Data Mapping
In the beginning we start with the data target. This may be strange if you have not done any mapping, but the first, best thing that you can do to make a mapping project successful and fast is to start with a well defined target for your data.
I believe that Steven Covey says it this way, “Begin with the end in mind.” We do the same thing in data mapping, except that we begin with the end or target if you will. The data target naturally leads us to the data sources that we need.
If one starts with the source, a lot of work goes into the project, like organizing the source data, before we know if we need any of it. Sure, you may know that you will need the shipping addresses if you are mapping to a shipping transaction, but spending time gathering the information on the source of this data is still not effective until we know where we will be putting it.
A guide to mapping data from source to target
Spreadsheets are great for mapping. We start with six columns. From left to right we have source, source data type, rules, target, target data type, and notes. We start wit the target and list the data elements that the target needs in the order that the target needs them to approximate the target form. If this is a database table then this is really simple, and we are just listing the columns names in order.
If the target is something less list like, we will need to add some location information. In XML we might want to include the xpath to the spreadsheet either in the cell above, or in a logical grouping. Both approaches work and I will show you and example of each.
As we list the target we will also want to note the data type in the column to the right. As we note the type of any data with specific formatting, like date or email addresses, we can place that definition here.
After we have the target well defined it is time to decide where this data will come from. We probably already have some idea, so now it is time to work down the source column and fill in the data reference. There may be more than one field that maps to a single field on the right. And there may be one field on the left that maps to multiple fields on the right. There may also be completely derived data that is calculated at runtime. There can also be multiple data sources. You will probably encounter all of these and more in your career as and integration engineer.
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