Index - Tool Configuration

• AnyLogic 6 Mac Preferences screen (October 27, 2012)
• I am learning AJAX (September 24, 2012)
• No STARTTLS command has been given. (August 09, 2012)
• Sweet Hibernate links (July 11, 2012)
• RunTheModel.com (June 07, 2012)
• Java Comparator (March 26, 2012)
• Monte Carlo analysis in AnyLogic (March 17, 2012)
• Windows Server 2008 Ports (February 27, 2012)
• Constraint Programming with Java (February 25, 2012)
• MySQL privileges (February 24, 2012)
• How to obtain a node's prerequisite nodes (February 11, 2012)
• How to turn an AnyLogic population into a DAG (February 04, 2012)
• MySQL import (January 18, 2012)
• MySQL crazy symbol problems (January 11, 2012)
• AnyLogic and Databases (January 07, 2012)
• Apache Commons Java Statistical Sample Awesomeness (January 03, 2012)
• Anylogic and JPA (October 08, 2011)
• SequelPro cutting off LONGBLOB when I export (August 27, 2011)
• PL-PLAN, a Java Open-Source AI Planner (August 21, 2011)
• RedirectMatch (July 27, 2011)
• Example of Rustiness: SSH vs Samba in Terminal (June 14, 2011)
• JAXB, I love you (June 09, 2011)
• Apache htdocs folder on OSX (May 20, 2011)
• Buckets (May 15, 2011)
• iPod iTunes sync problem fixed (April 27, 2011)
• Apple Mail - "From" dropdown box (April 15, 2011)
• ssh and sftp:// (February 23, 2011)
• http_referer vs remote_host (February 14, 2011)
• Syntax highlighter (January 28, 2011)
• Can't even articulate this one (January 20, 2011)
• BUILD FAILED - ${tomcat.home} not found (January 18, 2011)
• SequelPro (December 28, 2010)
• MySQL installation (November 13, 2010)
• CoRD - Remote Desktop Client (September 26, 2010)
• JESS (September 17, 2010)
• Keener - class project (September 04, 2010)
• create jar file (August 12, 2010)
• Apache virtual hosts (August 04, 2010)
• Subversion errors (July 23, 2010)
• Adventures with ANT, Part 8 (July 09, 2010)
• Adventures with ANT, Part 7 (July 08, 2010)
• mysql connector (July 02, 2010)
• lost MySQL admin password (July 02, 2010)
• Adventures with ANT, Part 6 (June 28, 2010)
• My ANT series (June 28, 2010)
• Adventures with ANT, Part 5 (June 28, 2010)
• Adventures with ANT, Part 4 (June 28, 2010)
• Adventures with ANT, Part 3 (June 28, 2010)
• Adventures with ANT, Part 2 (June 25, 2010)
• Adventures with ANT, Part 1 (June 25, 2010)
• Tomcat filters (June 02, 2010)
• enabling PHP on my mac (April 04, 2010)
• Maven & Ant, II (March 08, 2010)
• Good Jersey links (March 08, 2010)
• My first Jersey app (March 01, 2010)
• Maven, Ant (March 01, 2010)
• Jersey (February 26, 2010)
• catching up: jQuery (February 22, 2010)
• Java versions in OSX (February 18, 2010)
• MovableType: Immediately publish comments from... (April 11, 2009)
• Microsoft Access and Temporary files (March 07, 2007)
• Filesystem permissions on LDB file: connection pooling and Tomcat clustering (February 03, 2007)
• BibTeX 101 (September 02, 2006)
• Adobe SVG Viewer on OS X - Intel Mac (April 16, 2006)
• Haystack on OS X Intel Mac (April 15, 2006)
• Broken Java applications on OS X - Intel Mac (April 08, 2006)
• Firefox - "Piggy Bank" plugin on Mac OS X (April 05, 2006)

October 27, 2012

AnyLogic 6 Mac Preferences screen

Hahaha! This got me stumped for about 20 minutes! LOL!

