TEAM Zarate Tarrani Notes From the Field

Capstone. It's only fitting to put a capstone on my previous entries about architecture. I have a few loose ends in the form of documents and links that complete the picture of what constitutes architecture, and a tie-in to component-based software engineering, which is a close cousin.

The quick and dirty list:

• SEI essays on software architecture.
• ISO TC 184 SC 5 WG1 Page on international standards regarding enterprise modeling and architecture.
• Documenting Software Architectures: Organization of Documentation Package, also available in PDF format. This document is the basis for a forthcoming book to be published by Addison Wesley on 5 July 2002 titled Documenting Software Architectures: Views and Beyond. The authors of the paper are the same authors of the book.
• Proceedings from Component-Based Software Engineering Workshop.
• Packaging Predictable Assembly with Prediction-Enabled Component Technology and the related document, Predictable Assembly from Certifiable Components.

Also related are two documents from IBM: Business Rules for Electronic Commerce and Multi-Dimensional Separation of Concerns Using Hyperspaces (see also: previous entries about separation of concerns).

Architectures Redeux. I've been discussing architecture within the context of web services, which is but one facet of the topic. First, I want to get a pet peeve out of the way: architect is a noun, not a verb. You can be a software architect, but you don't architect software. This atrocious misuse of the English language was introduced by Steve Jobs many years ago, and has unfortunately become a permanent part of the IT lexicon.

What is the essence of architecture? One of the best descriptions of software architecture is provided by Bredemeyer Consulting's Software Architecture Page. Despite the use of the dreaded word, architecting, the definitions provided capture the essence. My personal view is to consider architecture in its traditional form, which is the development of a high level design - the big picture. That is what those folks who design buildings for a living do. However, there are some marked differences between the original architects and software architects, which can be summarized in these three comparisons:

1. Those who design buildings are have stringent education requirements and are licensed. There are legal definitions as to who can proclaim themself to be an architect. In software anyone can claim that he or she is an architect - and they frequently do just that. No credentials other than a proclamation and, perhaps, some references that will support the claim that they actually functioned as a software architect.
2. Architects who design buildings are held to legal and engineering standards to which their designs must comply. Software architects can do pretty much anything they can get away with without legal or professional oversight.
3. Building architects blend design with engineering constraints. They use both creativity and a good deal of science and math. Software architects may or may not employ either - and they are not compelled to do so in order to claim to be an architect.

However, my objective is not to bemoan the misuse of English or the sorry state of software architecture, but to provide reference material that I hope will be used to get one thinking about the essence of software architecture and advance our profession through knowledge sharing. The resources that I am providing portray many different ways to approach architecture, and some are better than others. Moreover, some of the resources conflict with one another, but what they have in common is the fact that the approach is based on methodology and quantification. Each provides an opportunity to learn.

Resources that I recommend include:

• Introduction to Software Architecture
• Software Architecture: A Roadmap
• Discipline of Software Architecture
• Architecture Blueprint: the 4+1 model
• Software Architecture: Foundation of a Software Component Marketplace
• Object-Oriented Software Architecture A Practitioner's Approach
• USC's Software Architecture Page
• UCI's Software Architecture Research Page (also see their ArchStudio 3 architecture development tool page).
• Software Architecture Resource Sites
• The Three "R's" of Mature System Development: Reuse, Reengineering, and Architecture
• A Two-phase Process for Software Architecture Improvement
• Don't Let Architecture Astronauts Scare You, an interesting and opinionated essay by Joel Spolsky

Architectures also define the building materials and techniques needed to execute the design developed by the architect. This is true regardless of whether the architect is a licensed professional or a software architect. Both the building and the software architect need to understand the characteristics of the materials and techniques. To that end I am including miscellaneous references to materials and techniques that a software architect will find interesting:

• Java resources related to architecture
• Redundant Arrays of Independent Components(RAIC)
• xADL 2.0 Architecture Description Language
• xArch XML Representation of Architecture
• A Formal Architecture-Based Approach to Software Integration Testing

My next entry will depart from the architecture theme, and will focus on M-Commerce and related topics.

