Recursion in XSLT by Martien van den Akker


Last week I helped someone on the Oracle community forums with transforming a comma separated string to a list of elements. He needed this to process each element in BPM Suite, but it is a use case that can come around in SOA Suite or even in Oracle Integration Cloud.
You would think that you could do something like a for-each and trimming the element from the variable.


One typical thing with XSLT is that variables are immutable. That means that you can declare a variable and assign a value to it, but you cannot change it. So it is not possible to assign a new value to a variable based on a substring of that same variable.
To circumvent this, you should implement a template that conditionally calls itself until an end-condition is met. This is a typical algorithm called recursion. Recursion is a way of implementing a function that calls itself, for example to calculate the faculty of a number. Recursion can help circumventing the immutability of variables, because with every call to the function you can pass (a) calculated and thus different value(s) through the parameter(s).
I wrote about this earlier, but last week a co-worker asked a similar question, but just the other way around: transforming a list into a comma separated string. So, apparently it’s time to write an article about it. Read the complete article here.


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Technorati Tags: SOA Community,Oracle SOA,Oracle BPM,OPN,Jürgen Kress

About Jürgen Kress
As a middleware expert Jürgen works at Oracle EMEA Alliances and Channels, responsible for Oracle’s EMEA Fusion Middleware partner business. He is the founder of the Oracle SOA & BPM and the WebLogic Partner Communities and the global Oracle Partner Advisory Councils. With more than 5000 members from all over the world the Middleware Partner Community is the most successful and active community at Oracle. Jürgen manages the community with monthly newsletters, webcasts and conferences. He hosts his annual Fusion Middleware Partner Community Forums and the Fusion Middleware Summer Camps, where more than 200 partners get product updates, roadmap insights and hands-on trainings. Supplemented by many web 2.0 tools like twitter, discussion forums, online communities, blogs and wikis. For the SOA & Cloud Symposium by Thomas Erl, Jürgen is a member of the steering board. He is also a frequent speaker at conferences like the SOA & BPM Integration Days, JAX, UKOUG, OUGN, or OOP.

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