Article published | Fault Handling and Prevention (II)

Oracle Technology Network (OTN) published the article Fault Handling and Prevention - Part 2 (Fault Handling and Prevention for Services in Oracle Service Bus) by Ronald van Luttikhuizen and Guido Schmutz.


Part 1 of this article series on Fault Handling and Prevention discussed what fault handling is and why it is important. It also addressed the specific challenges in handling faults in a service-oriented landscape as compared to traditional systems. Part 1 concluded by presenting a sample scenario, an Order process implemented in a BPM and SOA environment, discussed potential pitfalls, and described generic fault prevention and recovery patterns.

Part 2 concentrates on concrete fault handling and prevention measures in the integration layer that are realized through Oracle Service Bus (OSB). The integration layer covers typical elements and integration functionality, such as Adapters for connectivity to back-end systems, Routing, Transformation, and Filtering.

More resources

• Fault Handling Slides and Q&A, Blog, Vennster

• Service Oriented Architecture: An Integration Blueprint, Book, Packt Publishing

• Patterns for Fault Tolerant Software, Book, Wiley Software Patterns Series

• Oracle Fusion Middleware Developer's Guide for Oracle SOA Suite, Oracle Technology Network
• SOA Made Simple, Book, Packt Publishing

Stay tuned for parts III and IV of the article! 

About the authors

Ronald van Luttikhuizen is Managing Partner and Architect with Vennster and an Oracle ACE Director
Guido Schmutz is Technology Manager for SOA and Emerging Trends with Trivadis and an Oracle ACE Director

Oracle User Group Norway 2013 | Part 2

Lonneke talked about our experiences and the middleware content at the Oracle User Group Norway (OUGN) Vårseminar 2013 conference in her last blog. This blog adds some photos to give you an impression of this unique "Conference as/on a Cruise".

Conference badge

Just before we left for Oslo, we found out that Justin Bieber was performing there in the same week that Vårseminar was held. Since the first day of the conference was ashore, we needed a hotel. Problem was that all the Beliebers and their entourage of concerned parents already booked all hotel rooms in the city. Fortunately there were some free rooms in a hotel in a smaller village nearby Oslo.

On our way to the hotel outside Oslo

Surroundings of the hotel, still snowy and icy in Norway

After the first day all attendees boarded the Color Line to continue the conference on the ferry from Oslo to Kiel in Germany. You can view the route we travelled on Markus Eisele's blog.

Waiting to board the Color Line

Cabin on board of the Color Line

Cabin on board of the Color Line

After boarding and several keynote speeches, the separate tracks started on the top deck including the middleware track. So far Norwegian was pretty readable. Words were recognizable since they looked like their Dutch or English counterparts. The Norwegian keynotes and Norwegian stand-up taught us that reading is one thing, but speaking and listening is completely different and unable to follow for Dutch people. The laughter was pretty infectuous though.

Lonneke Dikmans presenting on deployment best practices

Until that time the big ferry gently rocked and only added to the relaxed atmosphere. However, by the end of the day the Baltic Sea became so rocky that the presenters had to sit down to avoid falling down during their speeches.

Rocky sea

Rocky sea

Precautions for a rocky sea

Luckily I had no problems sleeping that night and didn't need a paper bag. On the second day of the cruise we arrived in Kiel. Between sessions there was time to leave the ferry and indulge in a German lunch. At least, if you weren't feeling to seasick.

Arriving in Kiel

Healthy German lunch

After boarding we set sail for Oslo again and continued with the conference sessions. Between sessions you could enjoy the amenities of the ferry.

Color Line promenade

Color Line promenade

One of the reastaurants on the Color Line 

One of the reastaurants on the Color Line 

Saterday we arrived back in Oslo and departed the Color Line to fly back home after a fun and successful conference. It took some days before the sea legs completely vanished.

A big thanks to the conference and user group board who put together a well-organized and unique conference! Thanks for having us.

Oracle User Group Norway 2013

Vennster participates in conferences on a regular basis. It is a great way to meet people and learn things. After hearing stories about a conference on a boat, Ronald van Luttikhuizen and me decided to try the Oracle User Group Norway Conference for ourselves. The first day of the conference is in Oslo, in a hotel. We did not have time to attend sessions that day. The first day on the boat I spent in the “Middleware Room”. Ronald gave his presentation about Service Design. It is based on a chapter of SOA Made Simple and he talked about service identification, service design guidelines and service implementation. The room was full and the audience was engaged; there were a number of questions during the presentation and afterwards as well.

