Connecting a tablet to a SAMP environment on the desktop

[Hugo Buddelmeijer]

Hi Mark et al.,

Thanks for your reply. With HUB-HUB communication it would probably be 
possible to create tablet SAMP clients with the current version of the 
profiles. However, your suggested change of the web profile would make 
tablet clients much more feasible. Therefore, I do think the proposed 
paragraph would be valuable addition to the web profile.


How it could be done now:
- Create one HUB-application using the standard profile.
- This has to be a native application, because it needs to be a server.
- This costs money for a developer license. However, this only has to be 
paid for the development/distribution of the HUB.
- Leave it to the tablet owner to ensure that inbound connections to the 
tablet are possible. This can be prohibitively hard.
- In my case this would require setting up an SSH tunnel, since I do not 
control the firewalls that 'protect' my tablet.
- Allow webapplications to connect to this HUB.

With the proposed changes:
- Allow the HUB to accept external connections on the web profile.
- Create a tablet web application that connects to the main HUB through 
the web profile.


Opening the port to the world by default would indeed be a security 
risk. However, making it possible for the user to do so temporarily 
would be very valuable.


A final note from a more general perspective. It seems that tablet world 
(and computing in general) moves to the paradigm where inbound 
connections should be prevented when at all possible. There is to true 
need for inbound connections to SAMP clients, as the web profile 
demonstrates. It would therefore be useful to take this development into 
account, irrespective of whether we consider this change to be good or bad.

Greetings,
Hugo


On 01/25/2012 11:56 AM, Mark Taylor wrote:
> Hugo,
>
> On Tue, 24 Jan 2012, Hugo Buddelmeijer wrote:
>
>> Tablets with a touch screen could be a valuable addition in the interactive
>> exploration of our data. Therefore, it would be nice to be able to connect a
>> tablet (iPad, android) to an existing SAMP setup. That is, to have the SAMP
>> HUB and most applications running on the desktop, and run only a simple
>> interactive visualization tool on the tablet.
>
> I think this is a very interesting idea, and certainly something it
> would be good to facilitate rather than preclude in the standard.
>
>> However, this seems not to be possible with either the default profile or the
>> proposed web profile. What are your ideas on this?
>>
>> - The default profile requires the tablet application to setup an XML-RPC
>> server. In practice this would often be impossible, for example due to
>> inbound-blocking firewalls or restrictions in the device itself.
>
> I don't know enough about tablet-like devices to understand the
> restrictions that a tablet-based application is likely to be
> operating under, but if as you say they are unable to run an XML-RPC
> server on a port of their choice then yes the Standard Profile
> is not suitable for data-consuming clients.
>
>> - The web profile could remove these restrictions. Running a SAMP application
>> on a tablet would then simply become loading a web page. However, this does
>> not work either because the spec recommends to block connections from another
>> device (sec. 5.2.3 and 5.4.2.1).
>
> Done like this (web profile hub connection from an external host)
> hub discovery is still an issue (as you noted before), each web app
> would need to know what host the hub resides on.  It could get the
> user to type it in or something, which would work but be a bit clunky.
>
> To get round the hub discovery issue, the nicest way
> for tablet SAMP connection to a desktop to work might
> be for the tablet to run a hub which talks to the desktop hub,
> and then web apps on the tablet can talk to the tablet hub
> using the web profile, while the tablet hub bridges connections to
> the desktop hub.  Then tablet applications can do hub discovery in
> the usual way, and they also don't need to know whether they are
> talking cross-host or just locally.  It would require a native
> application on the tablet (hub + hub-hub bridge) but this only
> needs to be written once, not for each app.  If the tablet-desktop
> hub bridging is done using the Standard Profile, this whole scheme
> could work with the Standard and Web profiles exactly as they stand.
> If running an XML-RPC server on an application-chosen port is impossible
> then it would have to use the Web Profile (or possibly some new profile)
> with the local-host restriction relaxed as you suggest.
>
>> My ideas to remedy this would be one of the following:
>> - (Optionally) allow external connections in the SAMP web profile?
>> - Add the long-polling option also to the default SAMP profile?
>> - A third profile?
>
> Since it's not clear (to me at least) what would be the best way
> to implement this kind of connection, I agree that it would be
> good to adjust the standard so as not to preclude the scenario
> you're talking about, if it can be done without too much disruption.
>
> I think the best thing would be to revise the text slightly to admit
> your first suggestion.  In fact external connections are not
> forbidden at the moment, but they are strongly RECOMMENDED against.
> I suggest addding the following text to the end of section 5.4.2.1:
>
>     There may be circumstances under which it is appropriate to relax this
>     local host restriction, for instance to enable collaboration with
>     a known external host not capable of Standard Profile communication,
>     such as a mobile device operated by the hub user.
>     However, it is RECOMMENDED that Web Profile implementations at
>     least restrict access to the local host in their default
>     configuration, and if access is permitted to external hosts
>     it is only by explicit user request, and to a named host or
>     list of hosts.
>     Opening the well-known Web Profile hub server port to the internet at
>     large would invite denial of service and perhaps phishing attacks
>     in which the user is bombarded with unwanted SAMP registration
>     requests.
>
> plus a couple of extra "under normal circumstances" clauses elsewhere
> in sections 5.4.2.1 and 5.2.3.
>
> Do you think that's a good way forward?  Anyone else have comments?
>
> Mark
>
> --
> Mark Taylor   Astronomical Programmer   Physics, Bristol University, UK
> m.b.taylor at bris.ac.uk +44-117-928-8776 http://www.star.bris.ac.uk/~mbt/