I wanted to adjust a setting on my AnyLogic 6 for Mac OS X. To do this, I had to go into the AnyLogic Preferences screen.

So, I went into the AnyLogic menu at the top of my screen then --> Preferences and nothing happened. I closed all my other windows and tried to figure out where the heck my Preferences window went. It was gone! I googled with nothing helpful.

Finally, I found that if you go under Tools --> there is ANOTHER Preferences option, and this one worked.

I think that Apple has documentation on how applications should work with OS X. I suspect this is a convention imposed by Apple but not recognized by AnyLogic. Apple thought that AnyLogic would put their Preferences screen under the AnyLogic menu (because that's where most OSX applications put their Preferences windows) but AnyLogic didn't do that, they put it under Tools.

Anyway, works now.

The whole reason I wanted to get into Preferences was because the Code Completion feature wasn't working on my AnyLogic. (I got a new computer so I had a new AnyLogic installation, and was trying to make the settings work how I'm used to.)

I figured out that my code completion wasn't working because it was set to Alt + Space instead of Control + Space.

Wheee!

September 24, 2012

I am learning AJAX

I just wanted to put these links somewhere I wouldn't forget. I guess I should learn to use delicious or something like that. Deja vu. OH well. Gotta run, here they are.

http://www.slideshare.net/domenicdenicola/callbacks-promises-and-coroutines-oh-my-the-evolution-of-asynchronicity-in-javascript

http://stackoverflow.com/questions/6182028/how-to-return-an-array-from-a-javascript-facebook-api-request

This one is awesome, too: It speaks EXACTLY to my "era", gently guiding me from early 00's technology into modern times...
http://www.ibm.com/developerworks/web/library/wa-ajaxintro2/

August 09, 2012

No STARTTLS command has been given.

I don't have much experience debugging SMTP. A colleage of mine (thanks GV!) figured out how to enable debugging so we could actually see the the SMTP transactions.

Anyway, this morning I was getting the SMTP error, "No STARTTLS command has been given."

I was like, um, dude, I am doing this:
props.put("mail.smtp.starttls.enable", "true");

But then the error went away when I deleted mail.jar from my build path, and made sure the path only contained mailapi.jar and smtp.jar. Go figure!!!

July 11, 2012

Sweet Hibernate links

A while ago, I learned about Jersey and started a blog post to keep track of links. (Hmm, perhaps i should get with the times and start using some kind of online bookmark management service?)

Until I figure that out, and as I focus on learning Hibernate, here's my collection of Hibernate links!

http://docs.jboss.org/hibernate/orm/3.3/reference/en/html/tutorial.html#tutorial-firstapp

This one is JPA, not hibernate, but related:
http://openjpa.apache.org/builds/1.2.3/apache-openjpa/docs/jpa_overview_persistence.html

June 07, 2012

RunTheModel.com

When you're working on a simulation model and are not sure how to do something, or whether something is even possible, sometimes what you really need is an example.

I just learned about this site on the AnyLogic newsletter -- this looks AWESOME and may satisfy my ravenous cravings for examples of simulation models!!!

http://www.runthemodel.com/

March 26, 2012

Java Comparator

I am lovin this today:

(i.e. lovin' both the javadeveloper tutorial site as well as the java.util.Comparator itself -- howcome I didn't know about this before? LOL)

http://www.javadeveloper.co.in/java-example/java-comparator-example.html

March 17, 2012

Monte Carlo analysis in AnyLogic

I struggled for a long time to get my own Monte Carlo analysis working in AnyLogic. Here are the tricks I don't want to forget.

When you create a new experiment, be sure to pick the "Paramaters Variation" kind. This will let you set the number of replications you want (i.e. the number of times you want the simulation to run though and to average the results).

The other important part is to check out the Sample Model, "influenza", and look at the Advanced tab on the MonteCarlo experiment. See how they create a new dataSet after each run and fill the 2D dataset on the presentation stage? The 2D dataset, in turn, is hooked up to the grid display.

