Recently, there have been several requests in the XPO newsgroup about problems with serialization, in conjunction with ASP.NET. I’m still unclear if these issues all had the same sources, but when somebody approached me personally about this today, I thought I’d just look into the web services problem. Please note that I made these tests on the .NET 2 platform, so there may be differences to .NET 1.1. What’s more, ASP.NET and web services are not something I usually have much to do with, so I m …

Many things change with the decision to work with purely object-oriented data in a specific situation. The outlook seems good: business processes and rules will be much easier to implement, completely typed data will be no problem at all and there’ll be no more structural problems trying to accomodate clumsy handling of records and rows in an otherwise OO application structure. There’ll be an object/relational mapping tool that takes care of all the persistence issues. There’s one thing though …

In a previous article, I showed how nullable types, as implemented in version 2 of the .NET framework, can be persisted using XPO. But what if .NET 2.0 is not yet an option? .NET 1.1 doesn’t have support for nullable types and there’s no such feature in XPO, either. If somebody comes from the database world, it’s certainly understandable that types that can also be null are something he’s accustomed to. On the other hand, XPO is about persisting objects, and in that world, no ordinary value t …

In this post I showed how nullable types can be simulated in .NET 1, especially for use with XPO. Prompted by Miha Markic, I had a look at the possibility of data binding with those simulated nullable types. I found that while the implementation I had suggested could be used without problems in a read-only situation, it obviously didn’t contain any logic that would enable editing the types via data-bound controls. Nevertheless, this is easy to do by creating a custom TypeConverter. Like this: …

The current version of Developer Express XPO has a Session object that handles one connection to the database together with an object cache for that session. Technically, the Session is a pivotal point in the XPO architecture, all object handling requests go through a Session object. Recently it came to my attention that some people regard it as a great problem that the Session object is tightly bound to a database connection. By default, this is a direct association: you can create more than o …

In XPO, an ORM product by Developer Express, it’s possible to use a custom “value converter” to persist information when the standard mapping techniques are not sufficient. This provides a flexible approach that can be used in many different scenarios.

Nullable types

Although the Developer Express knowledge base provides an article that shows how to persist a bitmap, I had never actually used that approach. With .NET 2.0, I was thinking about persisting nullable types and I found that XPO …