In a previous post I described how to have the integrated Weblogic of your SOA/BPM QuickStart refer to the same filebased MDS that you might refer to in the SOADesignTimeRepository in JDeveloper.

These days for my current customer I'm looking into upgrading 11g, as can be read from my previous posts. This customer also has a legacy with projects migrated from 10g.

In the 11g workspace there was a reference to the database MDS in the Development database. In 12c we have a designtime mds reference. I would recommend to refer that to the mds artefacts in your VCS (Version Control System: svn or git) working copy. To do so, call-up the Resources pane in JDeveloper and right click on the SOADesignTimeRepository:
Then navigate to the location in your working copy:
Mind that SOASuite expects an apps folder within this folder, so resulting references in the composite.xml, etc. are expected to start with oramds:/apps/....

Now, I migrated a few projects including a adf-config.xml. In stead of the DB MDS repo, I replaced it with a file-based reference in the adf-config.xml, refering to the SOADesignTimeRepository. If you create a new 12c SOA Application, the adf-config.xml will look like:

<?xml version="1.0" encoding="windows-1252" ?>
<adf-config xmlns="http://xmlns.oracle.com/adf/config" xmlns:adf="http://xmlns.oracle.com/adf/config/properties"
            xmlns:sec="http://xmlns.oracle.com/adf/security/config">
  <adf:adf-properties-child xmlns="http://xmlns.oracle.com/adf/config/properties">
    <adf-property name="adfAppUID" value="MyApplication-1234"/>
  </adf:adf-properties-child>
  <sec:adf-security-child xmlns="http://xmlns.oracle.com/adf/security/config">
    <CredentialStoreContext credentialStoreClass="oracle.adf.share.security.providers.jps.CSFCredentialStore"
                            credentialStoreLocation="../../src/META-INF/jps-config.xml"/>
  </sec:adf-security-child>
  <adf-mds-config xmlns="http://xmlns.oracle.com/adf/mds/config">
    <mds-config xmlns="http://xmlns.oracle.com/mds/config">
      <persistence-config>
        <metadata-namespaces>
          <namespace path="/soa/shared" metadata-store-usage="mstore-usage_1"/>
          <namespace path="/apps" metadata-store-usage="mstore-usage_2"/>
        </metadata-namespaces>
        <metadata-store-usages>
          <metadata-store-usage id="mstore-usage_1">
            <metadata-store class-name="oracle.mds.persistence.stores.file.FileMetadataStore">
              <property name="partition-name" value="seed"/>
              <property name="metadata-path" value="${soa.oracle.home}/integration"/>
            </metadata-store>
          </metadata-store-usage>
          <metadata-store-usage id="mstore-usage_2">
            <metadata-store class-name="oracle.mds.persistence.stores.file.FileMetadataStore">
              <property name="metadata-path" value="${soamds.apps.home}"/>
            </metadata-store>
          </metadata-store-usage>
        </metadata-store-usages>
      </persistence-config>
    </mds-config>
  </adf-mds-config>
</adf-config>

In the metadata-store-usage with id mstore-usage_2 you'll find the reference ${soamds.apps.home} in the metadata-path property. This refers to the folder as choosen in your SOADesignTimeRepository.

Now, I found in the past several times that although the adf-config.xml was similar to the above, that the MDS references did not work. In those cases, as a workaround, I put the absolute path reference in the metadata-path property.

Today I found something similar because of the upgrade, and searched on MDS-01333: missing element "mds-config" This resulted in this article, that gave me the hint.

It turns out that the snippet:

  <adf:adf-properties-child xmlns="http://xmlns.oracle.com/adf/config/properties">
    <adf-property name="adfAppUID" value="MyApplication-1234"/>
  </adf:adf-properties-child>

get's in the way. the UID refers to the application name and some generated number. It turns out not enough to change it the name of the application with a generated number. I haven't found what the proper number should be. So I just removed that snippet and then it worked.