Weblog for the AMIS Technology corner
Posts tagged BPEL
Book review of: Getting Started With Oracle SOA Suite 11g R1: A Hands-On Tutorial
Apr 18th
Getting Started With Oracle SOA Suite 11g R1: A Hands-On Tutorial
Authors: Demed L’Her, Heidi Buelow, Jayaram Kasi, Manas Deb, Prasen Palvankar (aka Oracle Product Management for SOA Suite)
A hands-on tutorial is what the cover of the book promises, and that is exactly what you get. A quick, very hands-on introduction into the most important components in the SOA Suite 11g. In no time at all, readers will be able to get a composite application up and running. An application that leverages many of the essential features and functions in the SOA Suite.
Some books are primarily an introduction into a certain topic, with lots of theory, background and explanations of what, why and how. Other books are mainly reference material that you use to look things up when you need them. This book is neither – it offers very little in the way of explanation and background and it would be fairly useless as reference guide. It is however a very good way to get to know the SOA Suite – both design time and run time – and get a feel for how to develop for it and run applications in it.
The book contains a large number of informative screenshots and also provides the salient code snippets. It is very focused on getting specific jobs done, and for these jobs it has all the information and illustrations you may need. It is hard to not get it to work following the very detailed instructions.
The book – or at least the paper copy I am holding – is written for the very first 11gR1 release, that was published on July 1st 2009. The functions made available with PS1 release (November 2009) are not discussed therefore.
OOW 2009: Introducing SOA and Oracle SOA Suite 11g for Database Professionals
Oct 11th
The Oracle Open World 2009 conference is almost underway. On Monday 12th October I will do two presentations, and I am done preparing the first one of them (the one that has actually sold one – probably scheduled in a small room).This presentation is one in which I introduce the key concepts and objectives of SOA (Service Oriented Architecture) as well as the Oracle SOA Suite 11g to an audience of database professionals. Whether DBA or Database Developer, SOA is unavoidable. But what (exactly) is it? And how does it impact – positively or negatively – the work and lives of database professionals? What can a database professional do to work well with SOA and the SOA technology once that starts being implemented in her or his organization?
SOA Suite 11g – Composite instance as WebService Result Cache using BPEL Correlation
Sep 17th
This article describes an architectural pattern, implemented in the Oracle SOA Suite 11g, that is somewhat similar to the Oracle Database 11g Function Result Cache. It introduces a SOA Composite Application in the role of Result Cache. In its most simple form, the result cache is initialized – loaded with values -, used by other SOA applications that need the cached values, refreshed/reset when required and terminated. Through this ‘result cache’ – frequently used and not-so-frequently changed values that are published by (possibly remote, expensive or slow-reacting) web services or adapter services can be made available to local consumers in a simple, cheap and fast manner. We achieve this using the fast native SCA binding used for invoking in-container services exposed by fellow composite applications (that’s for speed) and the BPEL correlation mechanism (that’s for finding the result cache in the first place).
What the actual value of this pattern and implementation are is not yet entirely clear to me. Your feedback is appreciated. What I do know is that this article is also a good demonstration of using correlation and of applying some of the XML manipulation techniques available in BPEL processes.
In a single picture, here is what I created: one or more Composite Instances are initialized; each instance is a cache, identified through its name. Upon initialization, the cache is loaded with values – supposedly important, frequently reused, hard-to-get-by values. Composite applications that are interested in these cached values can retrieve them from the cache, by calling the exposed service and passing the name of the cache (here is where correlation kicks in) and passing the name of the cache entry. The BPEL process looks for the entry and returns the value when found or null and an appropriate message when not found.
Chatting from SOA Suite 11g – how BPEL processes can use the XMPP protocol to notify the world
Aug 25th
Various scenarios may require sending email messages or other types of notifications to users as part of the process flow. For example, certain types of exceptions that cannot be handled automatically may require manual intervention. For example, a BPEL process can use the notification service to alert users by voice, IM, SMS, or email.
In a previous article (http://technology.amis.nl/blog/6019/configure-soa-suite-11g-for-sending-email-notifications-with-google-mail) I described recently how the fairly new SOA Suite 11g can use GMail or other public Email servers to send notifications, for example from BPEL processes or the Human Workflow Service. The SOA Suite 11g works with the User Messaging Service (UMS) to perform that feat and the essence of said article is to configure the email driver in UMS to use GMail – or any other email server for that matter.
This article looks at one of the other communication channels available in UMS, and also available to BPEL processes: Instant Messaging or Chat. After configuring the UMS XMPP driver in the Enterprise Manager console, the Chat channel is available to any BPEL process. We will discuss how to configure – and with which configuration details for Jabber.org – and subsequently how to make use of that communication channel from a BPEL process.
Advanced Concurrency control in BPEL Flow – controlling the execution of parallel branches
Oct 26th
In a previous article I discussed the parallel execution of activities in BPEL, more specifically in Oracle BPEL PM 11g (TP4). This article concluded that true parallellism hardly exists. The branches within a Flow get their chance in turns to execute their next step. Not until an activity is complete in one branch can the next branch take over and make one step. The only exception I was able to determine was the Receive activity that waits for an Asynchronous Service to call in with its results – when a branch is executing the Receive (waiting!), other branches can continue with their next step. It seemed that normal Wait operations and Synchronous calls (with nonBlockingInvoke set) should also free the lock the current branch has and allow others to run, but I could not observe that behavior in Technical Preview 4.
I hinted in that article that we can take more control over the way the activities in the parallel branches are executed. Right now it seems that when a Flow executes, the BPEL PM determines when which branch gets a chance to run, whereby it seems – though I do not know whether that is guaranteed behavior – that the branches (BPEL sequence activities) get a turn in the order in which they are defined in the BPEL process and one activity at a time. In this article we discuss the <link> element that gives us a little more control over when an activity is ready to run. It allows us to define dependencies between activities in different branches in the Flow. Read the rest of this entry »
Investigation into the true parallellism of the Oracle BPEL PM Flow activity in 11g (Technical Preview 4) – on flow, sequence, wait and (a)synchronous calls
Oct 23rd
The Flow activity is used to configure parallel activity in BPEL processes. In theory, activities contained in two or more branches (sequence containers) inside a Flow activity are executed in parallel. However, some sections in the BPEL PM documentation raise some doubt: "By default, Oracle BPEL Process Manager executes in a single thread, executing the branches sequentially instead of in parallel". I am not sure exactly what this means. But it certainly suggests that what I assumed to be pure parallel branches are in fact activity sequences that are both carried out, but sequentially! Time to investigate…
In this article, we will go through a number of steps to ascertain what exactly the parallellism for the Flow activity is. Note that I did this research in the 11g TP4 release of the SOA Suite. I will repeat the analysis in the 10g stack – as some findings seem erroneous and are perhaps due to the status of the Technical Preview. Read the rest of this entry »
Debug Logging in BPEL using Sensors – Part 1
Jul 22nd
When developing and/or debugging BPEL processes, the Oracle BPEL Console is your best friend. Every change to every variable, every activity that was executed, everything is right there for you to inspect, whether the instance is still in-flight or already completed. But although this sounds like the ultimate debugging tool, I’m sure you’ve noticed like me that when your processes get really big (which they tend to do rather quickly), there’s two reasons why debugging can be difficult. The first is plain and simple “information overload”. If your audit flow contains hundreds of activities and possibly thousands of variable data changes, finding an individual piece of information is not trivial. I find the second reason, however, to be of even more profound impact: the BPEL console will not show you the execution path through your process flow (which would indicate which parts of the code got executed, and which didn’t), but rather it displays a long, sequential list of Activities that were executed. Especially if you have a lot of switch and/or pick statements, and if your code contains loops (in which case each iteration will add all executed Activities to the list), determining “what happened” during execution of your instance from this long, long audit trail might prove a challenge.
In a “mini-series” of Blog entries, I will share a number of techniques that I have used in situations like this, to extract logging/debug information from a BPEL process instance using BPEL Sensors. This first entry will focus on a simple, straightforward form of logging, using a “Variable Sensor” to provide a sort of “management summary” of the execution of a BPEL process instance. 
Read the rest of this entry »
