/* Rambling comments... */

Sinking connection points in C++ objects. Posted by Len at 30 May 2002 01:00 AM
Sometimes it would be nice to be able to use a simple C++ object as a sink for Connection Point notifications. This article shows you how....

Designing asynchonous COM components for VB Posted by Len at 11 Apr 2002 01:00 AM
This example COM component provides three COM objects for using the Win32 Mailslot IPC mechanism. The component may be useful if you need to communicate from VB using Mailslots. However, the reason I wrote it was to demonstrate creating a...

AVL Tree Posted by Len at 7 Aug 2001 11:31 AM
A "generic" AVL Tree, from the dark days before templates... The code here is some of my first C++. Back in 1991 C++ was still pretty new. Looking back at my early C++ is better than looking back at my...

Rooms 1.7 Posted by Len at 2 Aug 2001 11:25 AM
In 1989 I taught myself C to write an adventure game, the code's fairly bad, but 10 year's later, the game's still quite cool!...

Java caches in the middle tier Posted by Len at 26 Jul 2001 08:18 PM
A common way to improve the performance of Java code is to cache objects rather than repeatedly create and destroy them. This is especially true when you're writing middle tier servers that service client requests and return results objects. Implementing a flexible caching scheme in Java is relatively easy, but there are a few things to watch for.

The CORBA Evictor Pattern in Java Posted by Len at 23 Jul 2001 01:00 AM
When a CORBA server allows its clients to create and destroy objects one of the recommended ways to handle the object lifetime issues is using the Evictor Pattern. In The Evictor Pattern we solved the problem for C++ servers, here...

CORBA - Keep Alive Posted by Len at 17 Mar 2001 01:00 AM
One way of making a reference counted implementation more robust is to run the keep-alive protocol yourself. We demonstrate this option here....

CORBA - The Evictor Pattern Posted by Len at 15 Mar 2001 01:00 AM
Since CORBA doesn't really support reliable reference counting implementations we'll compare one of the recommended methods of servant life-time management with our reference counted iteration interface....

CORBA - Iteration Posted by Len at 9 Feb 2001 02:00 AM
A CORBA style method of enumeration can be seen in the iteration interfaces on the CORBA Naming Service. Given the code we've already written for the enumeration interface we can easily implement an iteration interface as well as (or, more...

CORBA - Enumeration Posted by Len at 9 Feb 2001 01:00 AM
CORBA provides sequences as a way of returning collections of items from an method call. The problem with just using unbounded sequences is that the client has no control over how many items it receives as a result of the call. COM gets around this problem using the IEnum style interfaces that allow a client to control how it accesses the items in a collection.

CORBA - Reference Counting Issues Posted by Len at 9 Feb 2001 12:00 AM
At the end of the second article we have developed a self contained reference counting implementation that appears to work. Unfortunately, it's still far from reliable as CORBA doesn't provide the level of support for reference counting that's built into COM. In this article we discuss the problem and the various CORBA methods for controlling server object lifetime.

CORBA - More Reference Counting Posted by Len at 6 Feb 2001 01:00 AM
Although we managed to develop a working solution in the first CORBA reference counting article the results were ugly and fragile. In this article we attempt to clean things up a little and, in doing so, get intimate with the Portable Object Adapter and its Servant Managers.

CORBA - Reference Counting Posted by Len at 6 Feb 2001 12:00 AM
We've been developing code on Windows and Unix for quite some time, but most of the distributed component work we've been involved in has been done using COM. That's changing now as clients have more requirements for Unix based component solutions. We're currently evaluating CORBA ORBs and learning how the CORBA way of doing things differs from the COM way. The first difference that we came across was the way that CORBA servers deal with object lifetime issues. Adding reference counting to CORBA objects isn't as easy as it first seems Please note that these articles initially explore COM concepts implemented in CORBA, some of the early implementations, whilst working examples, aren't at all production quality... If you want something reliable, that works, skip forward to the Evictor Pattern.

COM+ Administration Posted by Len at 29 Jun 2000 01:00 AM
COM+ applications can be complex to configure and there's no standard way to save that configuration in a form that can be placed under version control. Luckily the COM+ Catalog is accessible by a set of completely scriptable COM objects....

OLEDB - Disconnected Recordsets Posted by Len at 21 May 2000 01:00 AM
If you are going to use the client cursor engine then often it's a good idea to disconnect your recordset......

MFC - Include/Exclude list boxes Posted by Len at 26 Feb 2000 01:00 AM
How to package lots of standard functionality into a CListBox derived class....

Using COM to write extensible applications Posted by Len at 26 Feb 2000 01:00 AM
Localise design decisions by writing key application functionality as pluggable COM objects. When the requirements change you just write a new plug in......

It's a wonder any code is ever reused Posted by Len at 1 Feb 2000 01:00 AM
It's rare that code can be viewed as a black box for reuse. If you include design choices and dependencies as valid parts of the code's interface then it's easier to explain why reusing nontrivial code is often harder than...

OLEDB - Client Cursor Engine updates Posted by Len at 2 Jan 2000 01:00 AM
Making the ADO Client Cursor Engine believe that your rowset is updateable involves jumping through a few extra hoops......

OLEDB - Updating data through an ADO recordset Posted by Len at 2 Jan 2000 01:00 AM
The ATL OLE DB Provider templates only seem to support read-only rowsets, and making them support updating of data isn't as easy as you'd expect!...

OLEDB - IRowsetLocate and Bookmarks Posted by Len at 16 Oct 1999 01:00 AM
Adding bookmark functionality is relatively easy and it enables our ADO recordset to be used with a greater number of data bound controls....

OLEDB - Custom Rowsets Posted by Len at 15 Sep 1999 01:01 AM
The ATL OLE DB Provider templates appear to rely on the fact that your data is kept in a simple array, but that's not really the case at all!...

OLEDB - Objects via ADO Posted by Len at 15 Sep 1999 01:00 AM
ADO seems to be the ideal way to expose tabular data from your own COM objects and the ATL OLE DB Provider templates can help!...

MFC - Templates Posted by Len at 30 Sep 1998 01:01 AM
Templates are a great way of reusing code, unfortunately MFC makes it hard to write MFC friendly template classes......

IEnumXXXX Posted by Len at 30 Sep 1998 01:00 AM
COM objects generally provide access to sequences using an IEnumXXXX style interface, this class wraps that with an STL style iterator...

Smart cards in Russia Posted by Len at 25 Feb 1995 08:21 AM
In February 1995 I flew to Perm in eastern Russia as part of a two-man team installing a smartcard system for a local bank. I was responsible for designing and implementing the card production system that was being used. For...

Rifts character sketch Posted by Len at 8 Apr 1993 07:17 AM
This character sketch is from a Rifts scenario that I made notes for but never got around to running.

The Order of the Silver Rose Posted by Len at 7 Feb 1992 10:24 PM
The Order of the Silver Rose was a religious order of Knights in an AD&D campaign that I ran. The campaign was set in The Forgotten Realms and was based around the FRE1-3 scenario packs.