 

OUGN 2013 - SOA Made Simple: Service Design from Ronald van Luttikhuizen

The next presentation was by Manas Deb and he talked about Adaptive Case management. He explained the concepts, the difference between BPM and Case Management and what makes case management adaptive. In short: in adaptive case management you don’t know in advance in what order tasks are executed (non-deterministic) and ad hoc tasks can be added by the case worker or case manager. Then he explained how the latest patch set of Oracle supports this concept by introducing a new component type: “Case”.

Cato Aune and Jon Peter Hjulstad presented about their experiences with Oracle WebLogic 12c. They talked about the differences between Oracle iAS and WebLogic, about licensing and their experience with migrating from Oracle iAS to WebLogic 12c in two projects. Very applicable to a lot of customers and a story well told.

I had the honor to close the day with my session about deployment best practices.

Deployment in Oracle SOA Suite and in Oracle BPM Suite from Lonneke Dikmans

The second day on the boat I attended two sessions: A talk about JEE7 and a talk about B2B by Ronald. Arun Gupta talked about JEE7. It was a very interesting presentation. The scope of JEE7 has two focus points: higher productivity and HTML5 support. He showed code samples from NetBeans to illustrate the different aspects. The WebSocket, JAX_RS 2.0 and JSON support were particularly relevant. Last but not least he talked about support for batch in the specification (finally!) which is very similar to Spring batch.  The last session of the conference was Ronald his story about using B2B for the Province of Overijssel, a very clear story about the ebMS specification, the use case and the solution.

 

OUGN 2013 - Using B2B in a Dutch Government Project from Ronald van Luttikhuizen

To summarize, there were not many presentations on Middleware but the ones that were there, were of very high quality and being on a boat surely spices up the whole experience!

Mobile for business users

As I mentioned in a previous blog, Oracle Fusion Apps breaks with Oracle's past in the sense that the user interaction is built from a user perspective. Rather than exposing a datamodel or a business process to the user, they have designed the user interface based on information they have gathered about their user. Their website tells this compelling story, go check it out (after finishing this blog ;).

The world goes mobile

These days you can't just design for the desktop anymore. People use other devices like tablets and mobile phones and these devices are showing up in the workplace more and more. On top of that, people are working from different locations: from the office, from home, en route, or wherever they happen to be. This creates a new challenge when creating services or application. Take for example a HR self service application or an expense report application. Employees expect this functionality to be available everywhere, and on all devices.
At the other hand, organizations are struggling with the application of 'apps'. When I started programming, every piece of software had to have an API. Then the world realized that you want to integrate systems in heterogeneous landscapes and every piece of software needed to have a 'service interface'. Now that we have apps, every piece of software I realize needs to have a REST API so that people can create an app for that. The problem with this approach is that creating a service interface on every piece of software does not create a good service oriented architecture and creating a mobile interface for every piece of software does not create a good mobile user experience for your customers, employees and partners. So how should you approach this?

Oracle Fusion Applications User Experience Patterns and Guidelines 

The ADF User Experience patterns and guidelines site is a very good starting point for organizations that want to start using mobile for their applications. The site has four sections:

1. Design guidelines. This section explains that mobile design differs from designing for desktops. It  then states 10 mobile design guidelines. The most important ones are at the top: know your user and define the essential mobile task
2. Know your user is a separate section that talks about getting to know your user. You have to revisit your idea of your user and determine who will use your application on a mobile device and in what context this will happen. Creating personas is a very good technique that you can apply. The site has some references to this technique at the bottom. 
3. Create a mobile task flow. This section explains how your mobile tasks fit in the overall business process. Unfortunately this section is rather short and uses flow charting to show the flow in the user interface, and not the overall business process. It is very important that the business process and the (mobile) user interaction that is designed from the perspective of the user are aligned: otherwise you get into trouble with rules and regulations that exist in your organization for the business process that people are accessing using their mobile device.
4. Mobile design patterns. Users may not be used to using mobile applications for work, they use it at home and in their personal lives all the time. So using patterns that people are familiair with is important. You as a developer doesn't have to re-invent the wheel when creating the mobile tasks and your users are happy because the application works the way they expect. This will save money because there will less calls to the helpdesk, less errors and your application will actually be used ;)

OBUG Connect

Ultan Ó Broin and me will present some mobile design patterns that are defined in the process of designing mobile applications for Fusion apps at OBUG connect 2013, this afternoon. We will explain the importance of patterns and show some of the patterns that can be built with either ADF Mobile, or the native platform of a device.