No Surprises Here. According to an 8 May eWeek article titled Error in MS Protocol Could Compromise Security, "Microsoft Corp. has already identified at least one protocol and two APIs that it plans to withhold from public disclosure under a security exemption in the federal antitrust settlement proposal agreed to in November, according to Jim Allchin, Microsoft's group vice president for Platforms, who testified in the antitrust case in court Tuesday."

Plans to withold from public disclosure? Yeah, and we need to destroy this villiage in order to save it, right?

Availability. Linda and I are now available for consulting assignments, either as a team or individually. Marcia Hopkins will be available in early June. A summary of our experience and qualifications is available on the TEAM Zarate-Tarrani page.

Dimming Light. Kate Hartshorn has taken an indefinite leave of absence from contributing her insights and thoughts here. Her time and efforts have been redirected towards a difficult, but surmountable, challenge. Until her return this weblog and its Postcards from the Revolution sister will be bereft of rare points of view and a touch of humor and class that is missing from most technical resources. When she does return it will be on a permanent basis.

Shedding Light. What are web services, and why is there so much debate about a definition? I subscribe to a large number of news services and this question arises, debate ensues, issues become murky and the process repeats itself. I go with the definition that is set forth in the W3C Web Services Architecture Requirements that states:

A Web service is a software application identified by a URI, whose interfaces and binding are capable of being defined, described and discovered by XML artifacts and supports direct interactions with other software applications using XML based messages via internet-based protocols.

That wasn't too difficult. We have a definition that is sanctioned by an internationally respected body, and until a better definition comes along why not go with it? It certainly cuts through the hype spewing forth from Microsoft, Sun and the industry experts.

If you're interested in web services architecture the following resources are essential reading:

• W3C Web Services Architecture Working Group. Yes, the W3C is a politically-charged organization, but they are respected and set standards to which the squabbling factions (a.k.a., Oracle, Microsoft, Sun, etc.) pay close attention. Ignore their standards and what is happening within their working groups at your peril. It's also interesting to note that the W3C cites the Architecture Trade-off Analysis (ATAM) approach supported by the Software Engineering Institute as an influence. I have a few papers on ATAM in the December 2000 issue of my old Information Technology Newsletter. If you want solid information about ATAM and related approaches read Evaluating Software Architectures: Methods and Case Studies, which I reviewed on Amazon.
• IBM is another reliable source of information. I have long admired their objectivity, which I've witnessed firsthand in numerous consulting engagements where they have played a role (they have no problem recommending products that compete with what IBM sells, and will not hesitate to provide professional support for those products as well). In the web services domain they publish some of the best information that is available from a commercial vendor. One such document is Web Services Architecture Overview, which is entirely consistent with the W3C views cited above. I also like their PDF document titled Web Services Conceptual Architecture, which is packed with information and describes architecture in both abstract and practical terms. Introduction to Web Services Architecture is a more generic paper published by IBM, and is well illustrated (a picture is worth a thousand words in this case). Web Services and UDDI look beneath the architecture at some of the moving parts, and related whitepapers complete the picture.
• Web Services Architectures: How they stack up, also available as a PDF document, is an interesting comparison of different approaches to web services architectures.
• Yet another source of information (and viewpoint) is the O'Reilly Web Services FAQs, which address the technical underpinnings more than the architecture. Their book titled Web Services Essentials, and another book (published by Addison Wesley) titled XML, Web Services, and the Data Revolution are worth reading.
• Architecting Web Services by William L. Oellermann Jr. is a still valid early work that attempts to do the right thing: define an architecture that is traceable to business requirements. Although this book goes into technical details, it remains at a high enough level of abstraction to be a book about architecture. I especially like the book's web site, which provides a test environment that allows you to test your web services, and other resources. While this book is not strictly about architecture, it comes the closest to addressing web services architecture in the real world than any other I've read (or read about).
• Doug Kaye's Web Services Strategies weblog, which contains news, opinions and trends.

