CODEWITHSUNDEEP
javamavendependency-managementtransitive-dependency
J Fabian Meier
J Fabian Meier

Reputation: 35901

Transitive effect of dependencyManagement

In Maven you can override the version number of a transitive dependency by an entry in dependencyManagement because dependencyManagement takes precedence over transitive dependency definitions.

But what about dependencyManagement definitions in the poms of (transitive) dependencies? Are they considered at all? If so, what do they override, how are they overridden?

Upvotes: 15

Views: 1510

Answers (2)

Anton Koscejev
Anton Koscejev

Reputation: 4857

Dependency management is implied to be transitive. There doesn't need to be a special rule for this, but rather it's a consequence of the already mentioned rules: Transitive Dependencies.

Consider this example structure:

  • your module
    • A - dependency
      • D - transitive dependency
    • B - dependency
      • D - transitive dependency

When A or B are built, their corresponding dependencyManagement section is checked to pick version for D, if it's not explicitly specified. Here's the important part: exactly the same process is used when A or B are used as dependencies to determine which version of D they depend on. Consequently, they do not affect each other in any way.

This could result, for example, in A depending on D:1.0, and B depending on D:1.1, their dependencyManagement sections have already been applied at this point to determine this and will not be taken into account anymore. With this information as input, dependency mediation rules are applied to pick just one version of D for your module.

Dependency mediation rules are also described in the linked page. But in a nutshell, the nearest definition wins and ties are broken based on order. Naturally, definitions in your module itself are always the nearest.

Now let's say your module is used as a dependency. Your project could depend on D:1.2 based on all the rules above due to a definition in your dependencyManagement section, but that's where the scope of your dependencyManagement ends.

(Note that import scope is an exception as it behaves completely differently from the other scopes.)

Upvotes: 2

Hisham Khalil
Hisham Khalil

Reputation: 1084

dependencyManagement definitions in the poms of transitive dependencies are considered as long as they are not been overridden in the dependencyManagement of your project or a closer dependency (in the tree of dependencies).

in another words,

Dependency mediation: the rule is easy

  • "nearest definition" which means that it will use the version of the closest dependency to your project in the tree of dependencies.

  • if two dependency versions are at the same depth in the dependency tree, the first declaration wins (declaration order).

for more details see Transitive Dependency

hope this helps.

Upvotes: 0

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