idef3_kbsi_report (1013870), страница 29
Текст из файла (страница 29)
IDEF3 does notimpose such restrictions. It provides a flexible yet formal mechanism for recording thefacts known about the operation of the system. Gaps and inconsistencies are madeobvious in the schematic layouts specifically to bring them to the attention of analysts anddomain experts. Likewise, capturing multiple viewpoints of a process serves to highlightdifferences. A better understanding of the process is achieved by both the experts and theanalyst as they attempt to fill gaps and resolve inconsistencies both in a view and betweenviews.
This creates an understanding of how perceptions about the process differbetween experts.In contrast, conventional techniques typically present the analyst’s assumptions aboutthe process interspersed with his understanding of the expert’s description. This model isthen presented to domain experts for validation. Often, the expert, either in the interest ofexpediency or because of increasing pressure for consensus, signs off on a process modelwithout completely understanding the implications.
Using IDEF3, it is possible to useprocess description schematics as discussion focal points to resolve inconsistencies (ifany) between differing viewpoints of how a process works.Types of ValidationValidation is the process of checking and ensuring that the IDEF3 process descriptionconstructed is both syntactically and semantically correct. As one might assume from thisdefinition, there are two types of validation: syntactic and semantic. Syntactic validationinvolves ensuring that the constructed IDEF3 schematic conforms to the grammaticalrules of the IDEF3 language. Semantic validation involves ensuring that the statementsmade in the IDEF3 description accurately capture the assertions of the domain expert.132The IDEF3 method provides the user considerable freedom in terms of how thesedescriptions can be structured; the syntax of the language imposes few restrictions onpossible schematic layouts.
These restrictions, or rules ensure that the syntax andsemantics of the constructed descriptions capture the user’s intent. Moreover, thesevalidation checks try to enforce standardization between the potential users of thelanguage in a manner that enhances the utility of the method as an unambiguous means ofcommunication.Build and Distribute KitsA primary means of validating IDEF3 process descriptions is through the review andapproval of kits13. Kits represent portions of the total description that have reached somestate of completion. The kit review task can be performed any time during thedescription development effort as a mechanism for acquiring additional facts or when asignificant portion of analysis work has been completed (e.g., completion of the initiallists of UOBs and objects, completion of one or more Object Schematics, completion of aProcess Schematic).
Kit production and the associated review cycle (discussed below)provide a disciplined approach that results in an accurate description of the process.Roles in the Kit Review ProcessThe team member roles described earlier in Section 4 are further specialized for thekit review process. The roles of the personnel involved in the kit review process are asfollows:1.Analyst: IDEF3 expert who is the primary developer of the IDEF3 description.The review process initiates and terminates with the analyst.
The analyst relieson the domain expert for the technical content of the description, during bothdescription capture and the kit review cycle.2.Reviewers: All personnel involved in the review of IDEF3 kits.3.Commentors: Reviewers who are knowledgeable in the application domain,and proficient enough in IDEF3 to offer structured comments in writing.Commentors read the material produced by analysts and verify its technicalaccuracy. They are responsible for finding errors and suggesting improvementsin the IDEF3 process description. The commentor determines whether the13The genesis of this kit review procedure comes directly from the original IDEFØ Function Modeling“yellow book,” AFWAL-TR-81-4023. This was done to maintain consistency among the IDEFmethods. The input from this document is greatly appreciated and acknowledged.133purpose has been met, and whether errors or oversights exist.
Commentors areauthorized to make written suggestions during the review process.4.Readers: Reviewers to whom IDEF3 kits are distributed for informationalpurposes only. Readers are often individuals from whom analysts may haveobtained information via interviews.5.Librarian: A person assigned the responsibility of maintaining files of projectrelated documents and description artifacts, making copies, distributing IDEF3kits, and keeping records.A “role” is not related to an individual’s job title; therefore, the same person mayperform several roles.The IDEF3 Kit Review CycleKits represent portions of an IDEF3 process description that have reached some stateof completion.
These draft portions of a description are distributed for review in the formof a standard IDEF3 kit. The IDEF3 kit review cycle illustrated in Figure 4-15 is basedon the kit review process for other IDEF methods. For clarity, the following steps do notmention the librarian, but focus on the interaction between the analyst and commentor.With large systems, the role of the librarian is essential. In smaller efforts, that role maybe assumed by the analyst.134AnalystLibrarianCommentorNew KitWritesCommentson KitProducesNew KitCommentedKitWritesResponse toCommentsReviewsAnalyst’sCommentsKit with CommentsControlCopyControlCopy ToAnalystFileDiscussionRequestedby AnalystorCommentorKit toCommentorFileFigure 4-15IDEF3 Kit CycleThe following are the major steps in the IDEF3 kit review cycle.1.The analyst assembles a kit (e.g., a pool kit, a scenario kit, an object kit, or adescription kit with Process Schematics and Object Schematics).
The analystretains one copy and gives one copy to the commentor for review.2.The commentor studies the kit within an agreed time period. The main purposeof this review is to determine whether the description complies with the overallgoals and context of the development effort. Comments are made directly onthe schematics, other documents in the kits, and the cover sheet.
The kit withcomments should be returned to the analyst by the date indicated on the coversheet.3.The analyst responds to the comments directly on the commentor’s copy of thekit. The analyst may agree with the comments, noting it on his working copyand incorporating it into the next version of the IDEF3 description. If there aredisagreements, the analyst notes the points of disagreement on the kit andreturns the kit to the commentor.1354.The commentor will read and file the returned kit if the analyst’s responses aresatisfactory. Otherwise, a meeting between the commentor and the analyst isarranged to resolve the disagreements.5.This cycle continues until a mutually acceptable (to the analyst and commentor)IDEF3 description is produced.Throughout the cycle, a project librarian handles copying, distribution, filing, andtransfer of IDEF3 kits between the analyst and the commentor (see Figure 4-15).The results of the IDEF3 kit cycle are an IDEF3 description to which the analyst andthe commentor have contributed, and, if necessary, a list of issues that requiremanagement action.
A valuable byproduct of this review cycle is a recorded history ofthe review process.Types of IDEF3 KitsIDEF3 kits have a structure similar to those for other IDEF methods. There are threetypes of IDEF3 kits:1.Scenario Kits address one scenario and all or part of its associateddocumentation. The following items may appear in a scenario kit.a.Process Schematics and all associated UOB decompositions. Some of thereview kits created early in the development process may omit some of thedecompositions.b.All available UOB elaborations and link specifications. Some of thescenario kits created early in the development process may omit some orall of these.2.Object Kits address one or more objects and the associated Object Schematics,their descriptions, and their associated object state descriptions.3.Description Kits are created in the later stages of a development effort.
Adescription kit is a compilation from the completed scenario and object kits for agiven project. It contains all the scenarios in the IDEF3 description and theirassociated documentation. An approved description kit is one of the finaldeliverables in a development effort.Scenario kits can provide any level of detail from a single-scenario Process Schematicto a complete process description that contains all elaborations and UOB decompositionschematics. Description kits can also provide any level of completion; however, they136reflect the current status of the entire project as opposed to that of the single scenario of aScenario Kit.Guidelines for Analysts and CommentorsCommentor GuidelinesNo set pattern of questions and rules can be adequate for commenting, since subjectmatter, style, and technique vary widely.
![](https://s.studizba.com/z.php?f=/templates/si/i/noavatar.png&w=100&h=100&t=1"){kind=avatar}
