Red Hat Summit Red Hat Summitサポートコンソール開発者トライアルの開始お問い合わせ

このコンテンツは選択した言語では利用できません。

2.7. API/Provider Build-Time Combination

Overview
リンクのコピー

This section explains how to set up a Maven project for an API/provider bundle, where the API packages and implementation packages are kept in separate Maven projects, but then combined into a single bundle at build-time.
You can demonstrate an API/provider build-time combination bundle by modifying the Maven configuration of the hello-paris-impl bundle. By exploiting the Bnd utility's provide:=true clause, you can modify the instructions for the Maven bundle plug-in, so that the org.fusesource.example.hello.paris API package gets included in the hello-paris-impl bundle at build time.

provide:=true clause
リンクのコピー

Whenever a bundle plays the role of provider with respect to a particular API package, you must indicate this explicitly by attaching the provide:=true clause to the API package, either in an import instruction or in an export instruction (otherwise, by default, the bundle plug-in would assume that the bundle is a consumer of the API package). In particular, for an API/provider build-time combination bundle, you must export the org.fusesource.example.hello.paris API package and attach the provide:=true clause, as follows: 
<instructions>
  ...
  <Export-Package>
    ...
	${project.groupId}.hello.paris*;provide:=true;version=${project.version},
  </Export-Package>
  ...
</instructions>
Copy to Clipboard Toggle word wrap
Exporting a package with the provide:=true clause has a very important side effect: if the code for the exported package is not in the current Maven project, the Maven bundle plug-in adds the package code to the bundle at build time.

Included Maven projects
リンクのコピー

Code from the following Maven projects is included in the hello-paris-impl bundle:
hello-paris-impl
Contains the private package, org.fusesource.example.hello.paris.impl. Build this bundle to create the API/provider build-time combination bundle, hello-paris-impl.
hello-paris
Contains the public API package, org.fusesource.example.hello.paris. This project is a prerequisite for hello-paris-impl and must be built (using mvn install) before the hello-paris-impl project. You do not deploy the hello-paris bundle directly into the OSGi container, however.

Import and export rules
リンクのコピー

The following import and export rules apply to the hello-paris-impl bundle, when it is configured as an API/provider build-time combination:
  • Exporting own packages—no own packages to export, because the hello-paris-impl Maven project contains only private implementation packages.
  • Exporting dependent packages—export the public API package, org.fusesource.example.hello.paris, with the provide:=true clause, which causes the API code to be included in the hello-paris-impl bundle at build time.
  • Importing own packages—import the public API package, org.fusesource.example.hello.paris.
  • Importing dependent packages—any external package dependencies must be imported.

Maven bundle plug-in settings
リンクのコピー

To include the API from the hello-paris bundle in the hello-paris-impl bundle, add the org.fusesource.example.hello.paris package to the Export-Package instruction with the provide:=true clause attached, as shown in Example 2.3, “Plug-In Settings for Build-Time Combination”. Compare this with the regular API/provider case, Example 2.2, “Plug-In Settings for API/Provider Combination”, which takes the same approach of exporting the API package with the provide:=true clause. The semantics, however, are a bit different, because the current example pulls in the API package from a separate Maven project.

Example 2.3. Plug-In Settings for Build-Time Combination

<instructions>
  <Bundle-SymbolicName>${project.groupId}.${project.artifactId}</Bundle-SymbolicName>
  <Import-Package>*</Import-Package>
  <Export-Package>
    !${project.groupId}*.impl*,
    !${project.groupId}*.internal*,
    ${project.groupId}.hello.paris*;provide:=true;version=${project.version},
  </Export-Package>
</instructions>
Copy to Clipboard Toggle word wrap

Assigning versions at package granularity
リンクのコピー

In the preceding example, the included org.fusesource.example.hello.paris API package is given the same version as the hello-paris-impl Maven project, by adding the version=${project.version} clause to the export instruction. In practice, however, you might not always want to assign versions in this way. You might prefer to assign distinct versions to the API package (from the hello-paris Maven project) and the implementation package (from the hello-paris-impl Maven project).
The alternative approach you can take is to store version information at package granularity in a packageinfo file (see the section called “Export versions at package granularity” for details). The Maven bundle plug-in automatically scans your source code, looking for packageinfo files and extracting the version information from them. In this case, you must omit the version clause from the export instruction, as follows: 
  <Export-Package>
    !${project.groupId}*.impl*,
    !${project.groupId}*.internal*,
    <!-- hello.paris version stored in packageinfo -->
 ${project.groupId}.hello.paris*;provide:=true,
  </Export-Package>
Copy to Clipboard Toggle word wrap

Generated MANIFEST.MF file
リンクのコピー

When you build the bundle using Maven, the Maven bundle plug-in automatically generates the following MANIFEST.MF file: 
Manifest-Version: 1.0
Import-Package: org.fusesource.example.hello.paris;version="[1.0,1.1)"
 ,org.fusesource.example.time;version="[1.0,2)",org.osgi.service.bluep
 rint;version="[1.0.0,2.0.0)"
Export-Package: org.fusesource.example.hello.paris;uses:="org.fusesour
 ce.example.time";version="1.0"
Built-By: FBOLTON
Tool: Bnd-1.15.0
Bundle-Name: hello-paris-impl
Created-By: Apache Maven Bundle Plugin
Export-Service: org.fusesource.example.hello.paris.HelloParis
Build-Jdk: 1.6.0_24
Bundle-Version: 1.0.0
Bnd-LastModified: 1302098214984
Bundle-ManifestVersion: 2
Bundle-SymbolicName: org.fusesource.example.hello-paris-impl
Copy to Clipboard Toggle word wrap
The Import-Package header imports both the public API package, org.fusesource.example.hello.paris, and the external package dependencies—for example, org.fusesource.example.time.
The Export-Package header exports the public API package, org.fusesource.example.hello.paris, while the uses clause declares a transitive dependency on the org.fusesource.example.time package.
The Export-Service header advertises the OSGi service as a HelloParis instance.

Bundle deployment
リンクのコピー

Because the hello-paris-impl bundle includes all of the code from the hello-paris Maven project, it is unnecessary to deploy the hello-paris bundle in this case.
トップに戻る
Red Hat logoGithubredditYoutubeTwitter

詳細情報

試用、購入および販売

コミュニティー

Red Hat ドキュメントについて

Red Hat をお使いのお客様が、信頼できるコンテンツが含まれている製品やサービスを活用することで、イノベーションを行い、目標を達成できるようにします。 最新の更新を見る.

多様性を受け入れるオープンソースの強化

Red Hat では、コード、ドキュメント、Web プロパティーにおける配慮に欠ける用語の置き換えに取り組んでいます。このような変更は、段階的に実施される予定です。詳細情報: Red Hat ブログ.

会社概要

Red Hat は、企業がコアとなるデータセンターからネットワークエッジに至るまで、各種プラットフォームや環境全体で作業を簡素化できるように、強化されたソリューションを提供しています。

Theme

© 2025 Red Hat