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4.7.6.2 Ssi tcp linksSsi tcp links give the possibility to exchange data between two processes which may run on the same or on different computers. Ssi tcp links can be opened in four different modes:
The Ssi tcp link describing string has to be
To open an ssi tcp link in launch mode, the application to launch must either be given with an absolute pathname, or must be in a directory contained in the search path. The launched application acts as a server, whereas the SINGULAR that actually opened the link acts as a client. The client "listens" at the some free port until the server application does a connect call. If the ssi tcp link is opened in fork mode a child of the current SINGULAR is forked. All variables and their values are inherited by the child. The child acts as a server whereas the SINGULAR that actually opened the link acts as a client.
To arrange the evaluation of an expression by a server, the expression
must be quoted using the command If SINGULAR is in server mode, SINGULAR is in an infinite read-eval-write loop until the connection is closed from the client side (by closing its connecting link). After an expression is read, it is evaluated and the result of the evaluation is written back. That is, for each expression which was written to the server, there is exactly one expression written back. This might be an "empty" expression, if the evaluation on the server side does not return a value.
Ssi tcp links should explicitly be opened before being used. Ssi tcp links
are bidirectional, i.e. can be used for both, writing and
reading. Reading from an ssi tcp link blocks until data was written to
that link. The
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