Welcome!

Microservices Expo Authors: Liz McMillan, Elizabeth White, Carmen Gonzalez, Pat Romanski, Yeshim Deniz

Related Topics: Microservices Expo

Microservices Expo: Article

BPEL4WS 1.1 To WS-BPEL 2.0 - An SOA Migration Path

BPEL4WS V1.1 has several shortcomings that will be addressed by the next release of the specification

BPEL4WS V1.1 is a public draft release of the "Business Process Execution Language for Web Services" specification dated May 3, 2003. BPEL4WS V1.1 is arguably the de facto standard for Business Process Management (BPM); however, because it's a draft release, BPEL4WS V1.1 has several shortcomings that will be addressed by the next release of the specification (named WS-BPEL 2.0), which is targeted to be released either toward the end of this year or during the beginning of 2006.

WS-BPEL 2.0, henceforth referenced as BPEL 2.0, is considerably different from the previous V1.1 draft release. The article will address these changes and demonstrate how to attempt to migrate a V1.1 business process to be compatible with a BPEL 2.0 engine. Sometimes this migration is simple and can be accomplished by means of syntactic changes to the process; sometimes the migration is not so easy, and mostly results in the rewrite of the process or process fragment. We will start with the simple cases and move toward the more complicated ones.

It is not the intention of this article to explain BPEL 1.1 or to explain the new features of BPEL 2.0, so it is highly recommended that the reader have a good familiarity with the BPEL language.

BPEL 1.1 Features That No Longer Exist
We will first address those features that have been removed from BPEL 1.1. The concept of "partner" is no longer available for BPEL 2.0. A "partner" groups several "partnerLinks," and in doing so represents a common endpoint. Aside from being descriptive, the "partner" concept did not have any executable property, so it was decided that the language did not need this concept.

The XML element "compensationHandler" and the XML attribute "enableInstanceCompensation" in the top-level "process" element have been removed. Instance (process) level compensation handlers never had any mechanism for being invoked; therefore, because they could not be used instance level compensation handling is no longer supported.

Since it is very unlikely that any BPEL 1.1 engine made use of either of these concepts, it is generally safe enough to just remove them from the process definition when migrating to BPEL 2.0.

Syntactic Changes
The following changes are just syntactic. You can simply do a simple find-and-replace to migrate to BPEL 2.0:

  • Replace the XML attribute "variableAccessSerializable" with "isolated"
  • Replace the XML tag "terminate" with "exit"
  • Replace the XML attribute "onMessage" of event handlers with "onEvent"
  • Move the XML attribute "joinCondition" that is present in BPEL activities to be a child element of "targets," as in the following XML fragment:
    <invoke name="settleTrade">
       <targets>
         <joinCondition>
           $buyToSettle and $sellToSettle
         </joinCondition>
         <target linkName="buyToSettle"/>
       </targets>
    </invoke>
  • Replace the XML attribute value "rendezvous" of the attribute "initiate" with the attribute value "join"
  • The schema type "tRole" no longer has a child element representing the port type; instead, the port type is now specified as an attribute directly in the role itself, as demonstrated in the following fragment:
    <plnk:partnerLinkType name="shippingLT">
       <plnk:role name="shippingService"portType="shippingServicePT"/>
    </plnk:partnerLinkType>
  • The attribute "portType" of messaging activities such as "receive," "invoke," "reply," "pick," and "onEvent" is no longer mandatory and can be omitted
  • The URI used to specify XPath 1.0 as the expression/query language of choice has been changed, so replace the attribute value "http://www.w3.org/TR/1999/REC-xpath-19991116" of the attributes "expressionLanguage" and "queryLanguage" with the attribute value "urn:oasis:names:tc:wsbpel:2.0:sublang:xpath1.0"
In addition to these, the syntax for assignments has been changed, but we will discuss this in a separate section.

