Implementing fallback

Webservices.nl has two server locations:

• ws1.webservices.nl
• ws2.webservices.nl

Despite our efforts to keep all servers up at all times it may still occur that one of the servers can not be reached for a short period of time.  Downtime can occur due to hardware failures or connectivity problems.  However, this does not mean that clients cannot continue using our services.  To ensure continuity of our services a client program can simply switch to the Webservices.nl fallback server location (ws2.webservices.nl).

All clients should detect request timeouts and take appropriate measures when they occur.  The request timeout should be set to 20 seconds (60 seconds for the Kadaster service methods).  If there is no response to a request within this time the client should switch to the alternative server location.  After a certain period (for example, 10 minutes) the client can try sending a requests to the primary server again.  If the primary server is available it should always be used in instead of the fallback server.

If you use the session token (reactid) to authenticate, you have to perform a new login when switching servers, since session tokens are bound to a single server.  Session tokens remain valid for a period of ten hours.  The secondary server (ws2.webservices.nl) does not offer Accounting methods.