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M. ModelerX WORKINGDATE: 08 Feb 1995NOTES:Obje ctStateNo .1 2 3 4 5 6 7 8 9 10REV:Objec t State Name :PR: AuthorizedLabel:PR: AuthorizedREVIEWER:DATE:DRAFTRECOMMENDEDRELEASEDPROJECT: Process Description CaptureOS5Transit ions Fro m Obje ct St at e( s):PR: Authorized requiring signatureTransit ions To Obje ct St at e (s) :PR: SubmittedFact s:Co nstraint s:State Co nditio ns: Authorizing official has signed the Purchase Request form.Approving official is not identical with the individual authorizing the Purchase Request.Exit Co ndit ions:Othe r:De sc ript io n:CONTEXT-SETTINGREFERENCE:Scenario 1ITEM DESCRIBED:FORM TYPE:Object State 5 - PR: AuthorizedObject State ElaborationFigure 5-20Elaboration for Object State PR: AuthorizedReview Object Schematic with Domain ExpertsAs with the Process Schematic, the correctness of the Object Schematic andassociated elaborations are confirmed through validation with the domain expert.
Afterreviewing the Transition Schematic, the domain expert observes that the allowable statetransitions displayed in the schematic do not include those representative of a failedrequest. Earlier descriptions provided by the domain expert represented the typical caseand had not included situations where approval had been withheld or when authorizationhad been denied. The domain expert’s response introduced two entirely new objectstates.1.PR: Disapproved2.PR: UnauthorizedThe domain expert also identified transitions through which the identity of the objectwas preserved and transitions where the object was actually transformed into an entirely174UOB/PreparePurchaseRequestUOB/ObtainAccountManagerApproval7810175Figure 5-21Completed Transition SchematicPR:ApprovedPR:UnpreparedPR:PreparedXUOB/ObtainAuthorizationSignatureX9PR:DisapprovedPR:AuthorizedUOB/ObtainAccountManagerApproval8UOB/OrderRequestedMaterialPR:ApprovedRequiringAuthorizationXPR:Unauthorized6PR:SubmittedPO:Issueddifferent object.
The domain expert’s comments to the analyst yield the schematicdepicted in Figure 5-21.UOB/SubmitSignedPurchaseRequestAdditional context-setting information is then added to the Transition Schematic asrequired. For example, the domain expert’s description indicated that purchase requestsinvolving direct projects require an authorization signature.
Additionally, the descriptionincluded discussion of a constraint that account managers or their designated backupsmust approve all requests involving their projects. This information is noted directly onthe schematic. The resulting Object Schematic is displayed in Figure 5-22.176Personapprovingrequestnot identical withRequestor10not identical withUOB/PreparePurchaseRequestUOB/Obtain AccountManagerapproval78submits177Figure 5-22Final Object SchematicPR:UnpreparedPR:ApprovedUOB/Requestauthorizationsignature9PR:DisapprovedPR:AuthorizedXUOB/Obtain AccountManagerapprovalAccountnumberhasPR:SubmittedX1mustincludeDesignatedbackup6PersonauthorizingrequestXPR: Preparedisauthorizedto signUOB/Order requestedmaterialUOB/Submit signedPurchaseRequest8AccountManagerPR:ApprovedrequiringauthorizationXincluded onhasis responsible forPR:UnauthorizedProjectsubkind ofinvolving-requiressubkind of2IndirectProjectDirectProject3AuthorizationsignaturePO:IssuedUNDERSTANDING IDEF3 PROCESS DESCRIPTIONSThe main purpose of an IDEF3 Process Description is to provide an accuraterepresentation of how a particular system or organization works.
An IDEF3 ProcessDescription captures the factual descriptions of the process flow and object statetransitions associated with a particular scenario. Reviewers of IDEF3 descriptions maynot create them, but must validate the facts in the descriptions. Readers of IDEF3descriptions may need to acquire knowledge from descriptions that others have created.The general procedure for reading and understanding IDEF3 process descriptions isaddressed in this section.An IDEF3 schematic, whether a Process Schematic or an Object Schematic, is usuallyread starting with the leftmost element in the schematic. Conventionally, a schematic isread from left to right. To obtain an overview of the described scenario, a mentalwalkthrough of the schematic is performed. During a mental walkthrough of a ProcessSchematic, for example, the reader notes precedence relationships and the logical layoutof the UOBs.
