VSAM to CSV using LegStar

I was wondering how hard it would be to translate a z/OS VSAM file content to a CSV file using LegStar.

So I started with a very trivial case:

CICS comes with a sample VSAM KSDS file called FILEA (see hlq.CICS.SDFHINST(DFHDEFDS)). FILEA is an 80 characters, fixed sized record file.

The records in FILEA are described by a COBOL copybook called DFH0CFIL (in hlq.CICS.SDFHSAMP). The content of DFH0CFIL looks like this:

02 FILEREC. 03 STAT PIC X. 03 NUMB PIC X(6). 03 NAME PIC X(20). 03 ADDRX PIC X(20). 03 PHONE PIC X(8). 03 DATEX PIC X(8). 03 AMOUNT PIC X(8). 03 COMMENT PIC X(9).

My first step was to extract the VSAM file content to a sequential file using a JCL like this one on z/OS:

//REPRO EXEC PGM=IDCAMS //SYSPRINT DD SYSOUT=* //IN DD DISP=SHR,DSN=hlq.CICS.FILEA //OUT DD DISP=(MOD,CATLG,DELETE),DSN=hlq.CICS.FILEA.BKP, // SPACE=(TRK,(45,15)),UNIT=3390, // DCB=(BLKSIZE=0,LRECL=80,RECFM=FB) //SYSIN DD * REPRO IFILE(IN) OFILE(OUT) //*

I then downloaded the sequential file to my workstation using regular FTP in binary mode:

ftp> bin 200 Representation type is Image ftp> get 'hlq.CICS.FILEA.BKP' 200 Port request OK. 125 Sending data set hlq.CICS.FILEA.BKP FIXrecfm 80 250 Transfer completed successfully.

On the java side now, I created a LegStar Transformer from the DFH0CFIL COBOL copybook. This results in a FilerecTransformers class.

The following code snippet, is what I needed to write to get my CSV file:

FileInputStream fs = null; try { String LS = System.getProperty("line.separator"); fs = new FileInputStream(new File("hlq.CICS.FILEA.BKP")); byte[] hostRecord = new byte[FilerecBinding.BYTE_LENGTH]; FilerecTransformers tf = new FilerecTransformers(); FileWriter fw = new FileWriter(new File("filea.csv")); fw.write("STAT;NUMB;NAME;ADDRX;PHONE;DATEX;AMOUNT;COMMENT"); fw.write(LS); int count = fs.read(hostRecord); while(count > 0) { Filerec javaRecord = tf.toJava(hostRecord); fw.write(javaRecord.getStat()); fw.write(";"); fw.write(javaRecord.getNumb()); fw.write(";"); fw.write(javaRecord.getName()); fw.write(";"); fw.write(javaRecord.getAddrx()); fw.write(";"); fw.write(javaRecord.getPhone()); fw.write(";"); fw.write(javaRecord.getDatex()); fw.write(";"); fw.write(javaRecord.getAmount()); fw.write(";"); fw.write(javaRecord.getComment()); fw.write(LS); count = fs.read(hostRecord); } fw.close(); } catch (IOException e) { e.printStackTrace(); } catch (HostTransformException e) { e.printStackTrace(); } finally { if (fs != null) { try { fs.close(); } catch (IOException e) { e.printStackTrace(); } } }

Of course this is a very contrived example, both because the VSAM file is fixed size and the record data is only made of characters.

In a more realistic case, the records will contain all sorts of numerics: compressed, zoned or edited and chances are that some redefines and arrays will complexify the setting. This is where LegStar should really become useful.

There are other interesting questions when you get to that point:

• Assuming you need to regularly extract the content of a file, how do you automate a distributed process like this one?
• How would you do that reliably; meaning you don't process the same data twice or miss part of it?

ETL (Extract Transfer Load) tools are typically focused on these issues. I became quite curious about them recently.