Examples Of Obtaining Event Data

Example 1:

from idmlib import *

command = idmgetvar("COMMAND")
# check for an add event
if command = "add":
  # call the add script
  os.system("add.py")

Example 2:

from idmlib import *

# obtain the event's association and CN attribute
association = idmgetvar("ASSOCIATION")
CN = idmgetvar("CN")
if CN = "bob":
  # for "bob", check to see if he's been enabled
  ENABLE = idmgetvar("REMOVE_Login Disabled")
  if ENABLE = "true":
    # bob is enabled again
    cmd = "appenable -association " + ASSOCIATION
    exec(cmd)

Handling Associations

The association value indicates which identity has been changed. If the identity has no association, an association must be generated for it using an implementation-specific rule that you have adopted. When Identity Manager processes an event for an identity with no association, it executes the driver’s Matching policy. This policy attempts to match the event’s identity to an identity on the external application’s system. Doing this usually involves executing a query. The default Matching policy included with the Scripting driver queries for matching Users and Groups based on the CN attribute. If the event’s identity matches an identity on the external application, both identities must be assigned the new association. Assigning this association can be done as part of the query-handling script. (Handling queries is discussed in Handling Query Events.) If no identity matches, an Add event is issued, and the new association can be assigned as part of the Add event-handling script:

# Adding an association
from idmlib import *

idmsetvar("COMMAND", "ADD_ASSOCIATION")
idmsetvar("ASSOCIATION", MyAssociation)
idmsetvar("EVENT_ID", EVENT_ID)
idmsetvar("DEST_DN", SRC_DN)
idmsetvar("DEST_ENTRY_ID", SRC_ENTRY_ID)

The above example demonstrates each name/value pair that must be set for an association to be assigned by the Identity Manager engine. The values of EVENT_ID, SRC_DN and SRC_ENTRY_ID are always sent by the engine during an add event, and therefore, are available for your add script to obtain using idmgetvar(). The example above also illustrates the idmsetvar() function. For detailed information on how to use idmsetvar(), see Section C.3, Python (idmlib.py) Reference. This function sets a name and value which indicates what action Identity Manager should perform. For example, the pair “COMMAND" and “ADD_ASSOCIATION" instructs the shim to create an add-association document to assign an association to an identity, as discussed above. The pair "EVENT_ID” and EVENT_ID instruct the shim to assign add-association document an event-id described by the variable EVENT_ID. This is important for the engine to match documents sent and returned on the subscriber channel.

The Subscriber can also issue MODIFY_ASSOCIATION and REMOVE_ASSOCIATION commands:

# Removing an association
from idmlib import *

idmsetvar("COMMAND", "REMOVE_ASSOCIATION")
idmsetvar("ASSOCIATION", MyAssociation)
idmsetvar("EVENT_ID", EVENT_ID)
idmsetvar("DEST_DN", SRC_DN)
idmsetvar("DEST_ENTRY_ID", SRC_ENTRY_ID)

# Modifying an association
my idmlib import *

idmsetvar("COMMAND", "MODIFY_ASSOCIATION")
idmsetvar("ASSOCIATION", OldAssociation)
idmsetvar("ASSOCIATION", NewAssociation)
idmsetvar("EVENT_ID", EVENT_ID)
idmsetvar("DEST_DN", SRC_DN)
idmsetvar("DEST_ENTRY_ID", SRC_ENTRY_ID)

Returning an Event Status

On the Subscriber channel, you often do not need Identity Manager to perform an action, but simply need to report a status. The status_ subroutines noted below can be used to indicate a status to Identity Manager. They take a message to be logged as the parameter.

Examples Using the Status() Functions

rc = exec(cmd)
if (rc = 0):
  status_success("Command was successful")
rc = exec(cmd)
if (rc == 0):  
  if (password eq "")
    # created, but no password
    status_warning("User added without password")

rc = exec(cmd)
if (rc != 0):
  status_error("Command failed")

Writing Values

The idmsetvar() function is used to set values to return to Identity Manager. It is passed a name and value. For detailed information on how to use idmsetvar(), see Section C.3, Python (idmlib.py) Reference. In the previous ADD_ASSOCIATION example, idmsetvar() is used to set the ASSOCIATION value. You can specify values for items listed in the table above. Generally, idmsetvar() is used is to add, modify and delete associations or return information for a query operation. Other information is returned to the shim through other command functions, such as status_success(), which use idmsetvar() indirectly.

Handling Query Events

For Query events, Identity Manager submits values that define the parameters of a search of the external application’s identity management system. Queries are usually issued from the Policies you have defined for your system. The table below specifies values that can be specified in queries. Not all values are relevant to your external application.

When a query invokes your query script, use the parameter information to query your external application using application-provided tools. Then return each identity by setting an INSTANCE command, followed by relevant values from the list below.

After returning all identities, call status_success() to indicate a successful query.

Subscriber Summary and Examples

Below is a more detailed summary of the actions to take for a non-Query event.

Below is an example add.py, which forms an association from an identity’s CN and class name, and uses a hypothetical tool called appadd.

#!/usr/bin/python

from idmlib import *

ClassName = idmgetvar("CLASS_NAME")
CN = idmgetvar("CN")
PhoneNumber = idmgetvar("Telephone")
EventId = idmgetvar("EVENT_ID")
SrcDn = idmgetvar("SRC_DN")
SrcEntryId = idmgetvar("SRC_ENTRY_ID")
if ClassName = "" || CN = "":
  status_error("Add event: missing CLASS_NAME and/or CN")
else:
  Command = "appadd -n " + CN + -t " + PhoneNumber
  rc = exec(Command) 
  if rc = 0:
    idmsetvar("COMMAND", "ADD_ASSOCIATION")
    idmsetvar("ASSOCIATION", CN + ClassName)
    idmsetvar("EVENT_ID", EventId)
    idmsetvar("DEST_DN", SrcDn)
    idmsetvar("DEST_ENTRY_ID", SrcEntryId)
    status_success("Add event succeeded")
  else:
    status_error("Add event failed with error code" + rc)

Handling a query is a similar process, except that you return INSTANCE items rather than using other commands. Below is an example query.py that searches an external application for a telephone number. It uses a hypothetical tool called appsearch.

