With standard Java and standard Java servers, fairly strict and familiar three-tier architecture came about. The question to ask now is “Will it last forever?” Like so many things, the fundamental tiers of computing do come up for reconsideration once and a while.

These breezes have been blowing subtly since people cast about for lighter versions of Enterprise Java Beans. More recently, Node.js has arisen as a JavaScript alternative to Java on the server side. Increasingly, the client is the object of interest.

Node.js and other browser-influenced technologies seem to encourage software architects to cast skyward their monolithic three-tier components. As these flying components drift down to earth, they may not settle back up in the same alignment. The sudden near-hegemony of mobile clients is pushing things ahead quickly.  A variety of new architectures are brewing.

In some ways, there seems a growing reaction to the rule of Java and the server. That view emerges from a look at a reporters’ notebook. It’s not going away, but as described in an interview with James Strachan, now senior software consultant with JBoss: “The server side is becoming thinner and thinner.” When SearchSOA.com and TheServerSide.com spoke with Strachan earlier this year at the CamelOne event, the topic of Node.JS was on the docket, but Strachan was expansive.

He said, looking forward:

The server side might just be Amazon Simple DB or Mongo DB or something; there might not be much of a three-tier architecture anymore.

Meanwhile, with flair, he continued:

….the client side is becoming bigger and more and more complex; it’s real-time now, everyone’s doing Ajax, real-time updates, and people are doing lots of single-page applications – which is when one Web page starts up and the entire app is in there. There are lots of models, containers, relationships and persistence and “yada-yada.”

Strachan notes this is highly driven by mobile applications:

In many ways the browsers won. Almost every mobile platform has Web capabilities inside it – Android, iPhone, iOS all have Web browsers and so forth. So the Web has kind of won … most browsers use JavaScript and HTML 5. Silverlight’s dead, Flash is kind of dying … the browser is really where it’s at …  with HTML and JavaScript.

Are the new approaches overblown? Is real change far off? Do you see a shift in emphasis to the client? If so, do you think services or SOA have had a hand in breaking down the status quo? -Jack Vaughan

@searchsoa

A lot of the recent syndication activity has been Twitter-like – not exactly mission critical or enterprise-oriented. But the potential for fast messaging across manifold applications will not be lost on future distributed systems designers. The step forward referred to here is Facebook’s endorsement of Activity Stream.

Social networking phenomenon Facebook this week disclosed details on its support for Activity Stream, an extension to the Atom feed format. This is an emerging open-source format, and the company, via its announced Facebook Open Streams API, is gaining huzzahs for going to open source, and not trying to set a de facto standard for this means.

Facebook in effect aggregates a stream of information that a user defines. Much of the excitement this week relates to the promise of bringing advanced Facebook aggregation capabilities to mobile devices. To show off the API, the Facebook folks created a sample client application known as Facebook for Adobe AIR.

Activity Stream Related
On the face of it: The Facebook Open Stream API - developers.facebook.com
View into the innards of underlying Atom Activity Extensions – martin.atkins.me.uk
Facebook_Desktop_for_AIR – ak.fbdcn.net [ZIP file]

One of Silverlight’s advantages over Flash is that it includes a subset of .NET, including WCF for easy communication with the servers that do the real work behind RIA widgets. When Silverlight was a Windows-only platform, interoperability wasn’t an issue; companies that wrote Silverlight apps probably had Windows servers, so the client and server ran the same platform.

But Moonlight brings Linux into the fold on the client side, and that raises the question of interoperability. For now, the question is largely one-directional: how can developers design Silverlight apps that run on Linux but talk to Windows servers? But if Silverlight comes to compete broadly with Flash as a platform, companies may start having to worry about Windows clients talking to Linux servers, too.

De Icaza suggested that one solution may be to just drop WCF, which uses SOAP. Although there’s certainly an architectural appeal to creating more cohesive communication between clients and servers, de Icaza said, he’s seen a general movement back to the simpler REST protocol. [Ed note: Microsoft offers a REST kit for WCF – but SOAP is the more common use. WCF with REST loses an important WCF characteristic: strong types.]

But de Icaza was careful to add a disclaimer: his work doesn’t focus around enterprise applications. In those tightly controlled environments, using WCF and SOAP still makes sense, he said.

Of course, SOA is all about the enterprise, so that’s a pretty big disclaimer for any architect working behind a corporate firewall. But data from many services within an enterprise eventually finds its way to the user in one form or another, and maintaining two protocols — one for internal communication and the other for external publishing — defeats one of SOA’s main objectives: modularity and reusability of services. What happens if that tax calculation service needs to communicate with a RIA shopping cart next year, for instance?

The saying goes that if you live on the cutting edge, you risk getting cut. SOA architects should keep a careful eye on RIAs, lest they have to re-architect their brand new systems.