IOException thrown when processing xsd dependencies in maven - maven

Question

I have a problem while processing .xsd file during my maven build.
I use jaxb2 plugin but I have to download external dependiencies from my .xsd files. The problem is that these dependencies (.xsd) are from enviroment which is unstable and very often my build fails because maven cannot download xsd file. How to configure jaxb plugin to force him to try download xsd few times to prevent build failure?
Part of my pom.xml configuration:
<plugins>
<plugin>
<groupId>org.jvnet.jaxb2.maven2</groupId>
<artifactId>maven-jaxb2-plugin</artifactId>
<configuration>
<strict>false</strict>
<extension>true</extension>
<args>
<arg>-Xfluent-api</arg>
<arg>-XtoString</arg>
<arg>-Xsetters</arg>
<arg>-XenumValue</arg>
</args>
<plugins>
<plugin>
<groupId>net.java.dev.jaxb2-commons</groupId>
<artifactId>jaxb-fluent-api</artifactId>
<version>${jaxb.fluentapi.version}</version>
</plugin>
<plugin>
<groupId>org.jvnet.jaxb2_commons</groupId>
<artifactId>jaxb2-basics</artifactId>
<version>0.9.3</version>
</plugin>
</plugins>
<bindingDirectory>src/main/resources/jaxb</bindingDirectory>
<bindingIncludes>
<include>bindings.xml</include>
</bindingIncludes>
<schemas>
<schema>
<fileset>
<!-- Defaults to schemaDirectory. -->
<directory>${project.basedir}/src/main/resources/orbeons</directory>
<!-- Defaults to schemaIncludes. -->
<includes>
<include>*.xsd</include>
</includes>
</fileset>
</schema>
</schemas>
</configuration>
<executions>
<execution>
<phase>generate-resources</phase>
<goals>
<goal>generate</goal>
</goals>
</execution>
</executions>
</plugin>
<plugin>
<groupId>org.codehaus.mojo</groupId>
<artifactId>build-helper-maven-plugin</artifactId>
<executions>
<execution>
<id>add-source</id>
<phase>generate-sources</phase>
<goals>
<goal>add-source</goal>
</goals>
<configuration>
<sources>
<source>${project.basedir}/generated-sources/orbeons</source>
</sources>
</configuration>
</execution>
</executions>
</plugin>
</plugins>

Answer 1

Author of the maven-jaxb2-plugin here.
You have two parts here: managing the downloads of external resources and compiling the schemas, rewriting "external" links to local files.
The first (managing downloads) is not in the scope of the maven-jaxb2-plugin, the second is supported with
catalogs.
In short, you can create a catalog file like this:
REWRITE_SYSTEM "http://www.w3.org" "w3c"
Or this:
REWRITE_SYSTEM "http://schemas.opengis.net" "maven:org.jvnet.ogc:ogc-schemas:jar::!/ogc"
And use this file to "rewrite" absolute links to local files or resources within Maven artifacts:
<configuration>
<catalog>src/main/resources/catalog.cat</catalog>
</configuration>
As for the first part, I don't think managing downloads with retries, continuations and all other stuff should be in the scope of the JAXB2 Maven plugin.
ps. You don't need build-helper-maven-plugin/add-source with maven-jaxb2-plugin, source directory is added automatically.

Answer 2

Apparently the maven-jaxb2-plugin does not support such a feature. (And neither does the maven-download-plugin nor even the maven-dependency-plugin).
Three solutions come into my mind at the moment (plus two and a half inspired by LIttle Ancient Forest Kami's comment) [Numbers reflect the precedence of what I would do]:
Use a CI tool (Jenkins, etc.) that supports retry on job failure. [1]
Handmade:
Use the GMavenPlus plugin with a script ... [2]
Use the Maven AntRun plugin with a script ... [3]
Use the Exec Maven plugin with a program ... [5]
... that performs the download and retry and bind it to the generate-resources phase in your project's POM.
Create a Maven plugin with appropriate parameters (url, outputDirectory, retryCount) that uses the maven-download-plugin and performs the retry. Bind its goal to the generate-resources phase in your project's POM. [4]
Create a check-download Maven project that uses the maven-download-plugin bound to the generate-resources phase to download the .xsd. [6]
Create a shell script that contains the following (in pseudo code):
download:
counter++
<check-download project>/mvn generate-resources
if error and counter < maxRetryCount goto download
if not error
<your project>/mvn ...
else
display appropriate error message
There is also a question Maven download retry? from 2005. Unanswered.