Bruce Robertson wrote: >> We use a system of updating an Sqlite database buit use port 80 to send >> data in XML format. >> >> Is there a reason you have access to the email port and not the HTTP >> port 80? It is very complex to identify a missing email but using port >> 80 and HTTP the process is almost trivial >> >> Our system maintains sync'd databases and compensates for network >> outages quite robustly. Remote work sites can continue to operate when >> the communication link is down and thus deliver 24/7 availability.. >> > > Could you describe this in more detail? > The application is actually a set of remote weighstations. The load cell is interfaced to a PC which has an internet connection. The local PC maintains a mirror of the parts of the central database relevant to that location. Transcaction data is embedded in an XML document and uses port 80 to penetrate a firewall and reach the central server. An ACK or NAK comes back in XML. Reference data updates come from the central server in XML and update the local mirror DB. Locally added reference data ytiggers an XML message to the central server.
Each table in the central server has a signature word which is updated at each modification. The remote mirros use that signature to verify their sync state. When the internet connection is broken local transactions are queued and when the connection is restored the queue empties. The remote application is a Windows or Linux program which implements HTTP protocol. The central server just uses a regular web server. XML is used to carry the data so that changes in database schema and message content will not break deployed systems. This system is easy to install because it will work anywhere a browser will work to support this simple distributed database. > > _______________________________________________ > sqlite-users mailing list > sqlite-users@sqlite.org > http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users > _______________________________________________ sqlite-users mailing list sqlite-users@sqlite.org http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
