The Zen of Python
http://www.python.org/dev/peps/pep-0020/
The Zen of Python
Beautiful is better than ugly.
Explicit is better than implicit.
Simple is better than complex.
Complex is better than complicated.
Flat is better than nested.
Sparse is better than dense.
Readability counts.
Special cases aren’t special enough to break the rules.
Although practicality beats purity.
Errors should never pass silently.
Unless explicitly silenced.
In the face of ambiguity, refuse the temptation to guess.
There should be one– and preferably only one –obvious way to do it.
Although that way may not be obvious at first unless you’re Dutch.
Now is better than never.
Although never is often better than *right* now.
If the implementation is hard to explain, it’s a bad idea.
If the implementation is easy to explain, it may be a good idea.
Namespaces are one honking great idea — let’s do more of those!
The Timeless Way of Building
The Timeless Way of Building
by Christopher Alexander
# Hardcover: 552 pages
# Publisher: Oxford University Press (1979)
# Language: English
# ISBN-10: 0195024028
# ISBN-13: 978-0195024029
http://www.amazon.com/gp/product/0195024028
add axis to webapp in tomcat
- Copy following jar files from C:toolsjavaapacheaxisaxis1_2axis-bin-1_2axis-1_2lib to C:toolsjavaapachejakartajakarta-tomcat-5.0.28commonlib
jaxrpc.jar
commons-discovery-0.2.jar
saaj.jar
wsdl4j.jar
log4j-1.2.8.jar
- Copy happyaxis.jsp, i18nLib.jsp in web application root dir
- Copy i18n.properties to WEB-INFclasses dir
- Copy web.xml below in WEB-INFweb.xml
C:toolsjavaapacheaxisaxis1_2axis-bin-1_2axis-1_2webappsaxisWEB-INFweb.xml
<!DOCTYPE web-app PUBLIC "-//Sun Microsystems, Inc.//DTD Web
Application 2.3//EN” “http://java.sun.com/dtd/web-app_2_3.dtd”>
Apache-Axis
org.apache.axis.transport.http.AxisHTTPSessionListener
AxisServlet
Apache-Axis Servlet
org.apache.axis.transport.http.AxisServlet
AdminServlet
Axis Admin Servlet
org.apache.axis.transport.http.AdminServlet
100
SOAPMonitorService
SOAPMonitorService
org.apache.axis.monitor.SOAPMonitorService
SOAPMonitorPort
5001
100
AxisServlet
/servlet/AxisServlet
AxisServlet
*.jws
AxisServlet
/services/*
SOAPMonitorService
/SOAPMonitor
<!–
AdminServlet
/servlet/AdminServlet
–>
5
<!– currently the W3C havent settled on a media type for WSDL;
http://www.w3.org/TR/2003/WD-wsdl12-20030303/#ietf-draft
for now we go with the basic ‘it’s XML’ response –>
wsdl
text/xml
xsd
text/xml
index.jsp
index.html
index.jws
prstat
Finding Processes that are Using Up the CPU
mpstat 5 5 command will print the CPU statistics 5 times at 5 second intervals.
| CPU | minf | mjf | xcal | intr | ithr | csw | icsw | migr | smtx | srw | syscl | usr | sys | wt | idl |
| 0 | 1 | 0 | 0 | 345 | 224 | 589 | 220 | 0 | 0 | 0 | 799 | 29 | 1 | 0 | 70 |
| 0 | 1 | 0 | 0 | 302 | 200 | 752 | 371 | 0 | 0 | 0 | 1191 | 99 | 1 | 0 | 0 |
| 0 | 0 | 0 | 0 | 341 | 221 | 767 | 375 | 0 | 0 | 0 | 1301 | 100 | 0 | 0 | 0 |
| 0 | 0 | 0 | 0 | 411 | 256 | 776 | 378 | 0 | 0 | 0 | 1313 | 99 | 1 | 0 | 0 |
| 0 | 0 | 0 | 0 | 382 | 241 | 738 | 363 | 0 | 0 | 0 | 1163 | 97 | 3 | 0 | 0 |
In the output sample above, 4 of the 5 samples have CPU 0 with a combined user time and sytem time at 100 and idle time at 0 (column headings usr, sys, idl). This indicates that the CPU is completely consumed on this system.
