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Lucas Jellema, active in IT (and with Oracle) since 1994. Oracle ACE Director for Fusion Middleware. Consultant, trainer and instructor on diverse areas including Oracle Database (SQL & PLSQL), Service Oriented Architecture, ADF, Java in various shapes and forms and many other things. Author of the Oracle Press book: Oracle SOA Suite 11g Handbook. Frequent presenter on conferences such as JavaOne, Oracle Open World, ODTUG Kaleidoscope, Devoxx and OBUG. Presenter for Oracle University Celebrity specials.
Posts by Lucas Jellema
It was fairly difficult to come up with a title for this article that sort of covers the content. To me it is quite clear what this is about – but how to convey that in a title? Let me explain: today in our project we discussed the implementation of a data service. The service operation under scrutiny takes a city as input and returns a list all open orders from customers located in that city. Nothing very special there. The interesting complication lies in the fact that the customers are part of a different domain than the orders. This means – under our architecture guidelines – that we cannot create a single SQL query that joins together the customers table with the orders table. A database link to join the tables across databases is out of the question and even if these tables currently reside in the same database – such a join is not allowed. Different data domains are treated as independent entities and no direct dependencies between the two should be created. Every design has pass the check ‘will it still work if one of the domains involved were to be relocated to the cloud or be replaced by a third party application’.
The architecture is service oriented. Every domain More >
Last week I was prompted to take a look at the new Oracle ADF Academy that has just published its first lesson: Developing Applications with ADF Mobile. As you probably already know, there are tons of resources on ADF. Blogs, books, tutorials, Oracle by Example instructions, YouTube movies, extensive documentations, how-tos, the forums, podcasts and more still. What could this ADF Academy add to the mix, I was wondering?
Here is what Oracle says about it:
To be useful, data held and used in information systems has to live up to a number of expectations. The data should be an accurate representation of its source. It should be reliable. The data should have internal consistency. The data should adhere to rules based on the logic of the real world. This accuracy, internal quality, and reliability of data is frequently referred as data integrity.
Safeguarding the integrity of data is a challenge, one that increases in complexity when multiple users access and manipulate the data simultaneously , obviously a common situation. And that challenge reaches new heights when the data is managed in multiple independent data stores rather than a single database.
Earlier this month, the Oracle Technology Network published an article that I recently wrote on this subject: http://www.oracle.com/technetwork/articles/soa/jellema-data-integrity-1932181.html. I was triggered into writing it by two recent experiences.
One was at a customer of mine where we are designing a service oriented architecture, based on a number of distinct and independent data domains. These domains are exposed through elementary (entity) services. A second tier of More >
We all know a lot of money is involved with professional sports. One of Europe’s major sports is football (or soccer as some like to call it). A lot of money changes in hand in football. And it seems that the results are determined primarily by the money. The major pan-European competition – the UEFA Champion’s League- is called out of reach for representatives from smaller countries – because of their lag in terms of yearly budget. And the national leagues are dominated by [clubs that have the] money.
Together with my son Tobias we decided to investigate. How much money is in the budgets for all clubs taken together in each of the major football leagues? And how is that money distributed over the clubs. Is it evenly allocated or are there wild variations? And is money a guarantee for success?
We decided to use the ADF DVT Treemap component to visualize our findings. From left to right, you see four treemaps, representing the football leagues of England, Spain, Germany and The Netherlands. The size of each treemap corresponds with the sum of all club budgets in that league. Inside the treemap, each area represents a club. The size of the area corresponds with the budget of the More >
In a recent article (http://technology.amis.nl/2013/04/02/adf-dvt-using-the-tree-map-visualization-component-to-compare-relative-sizes-and-distributions/) I discussed the ADF DVT Treemap component. This component visualizes data in such a way that comparisons between data values for different records and categories can quickly be made. The size of areas is a measure for some numerical value. As an additional dimension, the color of the areas can be used to identify groups (all members of the group having the same color) or to visualize a second numerical value (color can range for example from dark red to rich green depending on the net revenue per record).
This article describes the situation where we want to use multiple Treemap instances lined up. Each Treemap instance represents a collection of records on one or possibly multiple levels. Each instance can be drilled down into independently. And each instance can represent a different data set, even though we want to compare these data sets. Using a PanelGridLayout, it is easy to position multiple instances in a row or a grid. Using the inline style to scale the width and height of the Treemap instances, we can set the relative More >
The tree map component is one of those data visualization components that can tell an entire story through a simple picture. But of course that picture is anything but simple. And it is not even just a picture: it supports various forms of interaction such as drill down and popup. I had seen the Tree Map for the first time in demonstrations by Oracle Product Management. It seemed okay, but nothing very spectacular. Now, after having tried out the component for myself as well as studying the documentation, I may have to revise my initial opinion: it is actually a pretty cool and powerful component.
The Tree Map is used to present data values in a way that makes comparison easy, using two dimensions: (relative) size and color. The TreeMap uses containers for nodes with sizes relative to the numerical value associated with the nodes. Each node can have details and the container is presented with enclosed areas for each of the details. The size of these areas is proportional again to the value associated with the child node. All areas can be colored automatically – to create a pretty picture – or can be colored according to rules we can specify in order to have the colors also convey More >