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Re: [ecf-dev] Connection awareness API

Pascal Rapicault wrote:
What we are after in p2 is probably something like 1). Basically we would
like to handle gracefully the fact that the machine is not connected to the
network so that we could avoid prompting for silly things like "the file
does not exist", or not prompt the user to retry the download.
  

OK.  AFAIK, there is no cross-OS (java) API for getting that low-level info.  I think native code would have to be written.  Please others speak up if you know of something that provides cross-platform info on the lower layers (physical, link, network).  I don't think that in the case of windows it even exists at the winsock level (although I'm not sure about that).

We could easily create a piece of code that checked for reachability to a particular server/servers (e.g. www.www.eclipse.org)...and assume that if that connectivity is present that the network is functioning (and if it's not present that the network is not functioning), but this has some very obvious limitations. 

Scott



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  |Scott Lewis <slewis@xxxxxxxxxxxxx>                                                                                                                |
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  |"Eclipse Communication Framework (ECF) developer mailing list." <ecf-dev@xxxxxxxxxxx>                                                             |
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  |01/17/2008 04:55 PM                                                                                                                               |
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  |Re: [ecf-dev] Connection awareness API                                                                                                            |
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Hi Pascal,

This is a tough question to answer yes/no...because the answer depends
upon exactly what you mean by 'network is up'.

First, from a given process, 'the network' can/could mean a variety of
things:

1) The OS device (/eth0) is installed/working/connected at media layer
(e.g. wifi)
2) TCP/IP stack installed/active (obviously includes localhost)
3) DNS is functioning
4) A specific remote machine (e.g. gateway) is reachable (e.g. ping)
5) TCP/IP and/or UDP can be used for accessing a particular server
and/or peer
6) Accessing a set servers/peers (how much of 'the network').

Also, there is a further subtlety...between a) determining whether each
of these levels is working (without a specific connection being formed),
and b) being notified if an existing connection goes down.

Most ECF providers have plenty of support for b...and this is provided
via async notification of IContainer disconnection (once in connected
state of course...which, depending upon underlying protocols used...e.g.
IP/UDP/DNS/TCP, support such notification).  If detection of network
failure is what you are interested in, then the answer is generally
'yes'...for most/many providers.

In general, we don't provide cross-transport (or cross-OS) APIs for
accessing the state of the physical, data link, and network layers (in
OSI terms 1, 2, and 3 above)...mostly because these are specific to
hw-specifiic, OS-specific and tcp/ip stack-specific APIs.  So if that's
what you are asking the answer is generally 'no' (excepting the
discovery API with some providers).

Also...if you would/could describe the use case a little further, I'll
happily respond with more brevity :).

Scott


Pascal Rapicault wrote:
  
Hello,

Does ECF provide an API to know whether or not a network is up on the
machine?

Ths

PaScaL

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