you can use prstat to identify which processes are consuming the CPU resources. prstat -s cpu -n 5 command is used to list the five processes that are consuming the most CPU resources. The -s cpu flag tells prstat to sort the output by CPU usage. The -n 5 flag tells prstat to restrict the output to the top five processes.
| PID | USERNAME | SIZE | RSS | STATE | PRI | NICE | TIME | CPU | PROCESS/NLWP |
| 13974 | kincaid | 888K | 432K | run | 40 | 0 | 36:14.51 | 67% | cpuhog/1 |
| 27354 | kincaid | 2216K | 1928K | run | 31 | 0 | 314:48.51 | 27% | server/5 |
| 14690 | root | 136M | 46M | sleep | 59 | 0 | 0:00.59 | 2.3% | Xsun/1 |
| 14797 | kincaid | 9192K | 7496K | sleep | 59 | 0 | 0:00.10 | 0.9% | dtwm/8 |
| 14851 | kincaid | 24M | 14M | sleep | 48 | 0 | 0:00.03 | 0.3% | netscape/1 |
|
Total: 97 processes, 190 lwps, load averages: 2.18, 2.15, 2.11 |
|||||||||
In the example output, there is a process named cpuhog that is consuming the majority (67 %) of the CPU cycles. If this process is killed using the kill -9 13974 command, and the mpstat command is subsequently repeated, the output shows that the CPU is idle the majority of the time.
Note: The -s cpu option is the default setting for prstat. Therefore, if the intent is to sort output by CPU usage, specifying the -s cpu option is not necessary. For the purpose of this article, the -s cpu option is set to distinguish it from other ways of sorting the output produced by prstat.
command prstat -s cpu -a -n 8 asks for the top 8 processes consuming the CPU and a list of resource consumption statistics for each user.
| PID | USERNAME | SIZE | RSS | STATE | PRI | NICE | TIME | CPU | PROCESS/NLWP |
| 17005 | larry | 888K | 432K | run | 21 | 0 | 0:03.15 | 38% | cpuhog/1 |
| 17015 | larry | 888K | 432K | run | 21 | 0 | 0:03.06 | 36% | cpuhog/1 |
| 17175 | larry | 944K | 872K | run | 24 | 0 | 0:00.37 | 5.7% | find/1 |
| 16911 | moe | 944K | 872K | sleep | 58 | 0 | 0:00.48 | 3.3% | find/1 |
| 16915 | moe | 944K | 872K | sleep | 59 | 0 | 0:00.43 | 3.3% | find/1 |
| 17849 | curly | 944K | 872K | run | 31 | 0 | 0:00.00 | 3.0% | find/1 |
| 16472 | root | 132M | 42M | sleep | 59 | 0 | 0:01.00 | 0.9% | Xsun/1 |
| 16827 | kincaid | 6864K | 4704K | sleep | 48 | 0 | 0:00.05 | 0.4% | dtterm/1 |
| NPROC | USERNAME | SIZE | RSS | MEMORY | TIME | CPU |
| 7 | larry | 7504K | 5656K | 0.6% | 0:06.58 | 80% |
| 8 | moe | 8248K | 6800K | 0.7% | 0:01.31 | 6.6% |
| 3 | curly | 3336K | 2832K | 0.3% | 0:00.00 | 3.0% |
| 34 | root | 213M | 95M | 9.5% | 0:03.05 | 1.0% |
| 78 | kincaid | 433M | 294M | 30% | 0:00.38 | 0.7% |
| Total: 132 processes, 218 lwps, load averages: 3.90, 4.29, 2.45 | ||||||
Identifying Virtual Memory Usage
A good tool for determining if a system is paging is sar. The sar -g command will yield the paging statistics for a given system.
