File Archival using Peoplecode - Create ZIP / TAR / .GZ Files in PeopleCode

 

1. Identify Files to be Archived

In this step, we create a string array in PeopleCode that will hold the list of files to be archived in required format. For testing purposes, we will push three files into this array, as shown in the code segment below:

Local array of string &FileArray = CreateArrayRept("", 0);
&FileArray.Push("c:\dest.log");
&FileArray.Push("c:\dest.sql");
&FileArray.Push("c:\final.sql");

2. Define Output Stream / Archive Entry Format

The code we are writing can either create a tar file, a zip file or a tar.gz file for the inputs supplied. We use the values 1, 3 and 2 to indicate this respectively. The list of class files we require are shown below: (Note: for TAR file, we use JTAR library as per our earlier tutorial, check references below)

Format	Type of OutputStream	Archive Entry Format
tar	org.xeustechnologies.jtar.TarOutputStream	org.xeustechnologies.jtar.TarEntry
zip	java.util.zip.ZipOutputStream	java.util.zip.ZipEntry
tar.gz	org.xeustechnologies.jtar.TarOutputStream java.util.zip.GZIPOutputStream	org.xeustechnologies.jtar.TarEntry

We now write an evaluate statement in PeopleCode and set the values suitably. For .gz format, we will define GZIPOutputStream later, as we want to keep the code generic.

Evaluate &desiredOption
When 1 /* Just a TAR file */
When 2 /* TAR.GZ */
   &OutputStreamType = "org.xeustechnologies.jtar.TarOutputStream";
   &ArchiveEntry = "org.xeustechnologies.jtar.TarEntry";
   &finalFileName = "c:\myTarFile.tar";
When 3 /* ZIP file */
   &OutputStreamType = "java.util.zip.ZipOutputStream";
   &ArchiveEntry = "java.util.zip.ZipEntry";
   &finalFileName = "c:\myZipFile.zip";
When-Other
   Error "Wrong Option";
End-Evaluate;

3. Create Archive Entry Function

Zip and TAR files require that you add an entry on each file being added into the archive first. To create this function, we need to supply the following inputs:

• Archive File – The archive file to which we have to add entries.
• Name of the Input File – File name for which we have to create the entry
• Type of Archive –  This parameter will have reference to TarEntry or ZipEntry as a appropriate. At run time, we will create a Java object for this type and add the input file to the archive.
• Compression Option – Whether to follow TAR (includes .tar.gz) or ZIP option. We need this parameter as the constructor for ZipEntry and TarEntry class takes different arguments.

We use putNextEntry method to add the file to the archive. Once this step is done, we can add the actual bytes to the archive.  The PeopleCode segment for this step is shown below:

Function CreateArchiveEntry(&Archive, &fileNametoAdd, &typeofArchive, &desiredOption)
   /* Create an Archive entry for every file you want to add to the archive */
   Local JavaObject &ArchiveEntry;
   If &desiredOption = 3 Then /* Handle Zip entries differently */
      &ArchiveEntry = CreateJavaObject(&typeofArchive, &fileNametoAdd);
   Else /* Handle TAR and TAR.GZ */
      &ArchiveEntry = CreateJavaObject(&typeofArchive, CreateJavaObject("java.io.File", &fileNametoAdd), &fileNametoAdd);
   End-If;
   /* Add Archive entry to OutputStream */
   &Archive.putNextEntry(&ArchiveEntry);
   /* Call Add Bytes to File method to add actual file to the Archive */
   AddBytesToFile(&Archive, &fileNametoAdd);
End-Function;

4. Create Add Bytes to Archive Function

This function takes the archive and file name. It then reads the input file byte by byte and adds it to the archive. This method is generic across zip, tar and tar.gz formats. We have discussed this function in depth in our earlier tutorials, so we just provide the code for this function.

Function AddBytesToFile(&archive, &fileName)
   /* Read source file into input stream */
   Local JavaObject &in = CreateJavaObject("java.io.FileInputStream", &fileName);
   /* Java Array that will read bytes from input file */
   Local JavaObject &filebuffer = CreateJavaArray("byte[]", 1024);
   Local number &byteCount = &in.read(&filebuffer);
   /* Read bytes from input file and load it byte array  - Do until all bytes are read*/
   While &byteCount > 0
      /* Write Bytes of Data to corresponding Archive Output Stream */
      &archive.write(&filebuffer, 0, &byteCount);
      &byteCount = &in.read(&filebuffer);
   End-While;
   /* Close input stream */
   &in.close();
End-Function;

5. Handle .gz File Compression

For tar.gz files alone, we have to create a .gz file after creating the TAR file. To do this, we create an object of type GZIPOutputStream and read the TAR file created earlier to this stream to achieve the compression. The same add bytes method can be reused for this purpose. The PeopleCode segment is shown below:

