The LA Fox Developer Newsletter

June 1999

Levy Joins DataChannel (Con’t from page 1)

DataChannel was founded in 1996 by Dave Pool. Ten years ago,

he started a company called Spry. Spry developed a software

product Internet In A Box that made it easy for people to go

online. In 1995 he sold the company for $102 million. To see

some background information on DataChannel’s founder Dave

Pool along with a four minute video clip of how he runs the

company, go to: http://www.msnbc.com/local/KING/254456. asp.

My title at DataChannel will be Senior Architect. As for my role

at DataChannel without the details, I will be part of

DataChannel’s architecture department working directly for

DataChannel CTO (Chief Technology Officer) Norbert Mikula.

Norbert developed one of the first XML parsers (NXP) and has

been actively involved in XML- related efforts since the early

days of this standard. He has been actively involved with

industry initiatives and working groups such as XML-EDI, the

W3C XML working group and the W3C Extensible Style Sheet

Language working group. Norbert also serves as CTO on the

board of directors of OASIS (http://www..oasis-open.org), the

Organization for the Advancement of Structured Information

Standards, which is an international consortium dedicated to

accelerating the adoption of product-independent formats based

on public standards. He is also the author of numerous articles,

whitepapers and books including XML for Dummies. For more

information about Norbert, go to: http://www.datachannel.com/

news/pr_norbert.shtml.

Hopefully this detailed message helps clarify my current

activities and will minimize questions about my new position.

And just in case you don’t already know, VFP 6.0 SP3 was just

released and it’s a really great update. Information on SP3 and

many other VFP resources can be found at: http://

msdn.microsoft. com/vfoxpro/.

Ken Levy

http://classx.com

A Little Humor

A pregnant woman from Washington, D.C. gets in a car acci-

dent and falls into a deep coma. Asleep for nearly 6 months,

when she wakes up she sees that she is no longer pregnant

and frantically asks the doctor about her baby.

The doctor replies, “Ma’am you had twins! a boy and a girl. Your

brother from Maryland came in and named them.” The woman

thinks to herself, “No, not my brother... he’s an idiot!”

She asks the doctor, “Well, what’s the girl’s name?”

“Denise.

“Wow, that’s not a bad name, like it! What’s the boy’s name?”

"Denephew."

VFPCOM.DLL Released

By Jim Slater

VP Rocky Mountain FoxPro Users Group

A new enhancementto VFP 6.0, vfpcom.dll, is now available for

download on the VFP Web site at http://msdn.microsoft.com/

vfoxpro/downloads/readme_ VFPCOM. asp . This COM server

extends VFP’s functionality in two areas.

First is the ability to convert VFP cursors to ADO recordsets

(the .CursorToRS( ) method), and ADO recordsets to VFP

cursors (the .RSToCursor( ) method). Microsoft has stated that

the future of data access in MS products is ADO and OLEDB

(at least until they invent some new acronyms!). VFP develop-

ers new to ADO should feel at home in no time, since ADO

techniques for accessing and updating data parallel those

available natively within VFP.

As we all know, however, no other language matches VFP’s

ability to manipulate data. Vfpcom.dll allows us to create

cursors using the full power of VFP, then convert them to ADO

recordsets in a flash with a single method call. Ken Levy

provided a VFP-to-ADO conversion utility several months ago at

his web site www.classx.com . This new component repackages

his ideas into a Microsoft-supplied component that runs at the

C++ speed of a .dll.

In addition to ADO conversion, vfpcom.dll provides us with an

event-binding capability previously unavailable in VFP. When

designing a COM server, the programmer may wish to alert the

host application when a certain event has occurred. For ex-

ample, ADO supports the following methods to notify the host

that data has been retrieved or changed: Fetch Progress,

FetchComplete, WillChangeRecord, RecordChangeComplete,

WillChangeField, FieldChangeComplete.

If the COM server made calls to specific methods in the host to

alert it of these events, it could not be used with host applica-

tions that did not include those methods. For example, VFP

does not have a RecordChangeComplete() function or method,

so an attempt by a COM server to do something like

“oHost.RecordChangeComplete~” would generate an error.

Without knowing in advance whether a host includes a given

method, how can a COM server be designed to notify its host

when something happens? The solution is to include a “Raise

Events” capability in the COM server. This allows the compo-

nent to send out a signal saying in effect “if you are interested,

the following just happened; if you’re not, don’t bother”. Unlike a

direct method call, raising an event not supported by the host

application will not generate an error. While VFP does not allow

us to raise events, other languages such as VB and VC++ do.

Until now, VFP also was unable to respond to events raised by

COM servers. Vfpcom.dI! solves this by introducing a new

Bind Events() method. This allows us to create a VPF class with

method names identical

to one or more the COM server’s event

(Con’t, page 8)

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