Connecting a tablet to a SAMP environment on the desktop

Wed Oct 9 12:05:44 PDT 2013

Hi Mark,

Thanks for picking up on this and nice to see that people are making 
mobile-phone SAMP applications :).

Around the time of our discussion I decided to try a proof of concept 
and created a web-based SAMP application that ran on my Android tablet. 
IIRC it connected remotely from the browser using the web-profile, which 
worked fine. (With a warning pop-up in TOPCAT.)

Perhaps I'll picking the project up again. Programming in javascript is 
actually quite nice.

Hugo

On 10/09/2013 04:32 PM, Mark Taylor wrote:
> Hugo,
>
> following this up after a long time ... the web profile hub in
> v1.3-4 of JSAMP which I just released has this capability to
> allow non-local hosts just as you suggested; for instance start
> it with the system property -Djsamp.web.extrahosts=123.45.67.89
> to allow web profile connections from the named (or numbered) host.
>
> Maxime Heckel and Andre Schaaff at CDS have managed remote control
> of Aladin from an iphone(?) using the Web Profile.  I'd be interested
> to hear if you (or anybody else) find some other use for this.
>
> Mark
>
> On Mon, 30 Jan 2012, Mark Taylor wrote:
>
>> Hugo,
>>
>> thanks, I've made the change to the document.
>>
>> As far as the JSAMP implementation goes, it currently does not permit
>> the non-local host access you suggest, but I'll consider adding an
>> option for it in the future, especially if anybody wants to try to
>> develop a tablet client along these lines.
>>
>> I take your point about the mobile device view of the world (web-like
>> clients running in browser-like environments, rather than traditional
>> style clients, are becoming more common, even outside browsers as such).
>> Being a bit of an old-technology guy, it's something I hadn't thought
>> much about, but I expect you're right it is something we're going to
>> have to keep in mind.
>>
>> Mark
>>
>> On Mon, 30 Jan 2012, Hugo Buddelmeijer wrote:
>>
>>> 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/
>>>
>>>
>>
>> --
>> 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/
>>
>
> --
> Mark Taylor   Astronomical Programmer   Physics, Bristol University, UK
> m.b.taylor at bris.ac.uk +44-117-9288776  http://www.star.bris.ac.uk/~mbt/
>