OSGI Modularity With Liferay Exhibits Better Programming Scopes For Developers

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OSGI Modularity With Liferay Exhibits Better
Programming Scopes For Developers
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Intro

• There have been various developments in the field
  of Java since its evolution. It has provided a
  robust programming platform for the developers.
  Additionally, Java has also served as a true
  source to various other programing interfaces.
  Liferay has been the one which has enabled
  multiple organizations to work on same platform.
  Having not so much time of its release, Liferay
  has been well accredited by the users.
• Apparently, known to all the developers, Liferay
  has also been created into various versions so
  far. The beta version of Liferay 7 has been
  released recently for the developers. This newer
  version allows the old plugins to run swiftly.
  However, at some places the APIs have been
  modified, which would have to be adapted for the
  new version. Apart from all these, Liferay has
  come with various changes the one noticeable
  among which is working with OSGI.

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What Is OSGI?

• Open Source Gateway Initiated or OSGI as it is
  mostly abbreviated, is a framework. This is used
  to develop modular Java applications. The
  components also referred to as the bundles could
  be easily installed, uninstalled, started or
  stopped and that too remotely. The current
  version of Liferay i.e. Liferay 6.2, includes
  OSGI runtime which could run OSGI bundles
  encapsulated with Liferay plugins.
• OSGI is basically an open standards organization
  which has been maintaining its OSGI
  standard since March 1999. It comes up as a
  modular system and a service platform for Java
  programming language. The service registry of
  OSGI also helps the bundles to determine the
  inclusion or exclusion of the service. It has
  various illustrious members like that of IBM,
  Oracle, Red Hat, Adobe, Siemens, TIBCO, France
  Telecom, Deutsche Telekom, Technicolor and many
  more.

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Liferay OSGI Plugins-

• Generally distributed as JAR files, OSGI web
  bundles are similar to standard web application
  archives in terms of their architecture. OSGI
  specification doesnt need any file extension for
  web application bundles. Further, in order to
  create an OSGI plugin for Liferay, the user will
  need a Liferay Plugin SDK. The plugins could also
  be downloaded from the link.
• After the Plugins SDK are extracted and navigated
  to the shared folder, the user must create a
  folder for OSGI plugin project in the shared
  folder. A project made in such a format must end
  with shared.

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OSGI Areas of Specification-

• The OSGI framework, apart from the modularity
  also consists of services, lifecycle dynamicity
  and security. Other than that, the services and
  components on top of framework for the enterprise
  also offer addressing enterprise use cases like
• Service Distribution
• Component models and IoC
• Configuration management
• JavaEE integration
• Cloud computing

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Liferay Module Framework
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Hover.css

• And so on. The other illustrious OSGI
  implementations are open source which include
  eclipse equinox, Apache Felix, JBoss AS 7,
  Knopflerfish along with Oracle GlassFish, Eclipse
  ECF to name some of them.

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Advantages of OSGI Modularity-

• Implementation of OSGI modularity brings in
  various sorts of advantages.
• Some of these include-
• Improvement in maintainability
• As it tends to improve cohesion and reduces
  coupling and also makes the module boundaries and
  functionalities clear.
• Non Monolithic
• It allows for fine-grained updates of the system
• Concurrent versions
• Same modules with multiple versions could
  co-exist
• It also allows for gradual updates.

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Benefits of OSGI for Developers-

• OSGI has come up with better scopes and
  opportunities for the developers. Take a look at
  its benefits that developers will have while
  using this platform-
• It has been known to reduce the complexity.
• It offers modular architecture for large scale
  distributed system as well as for small embedded
  applications.
• Significant building of systems from in-house and
  off-shelf modules.
• Reduces maintenance and development expenses.
• Realizes the promise of component based systems.

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Benefits of OSGI for Businesses-

• Apart from providing programming convenience to
  the developers, OSGI also benefits to the
  businesses. It helps to reduce the operational
  costs by integrating multiple devices through a
  single network. This allows it to deal
  effectively with the costly application
  development along with remote service management.

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Some of its other benefits for the businesses
include-

• Package level versioning policy against bundle
  level versioning.
• Independent starting, stopping and dynamic
  updating of the modules.
• Single functionality implementations by acute
  modules that makes it easy for managing, bug
  fixing and testing of the applications.
• The user has the authentication to access the
  internal details of the installed modules

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Bringing Modularity Into Practice-

• While implementing OSGI into regular coding, you
  need to use classes normally from the point of
  Java. Consider the following code snippet-

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• Further when it comes to the OSGI Module Metadata
  in Manifest.MF then the utilization of packages
  would be like

1 Export-Package org.acme.package1 version1.2
2 Import-Package org.acme.package2 version(1.1, 2)
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• From the services, modularity and results, it
  could be certainly mentioned that implementation
  of OSGI with liferay portal development has truly
  brought a favorable change to the programming
  techniques and resultant outputs not only for the
  developers but also for the campaigns.

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• Original Source
• http//www.azilen.com/blog/osgi-modularity-liferay
  -exhibits-better-programming-scopes-developers/

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