February 27, 2012

Windows Server 2008 Ports

At work, a colleague and I were having trouble making a database connection to our server. We had php files on a developer's localhost and the test database was on a development server. But we kept getting:

Lost connection to MySQL server at 'reading initial communication packet', system error: 110

I thought, hum, is that port even listening? So I opened up my terminal and did this:

telnet my.server.ca 3306

and of course I got, "Operation timed out" and "telnet: Unable to connect to remote host".

So I went to the Windows Server 2008 Server Manager to check on the port: Go under Configuration, Windows Firewall with Advanced Security, Inbound Rules. It confused me at first because this came up blank and I thought I was in the wrong spot, but after a minute or so all of our ports show up and you can click on MySQL on 3306. It says it allows TCP connections from anyone. So..... Dude, it says the ports are open. What gives?

And here is the answer. There is a magical other secret window with MORE port configurations. Thanks, Microsoft for this bizarre obscurity. Here is what you do.

1. Go to Run and type in "firewall.cpl"
2. Click on the Exceptions tab, click Add Port, type in MySQL is 3306 on TCP, then OK
3. It works now

Alas. :)

February 25, 2012

Constraint Programming with Java

I was looking into how I could do some constraint satisfaction stuff using Java (because my simulation model is in Java). Here is a link to an awesome example that helped me get started. This uses a library called JaCoP (Java Constraint Programming solver); here's a link to the APIs.

February 24, 2012

MySQL privileges

Yet another one...

GRANT ALL PRIVILEGES ON dbnam.tables TO 'username'@'whatev.edu or %' IDENTIFIED BY 'password';
FLUSH PRIVILEGES;

February 11, 2012

How to obtain a node's prerequisite nodes

Last time, (blog post: How to turn an AnyLogic population into a DAG). I wanted to be able to generate a few random parents for each node, adding edges all the while, but I wanted to guarantee that the overall resulting graph would be a directed acyclic graph (DAG). So, in the blog post last time I explained how to connect the agents within a population to each other using a DAG. The tools I'm using are AnyLogic for the agent based modelling and jGraphT for the DAG java library.

In my application, my agents symbolize Learning Objects and I wanted to generate a DAG to represent prerequisite relationships between them. This is an abstract model (i.e. not based on an actual learning object repository). The idea is to be able to generate a "random" abstract graph given the particular parameters you want to study. For example, you might want to see how learners behave when you have 1000 learning objects verses only 10, or, what happens when each Learning Object has on average 2 prerequisites vs. an average of 10 prerequisites.

Anyway, today I wanted to write a method like learner.meetsPrerequisites(learning_object). In other words, for any learner, I wanted to be able to hold up a learning object and say if they had all the prerequisites or not. This involves looking at all the prerequisites that the learning object has, and, checking to make sure they are all in the learner's browsing history.

Given a learning object, you can "kind of" obtain the prerequisites using the jgraphT method,

(.......... ok I am planning to place a code snippet here but i do not have access to my model right now and I don't remember the method name!! ....._

However, this only gives you a Set of objects of type DefaultEdge. This isn't quite good enough if you want the Agent objects themselves so you can grab all the nodes that are pointing to it. (Also, note the subtlety that since it is a directed graph, we only want the TO nodes, not the FROM nodes.)

It took me a while to figure this out, but here's how you can get those references. Go back up to the DirectedAcyclicGraph object and use the method getEdgeSource(). As an argument to this method, you have to provide a reference to the DefaultEdge object we got above. So, just iterate through the set of DefaultEdges, and for each item you will call graph.getEdgeSource(item) to obtain the reference to the perquisite agent.

This link helped me figure out the getEdgeSource() part. Thanks demo!!!
http://massapi.com/source/jgrapht-0.8.2/src/org/jgrapht/demo/CompleteGraphDemo.java.html

February 04, 2012

How to turn an AnyLogic population into a DAG

Want to know how to turn an AnyLogic population into a Directed Acyclic Graph? This is even better than a new pair of heels!