Extensibility of Expression/Query Languages
In BPEL 1.1 expressions are used by switch conditions, while conditions and assignments such as XPath expressions are constrained as being an XML attribute value. Although this is not generally a problem for XPath 1.0 expressions, it is awkward for more complex languages such as XPath 2.0 or XQuery 1.0. XML attributes do not provide enough "real estate" for complicated expressions and also do not allow for the use of other XML features such as CDATA, or to write XML itself as the expression.

Hence, to allow for better extensibility of BPEL using external languages, the authoring of expressions and queries are now realized within XML tags (elements) instead of attributes. In practice this means that the XML attributes "for," "until," "joinCondition," "transitionCondition," "expression," "query," and "condition" must all be changed to be XML elements, which would then contain the expressions (the expressions are the former attribute values). The following snippet shows an example of this conversion for XPath 1.0. Note that the attribute "expressionLanguage" is optional.

<while>
   <condition
expressionLanguage="urn:oasis:names:tc:wsbpel:2.0:sublang:xpath1.0">
$itemsShipped < bpws:getVariableProperty('shipRequest','sns:itemsTotal')
   </condition>
   <sequence>
     <!- do something -->
   </sequence>
</while>

Listing 1 shows an example of a nonstandard usage of XQuery 1.0 as the expression language. BPEL 2.0 has thus far only standardized the usage of XPath 1.0.

Links
Links are used to specify synchronization dependencies between nested activities within a flow. In BPEL 1.1, links could not cross the boundary of structured activities such as "while," "isolated scope," "event handler," and "compensation handler." In BPEL 2.0, this restriction has been made stronger. Links that create a reentrant control path in scopes are no longer permitted. The reason for this tightening is to simplify the semantic of compensation handling. Figure 1 illustrates this banned scenario.

Messaging
Several aspects of messaging for BPEL 1.1 are unspecified. For example, there is no defined behavior for a process that receives a message for a request-response operation and finishes without replying. In BPEL 2.0, such a scenario would have trigged a new BPEL standard fault called "missingReply" fault.

More Stories By Alexandre Alves

Alexandre Alves currently works at BEA Systems, in the WebLogic Integration group. He has worked with integration technologies for over 10 years, focusing on CORBA, J2EE, and Web services.

Comments (1) View Comments

Share your thoughts on this story.

Add your comment
You must be signed in to add a comment. Sign-in | Register

In accordance with our Comment Policy, we encourage comments that are on topic, relevant and to-the-point. We will remove comments that include profanity, personal attacks, racial slurs, threats of violence, or other inappropriate material that violates our Terms and Conditions, and will block users who make repeated violations. We ask all readers to expect diversity of opinion and to treat one another with dignity and respect.


Most Recent Comments
SOA Web Services Journal News Desk 11/30/05 09:11:36 PM EST

BPEL4WS 1.1 To WS-BPEL 2.0 - An SOA Migration Path. BPEL4WS V1.1 is a public draft release of the 'Business Process Execution Language for Web Services' specification dated May 3, 2003. BPEL4WS V1.1 is arguably the de facto standard for Business Process Management (BPM); however, because it's a draft release, BPEL4WS V1.1 has several shortcomings that will be addressed by the next release of the specification (named WS-BPEL 2.0), which is targeted to be released either toward the end of this year or during the beginning of 2006.

