WebSphere SIP Performance and Enterprise QoS helps AT&T

Another effort from the my performance team members is documented in the latest IBM press release.

This effort shows how:

1. WebSphere Application Server is leading the way in critical new technologies (SIP)
2. The WebSphere Application Server has performance that is not only leading, but also carrier-grade while being enterprise capable - including High Availability.
3. Our commitment to driving open and trusted industry standard benchmarking

In WebSphere Application Server 6.1, we added support for the IETF Session Initiation Protocol (SIP). SIP is a request/response protocol for negotiating communication between two endpoints that has been widely adopted in the telecommunications industry. SIP is useful in Voice Over IP (VOIP), web click to call, conferencing, interactive voice response systems, instant messaging, and presence applications.


Below is a basic example of a session initiation between two parties. It shows a swim lane diagram of user@ibm.com starting a discussion with user@example.com with proxies inline to negotiate the session.

In the press release, we announce how AT&T plans to use our SIP technology:

"AT&T is using IBM WebSphere Application Server and BladeCenter systems as a Session Initiation Protocol (SIP) service logic execution environment platform to develop mission-critical services for deployment on AT&T's IP-based network."

The features needed to support AT&T include not only SIP, but also technology that makes such latency dependent applications such as VOIP possible, along with enterprise class high availability. Also, performance is quite important. Also mentioned in the press release, we detail an internal SIP benchmark we ran along with the results:

"IBM's WebSphere Application Server delivers telecom class infrastructures with a focus on SIP features. It is a carrier-grade application server that utilizes a converged HyperText Transfer Protocol (HTTP) and SIP container. It allows service providers to quickly offer new personalized and productivity enhancing services that subscribers demand. WebSphere Application Server 6.1.0.11 using Red Hat Linux and integrated in the IBM BladeCenter HT chassis, which is network equipment building systems (NEBS) compliant, has achieved an industry leading SIP performance measurement of 1296 calls per second, using a 13 message SIP call model (with 80 second hold time) which translates to over 4.6 million busy hour call attempts per blade. Using this call model, in a high availability, carrier-grade configuration, WebSphere Application Server achieved 660 calls per second per blade with session replication. These results were achieved while retaining extremely low end-to-end SIP message processing latency of under 50 milliseconds ninety five percent of the time. This exhibits the ability of WebSphere Application Server to handle the call volumes businesses demands while ensuring service quality."

What does this mean?

It means that our converged web container (supporting typical HTTP servlets, JSR 168 portlets, and now JSR 116 SIP Servlets) can perform SIP operations at carrier class speeds. We demonstrated this using an internally developed SIP call model benchmark. The benchmark is similar to benchmarks being used externally by other SIP platform vendors, but only IBM added high availability to the benchmarking scenario. IBM shows that we lead in performance where it counts – in enterprise ready high availability scenarios.

Based on my previous posts, you would assume we'd want to push SIP benchmarking to standardized benchmarking organizations so the measurements can be trusted by customers. Well, we are doing exactly that! IBM, along with other vendors, has formed a subcommittee at SPEC to develop an industry SIP benchmark. Erich Nahum (IBM) is chairing the group and has requested public feedback on the current proposal.

If you'd like to find out more about SIP, Erik Burckart has a two part article on SIP containing both an introduction to SIP as well as a guide to developing converged SIP applications.

Congrats again to my most excellent performance team members.

Update: Telephony Online coverage that includes comments on SIP performance.

The wonders of modern hardware

I was at an IBM conference a couple of weeks ago, where some new hardware ideas were being presented. Perhaps it's my engineering background, but there's something very cool about building things you can hold in your hand - and when you combine that with the latest new technological ideas (multicore, etc), it's very impressive. In that light, I'm happy to share a video that I saw recently.



http://video.google.com/videoplay?docid=5125780462773187994

Tim Francis

Rational Application Developer

I have not posted to this blog for a while, and I can now explain why. Today, at the WebSphere Technical Conference in Vienna, we announced the upcoming availability of an open beta for the next major version of Rational Application Developer (RAD 7.5). Those of you who've read my previous posts (hi Mom!) will not be surprised by the themes we're focusing on for RAD 7.5; better support for the complete application development lifecycle, including refactoring operations and quickfixes that cover the complete Java EE programing model.