A zillion thank yous to the JGraphT project founders and maintainers and also to Peter Giles at U Washington for contributing the dynamic DAG implementation. WOWZA this rocks! I had a rough time finding the javadocs on the jgrapht site, but there seem to be some javadocs here.

So... I have a population of Agents in Anylogic. I would like to arrange them in a random Directed Acyclic Graph.

Here is what I did.

1. In Main, under the advanced tab, import:

import org.jgrapht.demo.*;  

import org.jgrapht.*;import org.jgrapht.graph.*;

import org.jgrapht.experimental.*;

import org.jgrapht.experimental.dag.DirectedAcyclicGraph.CycleFoundException;

import org.jgrapht.experimental.dag.DirectedAcyclicGraph.*;import org.jgrapht.experimental.dag.*;

2. Download jGraphT and add the Jar to the Anylogic Dependencies. You can do this by clicking on your project name and there is a Dependencies tab. http://www.jgrapht.org/

3. Set the Replication of your agent population to be myAgent.size() where myAgent is the variable name you gave to the population.

4. Create a loop from 0 to whatever number of agents you want, and for each iteration go like

MyAgent newLO = add_myAgent("parameter1", "parameter2");
directedAcyclicGraph.addVertex(newLO);

... where MyAgent is whatever kind of Java class that your population is. And directedAcyclicGraph is a variable in your Main of type

 DirectedAcyclicGraph< MyAgent, DefaultEdge >

new DirectedAcyclicGraph< LearningObjectAgent, DefaultEdge >(DefaultEdge.class);

The method add_myAgent is automaticaly created for you by AnyLogic and you can find it in Main. Whatever the arguments are to the constructor are whatever the Parameters are that you put into that agent type.

5. So if you want to add some random edges to the DAG just pick any member of the MyAgent population, pick a random neighbour and badda bing badda boom

MyAgent randomNeighbour= myAgent.random();
try {
	directedAcyclicGraph.addEdge(myAgent,randomNeighbour);  //myAgent and randomNeighbour are both of type MyAgent
	myAgent.connectTo(randomNeighbour);  //i just did this so it could print a pretty graph.
       //unfortunately, I have only drawn regular lines between nodes, so there is no way to tell the edge direction from the visualization... u have to rely on the edge-printout which uses an ordered pair like (sourcenode, destinationnode)
} catch (IllegalArgumentException dcfe) {
        //oops, this means that connecting to this particular random neighbour would have created a cycle
	myAgent.disconnectFrom(randomNeighbour);
}
 

shaZAHM!

January 18, 2012

MySQL import

Another one of those things I've done a dozen times but can't remember the details...

cd /usr/local/mysql/bin   (unneccessary but including this so i can remember where the heck it is installed lol)
mysql -u username -p dbname < dbname.sql

Booya

January 11, 2012

MySQL crazy symbol problems

Thanks to Chris P. for letting me know how to fix crazy symbol problems in MySQL by changing the character set to be utf8. The default is like latin sweedish or something.
(Reference:
http://kb.siteground.com/article/How_can_I_change_my_MySQL_database_collation.html)

Here's the actual SQL to do it (because frequently I don't have phpmyadmin installed):

ALTER DATABASE 'databasename' DEFAULT CHARACTER SET utf8 COLLATE utf8_general_ci;

January 07, 2012

AnyLogic and Databases

Weird....

in AnyLogic, you can include Startup Code, and AnyLogic will execute it as it boots up your simulation model. So, I have a function called startUp() which calls all of the other functions in the correct order that I want. Two of these functions include MySQL database calls.

This has happened to me a couple of times so I thought I'd write it down. I noticed that for whatever bizarre reason, the functions inside startUp() that did database work were basically being ignored. Naturally this messed up a lot of my other stuff. I didn't notice this was happening, because it was working perfectly, until I started "clean up" and was deleting buttons from my interface and just adding the functions into my startUp() because I knew I wanted the stuff to run as part of my default model setup.

Since code works perfectly if I execute those functions with a button press instead of including them in my startUp(), my solution is to take the code back out of startUp(), create special buttons just for those, and press them every single time I boot up my model.

