Example Application: REST 101

For more advanced users, a later section of this guide shows how to interface directly to the REST API. Direct use can give you more control over the following:

• Management of JWT access tokens
• Policy of your application regarding insecure HTTPS configurations
• Control over the use of connection "keep-alive"

Direct REST API interface will be covered later. This approach works with Python version 1 and higher.

 1   #!/usr/bin/python3
    2   #
    3   # nc_rest_101.py
    4   #
    5   import os, sys, getpass, json
    6   import vov_rest_v3
    7
    8   url = os.environ['NC_URL']
    9
   10   vrest = vov_rest_v3.VOVRestV3()
   11   vrest.authorize(url, getpass.getpass('Password:') )
   12   r = vrest.submitRequest("GET", url + "/api/v3/project/1/project")
   13
   14   print ( json.dumps(json.loads(r), indent=2) )

Here is a line-by-line guide to the above program.

Line 1

This Python program is compatible with Python 3.

Line 6

Import the vov_rest_v3 Python module that comes with the Accelerator product. Copy it locally from $VOVDIR before running the Python program.

Line 8

Pull the URL for the NC queue out of an environment variable. The URL is what nc cmd vovbrowser shows.

Line 10

Allocate vrest, an instantiation of the VOVRestV3 Python class.

Line 11

The authorize() method function authenticates using the password and allocates a JWT token stored in the object. This example obtains your user password by interactive prompt.

Note: This example uses username/password authentication. To use key-based authentication, see VOV Security Keys.

Line 12

The HTTP get request is sent, returning a string containing the HTTP response data in JSON format.

Line 14

The HTTP response string is parsed into JSON and pretty-printed.

Here is a terminal session that shows how to run the program.

% echo $NC_QUEUE
My_NC_QUEUE
% export NC_URL=`nc cmd vovbrowser`
% echo $NC_URL
http://myhost:6330
% cp $VOVDIR/scripts/python/vov_rest_v3.py .
% python3 nc_rest_101.py
Password:
{
  "startrow": 1,
  "endrow": 1,
  "query": "SELECT project FROM 1",
  "errormsg": "",
  "columns": [
    {
      "col": 0,
      "field": "project"
    }
  ],
  "rows": [
    [
      "My_NC_QUEUE"
    ]
  ]
}

#!/usr/bin/python3 
# 
# nc_run.py 
# 
# Usage 
# 
#     export NC_URL=<URL FOR NC QUEUE> 
#     ./nc_run.py <command> [args] 
# 

import os, sys, random, json, getpass 
import vov_rest_v3 

def getMyPassword(): 
    return getpass.getpass('Password:') 

# Main body 
nc_url = os.environ["NC_URL"] 
scheme = nc_url.split(":")[0] 
hostport = nc_url.split("/")[2] 
url = "{0}://{1}".format(scheme, hostport) 
command = " ".join(sys.argv[1::]) 

vrest = vov_rest_v3.VOVRestV3() 
vrest.authorize(url, getMyPassword()) 

# Job attributes - required 
VOV_JOB_DESC = { 
    "command" : command, 
    "logfile" : "JOBLOG." + str(random.randint(100000,999999)),
    "rundir" : os.getcwd(), 
    "env" : "BASE", 
} 

# Job attributes - optional / User specified 
VOV_JOB_DESC.update( { 
    "priority,sched" : 4, 
} ) 
r = vrest.submitRequest("POST", url + "/api/v3/jobs", jsonData=VOV_JOB_DESC) 
print ("New job is %s" % json.loads(r)["jobid"]) 

#!/usr/bin/python3
# 
# nc_list.py 
# 
# Usage 
# 
#       export NC_URL=<URL FOR NC QUEUE> 
#       ./nc_list.py 
# 

import os, sys, json, getpass
import vov_rest_v3

def getMyPassword():
    return getpass.getpass('Password:')

def listJob(vr, url):
    query = ( url + '/api/v3/query' 
              + '?select=id,statusnc,PRIORITYPP,host,command' 
              + '&from=System:User:' + os.environ['USER'] ) 
    response = vr.submitRequest("GET", query)
    return response

def prettyPrint( text ): 
    dd = json.loads(text) 
    for ii in range(0, len(dd['columns']) ) : 
        sys.stdout.write("%9.9s " % dd['columns'][ii]['field']) 
    sys.stdout.write("\n") 
    if ('rows' not in dd): 
        return 
    for rr in range (0, len(dd['rows']) ) : 
        row = dd['rows'][rr] 
        for ii in range(0, len(dd['columns']) ) : 
            if (ii < len(dd['columns'])-1): 
                sys.stdout.write("%9.9s " % str(row[ii])) 
            else: 
                sys.stdout.write("%10.30s" % str(row[ii])) 
        sys.stdout.write("\n") 

# 
# Main body 
# 
nc_url = os.environ['NC_URL'] 
scheme = nc_url.split(":")[0] 
hostport = nc_url.split("/")[2] 
url = "{0}://{1}".format(scheme, hostport) 

vrest = vov_rest_v3.VOVRestV3()
vrest.authorize(url, getMyPassword())
json_text = listJob(vrest, url)
prettyPrint(json_text)