Upgrading of component-based application Program Analysis and Transformation MSE-Seminar 09.12.20081© Raphael Gfeller, [email protected].

© Raphael Gfeller, [email protected] 1

Upgrading of component-based application

Program Analysis and TransformationMSE-Seminar

09.12.2008


Agenda

• Component-based Software Engineering, CBSE– History– Benefits – Challenges

• Change management on CBSE– Approaches to reduce the effort for the consumer

• New fields of application• Questions• References09.12.2008


Component-based Software Engineering, CBSE

Component-based Software Engineeringalso known as Component-Based Development (CBD) or Software Componentry

- focus that software should be developed by combining prefabricated components together

(like in the field of electronics or mechanics)

In contrast to object-oriented programming, (OOP) which

- focus on modeling real-world interactions

Component based programming(for example

JavaBeans, DCOM)Distributed object computing

(for example CORBA)Object oriented programming

(for example C++, C#, Java)

Procedural programming(for example C)

Abst

racti

on

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History• 1968, Idea that software should be componentized from Douglas

McIlroy pipes and filters are included in UNIX

• 1986, definition of the modern concept of software component by Brad Cox Objective-C (Smalltalk-style messaging to C)

• 1990, IBM invents their System Object Model • 1990, as a reaction, Microsoft released OLE 1.0

– OLE custom controls (OCX)• 1993, Component Object Model (COM) as an interface standard

for software componentry was introduced by Microsoft

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Benefits• Decrease of development time and total cost

because systems are not developed from scratch.• Results in standard and reusable architectures• Separation of skills

because much complexity is packaged into specific frameworks.• Fast access to new technology

because we can acquire components instead of developing them in house.• Improved reliability by shared components• …Challenges• Change management (many stakeholders involed)

focused in this presentation• Robustness (input validity, error handling)• Composable with other components• Realizing an independent component• …09.12.2008


Change management on CBSE

Problem 1:A new version of a component may

• Change the behavior or• Not change the behavior

(no behavior changes are often done by refactorings)

Behavior changes Behavior does not change

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Change management on CBSEProblem 2:• Multiple stakeholders are involved

Producer, multiple consumer, multiple competitors, state, …Problem 3:• Different interests of the stakeholders

Size of the circle: Effort for the consumer Occurs most

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Problem 4:There is no deterministic reaction by the consumer if a new

component is shipped.

Possible reaction:• Ignore the new version• Adapt his software for using the new component. – That is the most common approach

• Adapt the shipped component to make it compatible with the exiting application– source code has to be available

• Create a compatibility wrapper for the new component09.12.2008



Problem 5: Dilemma for

the component consumer

Using of the new version or not ?

Benefits• Less bugs• Performce

improvements• New features

Costs• New behavior?• Upgrading the

software• Retest the software

Decision drivers:• Group change steps (remove features, add features,

bug fixing, …) together better ratio between benefits and efforts for the consumer

• Reduce the effort to adapt the new version focused on the next slides

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“Using the new version of a component in a successful way;

Implicates that the changes between the current and the new one are known!”

2008, Raphael Gfeller

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Approaches to reduce the effort for the consumer

Detection of behavioral changes• Communicated within release notes• Detected by the consumer by doing faithful Unit Testing's.

To reduce the effort for the consumer, the producer should write release notes careful!

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Detection of non behavioral changes• Approach 1:

No communication• Approach 2:

Communicated within release notes• Approach 3:

Using helper keywords within the programming language

API documentation \ release notes

Example 1:

Example 2:

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• Approach 4:Using Naming conventions

Old clients still use the old version New clients can us the new features orcan still use the old version

Example 2:

Example 1:

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• Approach 5:Coexistent

Old clients still use the old version New clients use the new features

Example 1:

Two versions of the “Person” exist in coexistent within the component09.12.2008



• Approach 6: COM-Style interface query, Coexistent

Clients using their favorite versionExample 1:

Two versions of the “Person” exist in coexistent within the component09.12.2008



• Approach 7:Automatic approach based on approach 3– Find code that is marked as deprecated– Find calls to deprecated code– Calls to deprecated code are replaced by their bodiesRealized by Jeff H. Perkins

Can handle about 80% of all deprecated codeExample 1:

Body of the deprecated method09.12.2008



• Approach 8:Automatic approach, Record and replay refactoring– Producer records all applied refactorings

Extension to the refactoring engine– Recorded refactorings are shipped– Consumer replays the refactoringsDemonstrated by Johannes Henkel and Amer Diwan in CatchUp

