Siemens XT65 - Manual (Page 36)

Java User’s Guide
5 Maintenance
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wm_java_usersguide_v12 Page 36 of 123 2008-02-25
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5 Maintenance
The basic maintenance features of the ME are described below. Explicit details of these func-
tions and modes can be found in
[1] and [2] .
5.1 IP Service
Apart from the standard Java IP networking interfaces (UDPDatagramConnection, SocketCon-
nection, ...) the ME also supports a set of Internet Services controlled by AT command. There
are some correlations between the Java and the AT IP Services.
•
The connection profile 0 is also used by Java: when Java starts up a networking connection
it tries to set and activate connection profile 0 with the parameters configured by AT^SJNET
or in the connector.open method.
• Java tries to (re-)use an active Internet Service profile: if using connection profile 0 fails,
because e.g. this (or another) connection profile is already used by the Internet Services,
Java networking also uses this, already active, profile.
• Deactivation of the connection profile happens when all applications are finished: Java has
its networking idle time. For the Internet Services an inactivity timeout referred to as param-
eter is available (configurable by AT^SICS and AT^SCFG).
So that means that Java networking and AT Internet Services can be used in parallel but care
has to be taken about configuring and activation of the connection profile. In the simplest case
use connection profile 0 for the Internet Services and set the parameters to the same values
as the Java networking parameters. This way it makes no difference whether the connection is
activated by the Internet Services or Java.
There are some aspects which have to be kept in mind for all IP Services (Java and AT com-
mand):
•
When an open TCP connection is cut (e.g. the other side dies/is switched off) it takes
around 10 minutes during which retransmissions are send, until the situation is detected as
an error (in Java an exception is thrown).
• The number of IP services used in parallel should be kept small. An active IP service uses
up resources and may deteriorate the overall performance.
• If a user rapidly closes and opens TCP/IP connections (e.g. SocketConnection, HTTPCon-
nection), a ConnectionNotFoundException reading "No buffer space available" may be
thrown, explaining that all TCP/IP socket resources are exhausted. In the worst case, open-
ing further TCP/IP connections is locked for up to 60 seconds.
• If a service is re-opened on the same port shortly after having closed the ServerSocketCon-
nection, the ServerSocketConnection may not work properly. To ensure that the service
works correctly the host is required to wait at least two minutes before reopening a server.
• For information about the bearer state, use the specific IP service command AT^SICI and,
in addition, the general network commands AT+COPS and/or AT+CREG.
Some Java products feature the BearerControl class. This class provides bearer state informa-
tion and a method to hang-up.