JarCastingwebresource
Introduction
Webresources are small static files that are downloaded during rendering a website. E.g.: CSS, Javascript, images, ...
Basic usage
- Install the org.everit.osgi.webresource module into your OSGi container.
- Install the WebResourceServlet (that is provided as an OSGi service) into your ServletContext.
- Use CommonContextWebResourceURIGenerator to generate URIs that point to WebResources. This class will pick up the URIGenerator(s) registered by WebResourceServlet within the same ServletContext.
You can also install custom WebResourceURIGenerator implementations in the servletContext. In this case:
- Get the Collection of WebResourceGenerators from the servlet context by calling WebResourceUtil.getUriGeneratorsOfServletContext(context);
- Add your generator to the collection
Create WebResource packages
To make an OSGi bundle also a WebResource package the everit.webresource capability must be provided. The capability can have the following attributes:
- resourceFolder: The folder in the bundle where the resources are located.
- libraryPrefix: A prefix that should be pasted in front of the folder structure in the URL. E.g.: "foo/bar"
- version: Optional attribute that can define the version of the webresources. If not defined, the version of the bundle will be used.
Version handling
The webresource_version can be specified as a parameter of the servlet request. Using ranges in the version expression is allowed. Examples:
- /alias/jquery/jquer.js?webresource_version=2.1.0
- /alias/jquery/jquer.js?webresource_version=[2.1.0,3)
Cache
There is a primitive, in-memory cache. The GZIP, Deflate and RAW data is stored in cache after the first request. When a bundle is stopped, all webresources are removed from the cache that came from that bundle.
WebConsole Plugin
There is a WebConsole plugin that is registered when the Extender component is started. It shows the registered webresources and the state of the caches.
Content-Encoding
GZIP, Deflate and RAW content encodings are supported.
ETag support
SHA-256 hash of the RAW content is concatenated with the last modification date of the webresource file.
Logging
Java Util Logger is used to log errors during transferring data. Such errors may happen if the connection is broken. The name of the logger is org.everit.osgi.webresource.stream.
Minimum requirements
- OSGi 6: WebResourceServlet is registered with prototype service scope. Luckily Felix and Equinox has OSGi 6 support now.
- Servlet 3.1: WebResourceUtil writes the content of the WebResources using asynchronous IO if possible.
- Java 8: Many of the features of Java 8 is used (time, optional, ...)
