信息集成: DBA 手中的 Rational Data Architect
原文出自Nelson King 他是一位超过25年开发经验的程序员，他现在为widely出版社签约技术作者。
为让各位专才能够更加准确的了解RDA，我在译文后附上了原文，供大家甄别。
DBA 手中的 RDA
如果要我说出 IBM Rational Data Architect（RDA）的最佳特性，我会说是该产品的多面性。当然，创建联邦数据源的简便性和成熟的基于 Eclipse 的 Workbench 也是极好的高级特性，但是它们只是对 RDA 本身用处有贡献。真正使 RDA 与众不同的是，它从逻辑数据模型到物理数据模型的转换能力、对已有数据库的管理和反向工程能力、分析模式的能力、应用业务规则的能力、创建存储过程的能力、发布模式和报告（打印或放在网上）的能力以及处理大量其他与数据库相关的任务的能力。
RDA 就像是企业数据库管理方面的瑞士军刀。这是否意味着它无所不能？不是的，瑞士军刀也不能作为铲车的替代品。但 RDA 是一个精心组织的工具箱，可以迅速适应各种情况。
为了说得更明白一点儿，假设我们使用 RDA 来处理 DBA 或数据架构师的一些日常工作。虽然这些事件是虚构的，但这些场景在现实中都能碰到。
上午 8 点：一切正常
当检查完服务器监视器和数据库状态仪表板之后，DBA 或数据架构师会一边喝一天中的第一杯咖啡，一边打开 RDA。至于我们，一开始的工作是继续为气象产品线设计一个传感器数据库。一开始还比较小的传感器属性列表，随着产品的增多而逐渐变长。设计过程采用典型的 “哦耶（oh yeah）” 方法 —— 就像这样，“哦耶，我们需要将它转换成华氏温度。” 对此我们望而生畏，因为我们没有用计算属性，对吗？我们有过争论，但是由于有个存储过程将在一个繁忙的循环中使用这个数字，我们决定破例。
Rational Data Architect eases the daily grind.
If I were asked to name the best feature of IBM Rational Data Architect (RDA), I’d have to say it’s the product’s versatility. Sure, the ease of creating federated data sources and the slick Eclipse-based Workbench are terrific high-level features, but they’re only contributors to RDA’s overall usefulness. It’s the ability to swing from logical to physical data models, explore and reverse engineer existing databases, analyze schemas, apply business rules, create stored procedures, publish schemas and reports (print or Web), and a raft of other database related tasks that make RDA stand out.
RDA is like the Swiss Army Knife of enterprise database management. Does this mean it does everything? No, and a Swiss Army Knife is not a substitute for a forklift either. But RDA is a well-organized toolkit that can quickly become second nature to use in all kinds of situations.
To show you what I mean, let’s pretend we’re using RDA to tackle jobs typical in a DBA or data architect’s day. These events are fictitious, but the situations are real enough.
8 a.m.: In Normal Form
After checking server monitors and database status dashboards, a DBA or data architect is likely to fire up RDA with the day’s first cup of coffee. For us, the day starts with the continuing design of a sensor database for the meteorology product line. What started with a small list of sensor attributes has grown with each product. The design process has taken the typical “oh yeah” approach — as in, “Oh yeah, we need to carry Fahrenheit conversion on that.” We wince at this because we don’t do calculated attributes, right? We argue, but because of a stored procedure that will use the number in a busy loop, we make an exception.
Jumping into RDA, we open the sensor database model, which is still in the logical design phase (see Figure 1), and then add the attribute with copious annotations. We use the RDA workbench to create a stub for the eventual stored procedure, with notes about the calculated value. RDA has a very good Analyze Model function, which checks for duplicate relations, normal forms, model and SQL syntax, and some business rules we built with Object Constraint Language (OCL). A validation routine may complain about this attribute, so we need useful documentation. RDA can store almost everything about a design, including text files, diagrams, bookmarks — whatever it takes to document the work.
10 a.m.: A Rogue Database
The phone rings. It’s a new department manager who wants to be a good scout. She informs us of a “test database” she discovered in her department that’s actually being used to track important sales results (with hours of manual data entry). She thinks we need to retain the information but wonders if it shouldn’t be integrated with corporate databases. We don’t usually operate like the Borg; however, resistance is futile — this rogue database will be assimilated. After some touchy negotiations and an exchange of what might be called data definitions, RDA is put to work before noon. (It happens this fast only in fiction.)
To get at the data, we use the Data Connection Wizard. Not everyone likes them in general, but most of the wizards provided in RDA are helpful not only for novices but also for anyone who wants to do routine work quickly. We scramble to establish a connection to the rogue database. It’s on the intranet, but it isn’t in DB2. Fortunately, RDA can handle a fairly wide range of data sources with JDBC (DB2, Oracle, SQL Server, Informix, and Sybase). A phone call finally gets the right password.
In this case, there is no schema or DDL, so we use the Physical Data Model Wizard to reverse engineer the model from the database. Looking at this model, we can immediately see there are similarities with official schemas, but we need a precise mapping. Integration modeling — mapping between schemas to discover relationships — is something RDA does very well. We also set up some transformations and other routines that will help clean the incoming data. Even with the graphical RDA tools, mapping requires experienced eyeballing and a lot of manipulation of details (see Figure 2). It takes time.
2 p.m.: Nineteen Remote Programmers
During an at-the-workbench lunch session, we discuss the plight of 19 of our developers who were recently moved off-campus. They’re already complaining about being out of the loop with their new project, so we decide to publish the entire set of RDA schema and entity diagrams to the Web. We’ll give them a couple of days to study the schemas, and then we’ll run a training session to explain what and why. RDA almost makes the publishing a one-button affair.
Some of these developers have asked if they can handle RDA themselves. Sure, we say, RDA can alter the functionality and UI for different roles including the Eclipse Developer, Java Developer, and data specialist. We try to make it clear that it helps to understand basic database management and design, but newbies with some database background are welcome in RDA. They also need to get their team support — in this case CVS — up and running.
4 p.m.: CL_MXPRF_TO?
One of the best things about RDA is the relative ease of going from a UML modeling tool into an integrated database design tool. I’ve seen plenty of decent modeling tools, but few that can convert from the logical into the physical database components with so much control.
We’re back to working on the sensor database, which needs to become a real database very soon. We’ll let RDA generate a syntax-specific DDL schema from the model, which is saved as a script and fed to the host RDBMS (in this case DB2) to execute. But first, we continue to run validation checks on the model. This afternoon, one test kicks out an attribute name that doesn’t comply with the corporate standard: CL_MXPRF_TO. We don’t know who put it into the schema, and we certainly don’t know what it is, because it isn’t annotated. Could it be a ringer to test us?
No, it’s something that we forgot to annotate; must’ve been late in the day. We figure out the attribute is the first of many that will come from WebSphere Information Integrator federated functions, but we haven’t worked out all of the connections. When we do, we’ll need to look at the whole thing with the RDA Impact Analysis window to study the dependencies, and make sure all the references are resolved. We put both of these items in the RDA Task List. We also make a note to think about the many different validation tests available in RDA (some are explicit, others are implicit) and decide priority and sequence for them.
Getting Carried Away
This brings up an important element of RDA: It’s so rich in features, including details of the UI, that it takes a while to learn them all and appreciate their use. I’m still exploring, for example, how RDA uses the Eclipse Modeling Framework (EMF) which, among other things, makes extending the functionality of RDA much easier (although not necessarily simple). I’m toying with the idea of learning how to build some data management Eclipse plug-ins. I’ve got some ideas. Just for fun, after hours, of course.…
下午 2 点：19 个远程程序员