Chapter 4. Locating Artifacts with Maven and HTTP
In Red Hat JBoss Fuse, Maven is the primary mechanism for locating artifacts and dependencies, both at build time and at run time. Normally, Maven requires Internet connectivity, so that dependencies can be downloaded from remote repositories on demand. But, as explained here, it is also possible to provide dependencies locally, so that the need for Internet connectivity is reduced.
4.1. Locating HTTP Artifacts
You can specify the location of an OSGi bundle (and other kinds of resource) using a HTTP URL—for example, by specifying a HTTP URL as the argument to the
osgi:installcommand. This approach is perhaps not as common as using Maven URLs, but it means that you have the option of providing OSGi resources through a Web server.
HTTP URL protocol
The HTTP URL protocol specifies the location of an OSGi bundle (or other resource) using a standard HTTP (or HTTPS) URL. Typically, a HTTP URL has a syntax like the following:
In a standalone (non-Fabric) container, a HTTP URL lookup can be triggered by either of the following events:
osgi:installis invoked on a Maven URL to install an OSGi bundle;
features:installis invoked to install a Karaf feature (a Karaf feature typically includes one or more Maven URL references).
HTTP URL handler
JBoss Fuse uses Java's built-in HTTP protocol handler to resolve HTTP URLs. Hence, HTTP URL resolution behaves exactly as you would expect in standard Java.
Karaf bundle cache
When you pass a HTTP URL as the argument to the
osgi:installcommand (or embedded in a Karaf feature description), JBoss Fuse downloads the referenced OSGi bundle resource, saves it in the Karaf bundle cache (under the
data/cachedirectory), and loads the bundle into the Karaf container runtime. The Karaf bundle cache is used to persist all of the bundles currently installed in the Karaf runtime.
When a Karaf container is stopped and restarted, it loads its installed bundles directly from the Karaf bundle cache, not from the local Maven repository (or anywhere else). Hence, if you have updated any artifacts in the local Maven repository in the meantime, those changes are not automatically reflected in the state of the Karaf container.
Configuring a HTTP proxy for HTTP URLs
To configure a HTTP proxy (which will be used when resolving HTTP URLs), open the
InstallDir/etc/system.propertiesfile in a text editor and set the
http.proxyPortsystem properties with the host and port of the proxy—for example:
You can optionally specify a list of non-proxy hosts (hosts that can be reached without going through the proxy) using the
An advantage of using the system properties approach to configuring the proxy is that these settings will be used both by the
mvnURL protocol handler and by the
httpURL protocol handler (see the section called “Configuring a HTTP proxy for Maven URLs”).