Apart from the general definition of a software module, There can be a more precise definition for it. The presentation describes the more specific definition of software modules. The content is taken from Kirk Knoernschild book Java Application Architecture

1. Chapter 1: The Case for
Modularity
By Syed Ali Raza

2. Define a Module
 “chunk of software”
 A software module is a deployable,
manageable, natively reusable,
composable, stateless unit of software
that provides a concise interface to
consumers.

3. Elements of a module
 DEPLOYABLE
 MANAGEABLE
 TESTABLE
 NATIVELY
REUSABLE
 COMPOSABLE
 STATELESS

4. Deployable
 a unit of deployment
 a module is a discrete unit of
deployment that can alongside other
software modules.
 modules represent something more
physical and coarse-grained than
classes or packages, which are
intangible software entities.
 Examples of deployable units of
software include EAR, WAR, and JAR
files.

5. MANAGEABLE
 They can be installed, uninstalled, and
refreshed.
 This includes improving build
efficiency, allowing developers to
independently develop autono-mous
modules, and planning the
development effort along module
boundaries.
 It include EAR, WAR, and JAR files.

6. TESTABLE
 A module is a unit of testability.
 A module can also be independently
tested.
 It include classes, packages, and
JAR files

7. NATIVELY REUSABLE
 Modules are a unit of intraprocess reuse.
 modularity is a way to organize units of
deployment in a way that they can be
reused across applications, but a module
is always invoked natively (the
operations exposed by a module are
invoked by calling the method directly.)
 a module is deployed with each process
that intends to reuse its functionality.
 It include classes, packages, and JAR
files.

8. COMPOSABLE
 Modules can be composed of other
modules
 this involves coarse-grained modules
being a composition of finer-grained
modules.

9. STATELESS
 Modules are stateless.
 There exists only a single instance of
a specific version of a module.
 We don’t instantiate software
modules, although we do instantiate
instances of the classes within
software modules,
 WAR, EAR, and JAR files

10. SUCCINCT DEFINITION OFA
SOFTWARE MODULE
 After applying each segment of the
definition
◦ The best candidate as the unit of
modularity on the Java platform is the
JAR file!

11. Reference
 Java Application Architecture by Kirk
Knoernschild.