Annoying and weird, but at least it works.

By the way, if you don't know what AnyLogic is and are interested, I highly recommend Dr. N. Osgood's online resources which include some information about using AnyLogic with databases. (Material for Agent-Based Modeling Bootcamp for Health Researchers 2011Click the first link that reads, "lecture slides"). I learned about AnyLogic myself from taking his class, Computer Science 858 at the University of Saskatchewan, during the Winter (January) Term in 2011.

January 03, 2012

Apache Commons Java Statistical Sample Awesomeness

Oh my gosh! This is so awesome!

Say you want to generate a set of numbers, but they are not totally random numbers. For example, in my case, I wanted the random number to be 2 most of the time, but I wanted a bunch of 3's and 1's in there, maybe the odd 0 or 4, and I wanted to allow even more extreme higher and lower numbers than the 1, but for those to be very rare.

How do you do this? Well, you just dream up a Normal Distribution, set the mean to be 1, standard deviation to be like 0.5, and badda bing badda boom, do this for as many "random" numbers as you want:

double sort-of-random-num = normalDistribution.sample();

And how do you obtain the mythical normalDistribution object, you ask? Why, I will show you:

import org.apache.commons.math.distribution.NormalDistributionImpl;
NormalDistributionImpl normalDistribution = new NormalDistributionImpl(2, 0.5);  //(mean, stddev)

Of course, you will have to download the library jar from the Apache website and make it visible to your JVM. Mine is called commons-math-2.2.jar

Then, each time you call .sample() you get a new number. After rounding off, here's what I got:

3
2
2
2
2
1
2
2
2
2
2
2
2
2
2
1
1
1
1
1
3
1
2
2
1

etc.

Sweetie beans!

October 08, 2011

Anylogic and JPA

(Very rough notes this time -- sorry!)

• in anylogic, i have a path for each learner visiting an LO
• each visit has a pre and post assessment
• therefore, by summing the difference of (post - pre) over each assessment, each path can be given a utility score (useful paths having a positive number, detrimental paths having a negative)
• in anylogic, I couldn't align learning objects sequentially (for a given learner) and graph the score for each one.
• so I started trying to use JPA (Java Persistence API) so I could dump the scores into a database and then take them out again for analysis in the dimension that I want. Anylogic tools would only allow me to sample the SUM, Average, Min or Max of ALL paths. I want a vector of each path.
• But I can't get JPA to work with Anylogic because I can't get anylogic to see the persistence.xml (at least I believe this is teh problem because I am getting a java exception: javax.persistence.PersistenceException: No Persistence provider for EntityManager named ...)
• Therefore I decided to backtrack away from JPA. Next time, I should resume what I was doing but instead of using JPA, manually inject to MySQL.
• (!) Or, I could ditch anylogic and try to get my JPA working only from command line and THEN see if I can hook it up to Anylogic.
• But before I do this, I need to articulate what I plan to query out again.

That is what I accomplished today! I wish that I could come back and continue working on this right away. :(

Here are some of the JPA articles I was using:

• http://schuchert.wikispaces.com/JPA+Tutorial+1+-+Getting+Started
  
• http://stackoverflow.com/questions/3739387/javax-persistence-persistenceexception-no-persistence-provider-for-entitymanager
  
• http://www.myhomepageindia.com/index.php/2009/04/02/jpa-hibernate-with-oracle-on-eclipse.html
  
• http://javahowto.blogspot.com/2006/07/helloworld-with-jpa-hibernate-and.html
  

August 27, 2011

SequelPro cutting off LONGBLOB when I export

I love my SequelPro database client, but it's trimming off data whenever I try to export, and I don't want it to do that. This post is how I found a work-around.

So, I have a table in the database that has a LONGBLOB field. I want to export all of these to a human readable file. CSV will be fine, I can just read it in Excel, or even SQL is fine, or even XML. I just want to read the results of the darn query in a file that I can email to someone in its entirety. Unfortunately, no matter how i try to export, it cuts off the entries after the first sentences (maybe 255 characters if I had to take a guess?).

