Python API Wrapper Tutorial

Revision as of 08:03, 13 November 2014 by Admin (talk | contribs) (→‎Installation)

Important notice: The Python API wrapper for the MailStore Server Administration API provided on this website, represents an example implementation of an API client. This wrapper should help system administrators and developers to quickly understand how the Administration API of MailStore Server works and how to use it in own scripts. Please understand that beyond this documentation no further support for the Python API wrapper is provided.

This document explains the installation and usage of the Python API wrapper for the MailStore Server Administration API. In order to prevent loss of data, service interruption or other problems, it is highly recommended to use a non-productive test environment for this tutorial as well as for script development in general. The 30-day-trial version of MailStore Server is perfectly suited for this.

Installation

The API wrapper library is tested against Python 3.2 to Python 3.4 and is compatible with 32bit and 64bit versions of Python.

Python binaries for various operating systems can be downloaded from the Python download page or installed using the package manager of most Linux distributions.

Additionally the mailstore folder of the Python API wrapper library has to be installed in Python's site-packages directory.

In UNIX like operating system the location of the site-packages directory can be found by executing the following command in the a shell: 

python3 -c "from distutils.sysconfig import get_python_lib; print(get_python_lib())"

In Windows the location of the site-packages directory can be found by opening a cmd, navigating in the Python3 installation direcotry and executing the following command: 

python -c "from distutils.sysconfig import get_python_lib; print(get_python_lib())"

Instantiating the API Client

Before the API wrapper library can be used, it must first be imported with: 

 import mailstore

Now the mailstore.server.Client class can be instantiated as follows: 

serverClient = mailstore.server.Client(username="admin", password="admin", host="127.0.0.1", port=8463)

Default values can be omitted. The default admin credentials (username and password set to admin) are only usable when connecting from the MailStore Server computer itself to localhost. Find a listing of all default values in the following table:

Parameter Default Value Description
username admin Username used for connecting to the API.
password admin Password used for connecting to the API.
host 127.0.0.1 Hostname or IP address of the MailStore Server computer.
port 8463 TCP port on which MailStore Server is listening for API requests.
autoHandleToken True If set to True, the caller does not need to handle tokens of long running tasks, but instead has to wait for the result. When set to False and the statusCode is running, a status token is returned and must be handled appropriately by the caller of the method. Further details about token handling is described the corresponding section Automatic Token Handling of this document.
waitTime 1000 Specifies the number of milliseconds the API should wait for a final result. Otherwise the process is treated as running, in which case token handling as defined by the status of autoHandleToken becomes necessary.
callbackStatus None Name of callback function to which interim statuses of long running tasks should be passed. This allows keeping track of the tasks' progress even if autoHandleToken is enabled. This can be quite useful in order to notify users about the progress without having to deal with the token logic as a whole.
logLevel 2 Has to be in the range 0 to 4, where 0 (NONE) has the lowest verbosity and 4 (DEBUG) the highest. The loglevels are defined in the following order (low to high verbosity) NONE, ERROR, WARNING, INFO and DEBUG. Log entries will always be printed to stdout.

Invoking API Method

After the API client has been successfully instantiated, API methods can easily be invoked. When the method call was successful, the statusCode is succeeded and the result is stored in the dictionary result as shown in the following example: 

print(serverClient.GetServerInfo()["result"])
 
{'logOutput': None, 'statusText': None, 'error': None, 'percentProgress': None, 'token': None, 'result': {'machineName': 'WIN-2012-R2-X64', 'version': '9.0.3.9857'}, 'statusVersion': 2, 'statusCode': 'succeeded'}

If autoHandleToken was set to False and the statusCode returns running, manual token handling is required as described in the Automatic Token Handling section.

For any other statusCode value than succeeded and running the occurrence of an error has to be assumed, in which further information such as the error message and error details are available in the dictionary error as shown below: 

userInfo = serverClient.GetUserInfo("john.doe")

if userInfo["statusCode"] == 'succeeded':
    print(userInfo["result"]["emailAddresses"])
else:
    print(userInfo["error"]["message"])

Examples

Create a list of all email addresses assigned to MailStore users. 

serverClient = mailstore.server.Client()
emailAddresses = list()
for user in serverClient.GetUsers()["result"]:
	emailAddresses += serverClient.GetUserInfo(user["userName"])["result"]["emailAddresses"]
print(emailAddresses)

Long Running Tasks

The execution of certain API methods like VerifyStore may take several minutes or even hours until it finishes. There are different options available to deal with these long running tasks:

  1. Automatic Token Handling
  2. Automatic Token Handling with Callback Function
  3. Manual Token Handling

Generally it is recommended to expect that every method call can become a long running task, as this depends on the waitTime value, the called method but also the overall load on the server. Thus it is not advisable to globally turn of automatic token handling when instantiating the API client.

