[sr-dev] [Kamailio-Users] new module: mi_rpc

[Andrei Pelinescu-Onciul]

On Jul 13, 2009 at 22:26, Daniel-Constantin Mierla <miconda at gmail.com> wrote:

[...]
> >
> >It's possible to have full mi_xmlrpc , xmlrpc+mi output compatibility
> >(meaning identical output). I'm working on it right now.
> >  
> 
> How will this look over fifo or udp?

It should look the same as in kamailio, if you use mi_fifo or mi_udp
commands in sercmd and use it in non-interactive mode.
E.g.:
sercmd -f "%v" mi_fifo pwd  
200 OK
WD:: /home/andrei/sr.git


If you don't add -f "%v" you'll see double '\n' (sercmd adds one at the
end of each value by default).

In this mode sercmd can be used as a fifo or mi_datagram replacement
(one will have to exec sercmd via a pipe instead of directly
writing/reading from the fifo or datagram socket).


I've added mi_fifo, mi_dg, mi_xmlrpc and also slightly changed mi output
(to have one function generating all of them).
Now all of them output "lines" (each output value is a string containing
one line). This was done to be compatible with mi_xmlrpc and to avoid
code duplication.
If the old mi output (with '+') is still "wanted" I can re-add it.


> 
> I hoped to get with mi_rpc output in the native RPC format. AFAIK, there 
> are "member" elements in the structure that can have name and value. 
> That maps to mi node name and value. Attributes are something that maybe 
> can be encoded in the value

I was thinking of adding various mi_rpc commands. One would encoude
 node children to structs, another attributes to structs a.s.o.
Unfortunately there's no clean solution, at least for the next release.

> 
> Next would have been a MI "rpc" command to be able to execute rpc 
> commands via MI, with output in MI format. However, this is more complex 
> and probably makes no sense.
> 
> If you try to get name, value and attributes in one string and return 
> the array of them, it is useless for those having ser xmlrpc parsers and 
> inconsistent across the ser rpc commands reply.

Yes, I agree.
> 
> 
> >>However would be good to get a single command, but I do not know if is 
> >>possible considering that MI reply trees have:
> >>- name for nodes
> >>- values for nodes - string or other nodes
> >>- attributes for nodes - string
> >>    
> >
> >mi_xmlrpc transforms all that values in a string and then adds it to the
> >xml reply. So the xmlrpc result will be an array of strings, each string
> >containing a node name, value and attributes list (similar output to
> >mi_fifo and mi_datagram only encapsulated in xmlrpc, one string
> >corresponding to each mi_fifo line).
> >
> >So all that extra stuff is for nothing, all the mi_* modules transform
> >it to a simple string in the following format:
> >
> ><node name>:: <node value>[ <attr name>=<attr value>...]
> >
> >
> >What I profoundly dislike in mi is this completely useless and overly
> >complex tree structure. I understood that it was made this way to map on
> >a xml document, but the questions remains why?
> >  
> 
> Next transport was planned among firsts - soap - but no devel resources 
> for it.

I hope this is not a goal any longer (or if soap support is still
desired at least it could be made to work based on normal rpc and
without all the add-ons).

> 
> >The only link between xmlrpc and pure xml is the _transport_. xmlrpc
> >encapsulates rpc in xml, you don't need to build xml documents by hand.
> >xmlrpc is quite simple, it has a limited number of basic types (int,
> >string, float, array and struct) and a very simple format: each function
> >call is represented by a method name and a list of parameters and each
> >answer by a _single_ value or a fault. There are _no_ named values and
> >no attributes. Structures have named members, but that's about it.
> >
> >So all this extra "features" from mi cannot be used in a consistent way
> >(you would have to write your own parsers for the mi_* output and even
> >then is not clear how one would deal with values containing spaces in
> >them, or even worse spaces and '=').
> >  
> 
> This I hoped to fix with mi_rpc - the output of the mi command to be 
> XMLRPC properly formatted.

I hoped the same, but a few greps through modules_k changed my mind :-)


Andrei