Steve pointed out that RPC does NOT require synchronous communications. This is true. One can simulate the request-response of a remote procedure using asynchronous communications. But the idea is that RPC appear synchronous - like a programming language procedure that blocks.

Some synchronous technology can appear asynchronous. E.g. CORBA has oneway operations. And many queue based (messaging) technologies use connection based technology underneath. E.g. Some publish subscribe technologies are actually connection based. The publisher connects to the notification service and so does the subscriber when retrieving messages. They are asynchronous to the application in the sense that they are decoupled.

Back to the Steve conversation. Steve maintained that RPC basically implied location transparency. I'm not sure I agree. Though many RPC technologies have location transparency I don't think that that the orginal intent for RPC was that it have location transparency. I certainly regard come technologies today as RPC that don't have location transparency. RFC 707 doesn't mention location transparency and as it works through command/response, request/reply and procedure call models it speaks of making it easier but I don't see transparent. In fact in order not to "mislead the application programmer" the paper suggests the model be clarified with "Local procedure calls are cheap; remote procedure calls are not."

Location transparency is very often a bad thing. (more often than not as we discovered with novice developers of CORBA and distributed Java technologies and many more.) Because location transparency hides the network, this can mislead the developer and also introduces issues of extra exception handling that the developer has make sure that they cover. Steve wrote an excellent paper on some of the issues in IEEE's Internet Computing back in late 2005 - I have a copy but I don't have a public URL for it, sorry.

But one could argue this both ways. i.e. The technology is not good because it misleads the programmer OR you could say that one needs better than average programmers to develop distributed application architectures using RPC. But it seems that one could say the same thing about RESTful developers. So before we accept the former (the technology is not good) let us remember that not all REST developers are building truly RESTful based applications/services. In fact RESTful Web services points out that most REST based services are REST-RPC and not RESTful.

Again, I wish to point out that I continue to warm to REST and Resource Oriented Architectures, I see the potential, and look forward to implementing. I'm just not willing to say that REST is useful in all situations or that SOAP and WS-* are evil and there is no place for them. And, as the book points out, there is still a lot of confusion with REST based on the wide deployment of REST-RPC services rather than RESTful.

The book has this to say about breaking the uniform interface: "occasionally it's unavoidable" (p101). Even while it's undesirable. The section on POST describes this scenario. And so some "overloading" is required. Does this mean then that REST is broken? Or should the REST community loosen the definition of RESTful? Is "reshuffling" the resources acceptable, or a hack that demonstrates something that needs to be addressed with the model?

First let me say that I like REST. I think the architecture makes a lot of sense in many cases and I look forward to implementing my first RESTful services(s). Having said that the REST community don't do themselves many favors with the enterprise community, especially those that have been around the block several times and have built several flavors of architectures over the years. We know our architectures -we know our terminology. It seems the REST guys confuse some terms. So I'm going to target some areas to help unravel the muddle.

I've decided to base this critique on the new popular book RESTful Web services by Richardson & Ruby. I'm assuming that the REST community stand by this book - otherwise, sadly, it just adds some more confusion. To the authors I say thank you, I'm enjoying the book. Don't think I don't like it just because of this blog. It has not only helped me appreciate some of the confusion in the industry but it has helped me to appreciate the RESTful resource oriented approach.

Before I start I'll summarize by saying this. Perhaps much of the present confusion is that the REST community has changed the semantics of some popular enterprise computing terminology. We shall address these below.

Before I start I need to point out that I work with Microsoft in their partner program. I'm committed to that. Microsoft technologies and products play a big part in the enterprise and will continue to do so. It's not going away. Microsoft often have some "negative" things to say about certain products etc. of their partners so I think it's okay for me to be critical if it's constructive and can lead to better products. (Also see the disclaimer about these being my opinions and not that of my company on the right ;-)

Yesterday I was listening to Mr. Ballmer talk about "optimized desktops" and "enabling people to realize their potential" (never mind that the promise of technology to help people realize their potential seems a bit of a stretch). While I was listening I was shaking my head in disappointment. I had wanted this to be a positive upbeat, experience but what had just happened to me had already soured my perspective.

You see I decided to leave my Mac at home and be a good corporate citizen and take my newer Dell/Microsoft Vista laptop. Sigh, what a mistake. Those of you that own a Mac, know how easy it is to just connect to the internet, especially on WiFi. Well I had being in the main conf. dining area with my Vista laptop trying to connect for an hour. I've seen colleagues with this problem before. Now I was experiencing it first hand. You see I made the mistake of just putting my laptop to sleep and then opening it, reawakening it (always hit-or-miss IMO) and trying to connect. Well Vista couldn't see the WiFi at the conf. center. I scoured the conference information book to see if there was some SSID I was supposed to be using. I then decided that perhaps the Colorado Conference Center was a little behind and I had to be somewhere special Microsoft's Blue Lounge for WiFi access. I headed outside the dining area.