The RAD 7.5 beta also provides support for the WebSphere EJB3 feature pack, the beta for which is available now for WebSphere 6.1. The RAD support for EJB 3.0 allows us to really exploit annotation based programming models. Previous versions of the spec focused on deployment descriptors, and the matching RAD releases had advanced editors to support that. In RAD 7.5, the focus is on Java developers, and using the Java editor as a base - but extending the already powerful Eclipse editor by adding significant new function and capability to support developing an annotation based application.

The intent is simple; most developers creating applications for WebSphere are quite comfortable using Java, and we have a great Java editor in RAD/eclipse - so it's a mistake to force them to switch to a whole new environment (with wizards and graphical editors) when they want to define some aspect of server interaction (such as Web Services or EJBs). This is a natural extension to what the spec defines, but the way we're supporting that pattern within RAD is new, easy to use, and productive.

The other aspect that I'm thrilled about is just the fact that we're running an open beta, less than a year after we shipped the last major version of RAD. We're not done yet, and we have more good ideas that we're still implementing - but the code is great quality, and the performance is good... and this shows a commitment to delivering a rock solid, robust, and well performing RAD. The intent is to encourage developers to explore the product, and not feel concerned that they'll get in trouble if they try something non-standard or off the golden path.

I'm really pleased with the progress the team has made on RAD 7.5; this is going to be the best version of RAD we've ever delivered, and the open beta gives you a chance to see where we're at, comment on what you see, and help us refine the product to make it exactly what you need. You can sign up for the beta here, and there will be newsgroups available to report problems, ask questions, and give us your feedback.

Tim Francis

InfoQ interview on IBM SPECjAppServer leadership and benchmarking in general

InfoQ recently did an interview with myself and John Stecher who leads our JEE / SPECjAppServer performance work. The interview explains in further detail our work that led to the 37% leadership over both BEA and Oracle that I posted here:

http://webspherecommunity.blogspot.com/2007/10/websphere-beats-bea-and-oracle.html

Here is the interview:

http://www.infoq.com/news/2007/11/ibm-specj

Feel free to post follow-up questions here or on the InfoQ forums.

InfoQ is an excellent news site for tracking important news in enterprise computing.

SPEC is a non-profit organization that establishes, maintains and endorses standardized benchmarks to measure the performance of the newest generation of high-performance computers. Its membership comprises leading computer hardware and software vendors, universities, and research organizations worldwide. For complete details on benchmark results and the Standard Performance Evaluation Corporation, please see www.spec.org/. Competitive claims reflect results published on www.spec.org as of October 03, 2007 when comparing SPECjAppServer2004 JOPS@Standard per CPU Core on all published results.

WebSphere Beats BEA and Oracle Performance By Over 37%

I wanted to take the time to congratulate some of my performance team members who have worked to prove our performance leadership, displacing both of the current top SPECjAppServer 2004 leaders - BEA and Oracle. You can see this documented in our latest launch press release here.

"A powerful IT infrastructure is also required to support the growing number of transactions across the enterprise, as well as with customers, partners and suppliers. IBM recently beat competitors by 37 percent in an industry benchmark that measures high-volume transaction processing that are typical in today's customer environments. IBM WebSphere Application Server established record-breaking SPECjAppServer2004 benchmark performance and scalability results involved more than 15,500 concurrent clients and produced 1,197.51 SPECjAppServer2004 JOPS@Standard (jAppServer Operations Per Second), which translates into more than 4.3 million business transactions over the course of the benchmark's hour long runtime."

This shows our commitment to standard benchmarking organizations as I described in my last blog post. By leading this benchmark that was designed and approved by all participating SPEC vendors, IBM customers truly benefit from the demonstrated performance leadership.

We chose to lead in a category that matters most to our customers - per core performance. If you look at the result and the number of J2EE server cores and divide it out, we lead Oracle by 37% and smash BEA by 56% with approximately 300 JOPS/core. Comparing per core (CPU) normalized performance is really the best way to compare one application server and hardware stack to another. This demonstrates IBM's leadership of the industry in J2EE performance without question.

This result also shows the combined power of an IBM stack. Specifically, we achieved this by running WebSphere Application Server v6.1 on the IBM 5.0 JVM on AIX 5L V5.3 with an IBM POWER6 p570 server powered by two dual-core IBM® POWER6® 4.7 GHz processors against IBM DB2 Universal Database v9.1 running on a single POWER6-based server.

Congrats again to my team who yet again dominates where it matters - in customer focused standards based benchmarks.