$ sar -g 5 5
Getting the Resource Statistics for Each Thread Within a Process
SunOS tartan 5.8 Generic_108528-01 sun4u 02/12/01
| 13:20:37 | pgout/s | ppgout/s | pgfree/s | pgscan/s | %ufs_ipf |
| 13:20:42 | 39.92 | 538.72 | 670.26 | 1147.31 | 0.00 |
| 13:20:47 | 36.60 | 483.80 | 515.40 | 353.80 | 0.00 |
| 13:20:52 | 40.20 | 508.20 | 632.00 | 1125.20 | 0.00 |
| 13:20:57 | 35.80 | 462.60 | 580.40 | 1141.60 | 0.00 |
| 13:21:02 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 |
| Average | 30.51 | 398.72 | 479.69 | 753.74 | 0.00 |
A common cause for system paging is a process or group of processes that are using a majority of the system’s memory. prstat is an excellent tool for identifying which processes are consuming the majority of a system’s memory. Use prstat -s size, which is similar to the previous command, but which sorts prstat output by size instead of by CPU usage.
top five processes on a system in terms of virtual memory consumption
$ prstat -s size -n 5
| PID | USERNAME | SIZE | RSS | STATE | PRI | NICE | TIME | CPU | PROCESS/NLWP |
| 21307 | kincaid | 1001M | 616M | run | 2 | 0 | 0:01.16 | 32% | memhog/1 |
| 16472 | root | 138M | 43M | sleep | 59 | 0 | 0:17.28 | 1.2% | Xsun/1 |
| 18133 | kincaid | 92M | 31M | sleep | 49 | 0 | 0:01.42 | 0.0% | soffice.bin/9 |
| 16574 | kincaid | 44M | 24M | sleep | 49 | 0 | 0:10.37 | 0.2% | .netscape.bin/1 |
| 16674 | kincaid | 36M | 25M | sleep | 49 | 0 | 0:00.08 | 0.0% | sdtperfmeter/1 |
| Total: 130 processes, 220 lwps, load averages: 0.51, 0.36, 0.23 | |||||||||
$ sar -g 5 5
SunOS tartan 5.8 Generic_108528-01 sun4u 02/12/01
| 13:20:02 | pgout/s | ppgout/s | pgfree/s | pgscan/s | %ufs_ipf |
| 13:20:07 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 |
| 13:20:12 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 |
| 13:20:17 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 |
| 13:20:22 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 |
| 13:20:27 | 0.00 | 0.00 | 3.80 | 590.60 | 0.00 |
| Average | 0.00 | 0.00 | 0.76 | 118.07 | 0.00 |
Getting the Resource Statistics for Each Thread Within a Process
by using the -L switch, prstat will report statistics for each thread of a process.
$ prstat -L -p 3295
| PID | USERNAME | SIZE | RSS | STATE | PRI | NICE | TIME | CPU | PROCESS/LWPID |
| 3295 | kincaid | 28M | 10M | sleep | 38 | 0 | 0:00.01 | 2.1% | java/16 |
| 3295 | kincaid | 28M | 10M | sleep | 55 | 0 | 0:00.01 | 1.9% | java/17 |
| 3295 | kincaid | 28M | 10M | sleep | 48 | 0 | 0:00.01 | 1.8% | java/15 |
| 3295 | kincaid | 28M | 10M | sleep | 58 | 0 | 0:00.01 | 1.8% | java/23 |
| 3295 | kincaid | 28M | 10M | sleep | 52 | 0 | 0:00.01 | 1.7% | java/12 |
| 3295 | kincaid | 28M | 10M | sleep | 48 | 0 | 0:00.01 | 1.6% | java/22 |
| 3295 | kincaid | 28M | 10M | sleep | 58 | 0 | 0:00.01 | 1.5% | java/13 |
| 3295 | kincaid | 28M | 10M | sleep | 58 | 0 | 0:00.01 | 1.5% | java/14 |
| 3295 | kincaid | 28M | 10M | sleep | 48 | 0 | 0:00.01 | 1.4% | java/19 |
| 3295 | kincaid | 28M | 10M | sleep | 48 | 0 | 0:00.01 | 1.4% | java/18 |
| 3295 | kincaid | 28M | 10M | sleep | 38 | 0 | 0:00.01 | 1.4% | java/21 |
| 3295 | kincaid | 28M | 10M | sleep | 58 | 0 | 0:00.01 | 1.3% | java/24 |
| 3295 | kincaid | 28M | 10M | sleep | 58 | 0 | 0:00.01 | 1.2% | java/20 |
