Provided intial OSGi support for WebJars

[Sandared]

I've added the bnd-maven-plugin to generate the necessary Manifest content, like

• Bundle-Version
• Bundle-Symbolic-Name
• Require / Provide-Capability
• WebJars-Resource

WebJars-Resource can be used in an OSGi environment to find WebJar bundles with a BundleTracker and register their resources at a HttpService.

Require-Capability is redeclaring the dependencies that are also used by maven, but in a format that the OSGi resolver can use to automatically resolve those dependencies.

The Bundle-Version has to be set manually if the ${project.version} is not OSGi compatible, e.g. a version like this: 1.2.3-2-SNAPSHOT. Bnd would ignore the "-2-" part and create the version like this: 1.2.3.SNAPSHOT, where probably something like 1.2.3.2-SNAPSHOT would be preferred. Therefore I had to create a new property bnd.bundle.version that is set to 1.2.3.2-SNAPSHOT to achieve this.

[jamesward]

I've tried to make bumping these easy by creating the unsnapshot plugin so I wonder if we can create a similar plugin that OSGI-ifies the version rather than having to edit it in multiple places.

[Sandared]

I've attached a piece of code that takes a maven version and tries to transform it into an OSGi version. In the worst case this will always return a version in the form 0.0.0.timestamp if the given maven version is completly malformed.

I have no experience with creating Maven plugins, so maybe you could just take this code an turn it into one?

public class OSGiVersion {
	
	public static void main(String[] args) {
		OSGiVersion osgiVersion = new OSGiVersion();
		
		String s1 = "1.2.3.4-_asdfasdf&/"; // malformed qualifier
		String s2 = ".asdf..33öjkhadsf"; // malformed segments and malformed qualifier
		String s3 = "1.asdf.3.asd.asdf.sdf"; // malformed segment and malformed qualifier
		String s4 = "1.2.3-beta1-2"; // everything ok
		String s5 = ""; // malformed version
		String s6 = "1.2-test"; // everything ok
		String s7 = "1.2-SNAPSHOT"; // everything ok
		
		System.out.println(osgiVersion.calculateVersion(s1));
		System.out.println(osgiVersion.calculateVersion(s2));
		System.out.println(osgiVersion.calculateVersion(s3));
		System.out.println(osgiVersion.calculateVersion(s4));
		System.out.println(osgiVersion.calculateVersion(s5));
		System.out.println(osgiVersion.calculateVersion(s6));
		System.out.println(osgiVersion.calculateVersion(s7));
	}

	/**
	 * @param mvnVersion
	 * @return a version that is compliant tothe description of OSGi versions by https://osgi.org/specification/osgi.core/7.0.0/framework.module.html#i2655136
	 */
	public String calculateVersion(String mvnVersion) {
		
		// default OSGi version
		String[] bndVersionSegments = {"0", "0", "0", Long.toString(System.currentTimeMillis())};
		
		if(mvnVersion == null || mvnVersion.length() == 0) {
			// malformed version -> error message?
			System.err.println("Malformed version");
			return toVersionString(bndVersionSegments);
		}
		
		// remove all whitespaces
		mvnVersion = mvnVersion.replaceAll("\\s+", "");
		
		// get all segments, but at most 4 
		String[] mvnVersionSegments = mvnVersion.split("\\.", 4);
		
		for (int i = 0; i < mvnVersionSegments.length; i++) {
			String mvnSegment = mvnVersionSegments[i];
			String[] numberAndRest = getNumberAndRest(mvnSegment);
			
			switch (numberAndRest.length) {
			case 0:
				// no leading number found in this segment
				if(i == 3) {
					// it's ok, because it is the qualifier, which doesn't need to start with a number
					bndVersionSegments[3] = formatQualifier(mvnSegment);
				} else {
					// malformed segment -> error message?
					System.err.println("Malformed segment");
				}
				break;
			case 1:
				// it's a number. This is always acceptable
				bndVersionSegments[i] = numberAndRest[0];
				break;
			case 2:
				// it's a number with something else as rest.
				if(i == 3) {
					// it's ok because it is the qualifier
					bndVersionSegments[3] = formatQualifier(mvnSegment);
				} else{
					if(i == mvnVersionSegments.length - 1) {
						// it's ok because it is the last segment of the maven version. The rest is used as qualifier
						bndVersionSegments[i] = numberAndRest[0];
						bndVersionSegments[3] = formatQualifier(numberAndRest[1]);
					}
					else {
						// malformed segment -> error message?
						System.err.println("Malformed segment");
					}
				}
				break;
			default:
				// malformed return -> error message?
				System.err.println("Malformed return value of getNumberAndRest()");
				break;
			}
		}
		
		return toVersionString(bndVersionSegments);
	}
	
	
	/**
	 * 
	 * @param segment a String in the form of a leading number part and anything else as rest, e.g. 123 or 123asdf.
	 * @return a String array 'result' with length 0 if segment has no leading number, 1 if segment is a number (result[0] == segment), 2 if segment has a leading number and anything else as rest (result[0] == number, result[1] == rest)
	 */
	private String[] getNumberAndRest(String segment) {
		String pattern = "(\\d+)(.*)";
		if(segment.matches(pattern)) {
			String number = segment.replaceAll(pattern, "$1");
			String rest = segment.replaceAll(pattern, "$2");
			if(rest.length() == 0) {
				return new String[] {number};
			}
			return new String[]{number, rest};
		} else {
			return new String[0];
		}
	}
	
	
	/**
	 * @param qualifier an arbitrary String
	 * @return a String that only contains a-z, A-z, 0-9, -, _
	 */
	private String formatQualifier(String qualifier) {
		String wellFormedQualifier = qualifier.replaceAll("[^\\w_\\-]", "");
		if(wellFormedQualifier.length() != qualifier.length()) {
			// warning?
			System.err.println("Malformed qualifier");
		}
		return wellFormedQualifier;
	}
	
	/**
	 * @return the values of the array with dots in between as one String
	 */
	private String toVersionString(String[] segments) {
		StringBuilder sb = new StringBuilder();
		for (int i = 0; i < segments.length; i++) {
			String segment = segments[i];
			sb.append(segment);
			if(i != segments.length - 1) {
				sb.append(".");
			}
		}
		return sb.toString();
	}
}

[Sandared]

@jamesward is there anything else you need for this plugin?

[jamesward]

I've created a repo for the plugin:
https://github.com/jamesward/osgi-version-maven-plugin

But the output isn't quite what I'd expect. For example:
https://github.com/jamesward/osgi-version-maven-plugin/blob/master/src/test/java/com/jamesward/osgiversion/UnsnapshotMojoTest.java#L32

The output of that one is 1.2.3.-beta1-.2 (the dashes are preserved. Anyhow, let's collaborate over on that repo and get it fixed up and released.

[Sandared]

The "-beta1-.2" part is regarded as the qualifier part of the OSGi version, which may contain dashes, but if those are not important, then I can alter the code to remove them. In OSGi they have no effect on the resolver, I think.

[jamesward]

I think it'd look better without the dashes in the qualifier, at least without leading and trailing dashes. Want to send a PR?

[Sandared]

I sent you a PR