Using Apache Sling you can easily create content-oriented web applications, which are based on REST principles. Sling also provides an OSGi container to facilitate dynamic modifications during runtime. A Sling application can be composed from any set of modules that are compatible. You can also use Sling’s Inject annotation to add Sling services to your application. It is a good idea to take a look at Sling’s documentation for more information.
The Sling engine is the engine that drives Apache Sling’s OSGi container. The engine is composed of five filter chains. Each filter is called only once when a request hits Sling from the outside. The engine is also responsible for figuring out which Servlet or script is the best suited for the task at hand. For instance, if a Servlet needs to access a file then it will make a SlingHttpServletRequest and pass that request to a processing method.
The Sling engine also provides an application framework, which allows you to compose and deploy applications. This framework is built on top of the CRX Content Repository and uses the OSGi container to provide inversion of control. The engine also supports servlets and OSGi services. The engine also includes a collection of modules, which include a core set of functionality and servlet support.
The Sling engine also provides a web application, which provides access to a workspace. There is also a SlingRequestProcessor that executes the entire Sling request processing pipeline. The engine can also be run using the maven bundle plugin, which gives you access to the sling servlet annotations. The engine’s source code can be accessed by opening it in a code editor.
The Sling engine also includes an in-memory cache to store and retrieve data from the cache for a given request. Using this feature makes it possible to avoid having to repeatedly send requests. For instance, you can use the cache to retrieve the content of a file that was uploaded to the server. This is a time saver as well as a security measure. The Sling engine is also able to detect which files are uploaded and remove them if they are not necessary. You can also configure the cache to limit the size of each request.
The Sling engine also includes a slew of other features, such as content caching, which helps your application save bandwidth and disk space by storing only the content it needs to display. It also uses a CRX Content Repository to store the content. This repository can also be used to provide access to the repository from your application. This feature is important when building content-oriented applications. The repository can also be used to store user profiles, which may be necessary in certain applications. The repository can also be used to display other content as well, such as news or events.
The Sling engine also includes the sling servlet, which extends from the Sling servlet class. The servlet provides a number of standard methods for uploading files, sending and receiving emails and making calls to other services.