I've by no means exhausted my thoughts on this topic, and you can be sure that it will resurface again in the near future.

Bright Light. When Kate does return I promise that I'll make sure she stays around, and her place will never be filled until that time.

Correction. In my last entry I left out one of the true Oracle gems off the beaten path on the web: Thomas B. Cox's home page. This little known page contains some of the most impressive whitepapers I've found, including a DBA capability maturity model, DBA checklist and Oracle security information that you won't find elsewhere.

XML Update. One of the themes I've started this month has been web services, with a focus on some of the common building blocks such as VoiceXML, and specifications such as the Web Services Flow Language. I'm going to provide a few updated links on ebXML, which is in a constant state of change and is emerging as an important standard.

Technical specifications, white papers and reference materials are available at ebXML.org's specification page. This is a primary source of up-to-date information, work in progress documents and deliverables related to ebXML. If you're unclear about what ebXML is and why you should be paying attention to it, the site's FAQ will answer any basic question and provide the business and technical reasons for ebXML.

Another source of information is Sun's online whitepaper titled Overview of ebXML Specifications. This paper sorts our the specifications and their relationships to one another.

Off the Beaten Path in Search of an Oracle. Actually, I am not seeking a source of wisdom - I'm updating my primary Oracle links and want to share the lesser known ones and some of my frequently visited favorites:

• Los Angeles Oracle User Group has always been a great source of information, especially since I live nearby. Their site has an extensive library of presentations from past meetings and other useful info.
• Ari Kaplan's page is one of those content-rick pages off the beaten path. Highlights are the extensive collection of Oracle tips and an equally extensive collection of links. In addition, he has six informative PowerPoint presentations that you'll want to download:
  1. Life Without Tools: Monitoring Database Activity With the Power of SQL
  2. Moving to the Web: How to Prepare for the Switch
  3. Introduction to Oracle
  4. A Bag of Tips and Techniques for DBAs and Developers"
  5. More Tips and Techniques for DBAs and Developers
  6. Password Management for Oracle 8
• Steve Rea has an impressive collection of tips and scripts
• Oracle Power is a portal dedicated to Oracle, and contains an impressive amount of information and content.
• DBA Support is another Oracle-oriented portal that is worth bookmarking.
Yet another Oracle portal, and one that impressed me, is Oracle Base.
• If you're looking for free Oracle and UNIX scripts and/or free and inexpensive tools, you'll like Oriole Corporation.
• DB Domain has a large listing of Oracle freeware and shareware utilities that are worth checking.
• If you're learning Oracle, do bookmark Teach Yourself Oracle 8 in 21 Days. This is the online version of the popular paper book of the same title.
• Two commercial sites that sell innovative and/or inexpensive utilities that DBAs will love are:
  1. Expand Beyond which sells DBA and admin tools that run on PDAs (both WIN CE and PalmOS), that allow DBAs to reach their instances over wireless connections. This is an excellent approach for Tier 2 and 3 DBAs, and the ROI can be significant for mission-critical databases.
  2. Benthic Software, which sells some of the best, cost-effective tools I've used. When I was roped into DBA chores a few years ago I purchased the full suite of tools, most of them in the USD 20.00-35.00 range. If you write SQL queries I highly recommend Golden, and if you write a lot of PL/SQL scripts you'll find the $35.00 USD cost of PLEdit to be a bargain.

More on Web Services. Two documents that neatly tie up my last entry on web services flow language are Web Services Architecture Directions and Web Services Flow Language Specification 1.0. Both files are in PowerPoint format.

Loose Ends. A few other documents and presentations tie any loose ends left from last week's entries. My descriptions are terse, but each is interesting and worth downloading and reading:

• Software Engineering Processes at Start-Ups (interesting presentation to say the least!)
• System Success Models
• High Dependability Computing in a Competitive Environment

Enjoy, and have a wonderful workweek.