SourceConverter Base Class (Extends Converter)
Overview
The SourceConverter, derived from the Converter class, is the base class for the CSV, flat file, and EDI source converter classes developed in the next three chapters. The lists below summarize the major attributes and methods.
Attributes:
DOM Document Output Document
RecordReader Reader
String Base Output Directory
String Schema Location URL
Boolean Validation Option
Methods:
Constructor
processFile (virtual)
processGroup
saveDocument
The processGroup method is listed here for completeness but will be developed in Chapter 8.
Methods
Constructor
The operations common to all our legacy format source converters include setting up the base output directory name and implementation-dependent DOM setup for output document validation.
Logic for the SourceConverter Constructor Method
Arguments:
Boolean Validation Option
String Base Output Directory
Call base class constructor
Validation Option <- Passed validation option
Base Output Directory <- From passed base output directory,
Appending directory separator character if required
Perform any implementation specific setup for validating
output documents before writing them
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saveDocument
This operation is coded as a separate function since it may be called within a while loop that reads records from the input file and after exiting the while loop to save the last document.
Logic for the SourceConverter saveDocument Method
Arguments:
DOM Document Output Document
String Output File Name
Boolean Validate
Returns:
Status value or throws exception
IF Validate is true
Validate output DOM Document
ENDIF
Save DOM Output Document to passed File Name, dependent on
implementation
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An enhanced version of this utility might give the option of looking up and calling an in-memory XSLT transformation on the DOM Document before it is saved to disk. We might even hand off the DOM Document in memory to a message handling service for e-commerce applications. We won't get that advanced in this book (KISS over efficiency), but the options certainly exist.
Derived Class Method
processFile
This method is declared as a virtual method in the base class and implemented separately in each of the derived classes for our legacy formats. The general processing model is to read a single file with multiple logical business documents, create a separate XML instance document from each logical document in the input file, and write a separate file for each of the XML instance documents. In an e-commerce type of situation where some of the documents are intended for different external organizations, we'll write the documents for each organization to a separate directory. The listing below shows the general logic.
Logic for the SourceConverter processFile Method
Arguments:
String Input File Name
Initialize Sequence Number
Open Input File
Call RecordReader's setInputStream method, passing the input
Stream
Record Length <- Call RecordReader's readRecord method
DO while Record Length => 0
Record Grammar <- get Grammar for Record Type
Call RecordReader's parseRecord method, passing Record
Grammar
Call RecordReader's toXMLType method
IF Break on Partner ID
Output Directory <- Base Output Directory + Partner ID
IF New Partner
Store new Partner in Partner Array
Make Output Directory for Partner
ENDIF
ENDIF
IF Break on Document
IF Output DOM Document != null
Call saveDocument, passing Output DOM Document and
Output File Path
Set Output DOM Document to null
ENDIF
Create new Output DOM Document
Create Root Element and Append to Output DOM Document
IF Schema Location URL is not null
Create noNamespaceSchemaLocation Attribute and
append to Root Element
ENDIF
Increment Sequence Number
Pad Sequence Number to 3 digits with leading zeroes
Output File Path <- Output Directory + Sequence Number
+ ".xml"
Call RecordReader's setOutputDocument method, passing
Output DOM Document
ENDIF
Call RecordReader's writeRecord method, passing Parent Element
and Grammar Element for Record
Record Length <- Call RecordReader's readRecord method
ENDDO
IF Output DOM Document != null
Call saveDocument, passing Output DOM Document and
Output File Path
ENDIF
Close input stream
Display completion message with the number of documents
processed
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