If desired, automatic token handling can be enabled or disabled for each invoked method by adding autoHandleToken=True to the method's argument list.

Once a method has been invoked with manual token handling or a callback function, it can be cancelled by using the CancelAsync method as described in Cancelling Long Running Tasks.

Automatic Token Handling

When autoHandleToken is set to True (default), the wrapper polls the status of long running tasks automatically in the background and will return the final result when the process has ended.

Code

import mailstore

serverClient = mailstore.server.Client(autoHandleToken=True)
storeID = 1
print(serverClient.VerifyStore(storeID))

Output

{'logOutput': None, 'statusText': None, 'error': None, 'percentProgress': 100, 'token': 'd242d822a59bd4db308eef8b85af7d2a', 'result': None, 'statusVersion': 71, 'statusCode': 'succeeded'}

Automatic Token Handling with Callback Function

If a caller wants to keep track of the progress of a long running task (i.e. to inform the user about the progress), although automatic token handling was enabled, he could pass the name of a function as callbackStatus argument to the instance of the API client.

Code

import mailstore

def showProgress(progress):
   print(progress["logOutput"], end="", flush=True)

serverClient = mailstore.server.Client(autoHandleToken=True, callbackStatus=showProgress)
storeID = 3
print(serverClient.VerifyStore(storeID))

Output

Verifying file group #3...
Creating a list of messages to be verified...
1249 messages are about to be verified.
Verifying...
  100 messages verified...
  200 messages verified...
  300 messages verified...
  400 messages verified...
  500 messages verified...
  600 messages verified...
  700 messages verified...
  800 messages verified...
  900 messages verified...
  1000 messages verified...
  1100 messages verified...
  1200 messages verified...
  1249 messages verified.
Finished. No errors have been found.
{'error': None, 'result': None, 'logOutput': '  1000 messages verified...\r\n  1100 messages verified...\r\n  1200 messages verified...\r\n  1249 messages verified.\r\nFinished. No errors have been found.\r\n', 'token': 'c56f032d9db263133c1a413f79744b84', 'statusVersion': 71, 'statusText': None, 'percentProgress': 100, 'statusCode': 'succeeded'}

Manual Token Handling

If autoHandleToken is set to False the caller must handle long running tasks and the corresponding tokens all by itself. To poll for status updates, the GetStatus method must be called periodically passing the last returned result as parameter. GetStatus will extract the status token itself, poll for the latest update and return the received data to the caller again. The main call has finished when the statusCode changes to something different than running. Calling GetStatus without passing a status token will result in an exception.

Code

import mailstore
import time

serverClient = mailstore.server.Client(autoHandleToken=False)
storeID = 3
status = serverClient.VerifyStore(storeID)

while True:
    if status["statusCode"] != "running":
        break
    print(status["logOutput"], end="", flush=True)
    status = serverClient.GetStatus(status)
    time.sleep(1)

Output

Verifying file group #3...
Creating a list of messages to be verified...
1249 messages are about to be verified.
Verifying...
  100 messages verified...
  200 messages verified...
  300 messages verified...
  400 messages verified...
  500 messages verified...
  600 messages verified...
  700 messages verified...
  800 messages verified...
  900 messages verified...
  1000 messages verified...
  1100 messages verified...
  1200 messages verified...
  1249 messages verified.
Finished. No errors have been found.

Cancelling Long Running Tasks

Tasks invoked by using the callback method or manual token handling, can be canceled at any time by using the CancelAsync method. Please notice that the API does not acknowledge the success of the cancellation request. Instead the caller must continue to monitor the statusCode of the canceled method.

Code

import mailstore
import time

serverClient = mailstore.server.Client(autoHandleToken=False)
storeID = 3
status = serverClient.VerifyStore(storeID)

while True:
    if status["statusCode"] != "running":
        break
    print(status["logOutput"], end="")
    status = serverClient.GetStatus(status)
    time.sleep(1)
    serverClient.CancelAsync(status)

Output

Verifying file group #3...
Creating a list of messages to be verified...
1249 messages are about to be verified.
Verifying...
  100 messages verified...
  200 messages verified...
  300 messages verified...
  400 messages verified...
  500 messages verified...
  600 messages verified...
  700 messages verified...
  800 messages verified...
  900 messages verified...
  1000 messages verified...
  1100 messages verified...

Methods Overview

All methods listed in the function reference are implemented in the Python API library. Use 

 pydoc3 mailstore.server

to access the build in documentation, which also includes an overview of all methods and their parameters.

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