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 accident 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 developers 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 example, 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 applications 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 component 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

(Con’t, page 8)

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