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Operator's guide
subscription list.
• Receiving a valid DSS_DEL packet, dssserver will find the
corresponding request in the subscription list, remove it, and
reply with a DSS_ACK packet. If the relevant data has already
been transmitted, dssserver will still send the DSS_ACK
packet to notify the client that the request has been dealt with.
• dssserver keeps a record of the subscriptions for each client
so that it can respond to DSS_LRQ packets. When a subscription
is fulfilled, it is removed from the relevant list.
• Other valid DSS commands are dealt with according to the
standard.
• When data arrives from connected digitizers, dssserver
examines the current queue of data requests, and generates the
required data or averages separately for each client, in
accordance with these requests. This data is placed in a train,
which is a data structure whose length is determined by the
reporting interval. Every train includes data from the vertical,
N/S, and E/W component of a particular instrument.
• As soon as the received or generated data fills the buffer, it is
ready for dispatch. dssserver forms the data into a DSS_DAT
message and sends it to the client, identifying it with the relevant
Data Identification Word.
• Every 10 minutes or thereabouts, dssserver checks the client list
for any clients which have not reported to it in the past 10
minutes, and purges the inactive clients from the list.
dssserver does not implement advanced prioritization or queuing schemes.
All clients connect with the same password.
Server configuration
dssserver needs to be configured before it can run. On a DCM, this can be
done by editing the text file /etc/dssserver.cfg, which determines the
mapping between incoming GCF streams and DSS stream identifiers. This file
can be edited using the DCM's Web page interface, by browsing to the
Configuration Data Transfer DSS dssserver.cfg→ → → page. Each line has
the format
stream-id:station-name:location-name:seedname
where stream-id is the Güralp stream ID, and the remaining three fields are
the stream identifiers used in DSS_REQ packets relating to that stream. A
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