Jul 27

In Note 6 we explored the transactional behavior of a JCA MDB invoked by a JMS Adapter and orchestrating an Oracle JCA Adapter (a transactional end point) and a Batch Local File JCA Adapter (a non-transactional end point). In this Note let’s explore the issue of transactionality of a JCA Message-Driven Bean invoked by a non-transactional end point.

Let’s take the example from the “Java CAPS Basics: Implementing Common EAI Patterns Companion CD” book, ISBN: 0-13-713071-6, Chapter 11 “Scalability and Resilience”, Section 11.2 “Exception Handling”, subsection 11.2.1 “Exceptions in Java Collaborations”, “Other Java Collaborations”. The book from which this section comes is available on the Companion CD. Let’s re-work this example using Java CAPS 6 JCA Adapters.

The example illustrates exception processing behaviour involving a Batch Inbound Adapter-triggered JCA Message-Driven Bean.
The Batch Inbound Adapter is designed to poll a directory for a file. When it finds a file that matches the name, or the name pattern, it immediately renames the fie by prepending a GUID to the original name then triggers the MDB and passes to it the original name of the file, the current name of the file and the directory in which the file was found. This behavior prevents other possible file pollers from getting hold of the file and gives the first comer exclusive access to the file. The MDB is designed to take the name of the file as given and rename the file to the original name with the suffix “~.in” appended, to indicate the file was read and processed. To do this the MDB will use the Batch Local File JCA Adapter’s capability to post-process the file by renaming or deleting it. To explore the transactional behavior the MDB will explicitly throw an exception after it renames the file.
The complete Note is available in 07BatcyhInboundTriggeredJCANonTransacionality.pdf.

Jul 27

Rather then inventing an example to discuss and illustrate the use of the Oracle JCA Adapter let’s build a solutions that uses the Oracle JCA Adapter and shows additional Java CAPS 6 facilities of interest.

Let’s take the example from the “Java CAPS Basics: Implementing Common EAI Patterns Companion CD” book, ISBN: 0-13-713071-6, Chapter 11 “Scalability and Resilience”, Section 11.2 “Exception Handling”, subsection 11.2.1 “Exceptions in Java Collaborations”, “JMS-Triggered Java Collaborations”. The book from which this section comes is available on the Companion CD. Let’s re-work this example using Java CAPS 6 JCA Adapters.

This example illustrates exception handling involving a JMS-triggered JCA Message-Driven Bean.
The MDB is designed to receive a JMS message, update a field in a database table row with the value of the text message, write the text message, together with the timestamp, to a file and finish.

The complete Note is provided in 06JMSTriggeredJCAwithOracle.pdf

Update: Thanks to Dao Tien Tran for pointing out a typo on page 5. I corrected the typo and uploaded the corrected document.  Change is marked in color and with a change bar.

Jul 23

Java CAPS 5.x used to have a Scheduler eWay. Java CAPS 6 also has the Scheduler eWay but only on the Repository-based side. At this point in time there is no Scheduler JCA Adapter or a Scheduler Binding Component. Why would one be bothered by that? One would be bothered because there are business requirements that call for scheduling of activities. The one that comes to mind immediately is polling an FTP server for a file which to transfer. For polling the local file system there is the Batch Inbound JCA, which was used in solutions discussed in JCA Notes 2 and 3. For Batch FTP JCA there is no such thing.
Rather then ignoring the issue of lack of the Scheduler JCA Adapter I determined to see what can be done to provide this functionality for non-Repository-based Java CAPS 6 solutions.
When asked, one of my colleagues in the US suggested that EJB Timers are the way to go and provided the links to the material. I looked at what was discussed, threw up my hand in the air and exclaimed. I will not quote what I said. In short, EJB Timers may be all very well for a competent Java EE developer but not for a regular Integration, or SOA, developer. EJB Timers are, in my view, way too complex to implement and do not offer sufficient advantage over a Scheduler eWay to make it worth while to spend the time developing a solution that uses them.
The next thing I looked at was the open source Quarz scheduler, which also turned up to require more effort then I considered worth while for the Notes.
I felt that the simplest thing to do will be to use an external scheduler, a native one, provided by the OS. For Windows, on which I develop for the Notes, there is the “Scheduled Tasks” scheduler. For Unix there are Cron facilities. Both are well know and typically good enough in terms of timer resolution and scheduling flexibility. Above all else, using one does not require me to write scheduler code myself, merely write the code that triggers my solution when the scheduled event fires.
So, this Note walks through implementation of a Scheduler solution, which can be used to trigger a Batch FTP JCA solution or any other JCA-based or JBI-based solution that has to be triggered to some schedule.

