Welcome!

Microservices Expo Authors: Chris Schwarz, Elizabeth White, Yeshim Deniz, Kevin Jackson, Jason Bloomberg

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
Colocation is a central pillar of modern enterprise infrastructure planning because it provides greater control, insight, and performance than managed platforms. In spite of the inexorable rise of the cloud, most businesses with extensive IT hardware requirements choose to host their infrastructure in colocation data centers. According to a recent IDC survey, more than half of the businesses questioned use colocation services, and the number is even higher among established businesses and busine...
In his session at Cloud Expo, Alan Winters, an entertainment executive/TV producer turned serial entrepreneur, presented a success story of an entrepreneur who has both suffered through and benefited from offshore development across multiple businesses: The smart choice, or how to select the right offshore development partner Warning signs, or how to minimize chances of making the wrong choice Collaboration, or how to establish the most effective work processes Budget control, or how to ma...
Cloud Expo, Inc. has announced today that Andi Mann and Aruna Ravichandran have been named Co-Chairs of @DevOpsSummit at Cloud Expo Silicon Valley which will take place Oct. 31-Nov. 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. "DevOps is at the intersection of technology and business-optimizing tools, organizations and processes to bring measurable improvements in productivity and profitability," said Aruna Ravichandran, vice president, DevOps product and solutions marketing...
SYS-CON Events announced today that CA Technologies has been named "Platinum Sponsor" of SYS-CON's 21st International Cloud Expo®, which will take place October 31-November 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. CA Technologies helps customers succeed in a future where every business - from apparel to energy - is being rewritten by software. From planning to development to management to security, CA creates software that fuels transformation for companies in the applic...
There's a lot to gain from cloud computing, but success requires a thoughtful and enterprise focused approach. Cloud computing decouples data and information from the infrastructure on which it lies. A process that is a LOT more involved than dragging some folders from your desktop to a shared drive. Cloud computing as a mission transformation activity, not a technological one. As an organization moves from local information hosting to the cloud, one of the most important challenges is addressi...
In the decade following his article, cloud computing further cemented Carr’s perspective. Compute, storage, and network resources have become simple utilities, available at the proverbial turn of the faucet. The value they provide is immense, but the cloud playing field is amazingly level. Carr’s quote above presaged the cloud to a T. Today, however, we’re in the digital era. Mark Andreesen’s ‘software is eating the world’ prognostication is coming to pass, as enterprises realize they must be...
Hybrid IT is today’s reality, and while its implementation may seem daunting at times, more and more organizations are migrating to the cloud. In fact, according to SolarWinds 2017 IT Trends Index: Portrait of a Hybrid IT Organization 95 percent of organizations have migrated crucial applications to the cloud in the past year. As such, it’s in every IT professional’s best interest to know what to expect.
A common misconception about the cloud is that one size fits all. Companies expecting to run all of their operations using one cloud solution or service must realize that doing so is akin to forcing the totality of their business functionality into a straightjacket. Unlocking the full potential of the cloud means embracing the multi-cloud future where businesses use their own cloud, and/or clouds from different vendors, to support separate functions or product groups. There is no single cloud so...
Both SaaS vendors and SaaS buyers are going “all-in” to hyperscale IaaS platforms such as AWS, which is disrupting the SaaS value proposition. Why should the enterprise SaaS consumer pay for the SaaS service if their data is resident in adjacent AWS S3 buckets? If both SaaS sellers and buyers are using the same cloud tools, automation and pay-per-transaction model offered by IaaS platforms, then why not host the “shrink-wrapped” software in the customers’ cloud? Further, serverless computing, cl...
The taxi industry never saw Uber coming. Startups are a threat to incumbents like never before, and a major enabler for startups is that they are instantly “cloud ready.” If innovation moves at the pace of IT, then your company is in trouble. Why? Because your data center will not keep up with frenetic pace AWS, Microsoft and Google are rolling out new capabilities. In his session at 20th Cloud Expo, Don Browning, VP of Cloud Architecture at Turner, posited that disruption is inevitable for comp...