As I left the dining area I noticed some people sitting around with laptops and asked if they were online. "Sure" they said. hmmmm... Of course! I remembered. This is still Windows! See my problem was that I expected more from Vista in this area. But I needed to reboot. Of course, I couldn't wake my laptop from sleep - hey, sometimes it wakes sometimes it doesn't you just don't know. I tried everything and then I decided that I was going to reboot anyway I might a well do the horrible hard boot by holding down the power button - not elegant but some things don't change. (For those of you shutting "user error, user error" remember I have two degrees in computer science (B.Sc. and M.Sc.) and have been working on computers since before 1984 in some way or other. I've programmed Windows, Solaris, Cray, IBM Mainframe, HP/UX, AIX, OS X, Linux .....)

After the hard reboot sure enough there was the WiFi hotspot MSFTINET. Yea! I connected! But woops, gotta go into see Mr. Ballmer's keynote. Hopefully the laptop will remember MSFTINET. Well when I got around to the overflow room - my delay contributed to missing the main hall - I discovered that MSFTINET was not visible from here. But that's fine there was MSFTEVENT and MSFTWAN and some others. Forget it. No luck. I closed my laptop disappointed and instead watched Mr. Ballmer jump around the stage like a rock star. Fair play to him - he's a lot to be excited about.

Ballmer talked about how Microsoft was once a desktop company and still is but that was once perceived as not-an-Enterprise-company. However now they are told how they can be a "better enterprise company", inferring that they are at least an enterprise company now. I think that is very fair- there is no denying that fact. Microsoft are a very strong enterprise company. Sun and HP have slipped up in this area. IBM are still very strong. But I couldn't help thinking, "you could still be a better desktop/laptop company". Now maybe I'm being unfair perhaps this is a Dell problem.

So enough about the negative experience. Here are some of the positives. Ballmer introduced Sliverlight a "cross-browser, cross-platform plug-in for delivering the next generation of Microsoft .NET–based media experiences and rich interactive applications for the Web." The technology walkthrough and demo, performed by someone else (I'm ashamed I can't remember their name) was very impressive. Actually I decided to download it on my Mac today to see it work. Some bad news for Microsoft - I promise this was supposed to be a positive section - it wouldn't install on Safari. The install reported that I required "10.4.8 or higher" to install and so it wouldn't install. Well I have 10.4.10!!! Come on guys (MS)!!! I wanted to try this out and say really positive stuff! Anyway I'm sure this is a small glitch. I'll try it on Vista later or on Firefox. It looked really slick.

Microsoft also talked about the Cloud Platform - a place for developing new service based applications etc. Hmmm... we (at IONA) have been talking about the cloud for about 3 years. Sounds very familiar.

So I really need to say something completely positive with no negative strings. Ah yes, I saw Surface. I had seen a YouTube demo of this technology (or like technology ? ) some years ago. It is so very very cool. Honestly it's the type of technology and product you'd expect from Apple. Congratulations to Microsoft for swooping this up. Reader, if you haven't seen this yet check out the cool promotion demos here. (Skip the introduction).

So tonight, if they'll still let me, I'll be seeing Earth Wind and Fire at one of the Microsoft events. Oh you thought that "After the Love is Gone" was about Vista. No, it's one of my favorite EW&F hits.

Update: Sigh. So it's not Earth Wind and Fire but instead Earth Wind Fire and Water, a cover/tribute band. Did someone say, After the Love is Gone?

Update: Went to a Silverlight presentation and afterwards mentioned the trouble with downloading Silverlight on Safari (I said it privately not in the general Q&A) The guy blew me off with "well it's beta!". Well don't waste my time! It could easily have checked my browser and said not to bother downloading cause it doesn't really support OS X in beta. (BTW it wouldn't load for Firefox on OS X either) Instead I went through the download process to get the crazy message. BTW the Silverlight demo called Top Banana was really cool. Beau from Metaliq said that the development was remarkably easy. They did say that Silverlight will not support WCF.

Today I've just finished my presentation on OSGi at Burton Group's Catalyst conference in San Francisco. My presentation was well received. I'll blog on OSGi soon. I will say that it was amazing how complimentary the presentations in my session were. It was almost as if we had rehearsed the message but we had not.

One of the cool presentations was Jeff Barr's from Amazon regarding their web services. His discussion on Amazon's approach to web-Scale Computing really was an eye opener. I'm embarrassed I didn't know about this before. I knew that Amazon was providing Web service APIs for developers but I had no idea that they had a complete infrastructure for organizations to utilize. Hardware and infrastructure as a service. This is not unlike what some of the large telecommunications companies are trying to do - i.e. provide their infrastructure for people to deploy their services. Amazon is providing that and more - the ability to host your entire IT on their "network".

