pseudo-code”, structured English –English embedded within programming language syntax –close to flowcharts

15 PDL modelling basic control - a block: BEGIN block-name statements END block-name PROCESS process-name process description END process-name

16 PDL modelling basic control - a condition: IF condition THEN block ELSE block ENDIF Remark: There is a CASE construct.

17 PDL modelling basic control - a iteration: DO-WHILE condition block ENDDO Remark: There are REPEAT and DO-FOR constructs.

18 Read & Check Query - PDL PROCESS read&check_query event: query window is activated; initialise interface (query window); DO WHILE user keeps interface active => query call read_query => query-i; call check_query => query_error_info or query+; IF query_error_info THEN call error_handling_for_query => query- ENDIF ENDDO END.

19 End of Section 2f coming up: software design