Guralp Systems CMG-DCM - Manual (Page 69)

Operator's guide
dssserver fulfils requests by following this procedure:
•
Receiving a valid DSS_REQ packet, dssserver will send a
DSS_ACK packet immediately and add the request to an
internal 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
DSS expects streams to be named using station, channel, and network
codes according to the FSDN SEED naming convention. Before using
the SeedLink server, you will need to tell it which streams to output,
and what SEED codes to use for each one. This is done on the Seed
name mappings page (see Section 5.7, page 75.)
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