The SeedLink protocol is a robust data transmission intended for use on the Internet or private circuits that support TCP/IP. The protocol is robust in that clients may disconnect and reconnect without losing data, the transmission is started where it ended. Requested data streams may be limited to specific stations, locations and/or channels. All data packets are 512-byte Mini-SEED records. The most common implementation, and the one used at the DMC, is the seedlink server within the SeisComP package developed by GEOFON.
Real-time Data from the IRIS DMC
The DMC runs a publicly accessible SeedLink server on the following host and port:
All open data that the DMC receives in real-time is available via this SeedLink server.
The following software is available from the DMC ( SeedLink downloads )
libslink - A SeedLink client library written in C.
slink2orb - SeedLink to Antelope ORB client (licensed Antelope libraries are required).
slink2ew - SeedLink to Earthworm client. Windows binaries available.
slarchive - A SeedLink client that writes all received data to the local disk in user defined directory and file structures.
slinktool - Command line SeedLink client useful for data stream inspection and server testing.
ewexport_plugin - An Earthworm export process plugin (data source) for a seedlink server.
orbplugin - An Antelope ORB plugin (data source) for a seedlink server (licensed Antelope libraries are required).
Other SeedLink related software is available (or referenced by) the GEOFON SeisComP website
slink2orb - Antelope client configuration
The SeedLink protocol can be summarized as a simple, ASCII-based, data selection phase followed by the streaming of data packets from the server. SeedLink packets are composed of a small header followed by a 512-byte Mini-SEED record (data only SEED). The negotiation phase allows the client to request only specified data from the server for each selected data stream. A data stream is defined by a network and station code pair.
By utilizing sequence numbers for each packet in a data stream the SeedLink protocol allows for connections to be resumed, eliminating most data gaps. The ability to resume data streams is primarily dependant on how much data, time-wise, the remote SeedLink has in its buffer.
Special, out-of-band packets created by a seedlink server and recognized by libslink are used to communicate server details to clients and to implement keep-alive packet swapping. These special INFO packets are XML formatted data embedded in Mini-SEED comment records.
The protocol allows for two different modes of data transmission, uni-station and multi-station modes. Uni-station mode operates by transmitting a single data stream (data from a single station) through one network connection. In this mode the data stream does not need to be specified by the client as it is implied by the internet address and port. Multi-station mode operates by transmitting multiplexed data streams (data from multiple stations) through a single network connection. Almost all connections are negotiated as multi-station, even if only a single station is requested; uni-station mode, for most publicly accessible servers is deprecated.
DMC » SeedLink