/* We will now create a GZIP file only for Option 2*/
If &desiredOption = 2 Then
   Local JavaObject &gzip = CreateJavaObject("java.util.zip.GZIPOutputStream", CreateJavaObject("java.io.FileOutputStream", "c:\myTarFile.tar.gz", True));
   AddBytesToFile(&gzip, "c:\myTarFile.tar");
   &gzip.close();
End-If;

File Compression  - Create ZIP / TAR / TAR.GZ Files in PeopleCode

The complete PeopleCode example to compress files and create zip / tar / tar.gz output is shown below:

Function AddBytesToFile(&archive, &fileName)
   /* Read source file into input stream */
   Local JavaObject &in = CreateJavaObject("java.io.FileInputStream", &fileName);
   /* Java Array that will read bytes from input file */
   Local JavaObject &filebuffer = CreateJavaArray("byte[]", 1024);
   Local number &byteCount = &in.read(&filebuffer);
   /* Read bytes from input file and load it byte array  - Do until all bytes are read*/
   While &byteCount > 0
      /* Write Bytes of Data to corresponding Archive Output Stream */
      &archive.write(&filebuffer, 0, &byteCount);
      &byteCount = &in.read(&filebuffer);
   End-While;
   /* Close input stream */
   &in.close();
End-Function;
Function CreateArchiveEntry(&Archive, &fileNametoAdd, &typeofArchive, &desiredOption)
   /* Create an Archive entry for every file you want to add to the archive */
   Local JavaObject &ArchiveEntry;
   If &desiredOption = 3 Then /* Handle Zip entries differently */
      &ArchiveEntry = CreateJavaObject(&typeofArchive, &fileNametoAdd);
   Else /* Handle TAR and TAR.GZ */
      &ArchiveEntry = CreateJavaObject(&typeofArchive, CreateJavaObject("java.io.File", &fileNametoAdd), &fileNametoAdd);
   End-If;
   /* Add Archive entry to OutputStream */
   &Archive.putNextEntry(&ArchiveEntry);
   /* Call Add Bytes to File method to add actual file to the Archive */
   AddBytesToFile(&Archive, &fileNametoAdd);
End-Function;

/* PeopleCode - Create ZIP / TAR / TAR.GZ Archive - Common Example
You can use this code to

1- TAR Single or multiple files
2 - TAR.GZ Single or Multiple Files
3- ZIP Single or Multiple Files */

Local array of string &FileArray = CreateArrayRept("", 0);
&FileArray.Push("c:\dest.log");
&FileArray.Push("c:\dest.sql");
&FileArray.Push("c:\final.sql");

/* This value defines the final output */
Local number &desiredOption = 3;
Local string &finalFileName, &ArchiveEntry, &OutputStreamType;
Evaluate &desiredOption
When 1 /* Just a TAR file */
When 2 /* TAR.GZ */
   &OutputStreamType = "org.xeustechnologies.jtar.TarOutputStream";
   &ArchiveEntry = "org.xeustechnologies.jtar.TarEntry";
   &finalFileName = "c:\myTarFile.tar";
When 3 /* ZIP file */
   &OutputStreamType = "java.util.zip.ZipOutputStream";
   &ArchiveEntry = "java.util.zip.ZipEntry";
   &finalFileName = "c:\myZipFile.zip";
When-Other
   Error "Wrong Option";
End-Evaluate;
/* Create Archive Object */
Local JavaObject &myArchive = CreateJavaObject(&OutputStreamType, CreateJavaObject("java.io.FileOutputStream", &finalFileName, True));
For &i = 1 To &FileArray.Len
   CreateArchiveEntry(&myArchive, &FileArray [&i], &ArchiveEntry, &desiredOption);
End-For;
/* Close output Stream */
&myArchive.close();
/* We will now create a GZIP file only for Option 2*/
If &desiredOption = 2 Then
   Local JavaObject &gzip = CreateJavaObject("java.util.zip.GZIPOutputStream", CreateJavaObject("java.io.FileOutputStream", "c:\myTarFile.tar.gz", True));
   AddBytesToFile(&gzip, "c:\myTarFile.tar");
   &gzip.close();
End-If;

6. Test zip/ tar/ tar.gz output

This program is tested with different input options for the same set of input files. The output files produced by the program in each of these cases are shown below:

Output TAR, ZIP and TAR.GZ Files Created in PeopleCode

We have now successfully created a generic PeopleCode implementation to create tar / zip / tar.gz files .

We have now completed the compression part of this tutorial series. The next step would be to define Peoplecode to extract TAR, GZ and ZIP files. We will discuss that in the upcoming posts. Meanwhile, you should checkout the references section of this tutorial that will have detailed technical information on some of these approaches.