1. Visual FoxPro Database Publishing on the Internet
by Rick Strahl
West Wind Technologies ™

2. Internet Development
Businesses are expanding their operations onto the Internet
Internet Development is exploding
Active, Database Applications are in high demand

3. Why build Web Applications? Issues that make the Web hot
Distribute widely
Administer centrally
Universal Client Interface
Application Platform of the future

4. Limitations of Web Applications Or: Two steps forward, one step back...
Configuration issues
Interface limitations of HTML
Indirect data accesss through server
Mostly non-visual development
Server based programming model

5. Browser provides the Active interface
Web Server provides data / application connectivity
The Internet Server API (ISAPI) is the building block for server side extensions

6. How the Active Web Works
Client side
Server side
Active Documents
Web server
Static
HTML
Pages
Web Browser
Displays HTML
HTTP
Browser
Scripting:
VBScript
JavaScript
ActiveX Controls/
Java
Server Extensions
ISAPI/CGI
Dynamic Data and Database
‘TheWall’

7. Common Gateway Interface Traditional Web Interface
CGI.exe (1)
(EXE, CMD, BAT)
CGI.exe (2)
(EXE, CMD, BAT)
CGI.exe (n)
(EXE, CMD, BAT)
New system process for each instance of script.
(relatively slow, resource intensive)
Web Server
HREF=“/cgi-bin/cgi.exe?Parms”

8. HREF=“/scripts/isapi.dll?parms”
Internet Server API (ISAPI) Extending the Architecture within the Server
Web Server
HREF=“/scripts/isapi.dll?parms”
MyISAPI (1,2..n)
(Multithreaded, In-Process DLL)
OtherISAPI
(Multithreaded, In-Process DLL)
Loads DLL once after which it stays resident, processing multiple requests simultaneously.

9. ISAPI Internet Server API (ISAPI)
The extension interface for IIS
Static content
(e.g., HTML)
Microsoft Exchange
Databases
(FoxPro, SQL, Access etc.)
Custom scripts, Interfaces to other applications etc.
MAPI
ODBC
Exchange
Web Connector
Internet Database Connector
Active Server Pages
(Denali)
Custom ISAPI Scripting
ISAPI
Microsoft Internet Information Server

10. Getting Started What you need for building Web apps
Fast Pentium box (133Mhz/32-64megs)
WindowsNT (recommended)
Web Server
Connector Interface/Application
Web browser
Basic HTML skills
Everything can run on 1 box!

11. Connecting Visual FoxPro Data Some of the tools available for IIS
Active Server Pages (IIS 3.0)
FoxISAPI connector (OLE)
West Wind Web Connection (ISAPI/OLE)

12. Active Server Pages (IIS 3.0) Server side scripting for IIS
Object Based Architecture
Tight integration with IIS
Database Connectivity with Active Data Objects (ADO)
Supports external object creation
Several sophisticated objects are built-in

13. Active Server Architecture Components Galore
Response/Request
Objects
(Input and Output)
Server Object
(System Services)
ASP.DLL
(ISAPI Extension)
Scripting Engine
(VBScript/JavaScript)
Active Data
Objects
(ODBC)
Session/Application
Objects
(Keeping State)

14. Active Data Objects Lightweight ODBC Connector
Implements OLE DB (ODBC 3.5)
Based on Visual Basic’s Remote Data Object
It’s fast especially when tied to a persistent connection object!
Implemented as Automation Object.

