VersionCompatibility.java

/*-
 * -\-\-
 * Helios Client
 * --
 * Copyright (C) 2016 Spotify AB
 * --
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 * -/-/-
 */

package com.spotify.helios.common;

//* Using the meanings from http://semver.org
public class VersionCompatibility {
  public static final String HELIOS_VERSION_HEADER = "Helios-Version";
  public static final String HELIOS_SERVER_VERSION_HEADER = "Helios-Server-Version";
  public static final String HELIOS_VERSION_STATUS_HEADER = "Helios-Version-Status";

  public enum Status {
    EQUAL,
    COMPATIBLE,
    MAYBE,
    INCOMPATIBLE,
    INVALID,
    MISSING
  }

  public static Status getStatus(final PomVersion serverVersion, final PomVersion clientVersion) {
    // WARN has to be dealt with on an ad-hoc basis.  Since no warnings at this time, we don't
    // have any code here

    if (serverVersion.equals(clientVersion)) {
      return Status.EQUAL;
    }

    if (serverVersion.getMajor() != clientVersion.getMajor()) {
      return Status.INCOMPATIBLE;
    }

    // older clients, newer server within major version
    if (serverVersion.getMinor() >= clientVersion.getMinor()) {
      return Status.COMPATIBLE;
    }

    // newer client, older server within major version
    return Status.MAYBE;
  }
}