| 3295 | kincaid | 28M | 10M | sleep | 58 | 0 | 0:00.00 | 0.0% | java/1 |
| 3295 | kincaid | 28M | 10M | sleep | 58 | 0 | 0:00.00 | 0.0% | java/11 |
| 3295 | kincaid | 28M | 10M | sleep | 0 | 0 | 0:00.00 | 0.0% | java/10 |
| 3295 | kincaid | 28M | 10M | sleep | 59 | 0 | 0:00.00 | 0.0% | java/9 |
| 3295 | kincaid | 28M | 10M | sleep | 0 | 0 | 0:00.00 | 0.0% | java/8 |
| 3295 | kincaid | 28M | 10M | sleep | 0 | 0 | 0:00.00 | 0.0% | java/7 |
| 3295 | kincaid | 28M | 10M | sleep | 59 | 0 | 0:00.00 | 0.0% | java/6 |
| 3295 | kincaid | 28M | 10M | sleep | 58 | 0 | 0:00.00 | 0.0% | java/5 |
| Total: 1 processes, 24 lwps, load averages: 1.30, 1.22, 1.21 | |||||||||
Getting the micro statistics on a process
use the -m option to have prstat print out the micro statistics of the process.
| Column Heading | Meaning |
| USR | The percentage of time the process has spent in user mode |
| SYS | The percentage of time the process has spent in system mode |
| TRP | The percentage of time the process has spent in processing system traps |
| DFL | The percentage of time the process has spent processing data page faults |
| LCK | The percentage of time the process has spent waiting for user locks |
| SLP | The percentage of time the process has spent sleeping |
| TFL | The percentage of time the process has spent processing text page faults |
$ prstat -m -p 3295
PID USERNAME USR SYS TRP TFL DFL LCK SLP LAT VCX ICX SCL SIG PROCESS/NLWP 3295 kincaid 0.8 0.0 0.0 0.0 0.0 0.0 99 0.0 22 4 25 0 java/24
In addition, the -m option can be used with the -L option so the micro statistics of each thread of a process can be monitored.
Some of the other Solaris tools that are worth reading about are: sar, iostat, netstat, and mpstat. All of these are great tools for identifying system performance issues. prstat is a nice complement to these tools because it helps further identify the processes and threads that may be responsible for system performance problems.
Solaris perofmrnace monitor cmds
Solaris perofmrnace monitor cmds
iostat
vmstat
netstat
(more…)
getting started google app engine using python
==============================================
getting started google app engine using python
==============================================
download and install python 2.5
http://www.python.org/ftp/python/2.5.4/python-2.5.4.msi
download and install app engine sdk for pyton
http://googleappengine.googlecode.com/files/GoogleAppEngine_1.2.3.msi
2 scripts of interest in C:toolsgoogleappengine
* dev_appserver.py, the development web server
* appcfg.py, for uploading your app to App Engine
C:toolsgoogleappengine>mkdir helloworld
C:toolsgoogleappengine>cd helloworld
C:toolsgoogleappenginehelloworld>
C:toolsgoogleappenginehelloworld>ep helloworld.py
copy this and paste in helloworld.py
print ‘Content-Type: text/plain’
print ”
print ‘Hello, world!’
C:toolsgoogleappenginehelloworld>ep app.yaml
copy this and paste in app.yaml
application: helloworld
version: 1
runtime: python
api_version: 1
handlers:
- url: /.*
script: helloworld.py
start the webserver with following cmd
google_appengine/dev_appserver.py helloworld/
QUESTION: how does dev_appserver.py knows where is helloworld/
on file system ?