Next: apply!

The next step is that projects start using these techniques to built user interaction for professional users, like we have been doing for consumer software for a long time. It is time that professionals get the user experience they deserve and need to be productive and happy while doing their job!

SOA Made Simple

The book SOA Made Simple is published! SOA Made Simple is written by Vennster's Lonneke Dikmans and Ronald van Luttikhuizen. You can download a sample chapter and order the book from the Packt Publishing website. 

SOA Made Simple is a concise and indispensable handbook for finally understanding exactly what Service Oriented Architecture is. Split into three clear sections, in this book you’ll learn from both theory as well as step-by-step implementation examples to aid in your understanding of this often poorly- articulated industry term.

A short abstract for SOA Made Simple:

SOA is an industry term which is often preached like a religion rather than taught like a technology, and over time, grasping the concept has become unnecessarily difficult. Many companies proclaim that they don’t know where to begin with SOA, while others have begun their SOA effort but haven’t reaped the benefits they were convinced it would bring. “SOA Made Simple” explains what SOA is in simple terminology and by using real-life examples. Service-orientation is already a very natural way of thinking for business stakeholders that want to realize and sell services to potential clients, and this book helps you to realize that concept both in theory and practice. After reading “SOA Made Simple” you will have a clear understanding ofwhat SOA is so you can implement and govern SOA in your own organization. If you are an architect who wants to be completely clear in your understanding of what SOA is, then this book is essential. In fact, anyone (designer, developer, administrator or team lead) who is implementing or about to implement an architecture in an IT environment should not miss out on “SOA Made Simple”. 

From the Trenches 3 | Patching OSB and SOA Suite to PS5

In two previous blogs (part I and part II) I talked about a recent upgrade from Oracle Fusion Middleware 11g PS2 to 11g PS5. This blog finishes with a post-installation step that was required to complete the upgrade and a quick note.

All in all, after a good preparation the team was able to patch a production environment to PS5 in almost an afternoon. The environment runs several Fusion Middleware products (OSB, SOA Suite, OID, WebLogic Servers for JEE apps) and spans multiple WebLogic Domains and multiple WebLogic Managed Servers in single-node clusters.

Migrating running composite instances that use While activities

One of the new features in SOA Suite 11g PS3 is that the Enterprise Manager Fusion Middleware Console shows the loop count in the BPEL Audit Trail when using While activities. This is shown in the following figure.

This feature works for new instances that are created after applying the patchset and for running instances that haven't reached the While activity yet when the patchset is applied. However, when you have running instances that are executing a While activity (also when the instance is in the dehydration store), you see the following entry in the SOA Suite log after applying the patchset:

ORABPEL-02118

Variant not found.
The variable "__loopCondition" is not declared in the current scope. All variables must be declared in the scope before being accessed. This was an internal error. The flow was not generated correctly by the BPEL compiler.

The audit trail will show the following message:

The transaction was rolled back. The work performed for bpel instance "xxx" was rolled back to the previous dehydration point, but the audit trail has been saved. You can recover the instance from the recovery console by resubmitting the callback message or activity for execution.

It seems SOA Suite uses an internal variable to count the number of times a loop is executed. Probably, this variable is not initialized when using a SOA Suite 11g version predating PS3 and thus results in the error.

There are two solutions to this:

• Validate there are no running instances that execute a While loop while patching your environment;
• If not, use the patch as indicated in patch reference 1451018.1 at the Oracle Support Site.

After applying the patch and restarting SOA Suite you will notice the following log entry indicating the loop count exception is handled by SOA Suite:

<Warning> <oracle.soa.bpel.engine> <BEA-000000> <Handling Exception on setting __loopCondition. This is expected for in-flight instances created before SOA upgrade from PS3 or older versions. 