SPEC is a non-profit organization that establishes, maintains and endorses standardized benchmarks to measure the performance of the newest generation of high-performance computers. Its membership comprises leading computer hardware and software vendors, universities, and research organizations worldwide. For complete details on benchmark results and the Standard Performance Evaluation Corporation, please see www.spec.org/. Competitive claims reflect results published on www.spec.org as of October 03, 2007 when comparing SPECjAppServer2004 JOPS@Standard per CPU Core on all published results.

A few pictures from London

I went to London for a couple days at the end of last week for a customer visit. My first time in London, but unfortunately the quick turnaround didn't leave much time for sightseeing. Here's a couple of my favorites pictures that I snapped:

SCA Rock Rolls Forward

My colleagues who have been working over in open source land at Apache inform me that Apache Tuscany SCA Incubator project 1.0 level has been released. The formal announcement, source and binaries are located here. This is a significant milestone in the life of SCA as an open initiative.
Congratulations!

Perspective in Benchmarks - My thoughts on Microsoft StockTrader

I wanted to take the time to respond to claims coming from Microsoft. On June 4th, Greg Leake, Technical Marketing Manager for .NET of Microsoft started to discuss an effort with which he was involved. The effort was “porting” IBM’s WebSphere Performance Sample – Trade 6.1 to Microsoft .NET 3.0. Since then, Microsoft has been interviewed by trade press, has created video podcasts, and has started discussions on Microsoft forums and other development community sites. Please do not be fooled by these marketing statements.

In my opinion, Microsoft uses their report to focus on three points

- Attempt to prove that Microsoft is interoperable with WebSphere software
- Attempt to prove Microsoft’s SOA relevancy and readiness for the enterprise
- Attempt to prove Microsoft performance is better than WebSphere software performance

I’d like to state up front that I was personally involved with the development of IBM’s Trade benchmark starting with Trade 3 and ending with Trade 6.1. Others on my team have made significant contributions to the code as well to ensure that Trade continues to be an credible and useful tool to express performance concepts and release to release enhancements to IBM customers for J2EE (Java EE) programming.

Some level of interoperability

I applaud any effort by Microsoft or any other software vendor in pursuit of interoperability. However, the interoperability the Microsoft report speaks to is basic web services functionality (SOAP/WSDL/XML) only. It does not focus on interoperability of transactions, security, reliability, durability and does not use industry standard schemas that many of our customers need for cross enterprise (B2B) or intra-enterprise web services interoperability with .NET clients calling WebSphere servers. Independent of the Microsoft report, Microsoft and IBM have already focused on interoperability of these higher value qualities of service in Web Services through industry standard WS-I efforts as shown here and here. I am very happy to see IBM and Microsoft continue to focus on standards based interoperability. I am confident that WS-I will continue to facilitate customer focused web services interoperability in these higher value web service functionalities.

Is Microsoft enterprise ready?

Press coverage has cited the Microsoft report as helping Microsoft prove it is ready for the enterprise. From our quick look at Microsoft code, this doesn’t seem to be the case. Many of the “enterprise ready” features stressed by the Microsoft report are hand coded into the application. Areas such as multiple vendor database support, load balancing, high availability, scalability, and enterprise wide configuration for services contribute to the significantly higher lines of code count in the Microsoft application as compared to the WebSphere implementation. You should equate higher lines of code count to more maintenance and support costs long term and think about the value of this being provided in the application server product versus in the application itself. Some of the increased lines of code are for comments, but the comments themselves point out how many places where Microsoft deviated from using framework classes and instead implemented custom extensions to fill in gaps of functionality lacking in their framework.

As an author of Trade, I must admit an embarrassing fact. Four years ago, my team added web services capability to Trade as an optional component – to demonstrate web services as an alternative to remote stateless session bean methods. Since that time, I personally have worked hand in hand with many enterprise customers adopting web services. We have found that the Trade approach to web services wasn’t the best. Specifically the fine grained “services” in Trade average around 400-800 bytes of passed data. As you’ll see in my recent blog post, industry standard schemas for B2B typically have much larger payloads. While Trade was a fun exercise for my team to learn web services, it in no way mirrors what we know now our customers have told us are good web service practices. Current SOA principles motivate more coarse gained services. The embarrassing fact is that we never have gotten around to removing the poor examples of web services usage from Trade. However, it is interesting to note that Microsoft did not recognize or point out the obvious flaws in these web service patterns during their analysis – they merely parroted what they saw.

