Lambda the Ultimate

inactiveTopic Web Services Federation Language (WS-Federation)
started 7/8/2003; 11:05:23 AM - last post 7/11/2003; 2:53:18 AM
Ehud Lamm - Web Services Federation Language (WS-Federation)  blueArrow
7/8/2003; 11:05:23 AM (reads: 1283, responses: 5)
Web Services Federation Language (WS-Federation)
By using the XML, SOAP and WSDL extensibility models, the WS* specifications are designed to be composed with each other to provide a rich Web services environment. WS-Federation by itself does not provide a complete security solution for Web services. WS-Federation is a building block that is used in conjunction with other Web service and application-specific protocols to accommodate a wide variety of security models.

I am consulting on web services security this week, and looks what comes along...

Once more an XML based "language" (or DSL). While it wouldn't be wise to confuse this sort of thing with full blown programming languages, I think the trend seen here is interesting.


Posted to xml by Ehud Lamm on 7/8/03; 11:07:05 AM

Ehud Lamm - Re: Web Services Federation Language (WS-Federation)  blueArrow
7/8/2003; 1:23:17 PM (reads: 653, responses: 2)
Some related thoughts...

In the old days (~ 30 years ago) IT systems were often written in assembly language. Since this kind of code is hard to maintain, many systems were table driven, and in fact quite flexible. You could often configure the software from the outside by changing the configuration tables, allowing you at times to supply entry points to new external routines ("user exits" or hooks), change the format of reports etc.

With compiled high level languages systems were usually much "cleaner" from a traditional SE point of view, with modules defining the various kinds of functionality (today we have classes and EJBs), but this could lead to less flexible systems, which didn't allow user customization, or even programmer customization without changing the code and recompiling. Maybe if reflective languages were in the mainstream the trend would have been different, but it wasn't.

It seems that some of these XML standards are bringing us back to the old days of table driven programs, with XML configuration files instead of fixed layout tables. The principle remains the same: Prgograms that can be customized from the outside, at times even while the software is up and running. This is a good trend.

I am curious to know if others share this feeling, and noticed the trends I am talking about. It seems like this is related in some respects to the debate about how programming language expressiveness affects programming style and helps entrench design methodologies.

Marc Hamann - Re: Web Services Federation Language (WS-Federation)  blueArrow
7/8/2003; 2:17:23 PM (reads: 666, responses: 1)
The principle remains the same: Programs that can be customized from the outside, at times even while the software is up and running. This is a good trend.

I think though there is a fundamental tension between configuration and "programming". If the configuration is sufficiently full-featured, it approaches the complexity of a DSL, and is just programming by a different name. In that case, I would want to see the details of the configuration design before declaring it a "good thing".

On the other hand, good software design generally involves empowering the user to "hot configure" the application precisely over those variables that a) are of highest utility within the application domain b) are most well-defined within the application and its domain.

I'm not sure this is a "new trend"; XML has just given people the "silver bullet" that makes them stretch the principle to the limit. ;-)

Ehud Lamm - Re: Web Services Federation Language (WS-Federation)  blueArrow
7/9/2003; 12:49:33 PM (reads: 615, responses: 0)
I'm not sure this is a "new trend"; XML has just given people the "silver bullet" that makes them stretch the principle to the limit. ;-)

It's not a new idea, that's for sure. Like I said, people have been doing this sort of thing for ages. But XML (and easy XML parsing) are helping these techniques to regain prominence.

That's why I said that in some respects this is similar to the influence reflective languages might have on the programmers using them.

Marc Hamann - Re: Web Services Federation Language (WS-Federation)  blueArrow
7/9/2003; 1:37:40 PM (reads: 550, responses: 1)
That's why I said that in some respects this is similar to the influence reflective languages might have on the programmers using them.

I suppose what I meant is that even between the "old days" of table driven and the "new days" of XML, there has always been a desire to find a configuration magic bullet.

Attempts at "dynamic configuration" have been common in applications whether they were using a reflective language or had some custom configuration scheme. The dream of a totally data-driven application that is common among hard-core database specialists is a variation on this theme.

From my point of view, this isn't a discrete space but a continuum, with a totally closed application that takes no input at one end and an interpreter for a full-featured PL at the other.

I think that bold, unexamined use of strong configuration schemes just happen to have been done in XML recently because it is "standard syntax" that looks like a configuration format, but is often used as a (possibly lousy) DSL.

The Pragmatic Programmers make a similar point in a recent interview:

Plain Text and XML

Ehud Lamm - Re: Web Services Federation Language (WS-Federation)  blueArrow
7/11/2003; 2:53:18 AM (reads: 463, responses: 0)
I guess we are essentially saying the same thing. I just wanted to actor in the impact that the programming languages de jour had on things.