The following commands are available with the JSON API:

change_constraints	change_script	cmd	cnst_alt	cnst_alt_v
cnst_time	consts	create_target	dec	devbytype
deviceinfo	devices	executor	expose	get
hasimage	inc	labellist	labels	lastimage
messages	night	obytid	plan	runscript
satisfied	script	selval	set	status
sunalt	taltitudes	tbydistance	tbyid	tbylabel
tbyname	tbystring	tlabs_add	tlabs_delete	tlabs_set
update_target	violated

Info about them can be figured out from the relevant code:

httpd.cpp and api.cpp json.py, this last one being the most informative

cmd

This can be used to send commands to the different devices in RTS2. For example to observe the target 8 next:

  http://observatoryserver/apipath/cmd?d=EXEC&c=next%208

note the URL code %20 is used to pass on the space between the command and the parameters.

devbytype

This will list the devices by type with the modifier being an interger t: for example:

http://observatoryserver/apipath/devbytype?t=2

will output mounts attached to this rts2 instance. Where the differt device types are:

1	SERVERD	9	GRB	21	IMGPROC
2	MOUNT	10	FOCUS	22	SELECTOR
3	CCD	11	MIRROR	23	XMLRPC
4	DOME	12	CUPOLA	24	INDI
5	WEATHER	13	FW	25	LOGD
6	ROTATOR	14	AUGERSH	26	SCRIPTOR
7	PHOT	15	SENSOR
8	PLAN	20	EXECUTOR

devices

This will list the devices connected to rts2

lastimage

This theoretically tells you which was the last image to be taken. Using the modifier 'ccd' However if this fails (claims not a single image has been taken) Looking at the status of the camera device will often state the last_image as a value.

runscript

Will run script. Example: runscript?d=C0&s=E%201 (in this case the script has a space which is replaced with '%20' to comply with http urls standards).

set

This will allow you to set values in rts2 devices. Modifiers are: 'd': device, 'n': name, 'v': value, 'async': async

status

get or status are identical. This will give the values of a specific module. Known modifier is: 'd': device

update_target

This can be used to change values in a target including its coordinates

  http://observatoryserver/apipath/update_target?id=15&ra=34&dec=-23