Python

Zenity GUI to a Shell Script

Published on October 21, 2007 · 2 min

I have to admit, I’m pretty lazy. I don’t (ironically) like to type, and I really don’t like typing the same command over and over. I found myself switching between my external monitor and laptop quite frequently, and decided to somewhat automate the task. Although I know there are other programs out there that allow this, they either had too many features, or crashed. Xrandr works just fine, but like I said, I’m lazy…

Enter Zenity. Initially I created a PyGTK monitor switcher, yet wanted something even simpler. If you aren’t in the know, Zenity allows you to create super fast, super simple dialogs to regular commands. After you click “ok”, the command is executed, and the dialog disappears. Perfect for switching displays.

And here is the simplistic code behind it:

#!/bin/sh

ans=$(zenity  --list  --text "How do you want to switch your monitor?" \\
--radiolist  --column "Pick" --column "Output Type" TRUE LCD FALSE VGA \\
FALSE Both);

if [ "$ans" = "LCD" ]
then
    xrandr --output VGA --off
    xrandr --output LVDS --auto
elif [ "$ans" = "VGA" ]
then
    xrandr --output LVDS --off
    xrandr --output VGA --auto
elif [ "$ans" = "Both" ]
then
    xrandr --output VGA --auto
    xrandr --output LVDS --mode 1024x768
fi

I send a big cheers and thanks to the Zenity guys, I’ll surely use this quick language more frequently.

Python, AST and SOAP

Published on March 7, 2007 · 2 min

For one of my projects I need to generate thumbnails for a page. And lots and lots and lots of them. Even though I can generate them via a python script and a very light “gtk browser”, I would prefer to mitigate the server load. To do this I’ve decided to tap into the Alexa Thumbnail Service. They allow two methods: REST and SOAP. After several hours of testing things out, I’ve decided to toss in the towel and settle on REST. If you can spot the error with my SOAP setup, I owe you a beer.
I’m using the ZSI module for python.

1. wsdl2py

I pull in the needed classes by using wsdl2py.

wsdl2py -b http://ast.amazonaws.com/doc/2006-05-15/AlexaSiteThumbnail.wsdl

2. Look at the code generated.

See AlexaSiteThumbnail_types.py and AlexaSiteThumbnail_client.py.

3. Write python code to access AST over SOAP.


#!/usr/bin/env python
import sys
import datetime
import hmac
import sha
import base64
from AlexaSiteThumbnail_client import *

print 'Starting...'

AWS_ACCESS_KEY_ID = 'super-duper-access-key'
AWS_SECRET_ACCESS_KEY = 'super-secret-key'

print 'Generating signature...'

def generate_timestamp(dtime):
    return dtime.strftime("%Y-%m-%dT%H:%M:%SZ")

def generate_signature(operation, timestamp, secret_access_key):
    my_sha_hmac = hmac.new(secret_access_key, operation + timestamp, sha)
    my_b64_hmac_digest = base64.encodestring(my_sha_hmac.digest()).strip()
    return my_b64_hmac_digest

timestamp_datetime = datetime.datetime.utcnow()
timestamp_list = list(timestamp_datetime.timetuple())
timestamp_list[6] = 0
timestamp_tuple = tuple(timestamp_list)
timestamp_str = generate_timestamp(timestamp_datetime)

signature = generate_signature('Thumbnail', timestamp_str, AWS_SECRET_ACCESS_KEY)

print 'Initializing Locator...'

locator = AlexaSiteThumbnailLocator()
port = locator.getAlexaSiteThumbnailPort(tracefile=sys.stdout)

print 'Requesting thumbnails...'

request = ThumbnailRequestMsg()
request.Url = "alexa.com"
request.Signature = signature
request.Timestamp = timestamp_tuple
request.AWSAccessKeyId = AWS_ACCESS_KEY_ID
request.Request = [request.new_Request()]

resp = port.Thumbnail(request)

4. Run, and see error.


ZSI.EvaluateException: Got None for nillable(False), minOccurs(1) element 
(http://ast.amazonaws.com/doc/2006-05-15/,Url), 



 xmlns:SOAP-ENC="http://schemas.xmlsoap.org/soap/encoding/" 
xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/" 
xmlns:ZSI="http://www.zolera.com/schemas/ZSI/" 
xmlns:ns1="http://ast.amazonaws.com/doc/2006-05-15/" 
xmlns:xsd="http://www.w3.org/2001/XMLSchema" 
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">

[Element trace: /SOAP-ENV:Body/ns1:ThumbnailRequest]

55. Conclusion

I’m not entirely certain what I’m doing wrong. I’ve also written another version but actually with NPBinding connecting to the wsdl file. It seems to work much better, as it fully connects, and I get a 200, but it doesn’t return the thumbnail location in the response, and I get a:

TypeError: Response is "text/plain", not "text/xml"

So, while I have things working fine with REST, I would like to get the SOAP calls working. One beer reward.

AWS in Python (REST)

Published on March 3, 2007 · 2 min

As some of you may know, I have some projects cooked up. I don’t expect to make a million bucks (wish me luck!), but a few extra bills in the pocket wouldn’t hurt. Plus, I’m highly considering further education, which will set me back a few-thirty grand. That said, one of my projects will rely heavily on Amazon Web Services. Amazon has, for quite some time now, opened up their information via REST and SOAP. I’ve been trying (virtually the entire day) to get SOAP to work, but seem to get snagged on a few issues. Stay tuned.
However, in my quest to read every RTFM I stumbled upon a post regarding Python+REST to access Alexa Web Search. After staring at Python code, especially trying to grapple why SOAP isn’t working, updating the outdated REST code was a 5 minute hack. So, if you are interested in using Alexa Web Search with Python via Rest, look below:

websearch.py


#!/usr/bin/python

"""
Test script to run a WebSearch query on AWS via the REST interface.  Written
 originally by Walter Korman ([email protected]), based on urlinfo.pl script from 
  AWIS-provided sample code, updated to the new API by  
Kelvin Nicholson ([email protected]). Assumes Python 2.4 or greater.
"""

import base64
import datetime
import hmac
import sha
import sys
import urllib
import urllib2

AWS_ACCESS_KEY_ID = 'your-access-key'
AWS_SECRET_ACCESS_KEY = 'your-super-secret-key'

def get_websearch(searchterm):
    def generate_timestamp(dtime):
        return dtime.strftime("%Y-%m-%dT%H:%M:%SZ")
    
    def generate_signature(operation, timestamp, secret_access_key):
        my_sha_hmac = hmac.new(secret_access_key, operation + timestamp, sha)
        my_b64_hmac_digest = base64.encodestring(my_sha_hmac.digest()).strip()
        return my_b64_hmac_digest
    
    timestamp_datetime = datetime.datetime.utcnow()
    timestamp_list = list(timestamp_datetime.timetuple())
    timestamp_list[6] = 0
    timestamp_tuple = tuple(timestamp_list)
    timestamp = generate_timestamp(timestamp_datetime)
    
    signature = generate_signature('WebSearch', timestamp, AWS_SECRET_ACCESS_KEY)
    
    def generate_rest_url (access_key, secret_key, query):
        """Returns the AWS REST URL to run a web search query on the specified
        query string."""
    
        params = urllib.urlencode(
            { 'AWSAccessKeyId':access_key,
              'Timestamp':timestamp,
              'Signature':signature,
              'Action':'WebSearch',
              'ResponseGroup':'Results',
              'Query':searchterm, })
        return "http://websearch.amazonaws.com/?%s" % (params)
    
    # print "Querying '%s'..." % (query)
    url = generate_rest_url(AWS_ACCESS_KEY_ID, AWS_SECRET_ACCESS_KEY, searchterm)
    # print "url => %s" % (url)
    print urllib2.urlopen(url).read()

You run it like this:

>>> from websearch import get_websearch
>>> get_websearch('python')

Python + Web Developement

Published on January 25, 2006 · 1 min

A developer just showed me an interesting framework to produce python-backed sites VERY quickly. This is mainly for you Ian, it natively supports AJAX as well. Here’s the link:

http://www.turbogears.org/

I watched the demo, pretty interesting.