1/15

ENT MetamodelImplementation & Applications

ENT metamodel, prototype implementationComponent substitutability checking, ENT based component comparisonCase Study: Component model OSGiAutomated generating OSGi component versionsFuture work

Lukáš Valenta

& what are we working on…

2/15

ENT MetamodelElement – interface element

Name, type Additional non-functional information –

Tag Classification:

Nature, Kind, Role, Granularity, Construct, …

Trait – related elements Equal classifier and meta-type Set of traits defines the component model

Categories – „similar“ traits Defined „angle of view“f Exports : role =

{ provided }f Needs : role = { required }

3/15

ENT Metamodel Implementation- Review of the Diploma Thesis

3 parts Definition of the concrete component model Classification system and categories ENT representation of the component

Applicable for any component model(now implemented: EJB, OSGi)

New: ENT based component comparison

4/15

Component Substitutability Checking

“a substitute component should be usable whenever the current one was expected, without the client noticing it” [Wegner, Zdonik, 1988]

“instances of type T' can be bound to variables declared to be of type T if T‘ <: T (subtype)”

short <: long structured types: use rules

recursively until primitive types are reached

Issue with statically typed languages (Java, C++, …)

Although int <: long, runtime error!

1 none If a = b

2

insertion if a is not defined but b is

specialization

if b <: a

3

deletion if b is not defined but a is

generalization

if a <: b

4 mutationif b contains both ins/spec and del/gen differences

5 unknownIf b cannot be compared to a

Compare two types a and b:

Diff(a,b): Type x Type -> differences

It returns:

5/15

ENT Based Component Comparison

Comparing structured types (e.g. whole components)

Input: ENT representations of two components (elements, tags)Appropriate parts are compared using subtyping rules

= The rules for comparing various metatypes

e.g. Enumeration: Subtyping relation between

values of the set must be specified

Authentication:supported <:

required List, Map, …

Output: comparison result

6/15

Comparison Result Representation

Hierarchical (tree) structure Complete information for all levels of comparison

“custom” depth XML representation

<component ctype="OSGi_R4" model="OSGi_R4"> <name>Log Service</name> <part name="" level="component"> <diff>Mutation</diff> <part name="Exports" level="category"> <diff>Mutation</diff> <part name="export_types" level="trait"> <diff>Mutation</diff> <part name="cz.zcu.Logger" level="class"> <diff>Mutation</diff> <part name="flush()" level="method"> <diff>Insertion</diff> </part> <part name="getItemCount()" level="method"> <diff>Generalization</diff> </part> </part> </part> <part name="Needs" level="category"> <diff>None</diff> </part> </part></component>

7/15

Case Study: Generating OSGi Component Versions

Practical use of ENT component comparison for OSGi platformWe are able to compare two components and get the complete information about the changes (at any „level of detail“)

8/15

OSGi Service PlatformOpen Services Gateway initiative

Common architecture to develop, deploy and manage services

Target range: embedded/mobile devices enterprise servers

The core formed by the Framework (= container) Supports the deployment of applications called bundles

Why? Simple component model … but contain versioned dependencies, industrial

importance

Practical applications: Eclipse Platform (Equinox) Enterprise Component Framework (ECP)

9/15

OSGi BundleBundles can share Java packages (exporters importers) and provide servicesBundle = JAR archive

Java classes + other resources needed to provide functionality

Manifest file Description of the contents Provide information about the bundle Specification of bundle dependencies … Primary source for generating the bundle ENT

representation

Bundle-Name: AExport-Package: cz.zcu.logging;version=1.3.0

10/15

OSGi Bundle – Versioned Dependencies

Every exported package has version identifier Well-known versioning schema: major.minor.micro

major – incompatible change minor – compatible change in component interface micro – change not affecting interface (e.g. bugfix)

Importers can specify the version range of required packages (+ other constraints)Framework resolves all constraints and link importers to the right exporters

Valid version identifiers all possible problems identified already

in the deployment phase Valid version identifiers = important !

Bundle-Name: AExport-Package: cz.zcu.logging;version=1.3.0

Bundle-Name: BImport-Package: cz.zcu.logging;version=“[1.2.6, 2)”

11/15

Differences and Versioning Related

In general: there is a connection between the change and the new version identifier

The knowledge of difference between two subsequent versions of an interface part is sufficient to determine the new version identifier of that part

d = Diff (Ri-1, Ri ) : difference between two consecutive revisions

Vold = majold.minold.micold : version of Ri-1

The new version identifier Vnew = majnew.minnew.micnew is defined:

Diff (Ri-1, Ri ) majnew minnew micnew

none majold minold micold+1

specialization, insertion

majold minold+1

0

deletion, generalization, mutation

majold+1 0 0

unknown unknown

12/15

Generating OSGi Component Versions

13/15

Example

Bundle-Name: ABundle-Version: 2.2.6Export-Package: cz.zcu.logging;version=1.2.5Require-Bundle: B

Bundle-Name: ABundle-Version: ?.?.? Export-Package: cz.zcu.logging;version=?.?.?Require-Bundle: B, C

Previous version: New version:

Exported package is specialized new version 1.3.0The whole bundle has new required dependency (C) its “needs” are specialized bundle is generalized (backward strict incompatible) new version 3.0.0

14/15

Future Work – My IdeasTry to find a way to solve a problem with statically typed languages (Java)Automated creation of the connectors between the „incompatible“ interfaces

15/15

Conclusion

At the abstract level of the component representation we can do the substitutability checksAnother component model can be added easily – implement the compare method for particular elements and tagsThe result can be used for another applications

Thank you