Such a reading will provide a general understanding of the system. Furtherdetails of a description may be obtained by reading each UOB and link with theirelaborations or descriptions. A comprehensive understanding of the IDEF3 ProcessDescription can be obtained by systematically studying the logic in the schematics.Description Reading StepsThe facts collected about a system are structured in the IDEF3 Process Description asa set of Process Schematics, Object Schematics, and their associated elaboration languagestatements. The approach to reading IDEF3 schematics depends on the reader and theamount of information the reader expects to derive.Because the schematic reading process is highly individualized, it is difficult toexpress the process in a strict algorithmic format. For example, some people first scanthe schematic, then break it up into logical pieces that are easier to understand.
InProcess Schematics, for example, logical groupings may be created and analyzed tounderstand the relationships between the UOBs and links in selected portions of theschematic. Once the meaning of the smaller pieces of the schematic are understood, thelarger picture becomes evident by taking into account the junctions and their associatedlogic.178The approach to reading an IDEF3 Process Description can be summarized asfollows:1.Carefully read the statement of purpose, the statement of scope, theobjective of the scenario being described, and the viewpoint of theIDEF3 process description.2.Scan the individual schematic elements (e.g., UOBs, links, junctions,object states) from left to right to gain a general impression of whatis being described and to understand generally the structure and logicof the description.3.Partition the schematic from left to right into logical groupings orstructures of schematic elements. Logical groupings are collectionsof elements that constitute a convenient partitioning of theschematic, enabling systematic review.
These groupings most oftencoincide with process paths (in Process Schematics) or transitionpaths (in Object Schematics) and may themselves contain logicalsubgroupings. To achieve a better understanding of the description,these groupings and subgroupings may have to be partitioned in thesame manner that the overall diagram was partitioned.4.Starting with the first element in the left-most grouping, read theschematic from left to right using the following guidelines.a.For Process Schematics, read the UOBs and theirelaborations. For Object Schematics, read the object statesand their elaborations.b.Examine the links (precedence links in Process Schematicsand transition links in Object Schematics), noting theconstraints displayed on the links and the information in thelink elaborations.c.Study all referents and notes within the bounds of theselected grouping.d.Conduct a mental walkthrough of the description, one basicgrouping at a time.e.When junctions are encountered, follow the paths notingthe conditions under which a path will be selected andthose under which other paths will be followed.For more casual readers, a simpler approach is often used.
This simpler approach isdescribed in the next section.179Quick Reading of IDEF3 Process Descriptions: An ExampleMore casual readers of an IDEF3 Process Description will follow a process similar tothat described in the preceding section. However, they can expect that as they gainexperience in the process, their approach will become personalized. An exampleapproach for reading a schematic is described in the following steps. This outline forreading a schematic would be repeated, with few modifications, for all decompositions,whether found in a Process Schematic or an Object Schematic. In general,decompositions are read after the parent schematic has been read and understood.The Big PictureA crucial step in the description-reading process is to understand the big picturerelevant to the real-life situation described. This big picture can be gained by reading andunderstanding the statement of purpose, statement of scope, objective of the scenariobeing described, and viewpoint of the IDEF3 Process Description.
These parts of thedescription bind the scope of the schematic and tell readers (particularly those familiarwith the process being described) what to expect in the top-level schematic. They alsoindicate the level of detail anticipated.Scan the SchematicReaders should become familiar with the scenario by scanning the schematic from leftto right. This involves becoming familiar with the individual elements (e.g., UOBs, links,and junctions) displayed in the schematic.
This is not an in-depth study of the schematic;rather, it provides readers with a general impression of the process being described and anoverall understanding of the logic flow in the scenario.Understand the DescriptionIn this step, readers gain a detailed understanding of the schematic associated with ascenario, object, or a decomposition of a schematic element. This is the part of thecommunication process that is most individualized and requires the most time.
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