jar dependency match with json report

Problem

Coursier command:

fetch -t \
com.esotericsoftware.reflectasm:reflectasm:1.09,classifier=shaded \ # from pants jar_dep A
com.esotericsoftware.reflectasm:reflectasm:1.09 \ # from pants jar_dep B
org.ow2.asm:asm:4.0,classifier=sources \ # from pants jar_dep C
-A jar,src,doc,test-jar --json-output-file x.out

  Result:
├─ com.esotericsoftware.reflectasm:reflectasm:1.09
│  └─ org.ow2.asm:asm:4.0
├─ com.esotericsoftware.reflectasm:reflectasm:1.09
│  └─ org.ow2.asm:asm:4.0
└─ org.ow2.asm:asm:4.0

Since there are 3 roots to resolve, the tree is correct. One com.esotericsoftware.reflectasm:reflectasm:1.09 wants the default jar, and the other wants the shaded classifier jar. (UI wise it could be better to show that which is which)

Now look at the json output:

{
  "conflict_resolution": {},
  "dependencies": [
    {
      "coord": "org.ow2.asm:asm:4.0",
      "files": [
        [
          "sources",
          "<cache_dir>/https/repo1.maven.org/maven2/org/ow2/asm/asm/4.0/asm-4.0-sources.jar"
        ]
      ],
      "dependencies": []
    },
    {
      "coord": "com.esotericsoftware.reflectasm:reflectasm:1.09",
      "files": [
        [
          "shaded",
          "<cache_dir>/https/repo1.maven.org/maven2/com/esotericsoftware/reflectasm/reflectasm/1.09/reflectasm-1.09-shaded.jar"
        ]
      ],
      "dependencies": [
        "org.ow2.asm:asm:4.0"
      ]
    },
    {
      "coord": "org.ow2.asm:asm:4.0",
      "files": [
        [
          "",
          "<cache_dir>/https/repo1.maven.org/maven2/org/ow2/asm/asm/4.0/asm-4.0.jar"
        ]
      ],
      "dependencies": []
    },
    {
      "coord": "com.esotericsoftware.reflectasm:reflectasm:1.09",
      "files": [
        [
          "",
          "<cache_dir>/https/repo1.maven.org/maven2/com/esotericsoftware/reflectasm/reflectasm/1.09/reflectasm-1.09.jar"
        ]
      ],
      "dependencies": [
        "org.ow2.asm:asm:4.0"
      ]
    }
  ]
}

For jar_dep A, it has to find the coordinate “com.esotericsoftware.reflectasm:reflectasm”. There are two of them, but it knows to find the one with classifier ‘shaded’:

    {
      "coord": "com.esotericsoftware.reflectasm:reflectasm:1.09",
      "files": [
        [
          "shaded",
          "<cache_dir>/https/repo1.maven.org/maven2/com/esotericsoftware/reflectasm/reflectasm/1.09/reflectasm-1.09-shaded.jar"
        ]
      ],
      "dependencies": [
        "org.ow2.asm:asm:4.0"
      ]
    },

Great. jar_dep A grabs reflectasm-1.09-shaded.jar into its collection. Then it needs to grab its dependencies as well. Given the clue org.ow2.asm:asm:4.0, it finds:

    {
      "coord": "org.ow2.asm:asm:4.0",
      "files": [
        [
          "",
          "<cache_dir>/https/repo1.maven.org/maven2/org/ow2/asm/asm/4.0/asm-4.0.jar"
        ]
      ],
      "dependencies": []
    },

and

    {
      "coord": "org.ow2.asm:asm:4.0",
      "files": [
        [
          "sources",
          "<cache_dir>/https/repo1.maven.org/maven2/org/ow2/asm/asm/4.0/asm-4.0-sources.jar"
        ]
      ],
      "dependencies": []
    },

Now, there is no way to tell which it needs, because all it knows is just org.ow2.asm:asm:4.0. Currently Pants’ behavior is to grab both. However the correct jar to grab is just asm-4.0.jar and not asm-4.0-sources.jar

Proposed solution

Option 1:

Add classifier to dependencies org:name:version, i.e. org:name:version:classifier. For the same example:

{
  "conflict_resolution": {},
  "dependencies": [
    {
      "coord": "org.ow2.asm:asm:4.0",
      "files": [
        [
          "sources",
          "<cache_dir>/https/repo1.maven.org/maven2/org/ow2/asm/asm/4.0/asm-4.0-sources.jar"
        ]
      ],
      "dependencies": []
    },
    {
      "coord": "com.esotericsoftware.reflectasm:reflectasm:1.09",
      "files": [
        [
          "shaded",
          "<cache_dir>/https/repo1.maven.org/maven2/com/esotericsoftware/reflectasm/reflectasm/1.09/reflectasm-1.09-shaded.jar"
        ]
      ],
      "dependencies": [
        "org.ow2.asm:asm:4.0:<empty classifier>"
      ]
    },
    {
      "coord": "org.ow2.asm:asm:4.0",
      "files": [
        [
          "",
          "<cache_dir>/https/repo1.maven.org/maven2/org/ow2/asm/asm/4.0/asm-4.0.jar"
        ]
      ],
      "dependencies": []
    },
    {
      "coord": "com.esotericsoftware.reflectasm:reflectasm:1.09",
      "files": [
        [
          "",
          "<cache_dir>/https/repo1.maven.org/maven2/com/esotericsoftware/reflectasm/reflectasm/1.09/reflectasm-1.09.jar"
        ]
      ],
      "dependencies": [
        "org.ow2.asm:asm:4.0:<empty classifier>"
      ]
    }
  ]
}

Now jar_dep A knows the dependency is org.ow2.asm:asm:4.0:<empty classifier>, thus finding the following and grabs asm-4.0.jar only.

    {
      "coord": "org.ow2.asm:asm:4.0",
      "files": [
        [
          "",
          "<cache_dir>/https/repo1.maven.org/maven2/org/ow2/asm/asm/4.0/asm-4.0.jar"
        ]
      ],
      "dependencies": []
    },

Option 2: Make both coord and dependencies to adopt org:name:version:classifier. I am not sure what the report would look like when --sources and --javadoc are both specified, so might need more thoughts there. But option 1 should be more straight forward.

[baroquebobcat]

One thought I had here is that with either option I think we ought to adopt Maven’s coordinate structure instead of org:name:version:classifier. Maven’s coordinates have 3 different forms.

• Default org:name:version, eg org.ow2.asm:asm:4.0
• Including packaging/type org:name:packaging:version, eg org.ow2.asm:asm:jar:4.0
• Including classifier org:name:packaging:classifier:version, eg org.ow2.asm:asm:jar:sources:4.0

By using the above scheme we don’t have to have an explicit value for empty classifier because it’s encoding in the formatting. It also opens up a place to include file-extension/packaging information on a per artifact level.

I don’t know enough about the currently accepted schema to be sure that this’ll work, but I’d appreciate some feedback.

[wisechengyi]

closed by d0b46864c832ec1315ff886e55f6b94dfa3dfb0d