SOA 11g MDS - Share Common Artifacts

As promised on my previous post, I am detailing the step-by-step instructions which allows for sharing of common artifacts (schema files/WSDLs) among SOA projects and more importantly helps in loose coupling of service bindings & remove service dependencies.

A typical use case is where the abstract WSDL definition of an external service can be stored in MDS and referenced from the SOA composite which will loosely couple the services and also guard against 'SOA Composite Invalidation' issues.

SOA 11g provides us with MDS repository (both file based & DB based) where common artifacts can be stored and referenced by all projects in the SOA infrastructure.

File based MDS is used during design/deploy time where as DB based MDS is used at run-time by the SOA infra. A configuration file named adf-config.xml that is part of every SOA project manages this partition mapping to be used by JDeveloper during design/deploy time.

All SOA projects that are deployed on the SOA infrastructure are stored in the MDS repository. If you create a connection from the JDeveloper 'Resource Palette' to the SOA MDS, there will be a 'deployed composites' folder which will contain all deployed artifacts.

Connection Information for the MDS connection:
username: XXX_MDS (usually DEV_MDS)
password: xxxxxxxxx
MDS Partition: soa-infra

The file based MDS repository is generally the 'seed' partition under a typical JDeveloper install;

<JDev_Home>\integration\seed


Under this partition there is a root folder (soa) available by default which contains all the configuration files, schemas & WSDLs required by various different SOA components during design time. These files are also pre-deployed on the database MDS repository.

We are now free to create custom folders under the 'seed' partition to hold artifacts that are common references in a SOA environment. Generally, we create an 'apps' folder under the 'seed' partition which in turn holds various folders to hold various artifact types;

 Once the artifacts that needs to be shared/referenced are placed under the appropriate namespace (in this case 'apps'), we can let the SOA project in JDeveloper to point to MDS for these artifacts from a common location.

adf-config.xml configuration:

As noted earlier, adf-config.xml is an important configuration file which holds the details regarding the MDS (both file based & DB based). By default, this file declares the 'seed' partition & the metadata store for 'soa' namespace.

This file can be found under <YourApplication>\.adf\META-INF.
Alternatively, in JDeveloper, expand the 'Application Resources' panel; drill through Descriptors -> ADF META-INF to find this file

Step 1: Just add the metadata store namespace for '/apps' in additions to default '/soa/shared' namespace - This is to let the JDeveloper reference the artifacts under the '/apps' during the design time from the file system metadata store.

<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_1"/>
        </metadata-namespaces>
        <metadata-store-usages>
          <metadata-store-usage id="mstore-usage_1">
            <metadata-store class-name="oracle.mds.persistence.stores.file.FileMetadataStore">
              <property name="metadata-path"
                        value="${oracle.home}/integration"/>
              <property name="partition-name" value="seed"/>
            </metadata-store>
          </metadata-store-usage>
        </metadata-store-usages>
      </persistence-config>
    </mds-config>
  </adf-mds-config> 

Step 2: In the SOA composite, reference the common artifacts from MDS as shown below;

 <import namespace="http://xmlns.oracle.com/bpmn/bpmnProcess/CreditCardProcess"
          location="oramds:/apps/orderprocess/common/CreditServiceProcess.wsdl"
          importType="wsdl"/>

Now that we have successfully referenced the SOA project to refer the file based MDS it is barely enough only during design time. For deploy time & run time, these artifacts must be made available in the DB based MDS.

There are two methods available for us to deploy the artifacts in SOA DB based MDS;

Approach 1: Ant based script which allows to deploy the artifacts into SOA MDS. I am not going to get to the details of this as this has been blogged in detail by Edwin Biemond; Reference below;

http://biemond.blogspot.com/2009/11/soa-suite-11g-mds-deploy-and-removal.html

Approach 2: For a simple JDeveloper based SOA deployment follow the steps below;

Step 1: Create a new application (Generic Application)

Step 2: Name the application (eg., OrderProcessMDSApp) and click 'Next'

 Step 3: Provide a name to the project (eg., OrderProcessMDSProj) and click 'Finish'

 Step 4: Now, right click on the OrderProcessMDSProj and choose 'Project Properties'. In the 'Project Properties' dialog, choose 'Deployment' and create a new deployment profile by clicking on 'New...' button

 Step 5: In the 'Create Deployment Profile' dialog, leave the default 'Archive Type' to 'JAR File' and name the deployment profile (eg., soamdsarchive) and click 'OK'

 Step 6: This will open up the 'Edit JAR Deployment Profile Properties' dialog. Click on the 'Contributors' section under 'File Groups -> Project Output'.

Step 7: Click on the 'Add..' button and choose the folder where the 'content to be deployed' is present. Here the '/apps' namespace under the file based MDS can be chosen where the content is already placed & available.

