3. Find out how the front end works
Review a copy of the application front end source code and see if you can work out what the requirements are and the basics of how it works from there. As ever, document what you have found. Searching the source code for phrases such as ODBC, DSN, Provider, Recordset are useful in VBA for locating database connectivity, but there will be different for other platforms. However, at first the key things to look at are:
* Source code
* Logs (application, development tool, operating system, web server, database server, ODBC trace). Not everything will apply to all applications but it gives you some sort of idea of where to look.
Once you have got this, look at
- How the front end is deployed to clients (eg file on network drive with shortcut on desktop, setup routine, network management tools, web page) - is anything else pushed out with it (eg ODBC data sources, Java runtime versions etc)
- search the source code for application messages received to work out where they are generated from. This applies to those that indicate both both success and failure.
- review the source code itself for comments and/or code
- run the application through debugging and profiling tools
- any documentation that may exist, even if outdated or incomplete.
- In the source code, does it reference external or third party code libraries (eg VBA may make use of ADO or DAO for database connectivity, the Adobe PDF writer for creating PDF files etc). Web applications may make use of JQuery from content delivery networks etc. This will help identify any dependencies the code has.
If the source code is unavailable, then the problem is a lot bigger and your time is better spent using information gathered to redevelop from scratch or investigate commercial alternatives.
This is particularly important if the application is a commercial product but has been end of life'd, or the vendor has closed down and there is no support available.