SOA is one of the big buzzwords these days, and a lot of people have started doing SOA for the first time in the past few years. I have some good memories of the "good old days of SOA," and now it seems like everybody's using the groundwork that was laid in the 80s and 90s. Now, people can just go download Weblogic and Systinet or JBoss, and and the various pieces, build a system using those frameworks, and they're "doing SOA." There are so many powerful tools; the IDEs such as Eclipse and Intellij do a lot of the tedious work for you.
My first introduction to SOA was in 1995 on a project called Datagate at Southwestern Bell. I came on the project when it was about six months old. All of the things that people take for granted now, that they use and it "just works" (or not), we had to build our own. There was no app engine, no UDDI, no SOAP. The things that people download and use today, we built and used back then. If you're a computer geek, this is the project of a lifetime. It was all message-based (that's a MOM for all you acronymophiles). Now I can look around and see SOA everywhere, but we were, in our own way, pioneers of the technology, because we did things no one had ever done before. Sure, not everything we did was new - Tuxedo had been around, so MOMs weren't exactly new.
What we did in the mid-90s that was new was to make the technology more accessible. It was hard to write Tuxedo services back then. We made it accessible to every C, VB, and PowerBuilder coder out there. There are some ways in which today's technology is better. But, what we built was so smokin' fast, and there's nothing that SOA folks are doing today that even comes close to the performance we delivered on those old, slow machines. We had a great, usable middleware product that was the framework for developers to construct clients and reusable services on a variety of platforms - about 12 unixes, MVS running on IBM 390s, Windows 3.0, Windows NT, and Tandem. It's one of those experiences that you looked back on, and think, we did it before most anybody else. What people today use, we built.
I wasn't one of the visionaries for that group. I was brought in to develop an interface so that VB and PB programmers could write clients on top of our C framework. In the end, I help design and architect that, the Directory Service Replicator, and the Dashboard for this system, and we did good work.
There was no SOAP back then. The Datagate team developed its own protocol. It was message-based, so was much more performant, scalable, and simpler than the RPC-style calls are today. Yes, even the message-driven services are RPC under the covers, not the true MOMs like what we built. A true MOM lets you fire off multiple messages to services without waiting for the ack that the message was received, then process the responses as they come back in. All this with one thread, not multiple threads that RPC pushes you towards for this kind of processing.
There was no UDDI then for service lookup back then. There was no LDAP, either. We built our own distributed, replicated X.500 directory service. Infrastruture and business services registered and reserved leases dynamically. If a service went down, its service entry went away, and clients would call one of the other instances that was still registered. And of course, it was fast - 10s of millis to do a service lookup, not 100s or 1000s like you see with UDDI. Smokin' fast.
I architected and led the development of the Directory Replication Service along with my friend Dave C. This cell-based, scalable solution allowed us to run multiple Directory Services, and replicate data between them in a scalable, available fashion.
We used XDR for marshalling. That's one piece we did download. I lead the charge to unit test the whole thing - and found only one bug. There was an endian issue on that affected one of the platforms, and we found it and fixed it.
There were no application engines. What we built was a resource manager that would control service lifecycle and heartbeat services to quickly detect outages.
There was no PKI, or even SSL. We bought licenses for the encryption libraries, then designed and built our own secure message protocol (with mutual authentication where needed), plus the infrastructure to support it. Certificate Revocation Service, Certificate Authentication Service, and al the APIs for services to use to load their certs, encrypt their messages. We built the services and the GUIs so that administrators could manage the PKI we built.
There was monitoring software available - Tivoli - but it was far more than our budget would allow. We built our own Dashboard that allowed us to closely monitor infrastructure and business services running over much of the United States, including Missouri, Texas, California, and more.
We did training to teach developers how to build reusable business in C, and how to build clients in C, in VB, and in PowerBuilder. I taught the VB and PowerBuilder classes.
Our team consisted of three subteams - Infrastructure, which was the team I was on, the Service Writers team, and System Adminstration, which handled the care and feeding of production systems.
At A.G. Edwards, we leveraged SOA frameworks for 6-1/2 years as part of a broker workstation, to develop the pretty scalable agedwards.com (which, last I heard some years back, had about 300,000 users signed up). I was a member of the Lead Architect Team that designed and developed agedwards.com. We used SOA for some other pretty cool stuff. One of my favorites was the BLServer, that used a modified version of what is now called the "Competing Consumers" pattern in a highly-available cluster of message-based services that self-allocated using leases to process roughly 1.5 million messages a day for about 4-1/2 years before it was mothballed in February of this year.
The industry has come a long way since then. Like I said, what we built, you can now go download, and the SOA business has experience explosive growth. After 2-1/2 years at Bell on the Datagate project, I did 6-1/2 years of SOA work at A.G. Edwards, continuing to architect systems using new SOA technologies as they emerged - Tengah, (now Weblogic) Dynamo, Novell's LDAP server, SiteMinder, WSDs, Big/IP, and various JMS providers. Some of this stuff I had more exposure to than others, but that gives you an idea of how things have changed over the past 14 years. Now there's CXF and JAXB and other exciting new tools coming along.
Every Tom, Dick and Harry does SOA now. Years after that work at Southwestern Bell, a small company hired a "SOA expert" (after I was already there!). This poor fellow didn't even know what LDAP is. When I described how it could be used for service lookup, he said you can't use it for that - it's for authentication. I explained to him that it's just a database that's optimized for reads. You can use it for anything that falls into that category. Now, he's an expert, downloading what other people have built and putting it all together. One boss at that company tried to get me to join a project where I would have been writing architecture documents all day for six months, and building nothing. His angle? That the SOA experience would look good on my resume. I kid you not.
On Datagate, we built SOA sooner, faster, more scalable, and at least in some ways better than what exists today. The primary advantage I see in today's world is standards. Almost everything is standards-based, and that means vendors can provide tools to do many of the things we used vi for. It's a change for the better, in most every way, because SOA is much more accessible today that it was in 1995. Plus, now it's an acronym. ;)
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