Saturday, May 12, 2007

Perils of Documenting Architecture

Writing Big Architecture Document, I couldn't help thinking of a nice Russian saying. It is about translation; rephrased for architecture and translated (!), in English it becomes:

Architectural documentation is like a lady. When she is fair, she isn't pretty. When she is pretty, she isn't fair.

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Monday, May 07, 2007

“Design of Everyday Things” – A Victim of Poor Design

Reading Design of Everyday Things by Donald A. Norman made me feel really frustrating. Not just because I was relating to all these everyday frustrations of fighting with everyday things Norman describes there. This only amplified the most frustrating part. Ironically, the book itself was poorly designed!

It is damn paperback. Paperback is a poor design for a book. It takes two hands to operate. I must hold tight to keep open, time to time press it. Yet just turn off your head, it closes or flips to another page. This design makes me fight with the book.

Everyone knows a better design for a book. I take a hard-cover. I put a book on a table, pull a nice strip, and it opens on the right page and remains open. I read it hands free. If anything, nice strip brings me back to my page again. I should have gotten DOED in hard cover. But I got mine in paperback.

It is an irony my book about better design is itself a victim of poor design. It is also a message. Always strive for the better design. But when economics enforces a compromise, don’t feel too bad about it. Donald Norman, the professor of human centric design, does it, too.

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Tuesday, May 01, 2007

ORCAS WCF+WF Training: Windows Workflow Foundation

In "WCF+WF in ORCAS: Deep Dive Training at Redmond", I promised a dedicated post about WinWF.

What is Windows Workflow Foundation in .NET 3.0? A runtime engine, topped up with services and tools.

Workflow runtime engine is superior. It implements traditional sequential and state-machine workflow, the two can nicely interplay. Dynamic update of a running workflow instance – known in WfMC fundamentals as AdHoc Workflows is there, too. Long running workflows are supported. Sweet part of WinWF, the Rule Engine, rulez and can be rehosted outside of WinWF applications. Runtime scales up and down, performs exceptionally well. It is well designed for flexibility and extencibility. They call it "future proof". Ok, my bullfighter is scorning at me here.

What is cooking with ORCAS?
Two new activities - ReceiveActivity and SendActivity – bring elegant integration with WCF. We did a lab, which soon will be available on the community site. Handling external events will be simplified: workflow/host communication made easier. That’s it, in my notes. Will double check when I get the presentation video & .ppt.

There is no updates on UI components. This is disappointing. Rule Set Editor can be rehosted, but you can’t use it unless you are a programmer. Workflow designer can be rehosted. But it’s a total usability disaster, even for a programmer. Everyone agrees that normal user can’t possibly use it. Microsoft acknowledges but “choose not to work on this problem” So if you think of exposing Workflow or Rules in your product, you are on your own. Like these people who reimplemented workflow designer with style.

Matt Winkler gave an exciting presentation on WinWF performance. He was sharing tricks to tune Worfklow Runtime to get the right performance trade-offs, based on scenarios. What I picked up:
Think when to track. Choose full reliability (Persist on Choice) or full speed (no persistence). Or, use controlled save point. Implement them as an empty activity with [PersistOnClose] attribute on Execute override. Think what to track. Track only what you need. Partition tracking service to avoid polluting DB. Batch tracking reduces the load on SQL server. Bindable properties do not slow things down too much, but when you don’t need binding, use simple properties. Nesting compensations are expensive. Transactions use DTS – take performance hit. While is expencive: it’s 2000 times faster to do it inside [code] activity then using workflow while. Dynamic updates ARE SLOW (and if you think you need them, think again). Farms of workflow hosts are easily configurable with SQL Tracking Service. When tuned well, WinWF performs (detailed metrics in this article).

Am I sold on WinWF? Almost. I like the technology, but not entirely sure if it is ready for a prime time yet. In the next post, I will share my reservation.

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