@MicroservicesExpo Stories
When people aren’t talking about VMs and containers, they’re talking about serverless architecture. Serverless is about no maintenance. It means you are not worried about low-level infrastructural and operational details. An event-driven serverless platform is a great use case for IoT. In his session at @ThingsExpo, Animesh Singh, an STSM and Lead for IBM Cloud Platform and Infrastructure, will detail how to build a distributed serverless, polyglot, microservices framework using open source tec...
Cloud Expo, Inc. has announced today that Andi Mann returns to 'DevOps at Cloud Expo 2016' as Conference Chair The @DevOpsSummit at Cloud Expo will take place on November 1-3, 2016, at the Santa Clara Convention Center in Santa Clara, CA. "DevOps is set to be one of the most profound disruptions to hit IT in decades," said Andi Mann. "It is a natural extension of cloud computing, and I have seen both firsthand and in independent research the fantastic results DevOps delivers. So I am excited t...
In the world of DevOps there are ‘known good practices’ – aka ‘patterns’ – and ‘known bad practices’ – aka ‘anti-patterns.' Many of these patterns and anti-patterns have been developed from real world experience, especially by the early adopters of DevOps theory; but many are more feasible in theory than in practice, especially for more recent entrants to the DevOps scene. In this power panel at @DevOpsSummit at 18th Cloud Expo, moderated by DevOps Conference Chair Andi Mann, panelists discusse...
More and more companies are looking to microservices as an architectural pattern for breaking apart applications into more manageable pieces so that agile teams can deliver new features quicker and more effectively. What this pattern has done more than anything to date is spark organizational transformations, setting the foundation for future application development. In practice, however, there are a number of considerations to make that go beyond simply “build, ship, and run,” which changes ho...
Gartner is now treating algorithms like they are some kind of innovative addition to the modern digital discussion. Presumably the brilliant minds there have some novel insight into algorithms and, yes, the Algorithm Economy that CIOs should sit up and take notice of. Not only are algorithms nothing new, but much of what Gartner is saying about them is obvious. The bigger picture here is that software continues to improve, and enterprises are becoming increasingly software-driven, in part bec...
The Internet of Things is clearly many things: data collection and analytics, wearables, Smart Grids and Smart Cities, the Industrial Internet, and more. Cool platforms like Arduino, Raspberry Pi, Intel's Galileo and Edison, and a diverse world of sensors are making the IoT a great toy box for developers in all these areas. In this Power Panel at @ThingsExpo, moderated by Conference Chair Roger Strukhoff, panelists discussed what things are the most important, which will have the most profound...
The Internet of Things (IoT) is growing rapidly by extending current technologies, products and networks. By 2020, Cisco estimates there will be 50 billion connected devices. Gartner has forecast revenues of over $300 billion, just to IoT suppliers. Now is the time to figure out how you’ll make money – not just create innovative products. With hundreds of new products and companies jumping into the IoT fray every month, there’s no shortage of innovation. Despite this, McKinsey/VisionMobile data...
NHK, Japan Broadcasting, will feature the upcoming @ThingsExpo Silicon Valley in a special 'Internet of Things' and smart technology documentary that will be filmed on the expo floor between November 3 to 5, 2015, in Santa Clara. NHK is the sole public TV network in Japan equivalent to the BBC in the UK and the largest in Asia with many award-winning science and technology programs. Japanese TV is producing a documentary about IoT and Smart technology and will be covering @ThingsExpo Silicon Val...
SYS-CON Events announced today that Men & Mice, the leading global provider of DNS, DHCP and IP address management overlay solutions, will exhibit at SYS-CON's 18th International Cloud Expo®, which will take place on June 7-9, 2016, at the Javits Center in New York City, NY. The Men & Mice Suite overlay solution is already known for its powerful application in heterogeneous operating environments, enabling enterprises to scale without fuss. Building on a solid range of diverse platform support,...
Internet of @ThingsExpo, taking place June 7-9, 2016 at Javits Center, New York City and Nov 1-3, 2016, at the Santa Clara Convention Center in Santa Clara, CA, is co-located with the 18th International @CloudExpo and will feature technical sessions from a rock star conference faculty and the leading industry players in the world and ThingsExpo New York Call for Papers is now open.