#!/usr/bin/python

import os
from idmlib import *

SearchName = idmgetvar("SEARCH_ATTR_CN")
EventId = idmgetvar("EVENT_ID")
Association = idmgetvar("ASSOCIATION")
ClassName = idmgetvar("CLASS_NAME")
if SearchName = "":
  status_error("Query: no search value")
else:
  Command = "appsearch -n " + SearchName
  Results = os.popen(Command, ‘r’).readlines()
  if Results != "":
    phoneinfo = split(" ", Results)
    Phone = phoneinfo[0]
    idmsetvar("COMMAND", "INSTANCE")
    idmsetvar("CLASS_NAME", ClassName)
    idmsetvar("EVENT_ID", EventId)
    idmsetvar("ASSOCIATION", Association)
    idmsetvar("ATTR_Telephone", Phone)
    status_success("Query succeeded")
  else:
    # Return success with no results
    status_success("Query succeeded (no matches)")

Polling for Application Events

The Driver calls poll.py to detect application events. poll.py should be implemented as follows:

Below is an example of a poll.py that checks for a password change. It uses a hypothetical application tool called appchg.

#!/usr/bin/python

import os
from idmlib import *

# look for password changes with our ficticious app, appchg
results = os.popen("appchg --passwd-changes", ‘r’).readlines()
for result in results:
  fields = result.split(":")
  Association = fields[0]
  Password = fields[1]
  # submit event to the publisher changelog
  usclh = os.popen(usclh -t modify-password -a " + Association, ’w’)
  usclh.write(Password)
  usclh.close()

# look for attribute values being added to each user
results = os.popen("appchg --add-attr-changes")
for result in results:
  # Entries are in the format "association:attribute:value"
  fields = result.split(":")
  Association = fields[0]
  Attribute = fields[1]
  Value = fields[2]
  # submit event to the publisher changelog
  usclh = os.popen(usclh -t modify -c User -a " + Association, ’w’)
  usclh.write("ADD_" + Attribute + "=" + Value)
  usclh.close()
 
# look for attribute values being removed from each user
results = os.popen("appchg --add-attr-changes")
for result in results:
  # Entries are in the format "association:attribute:value"
  fields = result.split(":")
  Association = fields[0]
  Attribute = fields[1]
  Value = fields[2]
  # submit event to the publisher changelog
  usclh = os.popen(usclh -t modify -c User -a " + Association, ’w’)
  usclh.write("REMOVE_" + Attribute + "=" + Value)
  usclh.close()

In the above example, three separate events are submitted to the publisher change log, using the changelog tool, usclh. The first invocation submits a modify-password event to be published. The second event submits a modify event to be published for an attribute add. The third invocation submits another modify event to be published for an attribute removal. The second and third invocations can be combined into a single modify event, if desired.

Events submitted using usclh are processed through your driver’s Publisher Channel’s policies. See the Novell Identity Manager 3.6.1 Policy guides for more information.

Using the Heartbeat Script

Another script executed in the Publisher Channel is heartbeat.py. This script is executed when the Publisher Channel is idle for the interval specified in the Driver parameters. (You can set the interval to 0 so no heartbeat is issued.) You can use the heartbeat to check the availability of the external system or do “idle state” tasks. The heartbeat_success(), heartbeat_warning(), and heartbeat_error() subroutines can be used to indicate the result of the heartbeat. Below is an example based on a hypothetical tool called apphealth.

from idmlib import *

rc = os.sytem("apphealth")
if (rc = 0):
  heartbeat_success("Heartbeat succeeded")
else:
  heartbeat_error("Heartbeat failed with error code " + rc)

Driver Parameters

A driver has values known as driver parameters. The driver parameters are divided into driver settings applicable to the whole driver, and Subscriber and Publisher Settings for their respective channels. The idmgetdrvvar(), idmgetsubvar()and idmgetpubvar() functions can be used to retrieve these values. The table below shows parameters in the default Scripting driver. Other parameters can be added to the driver’s XML Configuration file (see the Novell Identity Manager 3.6.1 Administration Guide).

In the following example, a script retrieves the Publisher polling interval:

 PollingInterval = idmgetpubvar("pub-polling-interval")

Querying the Identity Vault

Scripts might need to retrieve information from the Identity Vault. They can do this by issuing a query.

Query support is currently limited. It returns only one instance based on the specified association or DN. If both association and DN are specified, association is used. The functions below allow you to retrieve information from the instance.

The following is an example of a query of the Identity Vault that retrieves the address and ZIP code for user Bob.

from idmlib import *

idmquery("User", "Bob", "SA,Postal Code")
Address = idmgetqvar("SA")
ZIPCode = idmgetqvar("Postal Code")
# ... etc. ...

Tracing and Debugging

The function trace() allows you to write a message to the Trace Log. Tracing is useful for script debugging and auditing.

from idmlib import *

trace("Trace Message")

When you develop scripts, you might need to do some debugging to track down problems. The following list indicates some facilities for debugging.

Although it is best to start the driver in production environments from the startup script, you can run usdrv manually. When you do so, any text written to standard output from scripts is displayed in the interactive shell.