Microsoft entitled this paper as “Service Oriented”. Later in the press, Microsoft alludes to this “Service Oriented” benchmark test to help draw credibility to Microsoft’s SOA strategy. Based on what I just said about Trade web services, you’ll see why IBM has never talked about Trade and web services to help customers understand web service performance. Meanwhile, this Microsoft report focuses on these trivial payload web services to prove they can support “Service Oriented” benchmarks. Follow-up posts and press coverage followed the “Service Oriented” title, proclaiming that this in some way helps Microsoft’s SOA strategy. Drawing that conclusion is incorrect. The industry agrees that SOA is more than trivial web services. SOA is about a business centric IT architecture that provides for a more agile and flexible IT support of business needs. Realistic web service usage is a cornerstone of SOA, but web services alone do not define SOA.

Is Microsoft performance better than WebSphere performance?

I believe Microsoft is trying to draw IBM out of our commitment to standard benchmarking organizations to confuse customers about performance. You can draw your own conclusions from specific comments apparently made by Greg Leake in press coverage, asking for IBM to “collaborate”. Some have commented correctly on community discussions that the Microsoft report isn’t specific enough in terms of topology, hardware, and tuning to make any sensible conclusions based on the performance data. It is a compelling story that this Microsoft report weaves – Microsoft beating IBM on its own benchmark. However, IBM didn’t run Trade as a benchmark in the way shown in the paper’s results. As a customer, you should always be careful how much you trust proprietary benchmark results produced by a single vendor. These things can always be coerced to create FUD and confusion.

We have reviewed the paper and results and found inconsistencies with the best practices for how to run WebSphere Application Server. Assuming items Microsoft chose not to document along with improvements in performance allowed by following best practices, we in fact believe that IBM WebSphere Application Server would win across all the scenarios shown in the results.

You may well ask, if WebSphere Application Server would win, why wouldn’t you say so and publish a contrary IBM report. I don’t believe publishing a proprietary view of performance would help our customers – for all the reasons stated above. At best, if IBM was to respond to this paper, you could expect both vendors to degrade to the lowest common coding styles for implementing the benchmark so they would “win”. As shown already by Microsoft’s implementation, Microsoft wouldn’t choose to use their framework classes and features, but instead code optimal patterns in the application code. When those patterns are not tested and supported by the formal product, no customer wins by seeing the resulting performance.

IBM has a history of competing in standard benchmarking organizations such as SPEC. We do so because such organizations are standards based and unbiased and therefore trusted. Standards-based benchmarking processes give all participating vendors equal opportunity to review run rules, implementation code, and the results of other vendors. Given this, if you find Trade and SOA benchmarks useful, maybe it is time for IBM and Microsoft to jointly propose a SOA benchmark to a standard benchmarking organization. SOA benchmarking under standard benchmarking organizations is where our customers and the industry can truly benefit.

Summary

I personally talk to many customers about performance, SOA, and web services. I stand behind all that I say technically independent of marketing. I build strong long lasting relationships with these customers, many of whom know me personally. In good faith, I can stand in front of them with results from a standards benchmarking organization. I can stand in front of them showing our SOA leadership based on both customer references and analyst reports. On the other hand, I cannot in good faith show a one-off competitive benchmark run by a single vendor. I hope you can understand this position and it helps you discuss the coverage of this Microsoft report and any similar efforts by any vendor that follow.

This Microsoft report shows basic levels of interoperability and work within the WS-I shows higher levels of interoperability. The Microsoft report points out that Microsoft has to hand code many enterprise ready features that are just taken care of for you in WebSphere technology. The title of this Microsoft report and its follow-on press coverage attempts to confuse the industry on SOA, which points out how desperate Microsoft is to get press coverage in SOA. This Microsoft report doesn’t do a good job of showing the true performance story. Specifically on performance, I encourage all customers to put their trust in standard benchmarking organizations

New Redbook with SOA customer case study

A new Redbook has been published called "Implementing and Testing SOA on IBM System z: A Real Customer Case".

The Redbook does a good job of breaking down SOA implementation into a series of logical decisions, with real world implications. It covers not only the overall architecture, but the steps to get there. The final solution includes much of the WebSphere Business Process Modeling stack, including WebSphere Application Server, WebSphere Process Server, and WebSphere Portal, as well as tooling from WebSphere Integration Developer and WebSphere Business Modeler.

In particular, the Redbook shows how the SOA solutions fit into the existing ecosystem at the customer shop. SOA is evolutionary, not rip-and-replace. A good read.

SOA certification program launched

Just saw this article on the CNN/Money website.

