-----
 Introduction
 -----
 Robert Scholte
 -----
 2015-12-28
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 ~~ Licensed to the Apache Software Foundation (ASF) under one
 ~~ or more contributor license agreements.  See the NOTICE file
 ~~ distributed with this work for additional information
 ~~ regarding copyright ownership.  The ASF licenses this file
 ~~ to you 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.

 ~~ NOTE: For help with the syntax of this file, see:
 ~~ http://maven.apache.org/doxia/references/apt-format.html

Comparison

  Here's a small matrix which should help you choosing the right instance. 

  In general: 
  
  * an Artifact holds a file mapped on a certain coordinate.
  
  * a Dependency contains an artifact and has transitive information
  
  * a MavenProject hold a pom-file and optional mainfile and can have attached (=classified) files, all using the same GAV.

*--------------------+-------------+----------------+---------------+
||                   || Dependency || Artifact      || MavenProject ||
*--------------------+-------------+----------------+---------------+
| Has dependencies   | yes         | no             | yes           |
*--------------------+-------------+----------------+---------------+
| filetype reference | type        | file-extension | packaging     |
*--------------------+-------------+----------------+---------------+
| version ranges     | yes         | no             | no            |
*--------------------+-------------+----------------+---------------+
| attached artifacts | no          | no             | yes           |
*--------------------+-------------+----------------+---------------+

This implies the following:

  * From dependency to artifact is possible, since you can map a type to an extension. 
    However, it is not possible to go from artifact back to dependency, there are several types which have jar as file extension.
    
  * There's no such thing as transitive artifacts. Filtering during resolution as based on DependencyFilters, 
    ArtifactFilters can only be applied afterwards, hence are less efficient.