Embed Size (px)
DESCRIPTION
Citation preview
Business Informatics GroupInstitute of Software Technology and Interactive Systems Vienna University of TechnologyFavoritenstraße 9-11/188-3, 1040 Vienna, Austriaphone: +43 (1) 58801-18804 (secretary), fax: +43 (1) [email protected], www.big.tuwien.ac.at
Concurrent Modeling in the Early Phases of the Software Development Life Cycle
Petra Brosch, Philip Langer, Martina Seidl, Konrad Wieland, and Manuel Wimmer
CRIWG 2010, Sept. 20-23, 2010, Maastricht, The Netherlands
Konrad Wielandwww.modelversioning.org
Reality vs. Truth
2
Modeler D Modeler C
Modeler B
Modeler AModeler E
The Elephant and the Blind WoMen
3Copyright: John Godfrey Saxe „The Elephant and the Blind Men“Picture: G.R. Guzlas
Common Knowledge Base
4
?
Modeler D Modeler C
Modeler B
Modeler AModeler E
Tool SupportOptimistic Model Versioning Systems
5
Model Repository
Sally
Harry Version 0
Version 0
t1
Version 1
Version 2
t2 t3
Check Out
Check Out
Check In
Check In
Fron
t End
Fron
t End
Back
End
t0
Merge
Com
parison
Conflict
Detection
Conflict
Resolution
Issues of Serial Versioning
6
Modeler A Modeler B Modeler C Modeler D
C C C C
C … Changes
It‘s a Fan! It‘s a Spear!
It‘s a Rope!
It‘s a Tree!
Tool Support Needed…
7
Modeler D Modeler C
Modeler B
Modeler A
Modeler E
to assist a collaborative process of modeling to allow integrating different points of view to promote multilateral perspectives for conflict resolution
Issues of Standard Merge Scenario
8
PassportPerson
passNonamebday
V1
Alice
PassportPerson
passNohashcitizen
namebirthday
V1a
Harry
PassportPerson
namedoB
V1c
*passNoexpiry
Joey
Person
namebirthdaypassNohashcitizen
V2
SallyPerson
namebdaypassNo
V1b
Sally
Model stored in the Repository
Passport as part of one
Person
One class for efficient querying
Severalpersons in
one passport
Delete/Update Conflict!
Issues of Standard Merge Scenario
9
PassportPerson
passNonamebday
V1
Alice
PassportPerson
passNohashcitizen
namebirthday
V1a
Harry
PassportPerson
namedoB
V1c
*expirypassNo
Joey
Person
namebirthdaypassNohashcitizen
V2
SallyPerson
namebdaypassNo
V1b
Sally
PassportPerson
namedoBhashcitizen
V3
*expiry
Joey
passNo
Delete/Update Conflict!
Update/Update Conflict!
Issues of Standard Merge Scenario
Only one modeler is responsible for conflict resolution Nearly impossible to divine the reasons behind the changes Own point of view would always be prioritized
Final version does not reflect all intentions of the modelers Conflicts are considered to be negative
Conflict Avoidance Synchronous modeling or locking
Conflict Resolution Often error-prone and time-consuming task
Conflicts are not subject of discussion
10
Conflict-tolerant Merge
To avoid conflict resolution during check-in To distribute the responsibility when merging To avoid loss of information To create a basis for discussion and consolidation (early project
phases!)
Merge incorporates ALL changes
Changes are represented in an unified view
Potential conflicts have to be marked, tracked, and managed later on in a collaborative setting
11 Conflict-tolerant Merge
Conflict-tolerant Merge
12
PassportPerson
passNonamebday
V1
Alice
PassportPerson
passNohashcitizen
namebirthday
V1a
Harry
PassportPerson
namedoB
V1c
*passNoexpiry
Joe
Person
namebdaypassNo
V1b
Sally
PassportPerson
hashcitizen
namebirthdaypassNo
V2
PassportPerson
namedoB
V3*
passNoexpiryhashcitizen
12
12
3
45
Delete/Update
Delete/Update
Violation
Update/UpdateUpdate/Update
Model stored in theRepository
Metadata Annotations
13
<<Delete/Update Conflict>>
--User related MetadataUser_del = SallyUser_upd = HarryUser_upd = JoeOwner = Alice
--Involved Model ElementsDel_Elements = {Passport}Upd_Elements = {expiry, hash, citizen}
--Time related MetadataRevision_del = 3Revision_upd = 2Revision_upd = 4
1
<<Update/Update Conflict>>
--User related MetadataUser_upd = HarryUser_upd = JoeOwner = Alice
--Involved Model ElementsUpd_Element = {doB}Upd_Feature = Attribute.nameUpd_Values = {Joe:doB,
Harry:birthday}
--Time related MetadataRevision_upd = 2Revision_upd = 4 5
<<Update/Update Conflict>>
--analogous to 2……
4
<<Delete/Update Conflict>>
--analogous to 1……
2
PassportPersonnamedoB
*passNoexpiryhashcitizen
1
2
3
45
3
<<Violation>>
--User related MetadataUser_upd = HarryUser_upd = JoeOwner = Alice
--Involved Model ElementsUpd_Elements = {Composition1}Upd_Elements = {Multiplicity *}
--Time related MetadataRevision_upd = 2Revision_upd = 4
Consolidation
14
PassportPersonnamedoB
*passNoexpiryhashcitizen
1
2
4
3
Delete/UpdateDelete/Update
Violation
Update/Update
Update/Update
birthday5
PassportPerson
namedoBhashcitizen
*passNoexpiry