15. Automation Server Access HTML containing VBScript code
OLE EXE Server
(OutOf Process)
TClass::Tmethod()
ASP Scripting Engine
HTML containing VBScript code
Creates Object Reference:
<% oServer=Server.CREATEOBJ(“Tserver.TClass“)
cVar=oServer.Tmethod(“Parm1“,1) %>
Web Server
ADO Data Object
(ODBC Data Access)
OLE DLL Server
(InProcess)
HREF=“MyPage.ASP”

16. Active Server Summary Pros: Cons: Tight Integration with IIS
No hassle configuration
Very easy for simple active content
Cons:
Code Management
Automation Server Scalability
Scripting Language Limitations

17. FoxISAPI Connecting VFP Automation servers
Direct link from Web pages
ISAPI DLL creates persistent Automation object
DLL does equivalent of:
Passes form vars in parameter
Passes server vars in INI file
oServer=CREATEOBJECT(“TOleServer.TOleClass”)
oServer.YourMethod(“UserId=1”,”c:\temp\fox2.ini”)

18. Visual FoxPro OLE Server multithreaded/running InProcess
How FoxISAPI works
Visual FoxPro OLE Server
(loaded once then stays in memory)
Method1
Method2
Methodn
returns HTML
Document
passes
HTML Form
Data
Web Server
FOXISAPI.DLL
(HREF=“foxisapi.dll/Server.Class.Method”)
multithreaded/running InProcess

19. Hello World with FoxISAPI
HREF=“/scripts/foxisapi.dll/TDevCon.TFoxIsapi.Helloworld?”
DEFINE CLASS TFoxISAPI AS Custom OLEPUBLIC
FUNCTION Helloworld
LPARAMETER lcFormVars, lcIniFile, lnReleaseFlag
LOCAL lcOutput
#DEFINE CR CHR(13)+CHR(10)
*** HTTP header - REQUIRED on each request!
*** System Defines
lcOutput="HTTP/ OK"+CR+;
"Content-type: text/html"+CR+CR
lcOutput=lcOutput+;
"<HTML><BODY>"+CR+;
"<H1>Hello World from Visual FoxPro</H1><HR>"+CR+;
"This page was generated by Visual FoxPro...<HR>"+CR+;
"</HTML></BODY>"
RETURN lcOutput
ENDDEFINE

20. FoxISAPI Method Rules Must take 3 parameters
lcFormVar - HTML Form vars or ‘parameters’ passed on the URL
lcIniFile - filename containing server var
lnReleaseFlag - Set to keep or release server reference.
Must return HTTP compliant output
HTML document including HTTP header
Use custom HTTP headers for things like authentication, redirection, Cookies etc.

21. Set up for FoxISAPI OLE Server must be registered
Copy FoxISAPI.dll into script dir
Directory must have Web Server Execute rights set!
Run DCOMCnfg on NT 4.0
Add IUSR_ account to default rights
Set user to Interactive user on the specific server
Need to re-run whenever server is rebuilt

22. FoxISAPI OLE Instancing
InProcess DLL
Very fast
Only 1 VFP server can be InProcess
MultiUse (Out of Process EXE)
Slightly slower
Multiple different servers
Single Use
Use for multiple pooled servers
Same server can be instanced more than once

23. Starter FoxISAPI class Provided on the CD
Send/SendLn() Send text to output
StandardPage() Generates a full HTML page
ContentTypeHeader() Adds HTTP header
StartRequest() Called to set up a request Decodes input vars and clears the output property.
GetFormVar() Retrieves a form variable passed in with the first parameter.
GetCGIVar() Retrieves a server/browser variable from the INI file.
ReleaseServer() Standard method that releases the OLE server.

24. Method example with FoxISAPI class
HREF=“/scripts/foxisapi.dll/TDevCon.TFoxIsapi.TestMethod?”
* TFoxISAPI :: TestMethod
FUNCTION TestMethod
LPARAMETER lcFormVars, lcIniFile, lnReleaseFlag
LOCAL lcOutput, lcUserId, lcName
*** Decode the Form Vars and assign INI file to class property
THIS.StartRequest(lcFormVars,lcIniFile)
*** Must always add a content Type Header to output first
THIS.HTMLContentTypeHeader()
lcUserId=THIS.GetFormVar("UserId")
lcName=THIS.GetFormVar("UserName")
THIS.SendLn("<HTML><BODY>")
THIS.SendLn("<H1>Hello World from Visual FoxPro</H1><HR>")
THIS.SendLn("The current time is: "+time()+"<p>")
THIS.SendLn("<b>Encoded Form/URL variables:</b> "+lcFormVars+"<BR>")
THIS.SendLn("<b>Decoded UserId:</b> "+ lcUserId+"<p>")
THIS.SendLn([To retrieve the Browser use ]+;
[THIS.GetCGIVar("HTTP_USER_AGENT","ALL_HTTP"): ]+;
THIS.GetCGIVar("HTTP_USER_AGENT","ALL_HTTP") )
THIS.SendLn("<HR></HTML></BODY>")
RETURN THIS.cOutput