Default Human Worklist Application and OWSM

The out-of-the-box Human Worklist Application is configured to use the oracle/no_authentication_service_policy policy of Oracle Web Services Manager (OWSM). This policy became available in later patchsets, but isn't shipped with SOA Suite and OWSM PS2. Without updating your OWSM policy store you'll see the following error when logging into the Human Worklist Application after applying PS5:

An error occurred for port: {http://xmlns.oracle.com/bpel/services/IdentityService} IdentityServicePort: oracle.fabric.common.PolicyEnforcementException: PolicySet Invalid: WSM-06162 PolicyReference The policy referenced by URI "oracle/no_authentication_service_policy" could not be retrieved

This can be fixed by updating the OWSM policies using the upgradeWSMPolicyRepository() command. This is documented in Upgrading the Oracle WSM Policies in the Repository. Make sure the Managed (or Admin) Server on which the OWSM PM application is deployed is running. Otherwise you'll see an error indicating that an MBean that is used for the policy upgrade cannot be reached.

See the Oracle Fusion Middleware Security and Administrator’s Guide for Web Services 11g Release 1 (11.1.1.6) for more information on OWSM and its policies.

From the Trenches 2 | Patching OSB and SOA Suite to PS5

In my previous blog I talked about a recent upgrade from Oracle Fusion Middleware 11g PS2 to 11g PS5. This blog continues with two post-installation steps that were required to complete the upgrade.

Patching Oracle B2B for ebMS-based services

In this particular project we implemented ebMS-based services using Oracle B2B and Oracle Service Bus 11g. Besides "plain" SOAP Web Services, ebMS is part of the Dutch government standards to exchange messages and expose services between organizations in the public sector. You can read more about implementing ebMS-based services using Oracle B2B, Oracle Service Bus and Oracle SOA Suite in this presentation.

The ebMS standard makes extensive use of SOAP headers to facilitate features such as guaranteed delivery and to avoid duplicate messages. The following snippet shows part of an ebMS message header.

One of the identifiers used in the ebMS message exchange is the manifest id. According to the ebMS specification maintained by OASIS this needs to be XML NCName type. This type has some restrictions; for example that its values cannot start with a number. In Oracle B2B 11g PS2 the manifest id value is prefixed with the text oracle. This prefix is removed in 11g PS5 resulting in the following error from the B2B trading partner at runtime:

09:06:00 Local Listener(8914) Result: "Error" "Fault sent:<SOAP:Fault><faultcode>SOAP:Client</faultcode><faultstring>org.xml.sax.SAXParseException: cvc-datatype-valid.1.2.1: '0A1A1A1A1A1A1A1A1A1A1A1A1A1A1A1A' is not a valid value for 'NCName'.</faultstring></SOAP:Fault>"

Luckily there is an easy-to-apply patch that solves this problem; see article 1497168.1 on Oracle Support. After applying the patch, the manifest id is prefixed with a text value again.

Changing namespaces in WSDLs and XSDs of JAX-WS Web Services

The environment that was patched contains several Java applications running on WebLogic Server. These applications expose Web Services using JAX-WS. A meet-in-the-middle approach was used to create them: the business logic implemented in Stateless Session Beans and JPA (EclipseLink) is integrated with the Java classes generated from the predesigned WSDLs and XSDs.

Depending on the developer that created the Web Service, deployment descriptors such as webservices.xml and weblogic-webservices.xml were added to the application. Descriptors are used for configuration, overriding default settings, and adding metadata. For Web Services this can be the endpoint, port configuration, linkage of the Web Service to EJB components, and so on. When deployed, the WSDL location of Web Services is listed in the WebLogic Console and the WSDL can be retrieved at runtime.

After the patch we noticed that these artifacts weren't identical to the original WSDLs and XSDs. More specifically, the namespaces of the XSD elements in the request and response message definitions were changed to the namespace of the service itself. At runtime however, the service accepted requests and responses as defined by the original contract. This makes it difficult to test these Web Services using clients that inspect the runtime WSDL; for example when creating a default project in soapUI.

This issue was resolved by removing the webservices.xml and weblogic-webservices.xml deployment descriptors from the Java archive and redeploying the Web Services to WebLogic Server. The WSDL that can be retrieved at runtime matches the original designed WSDL again.