Result of Standard Versioning Process
Joe
Sally
Joe
Harry
Alice
Realization
Conflict-tolerant merge algorithm Extension of standard versioning systems
Provision of conflict model Allows to store conflicts explicitly
UML Profile for conflict visualization Allows for reusing standard UML modeling editors
15
Conflict-tolerant Merge Algorithm 1/2
16
OriginModel V0 HeadModel
RevisedModel
apply Changesand annotations
MergedModel
V0+ +
Central Repositoryapply Changes
MergedModel(delta1+delta2(originModel))
without conflict resolution
Modeler B
Modeler A
copy
1
2
1 2
Conflict-tolerant Merge Algorithm 2/2Input: originModel, revisedModel, headModelOutput: mergedModel
mergedModel = headModel.clone()
ChangeSet c = calculateChanges(originModel, revisedModel)for c ∈ changeSet do
element = mergedModel.getElementById(c.getElement().getId())if c instanceof Insert then
container = mergedModel.getElementById(c.getElement().getContainer().getId())if container.isDeleted() then
container.annotate(new DeleteUpdate(c))endmergedModel.apply(c)
else if c instanceof Delete thenif mergedModel.getElementById(c.getElement().getId()).isUpdated()then
element.annotate(new DeleteUpdate(c))endelement.markAsDeleted()element.addMetaInfo(createMetaInfo(c))
else if c instanceof Update thenif element.isDeleted() then
element.annotate(new DeleteUpdate(c))endfeature = c.getUpdatedFeature()if element.isUpdated(feature) then
element.annotate(new UpdateUpdate(c), feature)element.addMetaInfo(createMetaInfo(c))
endmergedModel.apply(c)
endend...
17
Create a copy of the headModel as basis for the new
mergedModel
Add all inserted elementsincluding annotations if Delete/Update Conflict
Calculate change set between origin and revised
model
Do NOT apply deletions, just annotate element
Also store the updated feature.
Apply all updatesValidate merged model
Model-based for Conflict Representation
18
leftChange
rightChange
Update/UpdateConflict
PostMergeViolation
Constraint
1
*
violated
ConflictReportChangeReport
Change
Conflict
Change ReportConflict Report
AdditionalSpecification
dependsOn
*
1
1
*
*
Delete/UpdateConflict
ContradictingChange
*
UML Profile for Conflict Visualization
Representation and visualization of conflicts with UML Profile Light-weight extension of UML Stereotypes are used to extend standard UML metaclasses Apply stereotypes to instances of the extended metaclasses Tagged values provide additional information Syntactic sugar (e.g., icons) for defined stereotypes may be configured to
improve visualization
Profile is used as follows Stereotypes mark added, deleted, updated model elements Stereotypes mark update/delete and update/update conflicts as well as
violations Tagged values contain additional information like conflict metadata Involved user Revision number etc.
19
Turning Conflicts into CollaborationTool Support in Eclipse
20
Benefits of Realization
UML-conform models Profiled models are still compliant to UML Are handled by most UML tools
No editor modifications Modification of graphical editors of UML tools are not necessary
User-friendly visualization Merge conflicts in concrete syntax
Integrated view One single diagram to provide a complete overview of conflicts
Model-based representation Conflict information is not lost when importing/exporting the model Resolve conflicts at a later time Different diagram filters based on stereotypes
21
Conclusions
Conflicts are not considered as negative results of collaboration All opinions and intentions are covered Important in early phases of the software lifecycle
When a general agreement has not been established At this time, design flaws are cheap to correct
Novel kind of thinking for the modelers Models containing different points of view explicitly
Conflicts may serve as a basis for finding differences in stakeholder goals for detecting critical parts of models for improving the software development process
22
Ongoing Work
UI is of huge importance Models might grow big with many conflicting modifications Filters and strategies to guide the modelers
Language-independent annotations Model extensions for each Ecore-based model
Empirical Study with our students
23
Thank you for your attention!Questions?
• http://www.modelversioning.org
The End
Backup
25
Conflict Profile in EA
26
![Concurrent Cycle Collection in Reference Counted Systems · Concurrent Cycle Collection in Reference Counted Systems 3 – special programming idioms, like Bobrow’s groups [5],](https://img.pdfslide.us/doc/110x75/5ecee80ae3d25d0d837a385e/concurrent-cycle-collection-in-reference-counted-systems-concurrent-cycle-collection.jpg)