25. FoxISAPI Summary Pros: Cons: Full support for Visual FoxPro
Real Development Environment
Excellent performance
Cons:
Difficult First Time Configuration
No Web specific code support
Doesn’t run on non-ISAPI servers or Windows ‘95

26. West Wind Web Connection
Extensive Visual FoxPro framework for Web development
Support for multiple sessions
Works with Automation and File based messaging interchangeably
Scalable across multiple machines
Real-time, live debugging
Server Management

27. Web Server Visual FoxPro Web Connection Data Server Data Server
wc.dll
(ISAPI)
Visual
FoxPro
Data Server
(already loaded)
Server and Form Data
returns HTML Doc
HTML Link
HTML Document
FoxPro User
Code
Scripted
HTML
Web Browser
Database

28. How your code gets called
wwServer
Visual FoxPro form class
handles request routing on
incoming requests.
wwServer::Process()
Routes request to
your PRG file
invokes
MyPRG
creates new Process object
and calls Process method
To process this URL:
wc.dll?MyPRG~MyMethod
CGIProcess Class
Contains MyMethod() that
creates HTML output.
Class can contain
multiple methods.
Returns HTML object

29. How your code gets called Creates Process Object
DEFINE CLASS MyProcess...
Procedure Process
loCGI=THIS.oCGI
lcParam=loCGI.GetParam(1)
*** Any ‘global processing’ here
*** Check for Cookies, User Ids etc.
*** Route to appropriate method
CASE PEMSTATUS(THIS,lcParam,5)
=EVAL("THIS."+lcParam+"()")
RETURN
PROCEDURE CUSTLIST
<Your processing goes here>
<Create HTML document file>
wwServer
Visual FoxPro
form that’s an
OLEPUBLIC
Automation Object
or uses a timer
to poll for requests
on disk.
Creates Process Object
returns HTML object

30. Web Connection Framework Some of the features available
Class framework for easy access to CGI/HTML functionality
Solid error handling scheme
Hit Logging, Mulitple Session Management and Maintainence Routines
HTML scripting from files or memos
Single method output of tables to HTML
Built-in support for many advanced HTML/HTTP features

31. Sample Processing Code
*** wwCGIProcess :: CustList
FUNCTION CustList
loCGI=THIS.oCGI
loHTML=THIS.oHTML
lcClient=TRIM(UPPER(loCGI.GetFormVar(“Client“))
SELECT tt_cust.company FROM TT_CUST ;
WHERE UPPER(tt_cust.company)=lcClient
INTO CURSOR TQUERY ORDER BY company,Datein
IF _TALLY<1
THIS.ErrorMsg("No Matching Records found...")
RETURN
ENDIF
*** HTML output creation follows
loHTML.HTMLHeader("NWDS Customer List",;
"Customer List Sample",”#FFFFFF”)
loHTML.EnclosedText("H3","Time review for: "+lcClient)
loHTML.SendLn(“<p>”)
*** Now show the table
loHTML.ShowCursor()
loHTML.HTMLFooter()

32. Tools summary
Check out Active Server for sophisticated server scripting and connectivity to VFP via Auto servers
For more control use Visual FoxPro as a Web data server
FoxISAPI provides powerful OLE connectivity with an easy interface
For a complete Fox based Web environment check out Web Connection

33. ™