The secret is to go into SequelPro, go into Content view, click the row, press Command + C to "Copy" then paste it into a text file. Do this for each row. This will give you ALL the content for the LONGBLOB field.

August 21, 2011

PL-PLAN, a Java Open-Source AI Planner

Oh, oh! I am excited about this:

PL-PLAN, a Java Open-Source AI Planner

July 27, 2011

RedirectMatch

I had occasion to learn a new little trick today.

Suppose I have a system that has links like this:

www.mysystem.ca/folder/subfolder/file.php?somevariable=1235CRYPTICNUMBER678

Suppose circumstances arise that I must absolutely change the name of "folder" to "speedboat". I want the Apache to still accept all incoming links, including the cryptic numbers in the links, but just redirect them to the system in the new folder.

For example, the following link must get translated to the one above:

www.mysystem.com/speedboat/subfolder/file.php?somevariable=1235CRYPTICNUMBER678

I never know what that cryptic number is going to be because it is generated automatically by some system. But the number must get translated exactly.

So here is the Apache directive to do that. Use:

RedirectMatch /folder/subfolder /speedboat/subfolder

That is all you need to do.

June 14, 2011

Example of Rustiness: SSH vs Samba in Terminal

I talk a lot on this blog about being the sort of person with respectable age and experience (I have a comfortable decade behind me of computer geekdom) while struggling with forgetting critical details. I feel anxiety when I get into a situation where I KNOW I knew the answer at one time, and I prided myself on my familiarity with it, and yet, I have forgotten. What does it matter if you once knew; the only thing that matters is if you can help someone solve it when they need it, right?

Sure, details can be easily remembered and refreshed, but they definitely cause barriers and slow-down, and even prevent me from getting deeper into projects when I forget how to walk the walk.

Now I have a concrete example to share. A couple months ago I was trying to help a friend with a file permissions problem. Chown was not working. Why? Because I had instructed her to go to Terminal, then change directory to the mounted drive and execute the command. This failed. The correct approach would have been to SSH into the remote server and THEN do the chown.

In retrospect, it is glaringly obvious to me now about the different domains and "which user I actually am" when executing the terminal commands in these two different contexts.

But at the time, it had been months or years since I'd had the chance to go back and forth between Samba mounts, SSH sessions, etc. on a regular basis, and I was so preoccupied with the chown syntax I just forgot.

I am clinging for dear life to the idea that I can still keep my techno skills from dulling too much, even while I grow into leadership positions, and while my research is getting a little more theoretical/abstracted.... It must be possible to live in such conflict, it must! Because the techno stuff is the whole reason (for me) for pursuing the abstract. It creates possibility.

Ahh, I do enjoy being human.

Also, I am indebted to the two technical people who re-taught me this lesson. Maybe I will remember next time.

June 09, 2011

JAXB, I love you

Dear JAXB, I love you.

Thanks to my friend Collene for introducing me to JAXB. (Pronounce "Jack's Bee", only without the pause between words). I think that I will keep JAXB by my side for many years to come.

JAXB is the Java Architecture for XML Binding. It is an easy way to load the data from an XML document into a class. You just annotate the class to show which attributes match up with which fields in the XML.

For example, say this is your xml file:

  Jane
  Doe

Now, this is your java class:

@XmlRootElement
public class Person {
  private String firstName;
  private String lastName;
 @XmlElement(name = "first-name")
    public String getFirstName() {
        return firstName;
    }
 @XmlElement(name = "last-name")
    public String getLastName() {
        return lastName;
    }
}

May 20, 2011

Apache htdocs folder on OSX

I keep forgetting this so I am blogging it to be able to look it up later.

The Apache htdocs folder on OSX is /Library/WebServer/Documents.

So if I need to quick and dirty run PHP code locally, send it here.