IBM Federal SOA Institute Launches IT Certification Program: IBM today announced the first Service Oriented Architecture (SOA) certification and training program for Federal IT professionals. The program was established to provide knowledge, and share important skill sets needed, for SOA development and adoption.

The 12-week certification program is sponsored by the IBM Federal SOA Institute, and will begin September 12th through December 4th. A second series is scheduled for Spring 2008.

Two distinct course tracks are available: an entry level curriculum in order to become a certified SOA Associate, intended for those who are new to SOA concepts and would like to increase their overall understanding; and an advanced curriculum, to become a certified SOA Solution Designer, structured for senior IT professionals who require enhanced knowledge to deploy SOA capabilities within their organization.

Certification modules cover issues such as the value of SOA, determining return on investment, bridging the gap between technical and business teams, basic architecture, establishing solutions using existing assets and new components, identifying barriers to adoption, preparing for governance issues, and effective deployment and management within an organization.

More...

Web Services performance through the years

On my travels I get asked the simple question many times ... "are web services fast"?

I usually answer by showing the above graphic. Back when I started on Web Services in 2002, the answer was no. As you can see over 5 years, the answer has definitely changed to "it depends".

I say "it depends" with a little sarcasm. Obviously the performance shown in this chart tells you web services performs. However, in practice I find misuses of performance data and/or web services.

The first thing to be wary of is people trying to prove web services aren't viable are folks using "Hello World" string in/string out web services compared to legacy communication protocol xyz. I usually ask such folks how many distributed services in their architecture are string in string out with such small payloads. The answer is none. Usually the service uses complex industry standard schemas and has a small payload in with a large payload out. The above graph therefore is based on a 3k input document using banking industry standard schemas with a 10k output document.

The second thing to be wary of is primitive web services testing. The above graph is an example of primitive web services testing. This is because my team works on optimizing web services. It shows very clearly the impact of web services calling services that have zero business logic. If we optimize the performance of this primitive we will help in all scenario using web services. However, for customers you need to understand that when you add business logic, the performance impact of web services is far less of a concern. To accurately gauge performance impacts of web services in your application, I would suggest a measuring a vertical slice of your entire application, starting at the web service interface, then calling business logic, and finally any database logic. Comparing that vertical slice between web services and legacy communication protocol xyz is a useful comparison.

Lastly, don't replace every legacy communication protocol xyz in every application with web services. Web Services has been documented by almost every vendor to be useful when the service calls are coarse grained. Replacing "services" with calls that are under 1k of input with 1k of output (example a string in, a simple bean out) isn't usually a good idea. Reusable services in a SOA (for example) are typically much larger in payloads as they tend to be calling services that are not fine grained in payload or function.

Now, you may be asking two questions ...

1) How did we improve the performance over the years
2) What is the performance story for 2007 and the new Web Services Feature Pack?

I think those are two good posts to add in the next week or two ...

TCs created at OASIS for SCA

Well, not the timeliest blog ever, but I did want to mention to folks if they hadn't heard yet that the SCA architecture established by the OSOA organization has been accepted by OASIS for standardization and technical communities within the Open Composite Services Architecture Member Section as documented here.

This is the result of a lot of effort from my colleagues from IBM as well as contributors from the many vendors that comprise the OSOA organization. I look forward to the enrichment of a standards process to refining this technology into the valuable, open, multilingual SOA architecture we envisioned several years ago. Great progress!! and evidence that while this technology is not rolling out as fast as some of us would like, the value proposition and promise remains strong.

Obligatory First Post from Andrew Spyker

Terry invited me to join the community. I plan to get busy posting as much as I can, but I thought I'd start with an intro post. Someone beat me with a stick if I don't post within a week with real content.

I have been with IBM WebSphere Application Server for the past five years as a lead of our performance team. My time in performance has given me time to focus on many things - J2EE, Java, Security, Web Services, and more recently all things relating to our SOA foundation. Earlier this year I was promoted to STSM (Senior Technical Staff Member) and asked to broaden this focus more formally as a SOA Runtime Architect. This means I get to focus on more than performance (which I have traditionally done since performance allows you to experience all aspects of the product end-to-end) and more than WAS (ie. the rest of the SOA foundation). My focus as of late is how we can drive our XML strategy forward in both function and performance given XML is one of the core building blocks of all of our SOA runtimes. Also, I still advise the team I've built in WAS performance on daily basis. More on all of that later.

