Systems integration

Ways round exist: files dropped into a watched folder, reading the database directly, or the export tools the vendor supplies. All are more fragile than a proper interface and need watching at every version upgrade. Sometimes updating the software costs less than working around its limits for five years.

Not necessarily. Many accounting packages now handle Factur-X and the connection to a platform, so start by asking your vendor. Development earns its place when invoices originate elsewhere, in a shop, a trade application or an in-house tool, or when purchase invoices have to be matched to orders automatically.

Rarely. Most processes live comfortably with a sync every few minutes, and that arrangement copes far better with an outage at a supplier. Real time earns its keep on stock levels in a busy shop, where every unit sold counts, or on a payment that has to open an access straight away.

The maintenance agreement fixes response time and the scope covered. The commonest cause is not our code but the other end: an interface changed by a vendor, an expired certificate, a password reset without warning. So we watch the replies coming back from third-party systems, not only our own jobs.

Two well-documented systems with tidy reference data fit into a few weeks, acceptance included. As soon as several applications share the same customers and products, most of the elapsed time goes into sorting out that reference data rather than into development. The schedule is given after the data review.