Apache Tamaya - Extension: Remote Configuration

2019-06-04

Tamaya Remote Configuration (Extension Module)

Tamaya Remote is an extension module. Refer to the extensions documentation for further details.

What functionality this module provides ?

Tamaya Remote provides support for reading configuration from remote resources. It provides out-of-the-box support for reading scoped configuration from a Tamaya configuration server as provided with the Tamaya server module .

Compatibility

The module is based on Java 7, so it will not run on Java 7 and beyond.

Installation

To use remote support you only must add the corresponding dependency to your module:

<dependency>
  <groupId>org.apache.tamaya.ext</groupId>
  <artifactId>tamaya-remote</artifactId>
  <version>0.4-incubating-SNAPSHOT</version>
</dependency>

Reading Remote configuration from a Tamaya Configuration Server

The remote module allows reading JSON formatted configuration as provided by the Tamaya server extension . The JSON format used looks as follows:

{
  "java.vendor.url": "http://java.oracle.com/",
  "java.vendor.url.bug": "http://bugreport.sun.com/bugreport/",
  "java.vm.info": "mixed mode",
  "java.vm.name": "Java HotSpot(TM) 64-Bit Server VM",
  "java.vm.specification.name": "Java Virtual Machine Specification",
  "java.vm.specification.vendor": "Oracle Corporation",
  "java.vm.specification.version": "1.8",
  "java.vm.vendor": "Oracle Corporation",
  "java.vm.version": "25.45-b02",
  "sun.arch.data.model": "64",
  "sun.boot.class.path": "C:\apps\jdk18\jre\lib\resources.jar;C:\apps\jdk18\jre\lib\rt.jar;C:\apps\jdk18\jre\lib\sunrsasign.jar;C:\apps\jdk18\jre\lib\jsse.jar;C:\apps\jdk18\jre\lib\jce.jar;C:\apps\jdk18\jre\lib\charsets.jar;C:\apps\jdk18\jre\lib\jfr.jar;C:\apps\jdk18\jre\classes",
  "sun.boot.library.path": "C:\apps\jdk18\jre\bin",
  "sun.cpu.endian": "little",
  "sun.cpu.isalist": "amd64",
  "sun.desktop": "windows",
  "sun.io.unicode.encoding": "UnicodeLittle",
  "sun.java.command": "com.intellij.rt.execution.application.AppMain org.apache.tamaya.examples.remote.server.Start",
  "sun.java.launcher": "SUN_STANDARD",
  "sun.jnu.encoding": "Cp1252",
  "sun.management.compiler": "HotSpot 64-Bit Tiered Compilers",
  "sun.os.patch.level": "",
  "_class": "org.apache.tamaya.functions.FilteredConfiguration",
  "_info.filter": "java.v,sun",
  "_info.format": "application/json",
  "_info.timestamp": "1441463200571",
  "_timestamp": "1441463200571",
  "_type": "Configuration"
}

Basically there are no constraints about they keys provided. By default Tamaya uses keys prefixed with '_' to identify meta-data entries, but this is not a required precondition.

Finally such a remote configuration can be easily integrated by inheriting from the provided base class. Hereby a default ordinal must be defined and the protected Collection<URL> getAccessURLs() method must be implemented to define the URL from where the configuration should be accessible. Hereby multiple URLs can be provided, which are accesed in order as provided by the collection’s iterator. The first accessible URL determines the configuration read.

public class RemotePropertySource extends BaseRemotePropertySource{

    @Override
    protected Collection<URL> getAccessURLs() {
        try {
            String configServerUrl = System.getenv("CONFIG_SERVER");
            if(configServerUrl==null){
                configServerUrl = System.getProperty("configServer");
            }
            if(configServerUrl==null){
                configServerUrl = "http://localhost:8888/config?scope=CLIENT&scopeId={clientId}&format=application/json";
            }
            System.out.println("Reading config from " + configServerUrl.replace("{clientId}", Client.getClientId()));
            return Arrays.asList(new URL[]{new URL(configServerUrl.replace("{clientId}", Client.getClientId()))});
        } catch (MalformedURLException e) {
            Logger.getLogger(getClass().getName()).log(Level.WARNING, "Failed to configure remote config location,", e);
            return Collections.emptySet();
        }
    }

}