AGU 2018 Demo

This notebook shows how to use birdy's high-level interface to WPS processes.

Here we access a test server called Emu offering a dozen or so dummy processes.

The shell interface



In [1]:

    
%%bash
export WPS_SERVICE="https://bovec.dkrz.de/ows/proxy/emu?Service=WPS&Request=GetCapabilities&Version=1.0.0"
birdy -h









    



Usage: birdy [OPTIONS] COMMAND [ARGS]...

  Birdy is a command line client for Web Processing Services.

  Documentation is available on readthedocs:
  http://birdy.readthedocs.org/en/latest/

Options:
  --version         Show the version and exit.
  --cert TEXT       Client side certificate containing both certificate and
                    private key.
  -S, --send        Send client side certificate to WPS. Default: false
  -s, --sync        Execute process in sync mode. Default: async mode.
  -t, --token TEXT  Token to access the WPS service.
  -h, --help        Show this message and exit.

Commands:
  ultimate_question         Answer to the ultimate question: This process...
  sleep                     Sleep Process: Testing a long running process,...
  nap                       Afternoon Nap (supports sync calls only): This...
  bbox                      Bounding box in- and out: Give bounding box,...
  hello                     Say Hello: Just says a friendly Hello.
  dummyprocess              Dummy Process: DummyProcess to check the WPS...
  wordcounter               Word Counter: Counts words in a given text.
  chomsky                   Chomsky text generator: Generates a random...
  inout                     In and Out: Testing all WPS input and output...
  binaryoperatorfornumbers  Binary Operator for Numbers: Performs operation...
  show_error                Show a WPS Error: This process will fail...
  multiple_outputs          Multiple Outputs: Produces multiple files and...
  esgf_demo                 ESGF Demo: Shows how to use WPS metadata for...
  output_formats            Return different output formats.: Dummy process...
  poly_centroid             Approximate centroid of a polygon.: Return the...
  ncmeta                    Return NetCDF Metadata: Return metadata from a...
  non.py-id                 Dummy process including non-pythonic...
  simple_dry_run            Simple Dry Run: A dummy download as simple...



In [2]:

    
%%bash
export WPS_SERVICE="https://bovec.dkrz.de/ows/proxy/emu?Service=WPS&Request=GetCapabilities&Version=1.0.0"
birdy hello -h









    



Usage: birdy hello [OPTIONS]

  Say Hello: Just says a friendly Hello. Returns a literal string output
  with Hello plus the inputed name.

Options:
  --version    Show the version and exit.
  --name TEXT  Your name
  -h, --help   Show this message and exit.



In [3]:

    
%%bash
export WPS_SERVICE="https://bovec.dkrz.de/ows/proxy/emu?Service=WPS&Request=GetCapabilities&Version=1.0.0"
birdy hello --name stranger









    



Output:
output=['Hello stranger']

The python interface

The WPSClient function creates a mock python module whose functions actually call a remote WPS process. The docstring and signature of the function are dynamically created from the remote's process description. If you type wps. and then press Tab, you should see a drop-down list of available processes. Simply call help on each process of type ? after the process to print the docstring for that process.



In [4]:

    
from birdy import WPSClient
url = "https://bovec.dkrz.de/ows/proxy/emu?Service=WPS&Request=GetCapabilities&Version=1.0.0"
wps = WPSClient(url)
help(wps.binaryoperatorfornumbers)









    



Help on method binaryoperatorfornumbers in module birdy.client.base:

binaryoperatorfornumbers(inputa=2.0, inputb=3.0, operator='add') method of birdy.client.base.WPSClient instance
    Performs operation on two numbers and returns the answer. This example process is taken from Climate4Impact.
    
    Parameters
    ----------
    inputa : float
        Enter Input 1
    inputb : float
        Enter Input 2
    operator : {'add', 'substract', 'divide', 'multiply'}string
        Choose a binary Operator
    
    Returns
    -------
    output : float
        Binary operator result

Type wps. and the press Tab, you should see a drop-down list of available processes.



In [5]:

    
# wps.

Process execution

Processes are executed by calling the function. Each process instantaneoulsy returns a WPSExecute object. The actual output values of the process are obtained by calling the get method. This get method returns a namedtuple storing the process outputs as native python objects.



In [6]:

    
resp = wps.binaryoperatorfornumbers(1, 2, operator='add')
print(resp)
resp.get()









    



<birdy.client.utils.WPSExecution object at 0x11560f0a0>






    Out[6]:





binaryoperatorfornumbersResponse(
    output=3.0
)

For instance, the inout function returns a wide variety of data types (float, integers, dates, etc) all of which are converted into a corresponding python type.



In [7]:

    
wps.inout().get()









    Out[7]:





inoutResponse(
    string='This is just a string',
    int=7,
    float=3.14,
    boolean=True,
    angle=90.0,
    time=datetime.time(12, 0),
    date=datetime.date(2012, 5, 1),
    datetime=datetime.datetime(2016, 9, 2, 12, 0, tzinfo=tzutc()),
    string_choice='scissor',
    string_multiple_choice='gentle albatros',
    int_range=1,
    any_value='any value',
    ref_value='Scotland',
    text='https://bovec.dkrz.de/download/outputs/emu/36a1303a-5d4c-11ea-b021-109836a7cf3a/input.txt',
    dataset='https://bovec.dkrz.de/download/outputs/emu/36a1303a-5d4c-11ea-b021-109836a7cf3a/input_l93duzdg.txt',
    bbox=None
)

Retrieving outputs by references

For ComplexData objects, WPS servers often return a reference to the output (an http link) instead of the actual data. This is useful if that output is to serve as an input to another process, so as to avoid passing back and forth large files for nothing.

With birdy, the outputs are by default return values are the references themselves, but it's also possible to download these references in the background and convert them into python objects. To trigger this automatic conversion, set asobj to True when calling the get method. In the example below, we're using a dummy process called output_formats, whose first output is a netCDF file, and second output is a json file. With asobj=True, the netCDF file is opened and returned as a netcdf4.Dataset instance, and the json file into a dictionary.



In [8]:

    
out = wps.output_formats()
nc, json = out.get()
print(out.get())
ds, json = out.get(asobj=True)
print(json)
ds









    



output_formatsResponse(
    netcdf='https://bovec.dkrz.de/download/outputs/emu/38ff6da6-5d4c-11ea-b021-109836a7cf3a/dummy.nc',
    json='https://bovec.dkrz.de/download/outputs/emu/38ff6da6-5d4c-11ea-b021-109836a7cf3a/dummy.json'
)
{'testing': [1, 2]}






    Out[8]:




<xarray.Dataset>
Dimensions:  (time: 1)
Coordinates:
  * time     (time) float64 42.0
Data variables:
    *empty*
Attributes:
    title:    Test dataset

Progress bar

It's possible to display a progress bar when calling a process. The interface to do so at the moment goes like this. Note that the cancel button does not do much here, as the WPS server does not support interruption requests.



In [9]:

    
cli = WPSClient('http://cp4cds-cn1.dkrz.de/wps')
response = cli.cmip5_regridder()



In [10]:

    
from IPython.display import Image
result = response.get()
Image(result.preview)









    Out[10]: