alpakka-json-streaming cannot be used from Maven as-is

[laszlovandenhoek]

Versions used

2.0.0

Expected Behavior

Adding akka-stream-alpakka-json-streaming_2.xx as a Maven dependency works out of the box.

Actual Behavior

Given a pom.xml like this:

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <groupId>test</groupId>
    <artifactId>test</artifactId>
    <version>0.0.1-SNAPSHOT</version>

    <dependencies>
        <dependency>
            <groupId>com.lightbend.akka</groupId>
            <artifactId>akka-stream-alpakka-json-streaming_2.13</artifactId>
            <version>2.0.0</version>
        </dependency>
    </dependencies>
</project>

Running mvn verify from the command line yields this error:

[ERROR] Failed to execute goal on project test: Could not resolve dependencies for project test:test:jar:0.0.1-SNAPSHOT: Could not find artifact com.github.jsurfer:jsurfer:jar:1.6.0 in nexus

The issue is that there is no JAR, only a POM. However, in the published pom.xml for alpakka-json-streaming, the dependency on com.github.jsurfer:jsurfer:jar:1.6.0 is not qualified as a pom dependency, and thus assumed to be a JAR. It is specified here:

https://github.com/akka/alpakka/blob/master/project/Dependencies.scala#L301

[ennru]

I'm afraid sbt can not express this correctly.

[ennru]

Can we depend on the libraries it points to directly?

[laszlovandenhoek]

From the looks of it you could do away with the jsurfer dependency and keep only jsurfer-jackson, because the former is the parent of the latter and thus would be pulled in transitively. I'm unsure why the former was included in the first place. Removing the explicit jsurfer dependency and running sbt test locally yielded some test failures, but none related to json streaming. The build succeeded, at least, and that's where you'd expect problems, if at all.

I'll submit a PR.

[laszlovandenhoek]

Until the PR is merged and a new version is released, you can work around the problem by excluding the erroneous dependency like so:

<dependency>
    <groupId>com.lightbend.akka</groupId>
    <artifactId>akka-stream-alpakka-json-streaming_2.13</artifactId>
    <version>2.0.0</version>
    <exclusions>
        <exclusion>
            <groupId>com.github.jsurfer</groupId>
            <artifactId>jsurfer</artifactId>
        </exclusion>
    </exclusions>
</dependency>

[ennru]

Fixed with #2344, but I'll leave it open for others to find the temporary fix.

[ennru]

Releasing Alpakka 2.0.2 tomorrow.