Announcing Jolo, a Java library for printing text-based tables

Well, I’m at it again releasing another open-source project. I work with Hyperion and the Essbase Java API extensively, so it’s not uncommon for me to be doing things with grids and working on a command-line. I frequently write lightweight command-line clients to test things out. I didn’t love the options I was able to find in Java that would help print/format a text-based table. The ones I did find were clunky and hard to use.

So, you guessed it, I rolled my own. Jolo is a small and lightweight Java library with two goals: print out text-based tables, and have a tight and clean, yet flexible API. So let’s say we want to print out names, cities, and states in a three column table. The code looks like this:

public void testPrintTableWithColumns() {

    // setup table definition with column names/widths
    TableColumnList tcl = new TableColumnList.Builder()
        .add("Name", 40)
        .add("City", 15)
        .add("State", 2)

    // createRandomRows is a helper function in this case but would otherwise
    // be your data that is an Iterable<List<Something>>.
    Iterable<List<? extends Object>> data = createRandomRows(10, 3);

    // create the printer and print the data
    TablePrinter tp = new TablePrinter();
    tp.outputTable(tcl, data);

Having the TablePrinter separate from the concept of a TableColumnList is nice because we can plug-in different TablePrinter implementations if we want to. In the above example I have a helper method creating the data for me (createRandomRows()) but in your program this would be something that implements the Iterable interface and contains a List of something that extends Object. In Java parlance that means you can print anything that’s Iterable<List<? extends Object>> – note that the toString() method will be called, so you can pass anything in. If I get time I’ll enhance the API a bit to provide some convenience functions and syntactic sugar. Given some data, the above code generates this table:

|Name                                    |City           |St|
|Jason Jones                             |Seattle        |WA|
|Cameron Lackpour                        |Philadelphia   |PA|
|Tim Tow                                 |Huntsville     |AL|

Note that with a simple parameter in the builder we were able to constrain the width of a given column.

The Hyperion Connection

This isn’t ostensibly Hyperion- or Essbase-related (save for the names in my table, hehe), but if you work on the things that I work on then this might be up your alley. The Jolo page has more information including a link to the Github repository. I will likely push this to Maven Central as time permits to make its inclusion in anyone’s projects all the easier. Unlike many of my other projects, this one is not incredibly commented [yet], so that will be coming in the future weeks as time permits. The API is pretty clean though so you shouldn’t have a hard time using it. Licensed under the very business-friendly Apache Software License.

Using ODI error tables (and tables with dollar signs in their names) as models for transformations

I setup a solution awhile ago where ODI facilitates data movement from an ODI error table into another data store. As you may know, ODI has a naming convention where its temporary and work tables are prefixed with some combination of a letter (or two), a dollar sign, and perhaps an underscore. So if my original table in a relational data store is CUSTOMERS, then the error table for this table would be E$_CUSTOMERS.

So of course I fire up my RKM to build out the model metadata for these new tables, just like I normally would. Everything goes fine but when I go to build the interface and run it, things don’t work so well. A dollar sign ($) is a very common character for scripts and programming languages to indicate that variable interpolation should occur (in other words, to fill in a placeholder). For example, if the variable $color = “orange” and you interpolate a string such as echo “My favorite color is $color!” then the result is “My favorite color is orange!” Nothing too fancy here.

That being said, sometimes a dollar sign can wreak havoc when used where some code doesn’t expect it. I’m not sure if it ever got fixed, but I developed at a place once that would dole out Active Directory IDs based on letters from the first and last name – three letters from each, to be precise. But people with very short last names would have dollar signs appended to them. There was a bug in Hyperion where you couldn’t login with one of these user names, likely because it just never got tested (oops). I’ll assume that’s fixed now.

In any case, back to ODI. In a given ODI datastore, you have the name, resource name, and alias name. Name is typically how you see it in the ODI design context. Resource name is the actual resource in the schema/database. Alias is used by ODI in interfaces as, well, an alias. I didn’t record the exact error message but given that my interface was failing and the output in Operator was a bit odd, I immediately suspected the dollar sign throwing things off either for ODI’s generated code, on the target system (and Oracle database server), or both.

My quick solution? Just replace the dollar sign with an underscore in the alias in the datastore. You can delete the dollar sign entirely but I decided to just go with an underscore. By making the change in the datastore, subsequent interfaces leveraging this datastore will also benefit from the fix, as opposed to trying to adjust just the one interface. Of course, leave the resource name alone (and the name) since they don’t need to be changed (and in the case of the resource name, shouldn’t be changed).

Another approach to all of this would be to change the physical topologie’s naming convention so that error tables don’t have a dollar sign (or other entities that ODI names) but I quite like ODI’s preferred naming strategy (for the most part).