Document 00Scheduler.pdf contains the entire Note.

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Jul 17

Java CAPS 6 has the 5.x compatibility infrastructure which allows one to import 5.x projects right into Java CAPS 6, build, deploy and run without changes. One can also develop repository-based projects in Java CAPS 6 – that’s the 5.x-style projects. This is the old way of developing Java CAPS solutions – still good and valid.

If one were to decide to not use the old way there is the JBI infrastructure, which allows development of solutions that use BPEL Service Engine, XSLT Service Engine, IEP Service Engine, Java EE Service Engine, etc., and a variety of Binding Components. The implication is that business logic is implemented in BPEL 2.0, which is used to orchestrate other services and resources, including interaction with external systems through Binding Components. This is the new way of developing Java CAPS solutions – 100% compatible with the Open Source OpenESB project since it uses the OpenESB project-developed container and components.

Someone might ask “so what happened to eGate?”. “eGate” meaning Java Collaboration Definition-like logic components, eWays and the JMS messaging backbone.

While the facility seems underadvertised/downplayed, Java CAPS 6 provides a number of 5.1 eWay-based JCA Adapters and a moderately easy means of developing JCA Message-Driven Beans that can use these adapters to implement JCD-like logic components and, effectively, eGate-like solutions that do not use BPEL or the JBI infrastructure.

This Note discusses and illustrates the implementation of a mixed Java CAPS 5.x-like integration solution that retrieves a file from the local file system using JCA Adapters and passes its content to a BPEL 2.0 process executing in the JBI container. This requirement I have seen and heard of being implemented in 5.x many times by many customers.

Most of the material in the first 16 pages of this Note is the same as in Note 2.

The JCA Message-Driven Bean, the piece of JCD-like Java logic, will be triggered by a Batch Inbound Adapter (what one would have called the Batch Inbound eWay in 5.1), will read the content of the file using the Batch Local File Adapter (eWay) and will send the payload as a string to a BPEL 2.0 Business Process, which will be triggered by this message and will execute in the JBI container. The batch Inbound Adapter will be configured to use a regular expression to match the name of the file. Once it finds the file it will rename the file by prepending the GUID to the name and will pass the new name, the original name and the directory path to the Java code. This is exactly what the 5.1 Batch Inbound does. The JCA MDB will use the new name, the original name and the directory path to dynamically configure the Batch Local File Adapter to retrieve the file content and rename the file (post transfer) to the original name with some string appended to indicate that the file was processed. This, too, is exactly what one would do in a 5.1 JCD in the same circumstance. Once the payload is available the JCA MDB will use the OneWay WSDL interface and the JBI NMR to send it, as a String, to a BPEL 2.0 process. Both the JCA MDB and the BPEL process will be a part of the same JBI Composite Application and will communicate with one another using the Normalized Message Router (NMR).

The entire Note is available in 03JCA-BInboundThroughBLFToBPEL2.0.pdf

Apr 05

Transferring large payloads, on the order of tens or hundreds of megabytes, between a FTP server and a local file system, in either direction, requires selection of appropriate features of the Batch FTP and Batch Local File eWays, and tuning certain timing parameters.

Default timing parameter values result in timeout exceptions when transferring large payloads.

The Batch FTP eWay and the Batch Local File eWas are typically used to receive the entire payload before writing it out. This results in attempts to allocate memory many time the size of the payload being transferred and, for large files, causes memory exhaustion and application server failures.

Discussion in the attached document points out which timing parameters need to be tuned to facilitate transfer of large payloads. It also presents sample Java code that uses facilities of the Batch FTP and Batch Local File for streaming payload between the FTP server and the local file systems without using excessive amount of memory.

The material covered in the document was prepared using Java CAPS projects developed and tested in Java CAPS 5.1.0, exported, imported into Java CAPS Release 6 and tested again. It is expected that the code will work in all versions of Java CAPS from 5.1.0 up.

Streaming Large FTP Transfers with CAPS 5.1 and 6.pdf



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