Example 1:

Source: Henkel & Diwan: “CatchUp! Capturing and Replaying Refactorings to Support API Evolution”International Conference on Software Engineering, 2005

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• Approach 9: Automatic approach, detects refactorings

used by approach 8Uses – a fast syntactic analysis that finds candidates for refactoring– a precise semantic analysis step that finds the refactoring

Demonstrated by Daniel Dig in RefactoringCrawlerDetects up to 85% of applied refactorings

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Summary:

Best method to be used is approach 8 “Record and replay refactoring”

Less effort for the producer and consumer Information is collected on the source

Unfortunately the tool chain is not existent

Further work has to be done – Publicize this approach– Realizing a tool chain than can be used by everyone – Make these tools as a standard fitting for modern development environment – Shipping refactoring logs should be a part of new setup and deployment

assistants.09.12.2008


New fields of application

Based on approach 9:

Detect an illegal usage of a componentSituation:– Company A writes a well tested component CA, test T, test results R,

– Company B writes a component CB that includes CA in a illegal way and apply refactorings to hide the origin of CA. CB =some functions + CA + refactorings

It is not obvious that CA has been integrated into CB.

Solution:– Detect refactorings between CA and CB.– Replay this refactorings on T T’– Rerun T’ on CB R’

– If R and R’ are equal the chance that CA has been integrated into CB is high.09.12.2008




Detect cheating of studentsSituation:– Students have to solve a given problem in Java including writing of Unit Tests

Solution 1-n– A cheating student B will use the solution from student A. Apply refactoring to hide its

cheat. SB =some edits + SA + refactorings.

It is not obvious that SB has cheated.

Solution:– Detect refactorings between SA and SB.– Replay this refactorings on T T’– Rerun T’ on SB R’– If R and R’ are equal the chance that B has cheated is high.

Remarks:– Only valid if the given problem results in given solution09.12.2008




Reduce the transferred data in a CVSSituation:– Textual changes are transmitted from the client to the server– Assume that the often used method doLog is renamed to doLogging.

large amount of data has to be transferred

Optimization:– Transfer refactorings instead of the textual changes, if possible

Requirements– Client has to be able to record refactorings– Server has to have knowledge about the project structure like Microsoft Team Foundation Server does– Server has to be able to replay refactorings

CVS Client

transmit the changed file

CVS Server

CVS Client

transmitt refactoring

CVS Server

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Based on “approach 8” and “Reduce the transferred data in a CVS “:

Extend change management within a small companySituation:– A Company uses their common code C in different Projects P1-n

– During evolution, multiple versions of C exits. P1-n reference on one of the special versions of C.

Bug fixing of C becomes painful

Optimization:– Server has to have knowledge about all projects in a company.– Transmitted refactorings are forwarded to the C and to the referenced

projects P1-n that are using C.

Only one version of C exists. All projects within the company are using the actual version of the C.

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Based on “approach 9”:

Component EvaluationSituation:– Normally more than one component does the same job. Evaluation is a time intensive job.Assumption:– If a component CA is doing nearly the same job as CB

API of CA and CB is similar

Optimization:– Test the application with CA test T, application A and test result R

Realize a tool that:1. Find refactoring between CA and CB Ref

2. Apply Ref on A A’, on T T’3. Run T’ on A’ R’, store R’4. [For all component goto 1]5. Display all R’6. Convert A to use with the best component C.

Programcould do the job with

Component 1 from

Vender A

Component 2 from

Vendor B

Component 3 from

Vendor C

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Questions?

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References• Gfeller Raphael, Upgrading of component-based application, [Online]

7.12.2008. [Citied 7.12.2009]http://wiki.ifs.hsr.ch/SemProgAnTr/wiki.cgi?AUTOMATEDUPGRADINGOFCOMPONENT-BASEDAPPLICATIONS

09.12.2008

http://wiki.ifs.hsr.ch/SemProgAnTr/wiki.cgi?AUTOMATEDUPGRADINGOFCOMPONENT-BASEDAPPLICATIONS

http://wiki.ifs.hsr.ch/SemProgAnTr/wiki.cgi?AUTOMATEDUPGRADINGOFCOMPONENT-BASEDAPPLICATIONS

Upgrading of component-based application Program Analysis and Transformation MSE-Seminar 09.12.20081© Raphael Gfeller, [email protected].

Documents

new component

shipped component

raphael gfeller

independent component

change management

cbse problem

software componentry

cbse benefits