"We are a monitoring company. We work with Salesforce, BBC, and quite a few other big logos. We basically provide monitoring for them, structure for their cloud services and we fit into the DevOps world" explained David Gildeh, Co-founder and CEO of Outlyer, in this SYS-CON.tv interview at DevOps Summit at 20th Cloud Expo, held June 6-8, 2017, at the Javits Center in New York City, NY.
Companies have always been concerned that traditional enterprise software is slow and complex to install, often disrupting critical and time-sensitive operations during roll-out. With the growing need to integrate new digital technologies into the enterprise to transform business processes, this concern has become even more pressing. A 2016 Panorama Consulting Solutions study revealed that enterprise resource planning (ERP) projects took an average of 21 months to install, with 57 percent of th...
In 2014, Amazon announced a new form of compute called Lambda. We didn't know it at the time, but this represented a fundamental shift in what we expect from cloud computing. Now, all of the major cloud computing vendors want to take part in this disruptive technology. In his session at 20th Cloud Expo, Doug Vanderweide, an instructor at Linux Academy, discussed why major players like AWS, Microsoft Azure, IBM Bluemix, and Google Cloud Platform are all trying to sidestep VMs and containers wit...
"When we talk about cloud without compromise what we're talking about is that when people think about 'I need the flexibility of the cloud' - it's the ability to create applications and run them in a cloud environment that's far more flexible,” explained Matthew Finnie, CTO of Interoute, in this SYS-CON.tv interview at 20th Cloud Expo, held June 6-8, 2017, at the Javits Center in New York City, NY.
New competitors, disruptive technologies, and growing expectations are pushing every business to both adopt and deliver new digital services. This ‘Digital Transformation’ demands rapid delivery and continuous iteration of new competitive services via multiple channels, which in turn demands new service delivery techniques – including DevOps. In this power panel at @DevOpsSummit 20th Cloud Expo, moderated by DevOps Conference Co-Chair Andi Mann, panelists examined how DevOps helps to meet the de...
For most organizations, the move to hybrid cloud is now a question of when, not if. Fully 82% of enterprises plan to have a hybrid cloud strategy this year, according to Infoholic Research. The worldwide hybrid cloud computing market is expected to grow about 34% annually over the next five years, reaching $241.13 billion by 2022. Companies are embracing hybrid cloud because of the many advantages it offers compared to relying on a single provider for all of their cloud needs. Hybrid offers bala...
@DevOpsSummit at Cloud Expo taking place Oct 31 - Nov 2, 2017, at the Santa Clara Convention Center, Santa Clara, CA, is co-located with the 21st International Cloud Expo and will feature technical sessions from a rock star conference faculty and the leading industry players in the world. The widespread success of cloud computing is driving the DevOps revolution in enterprise IT. Now as never before, development teams must communicate and collaborate in a dynamic, 24/7/365 environment. There is ...
What's the role of an IT self-service portal when you get to continuous delivery and Infrastructure as Code? This general session showed how to create the continuous delivery culture and eight accelerators for leading the change. Don Demcsak is a DevOps and Cloud Native Modernization Principal for Dell EMC based out of New Jersey. He is a former, long time, Microsoft Most Valuable Professional, specializing in building and architecting Application Delivery Pipelines for hybrid legacy, and cloud ...
Containers, microservices and DevOps are all the rage lately. You can read about how great they are and how they’ll change your life and the industry everywhere. So naturally when we started a new company and were deciding how to architect our app, we went with microservices, containers and DevOps. About now you’re expecting a story of how everything went so smoothly, we’re now pushing out code ten times a day, but the reality is quite different.
For organizations that have amassed large sums of software complexity, taking a microservices approach is the first step toward DevOps and continuous improvement / development. Integrating system-level analysis with microservices makes it easier to change and add functionality to applications at any time without the increase of risk. Before you start big transformation projects or a cloud migration, make sure these changes won’t take down your entire organization.