ANSWER: dev_appserver.py calls dev_appserver_main.py
run dev_appserver.py with –debug argument
C:toolsgoogleappengine>python dev_appserver.py –debug helloworld/
INFO 2009-06-21 13:05:43,641 appengine_rpc.py:157] Server: appengine.google.com
Allow dev_appserver to check for updates on startup? (Y/n): n
dev_appserver will not check for updates on startup. To change this setting, edit C:Documents and SettingsAdministrator/.appcfg_nag
WARNING 2009-06-21 13:05:53,095 datastore_file_stub.py:404] Could not read datastore data from c:tempuserdev_appserver.datastore
WARNING 2009-06-21 13:05:53,095 datastore_file_stub.py:404] Could not read datastore data from c:tempuserdev_appserver.datastore.history
WARNING 2009-06-21 13:05:53,296 dev_appserver.py:3296] Could not initialize images API; you are likely missing the Python “PIL” module. ImportError: No module named _imaging
INFO 2009-06-21 13:05:53,426 dev_appserver_main.py:465] Running application helloworld on port 8080: http://localhost:8080
===========================================================================
I’ve added following line
print (”=========path=%s” % path);
on line# 393 (in main method)
seems like path is relative to the dir from where we are running script
if I run from c:
C:>python C:toolsgoogleappenginedev_appserver.py helloworld
=========path=helloworldapp.yaml
=========path=helloworldapp.yml
ERROR:root:Application configuration file not found in helloworld
It cant find it.
It works with absolute path
C:>python C:toolsgoogleappenginedev_appserver.py C:toolsgoogleappenginehelloworld
=========path=C:toolsgoogleappenginehelloworldapp.yaml
INFO 2009-06-21 13:13:06,308 appengine_rpc.py:157] Server: appengine.google.com
WARNING 2009-06-21 13:13:06,328 datastore_file_stub.py:404] Could not read datastore data from c:tempuserdev_appserver.datastore
WARNING 2009-06-21 13:13:06,328 datastore_file_stub.py:404] Could not read datastore data from c:tempuserdev_appserver.datastore.history
WARNING 2009-06-21 13:13:06,348 dev_appserver.py:3296] Could not initialize images API; you are likely missing the Python “PIL” module. ImportError: No module named _imaging
INFO 2009-06-21 13:13:06,378 dev_appserver_main.py:466] Running application helloworld on port 8080: http://localhost:8080
C:toolsgoogleappengine>python dev_appserver.py –debug helloworld/
=========path=helloworld/app.yaml
===========================================================================
C:toolsgoogleappengine>python dev_appserver.py –help
Runs a development application server for an application.
dev_appserver.py [options]
Application root must be the path to the application to run in this server.
Must contain a valid app.yaml or app.yml file.
Options:
–help, -h View this helpful message.
–debug, -d Use debug logging. (Default false)
–clear_datastore, -c Clear the Datastore on startup. (Default false)
–address=ADDRESS, -a ADDRESS
Address to which this server should bind. (Default
localhost).
–port=PORT, -p PORT Port for the server to run on. (Default 8080)
–datastore_path=PATH Path to use for storing Datastore file stub data.
(Default c:tempuserdev_appserver.datastore)
–history_path=PATH Path to use for storing Datastore history.
(Default c:tempuserdev_appserver.datastore.history)
–require_indexes Disallows queries that require composite indexes
not defined in index.yaml.
–smtp_host=HOSTNAME SMTP host to send test mail to. Leaving this
unset will disable SMTP mail sending.
(Default ”)
–smtp_port=PORT SMTP port to send test mail to.
(Default 25)
–smtp_user=USER SMTP user to connect as. Stub will only attempt
to login if this field is non-empty.
(Default ”).
–smtp_password=PASSWORD Password for SMTP server.
(Default ”)
–enable_sendmail Enable sendmail when SMTP not configured.
(Default false)
–show_mail_body Log the body of emails in mail stub.
(Default false)
–auth_domain Authorization domain that this app runs in.