More on Catalyst later.

BTW I do love San Francisco. What a beautiful town. Not perfect but really beautiful.

I won't give you my own opiniion of the panel. You can judge for yourself. Feedback welcome and appreciated. If you have trouble viewing it please let me know too.

Anyway, I guess the bigger question is whether anyone else is eating this dog foo... I mean JCAPS besides Sun. And from the article it sounds like Sun had a hard time stomaching it.

This article does a good job in explaining some of the difficulties that a novice can have trying to sell SOA. Ricigliano, a senior manager at Sun tries to sell SOA internally. The article says, "he quickly found that it didn't work to go into a meeting with business users and talk about SOAP, Web services, UDDI and WSDL, or even the virtues of Sun's very own SOA tools." He learned his lesson and concluded, "the trick is not to show business users how SOA works, but how SOA can work for them." Great quote!

However the article really doesn't give evidence that Ricigliano actually implemented anything. I can only conclude from the article that they're still eating.

One of the overriding themes Tony, Brian and I have been hearing lately is the idea that while the technology is more or less available for the rapid deployment of services on the network, consumers of those services will have difficulty trusting these services and the network. And service providers are wary of the impact that consumers or other service providers can have on their services. In order for the network provider to be successful the consumers of services must be confident in the quality of the services on the network. These consumers include the produces of new services based on composites (mashups) of other services.

We discussed the role of various technologies including ESBs and registries/repositories, we talked about SOA testing, best practices and use cases etc. I thought it went very well.

I was interested in Ross Manson's Mule & Spring talk. What I found most interesting is how Spring and Mule are maturing and therefore having to deal with enterprise class problems. It was like going back in time 10 years to an OMG CORBA event with people asking about high availability and other enterprise features. All middleware and container technologies go through the same cycle - cool "Hello World" type demo, add extra powerful features, hit the complexity of enterprise computing. The biggest challenge is trying to keep the "simple" technology simple as you layer on the extra functionality. Distributed SOA infrastructure manages to get complex as you try to continue to scale it. High availability wasn't something on offer with Mule ... yet.

IONA's Celtix Enterprise integrates with Mule and also contains Spring as a container for POJO type services. William Tam (IONA) showed me a really cool mash-up demo using Celtix with Spring and Mule. It involved a company tracking trucks through a city ... and of course it used the Google Maps API. I have it installed on my Mac and hope to play with it again soon. I hope someone can host this - perhaps I will. I'll let you know.

Check it out. I think he plans to build a specific search and also might work on a framework to allow you to configure which sites to search. And he plans to tidy it up some more. Very clever!

Update: It's been noted that this does not work of the permalink page linked to above. However I had to use the parmalink because the home page will change. So it works off the home page. Barry will fix the site so it works off of the permalink page.

Conor and I had lots to do. We mainly worked on the CSF sandbox activity which IONA has recently signed up to participate in (see CSF Network Mashups). We haven't published anything up there yet but we're working on a service that will allow ISVs to expose their CORBA based services in the CSF sandbox. It should be there in a week or so.

As well as building what is essentally a routing appliance that routes from SOAP/HTTP to CORBA IIOP, Conor and I also took a look at IONA's next generation integration with Microsoft's platform based on WCF. It's going to be pretty cool. WCF is not unlike Artix in that it is based on interceptor chains that abstract away much of the complexity of the middleware. By linking together various interceptor implementions different flavors of "middleware" can be achieved. Artix provides connectivity out of the box to legacy applications built on various middleware including CORBA, Tuxedo, MQ Series, Tibco RV and many more - including proprietary and custom technologies. And Artix runs on non-Windows platforms as well as Windows. So we can help extend the reach of WCF.

Anyway, it was a pretty geeky week as you can see. Conor and I received our geek shirts at the Microsoft Vista launch in Seattle and decided to take a picture in the Colorado snow before he headed back to Dublin to his team. (We may never live down this picture. My wife is proud and my Mac friends are threatening to disown me ;-) And no, the caption to the picture is not "I'm a Mac ... I'm a PC".

Now we need to get down to the real hard work of finishing out the sandbox project and pushing ahead on our other Microsoft related work! Fun stuff ... even for a Mac guy.

Java Business Integration is a Java community initiative to provide a better framework for building integration solutions than the proprietary EAI approaches or the inappropriate J2EE/JCA stack approach. JBI attempts to answer the concerns that many of us had with hub based proprietary EAI and our concern that J2EE, essentially a deployment container, was being used for integration.