So in the end you should see a mix of content on XML, SOA, and performance from me.

WS-AT interop between WAS and WCF

Anyone who has ever tried to set up interoperable WS-AtomcTransaction interop between WAS and WCF will know its easy once you have figured out how to configure the WS-AT service endpoints in both systems to use SSL with mutual certificate authentication. If you haven't got that far yet and don't want to have to figure this out for yourself, read Billy Lo's paper on Building transactional Web services with WebSphere Application Server and Microsoft .NET using WS-AtomicTransaction

Coping with the internet crash

Breaking News: All Online Data Lost After Internet Crash

We kept telling folks to migrate the internet from those two 386 boxes in the basement in Champaign-Urbana to z/OS on the mainframe, but did they listen? No.

Slightly off-topic: IBM visionary retires

Darryl Taft over at eWeek has an article about and interview with IBM's Irving Wladawsky-Berger, who is retiring after 37 years with IBM. This is slightly off-topic because Wladawsky-Berger isn't a WebSphere guy, but I thought the article and interview were interesting nonetheless. He's obviously had an varied career and been involved in a bunch of key IBM initiatives. That's one of the things I like most about IBM - there's no shortage of diversity when it comes to interesting things to work on. Full disclosure: I've never met Wladawsky-Berger.

Article about Irving

Interview with Irving

WAS V6.1 - Web Services Feature Pack is available

Quick note - the Web Service Feature Pack for WAS V6.1 that has been mentioned here before as a beta product is now complete and available - the announcement is here.

EJB3 Beta program

The EJB3 feature pack for WAS V6.1 is now entering beta, and can be downloaded from IBM's Early Program site.

I've mentioned the Web Services feature pack below. As you'd expect, the EJB3 feature pack follows the same idea - an optionally installable add-on that provides support for EJB3 applications.

Project Zero site is live

IBM's new incubator project named "Project Zero" is now up and running. Like the Jazz project, Project Zero is another IBM foray into "Community Driven Commercial Development". CD/CD is basically an open way of developing software that is intended to be sold. It's an interesting mix of open source style processes with standard commercial practices. I think it has a future. As for Project Zero itself, it's essentially a Web 2.0 mashup platform that tries to address enterprise-level mashup needs in a simple way. Check it out.

Progressive Leakiness

One of the things that has been popping into my mind recently is centered around the notion that all abstractions are leaky in the sense that no abstraction can actually completely hide the layers for what its built on. Joel Spolsky penned "the Law of Leaky Abstractions" which basically states that all abstractions leak through aspects of the layers for which they are built on, and therefore the user of the abstraction winds up being exposed to more complexity than otherwise necessary and/or originally intended. It is interesting in reading some of the internet material that has been published around the subject of leaky abstractions in that folks have extended the notion beyond computer science into the world of physics and even other disciplines like philosophy, etc.

I wonder if when building a good abstraction, you should just acknowledge that all abstractions will be leaky and design-in the leakiness. In this pursuit, we should use the laws of Progressive Disclosure whereby the user of an interface or software is only exposed those concepts which are minimally required to accomplish the desired task. I highly subscribe to the usefulness of progressive disclosure techniques, as they tend to keep simple stuff simple and can make learning a new thing easier.

One of the painful things about abstractions is they sometimes get in your way -- a good abstraction can step aside for situations like this. An excellent example of leaky abstractions and progressive disclosure techniques that I can think of that meld very well is in the area of computer language compilers: some of the better ones expose a way for the programmer to "drop down" into assembler, right in the middle of their higher-level language constructs, and allow the programmer to tailor the code specifically for a given hardware device. This capability of drop down allows the programmer to cope with, in a very natural way, leaks like: new instructions that the higher level language (i.e. the abstraction) has not been built to specifically exploit, or even something as tailoring specific condition codes that can arise on newer hardware that need to be handled for correct code behavior. This concept demonstrates good "Progressive Leakiness" in that most programmers get the 100% value of the language abstraction not needing to be exposed to the more complex assembler language techniques (progressive disclosure) but permits specific situations to be coded for which could not be handled by the abstraction or wind up causing the abstraction to misbehave (leaky abstraction).

It seems to me that SCA might be a good candidate for a Progressive Leakiness focus. I could envision casting an SCA Reference to a JAX-WS, for instance, to do specific Web Service stuff that would not otherwise be available or even maybe appropriate through the SCA abstraction.

I don't know, maybe wrong -- I could be in need of a vacation too, I can't tell....