Step 8: Now, click on the 'Filters' section and choose the artifacts under the '/apps' that you would like to deploy or upload to MDS database repository

Step 9: Click on OK to complete the deployment profile creation process. Now, we have created a project JAR deployment profile which contains the artifacts to be deployed on to the SOA MDS. Now, we will have to create a application deployment profile of 'soa bundle' type which will be deployed to the soa-infra.

Step 10: From the 'Application Menu', choose 'Deploy' -> 'New Deployment Profile..' option

Step 11: Under the 'New Gallery' go to 'Deployment Profiles' choose 'SOA Bundle' and click OK

Step 11: Under the 'Create Deployment Profile', provide a name to the application deployment profile (eg., soabundle1) and click OK.

Step 12: In the 'SOA Bundle Deployment Profile Properties' go to 'Dependencies' and choose the JAR archive that we created earlier eg., soamdsarchive and click OK

Finally, deploy the application to the soa server. This will ensure that the artifacts under the '/apps' metadata namespace is deployed on to the SOA MDS database repository.

You can verify the same from the SOA MDS connection created under the 'Resource Palette'. This should now reflect the 'apps' folder at the same level as 'soa' metadata store.

Now, if you try to deploy the SOA project which references MDS you may hit a deployment error complaining that the resource referenced is not found. This is because the JDeveloper consults adf-config.xml configuration file during design & deploy time (refer back to the initial architecture diagram). Since there is no information about the DB based MDS in the adf-config the deployer complains.

To fix this, go back to the adf-config.xml file and add the DB metadata store information so that the deployer can read & locate the referenced resources from MDS.

<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_2"/>
          <namespace path="/apps" metadata-store-usage="mstore-usage_2"/>
        </metadata-namespaces>
        <metadata-store-usages>
          <metadata-store-usage id="mstore-usage_2">
            <metadata-store class-name="oracle.mds.persistence.stores.db.DBMetadataStore">
              <property value="DEV_MDS" name="jdbc-userid"/>
              <property value="xxxxxxx" name="jdbc-password"/>
              <property value="jdbc:oracle:thin:@hostname:1521:orcl"
                        name="jdbc-url"/>
              <property value="soa-infra" name="partition-name"/>
            </metadata-store>
          </metadata-store-usage>
        </metadata-store-usages>
      </persistence-config>
    </mds-config>
  </adf-mds-config>

That completes our configuration and eventually this elaborate post. Now, the deployment will be smooth as we have referenced the DB MDS in the adf-config.xml file.

Hope this post helped you understand & implement the SOA MDS related activities. Let me know your feedback through comments.

Abstract WSDL vs Concrete WSDL

In recent times, the abstract WSDL terminology is used more than ever and I am seeing more & more coffee-table discussions on this topic. In this post I will make an effort to provide an illustrated explanation in regards to the differences & usage of concrete and abstract WSDL.

First up, abstract WSDL is not a new technology. A typical WSDL (Web Services Description Language) consists of the following sections; types, messages, portType, binding & service elements. A quick look at what each of these sections define will ease the task of clarification of the differences;

Types - Defines the data type definitions for messages that will be exchanged by the web service. Generally defined from a schema (XSD)

Message - Defines the set of actual messages that will be exchanged. A message can consist of one or more parts which is a logical separation which together constitutes the message.

PortType - Defines the abstract operations provided/available and abstract messages involved. Operation refers to the messages involved in the transaction.

Bindings - Defines the message format and protocol information for operations defined by the portType.

Service - Defines the endpoint where the webservice will be exposed

Based on these definitions, we can figure out that the Types, Message & PortType sections of a WSDL definition is abstract (since it has no information pertaining to the communication protocol & how or where the service is exposed) where as the Bindings & Service section is concrete.

Hence, if we have a WSDL which just has these elements (excluding the Bindings & Service sections), then the WSDL is referred to as "Abstract WSDL". This WSDL definition cannot be used to connect to the webservice due to the 'missing information' on where & how the service is exposed. But there are certain advantages with abstract wsdl which we will see in a bit.

Definition of concrete WSDL now becomes a no-brainer. If a WSDL has all the sections - including the concrete parts such as Bindings & Service then it is referred to as a concrete WSDL. This WSDL defnition can be used to connect to the actual service since it has the protocol and service endpoint information.

Now, where exactly do we use an abstract WSDL?

Coming to the world of SOA, I am taking the example of Oracle SOA composites referencing external services. Ever wondered why some SOA composites are in "Invalid State" even though all the services that it references are up & available? This is because of the usage of concrete WSDL reference where the referenced service is not available yet when the caller service composite starts up. There is no way for the server to know about the service dependencies when it starts. By leveraging the concept of the abstract WSDL, we would be able to effectively resolve dependencies both at design time as well as runtime.

More on resolving service dependency issues in SOA on my next post here