(Default gmail.com)
–debug_imports Enables debug logging for module imports, showing
search paths used for finding modules and any
errors encountered during the import process.
–allow_skipped_files Allow access to files matched by app.yaml’s
skipped_files (default False)
–disable_static_caching Never allow the browser to cache static files.
(Default enable if expiration set in app.yaml)
===========================================================================
The web server is now running, listening for requests on port 8080.
Test the application by visiting the following URL in your web browser:
* http://localhost:8080/
You can leave the web server running while you develop your application.
The web server knows to watch for changes in your source files and reload
them if necessary.
To shut down the web server, make sure the terminal window is active,
then press Control-C (or the appropriate “break” key for your console).
Updating ejb deployment descriptor in installed applications with the wsadmin tool
open wsadmin shell
ksh ./wsadmin.sh -lang jython -conntype SOAP -host yourhost.com -port 8879 -user userid -password password
print AdminApp.update('MyAppName', 'file', '[-operation update -contents /home/users/sg/1.xml -contenturi MyEJB.jar/META-INF/ejb-jar.xml]')
where
NOTE that -contenturi is
MyEJB.jar/META-INF/ejb-jar.xml
NOT
MyEJB.jar,META-INF/ejb-jar.xml
if you put , instead of / you will get
com.ibm.websphere.management.exception.AdminException: ERROR: File does not exist for update operation
P.S always look in dmgr logs for errors in deployment.
anonymous classes are not closure
anonymous classes are not closure
tired of doing “for”, lets implement internal iterator for my collection class
import java.text.*;
import java.util.*;
public class closure_test {
public static void main(final String[] args) {
test_without_closure();
test_with_closure2();
test_with_closure();
}
static void test_without_closure() {
try {
String userhome = null;
TheList lst = new TheList();
for (Iterator it = lst.iterator(); it.hasNext();) {
String child = (String) it.next();
if (child.indexOf("user.home") != -1) {
userhome = child.toString();
// no need to make userhome final
// and I can break too
break;
}
}
System.out.println(userhome);
} catch (final Throwable t) {
t.printStackTrace();
}
}
static void test_with_closure() {
try {
String userhome = null;
TheList lst = new TheList();
lst.forEach(new TheList.Closure() {
public void run(final Object child) {
if (((String) child).indexOf("user.home") != -1) {
//userhome=child.toString(); // wont compile
// local variable userhome is accessed from
// within inner class; needs to be declared final
// if I make userhome then cant assign value to it,
// see test_with_closure2 for ugly solution
// cant break
}
}
});
} catch (final Throwable t) {
t.printStackTrace();
}
}
static void test_with_closure2() {
try {
final String[] userhome = new String[1];
TheList lst = new TheList();
lst.forEach(new TheList.Closure() {
public void run(final Object child) {
if (((String) child).indexOf("user.home") != -1) {
userhome[0] = child.toString(); // now compile, its ugly
// still cant break?
}
}
});
System.out.println(userhome[0]);
} catch (final Throwable t) {
t.printStackTrace();
}
}
}
class TheList {
private static final MessageFormat FMT = new MessageFormat("{0}={1}");
private final ArrayList list = new ArrayList();
public TheList() {
Properties props = System.getProperties();
for (Iterator it = props.entrySet().iterator(); it.hasNext();) {
Map.Entry ent = (Map.Entry) it.next();
list.add(FMT.format(new Object[] { ent.getKey(), ent.getValue() }));
}
}
public void forEach(final Closure closure) {
for (Iterator it = list.iterator(); it.hasNext();) {
closure.run(it.next());
}
}
public Iterator iterator() {
return list.iterator();
}
public static interface Closure {
public void run(final Object child);
}
}
| anonymous classes are closure? NO |
| what does non-final do to a local variable that makes it non-accessible from inner class ? |
| closure implemented using inner class are ugly and difficult to use with all unnecessary method implementation. |
for loop in batch script
for /l %%X in (start, step, end) do command
example:
for /l %%X in (1,1,10) do (echo %%X)
This switch is an “ell”, not a “one”
