[Opensim-dev] dispatcher interface

Sun Dec 21 06:36:22 UTC 2014

I'll add some text to the feature proposal page. rather than dump all of
the documentation i'm working on into the proposal, i've started a google
site for documenting the behavior. we can move it to the opensim wiki later
if that is appropriate: https://sites.google.com/site/opensimdispatcher/

To answer your other questions...

1) authentication -- i'll finish the documentation for the authentication
tomorrow. the gist is that every message must have a valid capability
attached to it or the message will be rejected. a client can request the
creation of a capability for an authenticated user account. there are
criteria for limiting capabilities to estate managers or grid gods. i'm
adding another filter for IP addresses.

2) example serialization -- there is an example in the document.

{
    "$type": "Dispatcher.Messages.CreateCapabilityRequest",

    "_AsyncRequest": false,
    "_Capability": "a1b108dc-11aa-44cb-a971-760dbadef07c",
    "_Domain": "Dispatcher",
    "_Scene": "Test Region",
    "DomainList": ["Dispatcher", "RemoteControl"],
    "FirstName": "Test",
    "LastName": "User",
    "HashedPasswd": "99cafb4ff0e3a8a6708f3854b713b552",
    "LifeSpan": 300,
    "UserID": "16d0f788-2066-4b64-b248-ffa239f62240"
}

the dispatcher's also provide an introspection interface. so the following
will give you a message that contains a string representation of an
instance of the requested message type:

curl http://12.46.129.31:9002/Dispatcher/ -d '{
"$type":"Dispatcher.Messages.MessageFormatRequest",
"MessageName":"Dispatcher.Messages.CreateCapabilityRequest" }' -H
"Content-Type: application/json"

or you can request a list of supported messages with this command:

curl http://12.46.129.31:9002/Dispatcher/ -d '{
"$type":"Dispatcher.Messages.InfoRequest" }' -H "Content-Type:
application/json"

both of those commands are probing the dispatcher i'm running on the
traffic simulation region i've made available.

3) a new communication

well... its never stopped us before. you forgot the stats interface, the
remote administration interface, and the websocket interface. oh... and
don't forget all the methods that LSL supports. i'm sure there are more.

this is not a sim-to-sim communication module. its much more similar in
intent to LSL or the remote admin interface. json-rpc is essentially
identical. though the dispatcher requires some special format in order to
map each of the json messages to a C# class.

4 there would only be C# in core. the only non-C# code is the client
libraries which may or may not be distributed with core. they are not built
or compiled as part of building or installing opensim. its more like
distributing a bunch of assets for an avatar's library.

all that being said... if we actually had a reasonable distribution
mechanism we wouldn't be having this conversation because many (most) of
the modules we package as optional modules should be loaded dynamically.
something like PyIP or CPAN. but we don't have one of those.

so my question is... what's the point of putting it in core at all if we
going to require anyone who uses it to go digging for client libraries from
some other site? while someone could generate their own json libraries, the
effort of putting it in core is really not worth it for the *very* small
number of people who will do that. on the other hand... if there are some
useful commands already distributed with core (in a utility director or
something), then we have added value.

5. documentation. see above. working on it.

6. definitely turn it off by default. the site i pointed to has an example
configuration (which is also included in the github repository.

7. license... just copied with the Intel lawyers gave me when I asked.
remember that this has been used extensively by me for four years. and...
like all intel contributions, we would replace the license with the opensim
standard license.

--mic

On Fri, Dec 19, 2014 at 6:16 PM, Justin Clark-Casey <
jjustincc at googlemail.com> wrote:

