Book of the week: SAP Netweaver PI – Development 2nd

This week’s book a rather technical book about how to develop in SAP PI.

The book is SAP NetWeaver PI Development: Practical Guide by Valentin Nicolescu et al

 

I wanted to talk some more about the book, so I have created a video that you can see here.

SAP PI XML Mappings using groovy

Creating XML mapping in Java have for me always been difficult, it has been possible but I would prefer other tools. I was looking at scripting languages like Ruby/JRuby or Groovy for creating some web apps. Those languages seem quite hot right now. On the SCN Wiki a group has implemented the Grails (groovy on Rails) on the Netweaver system, as Composition on Grails. With this tool it is possible to applications with a Webdynpro look and feel. Grails is a framework for creating webapps with less coding.

Groovy is a scripting language designed on the basis of Java. Groovy script is compiled into Java classes, and both Java and Groovy can be mixed. This makes the implementation easier, just start writing Java and when you feel like use some of the smarter features of Groovy you can use them.

While I was looking at Grails, I thought that I would be possible to use it in PI. One place could be in java mappings. I’ll describe the steps that I have taken to implement this.

  1. Download and install the groovy library
  2. Get the Groovy plugin to Eclipse, this make developing much easier.
  3. Create a new Eclipse project
  4. Insert the aii_map_api.jar in the project, to be able to implement Streamtransformation service.
  5. Create a new Groovy file in the source folder, with the name GroovyMapIdoc.groovy, then Eclipse know that it is a groovy file.
  6. Create the mapping of your file. I have attached my example code bellow.
  7. Compile the Groovy files using the context menu on the GroovyMapIdoc.groovy file.
  8. Zip the content of the bin-groovy in the project folder and upload it, as an imported archive in the Integration builder. Alternative use ant build to create the zip files.
  9. Upload the two files Groovy-1.6.1.jar and asm-2.2.3.jar as imported archives. They can be found in <GROOVY_HOME>\lib
  10. Activate and use the mapping.

I would expect people trying this to have a good knowledge of using XI or PI Java mappings, because it is a requirement for the development of mappings.

One example I always have considered, was my first challenging mapping experience. Posting financial post with more than 1000 lines to the FIDCCP02 idoc. The FIDCCP02 only accepts 999 lines. The posting can be created multiply idocs with 998 lines and the post a balance on each item. This way all documents will balance.

The document is transformed from the left document to the right. I have for this example used a max size of 3 to make testing easier.

The code that I have used for the mapping is.

package com.figaf.mapping

import com.sap.aii.mapping.api.StreamTransformation;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.Map;

import groovy.xml.MarkupBuilder

class GroovyMapIdoc implements StreamTransformation{

   Map param;
   
    void setParameter(Map param) {
        this.param = param;
    }
    // Number of lines pr idoc
    def step=3
   
    /**
     * Implementation of the execution method
     */
    void execute(InputStream input, OutputStream out) {

        // Parse the input using the XMLSlurper
        def FICCP01 = new XmlSlurper().parse(input)
        // get the different lines using the GPath
        def Lines = FICCP01.IDOC.LINE
        // create a writer example
        def writer = new OutputStreamWriter(out)
       
        def xml = new MarkupBuilder(writer)
        // create the root element and fill data into it.
        xml.FICCP01(){
            // get the number of idocs to be created.
            def numIdocs =   Lines.size()/step + (Lines.size()%step>0?1:0)  
            // loop for each idoc
            for ( i in 0..numIdocs-1 ) {
                // find the limit for the current idoc
                def max = Math.min( Lines.size(), i* step+2)
                // create sum ellement to create balances
                def sum = 0.0;
                 def lineno=1;
                IDOC(){
                    // create the number segment, using GPATH
                    NR(FICCP01.IDOC.NR )
                    // for each line in the range do the following
                    Lines[i*step..max].each{oldline->
                         // create a  new Line node, in the out put element
                         // with the following content
                        LINE(){
                        NO(lineno++)
                        Text(oldline.Text.text())
                        Amount(oldline.Amount.toBigDecimal())
                    }
                   // update the sum
                  sum +=oldline.Amount.toBigDecimal()
                }    
                    // create a balancing line, with balances the result
                    LINE(){
                        NO(step+1)
                        Text('Balance')
                        Amount(-sum)
                    }
                }
            }
        }

        // write the xml to output
         writer.flush()
         writer.close()
       
    }
   
}

Behind the scenes the Groovy file is changed in to java classes. Because Java does not support Closures natively different subclasses are created. Try to have a look on them using a decompiler like jad.

Conclusion

Groovy could be a way to improve the how java mappings are created. The XML generation is easier to handle then how it would have been created in Java and it is more powerful than XSLT. It takes some effort to get use to the closures concept of Groovy and the other notation, but it seems to work real well.

I don’t think the performance issue with the mapping is a problem. There is an overhead to load the groovy libraries and the code is probably not as optimized if it was written directly in java. I have not made any measurements for this.