Release 10.1A: OpenEdge Development:
Programming Interfaces

Example 2 — reading customer data and writing a TEMP-TABLE

This example is a SAX version of the DOM example described in Chapter 19, "Progress XML Support and the Document Object Model (DOM)," in this book. The example reads an XML file containing the Customer table from the Sports database and writes the data to a temp-table. The example uses qname, assumes there is no namespace prefix, and, for clarity, omits code for transaction scoping and for validation.

Here is the EPI SAX Example 2 driver procedure, i-sax2d.p.

i-sax2d.p

DEF VAR hParser as HANDLE. DEF VAR hHandler AS HANDLE. /* create the SAX-READER object */ CREATE SAX-READER hParser. /* run the persistent procedure that contains the callbacks */ RUN "i-sax2h.p" PERSISTENT SET hHandler. /* give the SAX-READER the handle to the persistent procedure */ hParser:HANDLER = hHandler. /* Give the SAX-READER the info on the file to parse. This XML file does not use namespaces. */ hParser:SET-INPUT-SOURCE("FILE", "i-sax2.xml"). hParser:SAX-PARSE( ) NO-ERROR. /* By the time SAX-PARSE returns, the callbacks have been called as many times as necessary and we’re done processing the XML document (or there was an error) */ IF ERROR-STATUS:ERROR THEN DO: IF ERROR-STATUS:NUM-MESSAGES > 0 THEN /* unable to begin the parse */ MESSAGE ERROR-STATUS:GET-MESSAGE(1) VIEW-AS ALERT-BOX. ELSE /* error detected in a callback */ MESSAGE RETURN-VALUE VIEW-AS ALERT-BOX. END. ELSE MESSAGE "Document parsed successfully" VIEW-AS ALERT-BOX. DELETE OBJECT hParser. DELETE PROCEDURE hHandler.

Here is the EPI SAX Example 2 XML file, i-sax2.xml.

i-sax2.xml 

<?xml version='1.0' ?> <Customers>

<Customer Name="Lift Line Skiing" Cust-num="1"> <Country>USA</Country> <Address>276 North Street</Address> <Address2></Address2> <City>Boston</City> <State>MA</State> <Postal-Code>02114</Postal-Code> <Contact>Gloria Shepley</Contact> <Phone>(617) 450-0087</Phone> <Sales-Rep>HXM</Sales-Rep> <Credit-Limit>66700</Credit-Limit> <Balance>42568</Balance> <Terms>Net30</Terms> <Discount>35</Discount> <Comments>This customer is on credit hold.</Comments> </Customer>

<Customer Name="Hoops " Cust-num="3"> <Country>USA</Country> <Address>Suite 415</Address> <Address2>40 Grove St.</Address2> <City>Atlanta</City> <State>GA</State> <Postal-Code>02112</Postal-Code> <Contact>Michael Traitser</Contact> <Phone>(617) 355-1557</Phone> <Sales-Rep>HXM</Sales-Rep> <Credit-Limit>75000</Credit-Limit> <Balance>1199.95</Balance> <Terms>Net30</Terms> <Discount>10</Discount> <Comments>This customer is now OFF credit hold.</Comments> </Customer>

</Customers>

Note: There is no DTD or XML schema and no use of namespace prefixes. The lack of a DTD or XML schema means that the handlers need to validate the document, but the example omits that validation for the sake of clarity.

Here is the EPI SAX Example 2 handler procedure, i-sax2h.p (1 of 3).

i-sax2h.p

/*so we can create new records*/ DEFINE TEMP-TABLE Custt LIKE Customer. DEFINE VARIABLE hBuf AS HANDLE. DEFINE VARIABLE hDBFld AS HANDLE. hBuf = BUFFER Custt:HANDLE. /* variable in which to accumulate all the text data for one element coming in through potentially multiple calls (per element) to the Characters procedure */ DEF VAR currentFieldValue as CHAR. /* simple-minded state machine – the code makes minimal use of it, but it could easily be used to validate the structure of the document in this example */ DEF VAR iProcessingState as INT. &SCOPED-DEFINE READY-TO-START 1 &SCOPED-DEFINE GETTING-RECORDS 2 &SCOPED-DEFINE GETTING-FIELDS 3 &SCOPED-DEFINE DONE 4

PROCEDURE StartDocument: iProcessingState = {&READY-TO-START}. END.

PROCEDURE StartElement: DEFINE INPUT PARAMETER namespaceURI AS CHARACTER. DEFINE INPUT PARAMETER localName AS CHARACTER. DEFINE INPUT PARAMETER qName AS CHARACTER. DEFINE INPUT PARAMETER attributes AS HANDLE. IF qName = "Customers" THEN iProcessingState = {&GETTING-RECORDS}. ELSE IF qName = "Customer" THEN DO: /* starting a new customer, so create the record */ CREATE Custt. /*get the fields that are in the XML doc as attributes*/ cust-num = INTEGER( attributes:GET-VALUE-BY-QNAME("Cust-num") ). name = attributes:GET-VALUE-BY-QNAME( "Name" ). iProcessingState = {&GETTING-FIELDS}. END. ELSE IF iProcessingState = {&GETTING-FIELDS} THEN DO: /* get a handle to the field whose name corresponds to the element name */ hDBFld = hBuf:BUFFER-FIELD(qName). /* re-init the variable in which we accumulate the field value */ currentFieldValue = "". END. END.

PROCEDURE Characters: DEFINE INPUT PARAMETER charData AS MEMPTR. DEFINE INPUT PARAMETER numChars AS INTEGER. /* get the text value of the field (hDBFld was set to the correct field in StartElement */ currentFieldValue = currentFieldValue + GET-STRING(charData, 1, GET-SIZE(charData)). END.

PROCEDURE EndElement: DEFINE INPUT PARAMETER namespaceURI AS CHARACTER. DEFINE INPUT PARAMETER localName AS CHARACTER. DEFINE INPUT PARAMETER qName as CHARACTER. IF localName = "Customers" THEN iProcessingState = {&DONE}. ELSE IF localName = "Customer"THEN iProcessingState = {&GETTING-RECORDS}. ELSE IF iProcessingState = {&GETTING-FIELDS} THEN hDBFld:BUFFER-VALUE = currentFieldValue. END.

PROCEDURE EndDocument: /* show that data made it by displaying temp-table */ FOR EACH Custt: DISPLAY custt. END. RUN Cleanup. END.

PROCEDURE FatalError: DEFINE INPUT PARAMETER errMessage AS CHARACTER. /* not necessary to do anything with PRIVATE-DATA, this is just an example of what you could do */ SELF:PRIVATE-DATA = "FATAL". RUN Cleanup. /* RETURN ERROR in an error handler implicitly calls SELF:STOP-PARSING(), sets SELF:PARSE-STATUS to SAX-PARSER-ERROR, and raises the Progress ERROR condition */ RETURN ERROR errMessage + "(Line " + STRING(SELF:LOCATOR-LINE-NUMBER) + ", Col " + STRING(SELF:LOCATOR-COLUMN-NUMBER) + ")". END.

/* this is not a SAX callback, it is just a local utility */ PROCEDURE Cleanup: /* in case we've parsed previous documents */ hBuf:EMPTY-TEMP-TABLE( ). END.