> I would be happy to see this in core.  I do have the following
> questions/points.  I would ideally like to see much of this stuff in a
> feature proposal page [1] and that can later also become some documentation.
>
> 1.  Please could you go into detail about the authentication/access
> model.  Looking over the code, I see text about domains, capabilities,
> authentication by hashed password, etc. but I would like an overview on how
> this fits together.
>
> 2.  Please could you give an example serialization of one of the JSON
> messages.  I would like to see the basic form and what one expects to see
> in such a message.
>
> 3.  This would be yet another different kind of message passing in
> OpenSimulator, to join XMLRPC, JSON RPC, form, etc, where the majority of
> internal communication is via XMLRPC.  I'm not saying we should persist
> with XMLRPC in this case, but I would really like to see some agreement on
> how communication should evolve in the future, whether that should be
> JSON/BSON or something else.
>
> 4.  I don't feel that we should change our rule of only having C# code in
> core.  Having other languages or client code increases project complexity
> and implies a commitment to maintain code which is not part of the server
> system (hence I think one could make a case for separating out pCampbot but
> that's another topic).  I think it's fine for the client code to be
> external as long as there are open-source clients under a permissive
> license (Vivox being a historical exception) and the interfaces are
> documented.
>
> 5.  Regarding documentation, to be clear I think wiki pages will be
> required documenting the general approach, security model, etc.
>
> 6.  In this case, I don't think that this facility should be enabled by
> default as it does expose a method of interacting with the simulator with
> security implications, even on a private network.
>
> 7.  I see all the license notices are BSD but with an extra "EXPORT LAWS"
> text which I find rather bizarre as it purports to add "NO RESTRICTIONS TO
> THE EXPORT LAWS OF YOUR JURISDICTION".  I find this rather bizarre (why
> have such a paragraph if it doesn't do anything?).  Apparantly, Intel
> itself has ceased to use or recommend this license text [2] and has asked
> the OSI to remove it for future use as an approved license back in 2005
> [3].  Is it going to be a problem to remove this text before adding any
> code into core?
>
> [1] http://opensimulator.org/wiki/Feature_Proposals
> [2] https://en.wikipedia.org/wiki/Intel_Open_Source_License
> [3] http://news.cnet.com/Intel-to-stop-using-open-source-
> license/2100-7344_3-5648518.html
>
>
> On 19/12/14 00:11, Mic Bowman wrote:
>
>> i've had several requests for the dispatcher interface to be moved into
>> core. dispatcher package consists of two pieces:
>>
>> dispatcher -- the core modules that implement the message transfer,
>> message encoding and some of the basic messages
>> (informational messages and messages to create and renew access
>> capabilities).
>>
>> https://github.com/cmickeyb/scisim-addons/tree/master/dispatcher
>>
>> remote control -- a collection of messages that implement a OpenSim
>> remote scripting API. these messages include some
>> basics for accessing/creating assets, for getting/setting avatar
>> appearance, sending messages, managing objects in the
>> scene, and managing some of the region characteristics. there are also
>> messages for registering remote handlers for
>> touch events. clearly this is just a start (though there is a
>> surprisingly large number of things you can do with these).
>>
>> https://github.com/cmickeyb/scisim-addons/tree/master/rcontrol
>>
>> for more information on what the dispatcher is and why you might want to
>> use it, watch the OSCC presentation
>> http://www.ustream.tv/recorded/55195110 or take a look at the kinds of
>> scripts that you can write by looking in the
>> scripts directory of the rcontrol repository.
>>
>> with all that said...
>>
>> i would like to start the discussion about whether this is useful enough
>> to be moved into core & how that should happen.
>>
>> i don't have a particular stake in whether its moved to core. there are
>> benefits to both. its easier for me to change
>> for my purposes if if its outside core and its (much) easier for the
>> community to use it if its in core. if the
>> community believes there is sufficient value, then we should move it in.
>>
>> if it is not moved inside, i would appreciate suggestions on how to
>> distribute the libraries. this is an ongoing problem
>> for opensim... how to provide simple access to a dynamic set of region
>> modules. probably a bigger discussion.
>>
>> if we think the dispatcher API should be moved into core, then there are
>> a few questions about how that should happen.
>> clearly the region modules can be moved into OpenSim/Region/OptionalModules.
>> that's easy. the more interesting question
>> is where to put the client libraries (these are the perl & python
>> libraries that are used to build dispatcher clients)
>> and the control scripts that are rather useful for managing a region. I
>> would propose placing them in a directory under
>> OpenSim/Tools though they really aren't tools in the sense of the other
>> packages in that directory.
>>
>> the final question is about documentation. the api is already pseudo-self
>> documenting... the API lets you can ask any
>> simulator for the messages it supports & then ask for examples of the
>> messages themselves. i'm planning to add a
>> "documentation" string for each as well. some other methods for autodoc
>> would be useful though pulling out dispatcher
>> documentation from within the multitude of existing opensim autodoc might
>> be challenging (not something i have any
>> experience with).
>>
>> --mic
>>
>>
>>
>>
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>>
>>
>
> --
> Justin Clark-Casey (justincc)
> OSVW Consulting
> http://justincc.org
> http://twitter.com/justincc
>
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