SYS-CON Events announced today that Catchpoint Systems, Inc., a provider of innovative web and infrastructure monitoring solutions, has been named “Silver Sponsor” of SYS-CON's DevOps Summit at 18th Cloud Expo New York, which will take place June 7-9, 2016, at the Javits Center in New York City, NY. Catchpoint is a leading Digital Performance Analytics company that provides unparalleled insight into customer-critical services to help consistently deliver an amazing customer experience. Designed...
@DevOpsSummit taking place June 7-9, 2016 at Javits Center, New York City, and Nov 1-3, 2016, at the Santa Clara Convention Center in Santa Clara, CA, is co-located with the 18th International @CloudExpo and will feature technical sessions from a rock star conference faculty and the leading industry players in the world.
Cloud Expo, Inc. has announced today that Andi Mann returns to 'DevOps at Cloud Expo 2016' as Conference Chair The @DevOpsSummit at Cloud Expo will take place on June 7-9, 2016, at the Javits Center in New York City, New York. "DevOps is set to be one of the most profound disruptions to hit IT in decades," said Andi Mann. "It is a natural extension of cloud computing, and I have seen both firsthand and in independent research the fantastic results DevOps delivers. So I am excited to help the g...
Korean Broadcasting System (KBS) will feature the upcoming 18th Cloud Expo | @ThingsExpo in a New York news documentary about the "New IT for the Future." The documentary will cover how big companies are transmitting or adopting the new IT for the future and will be filmed on the expo floor between June 7-June 9, 2016, at the Javits Center in New York City, New York. KBS has long been a leader in the development of the broadcasting culture of Korea. As the key public service broadcaster of Korea...
SYS-CON Events announced today that Addteq will exhibit at SYS-CON's @DevOpsSummit at Cloud Expo New York, which will take place on June 7-9, 2016, at the Javits Center in New York City, NY. Addteq is one of the top 10 Platinum Atlassian Experts who specialize in DevOps, custom and continuous integration, automation, plugin development, and consulting for midsize and global firms. Addteq firmly believes that automation is essential for successful software releases. Addteq centers its products a...
In the rush to compete in the digital age, a successful digital transformation is essential, but many organizations are setting themselves up for failure. There’s a common misconception that the process is just about technology, but it’s not. It’s about your business. It shouldn’t be treated as an isolated IT project; it should be driven by business needs with the committed involvement of a range of stakeholders.
SYS-CON Events announced today that FalconStor Software® Inc., a 15-year innovator of software-defined storage solutions, will exhibit at SYS-CON's 18th International Cloud Expo®, which will take place on June 7-9, 2016, at the Javits Center in New York City, NY. FalconStor Software®, Inc. (NASDAQ: FALC) is a leading software-defined storage company offering a converged, hardware-agnostic, software-defined storage and data services platform. Its flagship solution FreeStor®, utilizes a horizonta...
With major technology companies and startups seriously embracing IoT strategies, now is the perfect time to attend @ThingsExpo 2016 in New York and Silicon Valley. Learn what is going on, contribute to the discussions, and ensure that your enterprise is as "IoT-Ready" as it can be! Internet of @ThingsExpo, taking place Nov 3-5, 2015, at the Santa Clara Convention Center in Santa Clara, CA, is co-located with 17th Cloud Expo and will feature technical sessions from a rock star conference faculty ...
SYS-CON Events announced today that Column Technologies will exhibit at SYS-CON's @DevOpsSummit at Cloud Expo, which will take place on June 7-9, 2016, at the Javits Center in New York City, NY. Established in 1998, Column Technologies is a global technology solutions provider with over 400 employees, headquartered in the United States with offices in Canada, India, and the United Kingdom. Column Technologies provides “Best of Breed” technology solutions that automate the key DevOps principal...
SYS-CON Events announced today that SoftLayer, an IBM Company, has been named “Gold Sponsor” of SYS-CON's 18th Cloud Expo, which will take place on June 7-9, 2016, at the Javits Center in New York, New York. SoftLayer, an IBM Company, provides cloud infrastructure as a service from a growing number of data centers and network points of presence around the world. SoftLayer’s customers range from Web startups to global enterprises.