May 15, 2011

Buckets

Here is a great idea for a software application. It's called Buckets, and it's like a big canvas that lets you drag around "Buckets" (they can be squares or circles or rectangles, whatever) and organize them into categories, order them alphabetically, put time ranges on them. Around the perimeter of the canvas are thousands of little slips of paper; these too you can categorize, order, timestamp. The purpose of the software application is to allow you to drop the papers into the buckets to organize them. You can pick if the slips of paper are only allowed in one bucket at a time or if they can exist in multiple buckets concurrently.

The software will give you reports and summaries. It lets you build online forms to let people create their own slips of paper, assigning those to buckets. Say, if each bucket were a timeslot, and the people were volunteers, you could use this as a means of letting people "grab" volunteer spots. You could put maximums for the number of slips of paper allowed in a given bucket.

April 27, 2011

iPod iTunes sync problem fixed

Whew! 'Finally fixed a problem that was causing me significant irritation. :)

I had just purchased a new album on the iTunes store and wanted to sync to my iPod. However, whenever I plugged the iPod into the computer, iPhoto would pop up. When I went to iTunes, the iPod wasn't showing up under Devices.

I figure that most people in this situation would be able to remember the last time they performed an iPod sync and be able to figure out the cause of the problem based on recent changes to their computer. Unfortunately, I am not in that situation -- I am torn so far away from the familiarity with my own machine's configuration that I might as well be using a stranger's computer. Have I mentioned how much this irritates me? LOL! Someday, I hope to be able to spend time on my computer again and configure it the way I want. Moping aside, here is how I solved the problem.

First, you can get iPhoto out of the way by going into iPhoto --> Preferences --> General and then on the dropdown menu for "Connecting camera opens:" change from iPhoto to "No application". This will be a pain in the butt the next time you want to sync photos from your camera, but we want to sync up our iTunes so we'll worry about that later.

Second, I found this helpful article on Apple's support site. I reset my iPod, performed a software update - which restarted my imac - and then it worked. Whew!

April 15, 2011

Apple Mail - "From" dropdown box

Yay! This great web page solved a problem I was having:

http://www.michaelvoong.com/2008/01/19/multiple-from-address-in-apple-mail/

See, I was sending out e-mail, and when people replied to me, the message went to the wrong account. I keep separate e-mail address for work and for personal. I was getting work messages at home, and, I was also uncomfortable with my home email address being sent around to professional colleagues. (I mean, I trust every single one of them, it's jsut that I rarely, rarely get a chance to work on my e-mail at home, so, if they sent me something it could be weeks before I notice.)

Anyway, ever since this started happening I started feeling anxiety every time I sent out email: What is my "From" address? How do I know what the mail client is using?? So, all I had to do was create an alias, i.e. if my e-mail address is stephanie.frost at usask.ca, I simply created steph.frost at usask.ca that would go to the same account. Then, you put in both of these addresses separated by commas according to the directions in the link above. When there is more than one address for the same account, then a From drop-down box will automatically appear, confirming which email address is being used.

This seems sort of a weird solution because I don't really care which of the 2 email addresses is used (stephanie.frost or steph.frost), I just wanted verification that it's one of those, and not my other account!!

February 23, 2011

ssh and sftp://

What is the difference between ssh and sftp???

If I ever learn the answer, I will come back and write it here.

P.S. I love CyberDuck for Mac! MacFusion is good, too. I have had problems with both (unexplainable buggyness). But between the two of them, I can usually get by.

February 14, 2011

http_referer vs remote_host

I don't know PHP very well. But today I learned the difference between $_SERVER['REMOTE_ADDR'] and $_SERVER['HTTP_REFERER'].

Basically, the former works at the Transport layer (ex: TCP/IP) and the latter works at the Application layer (ex: HTTP).

If you want to check your traffic for "user is coming from" type data, the former is secure, and the latter is absolutely NOT (because clients can be easily faked).

I am having a very difficult time obtaining documentation for the former. I believe that REMOTE_ADDR is the IP number taken from TCP/IP (or UDP, or whatever). I guess this would have to be built into the web server somehow, which would have to peel the headers off of incoming requests and make them available within the PHP environment.

The second one is easy. Here is what an HTTP packet might look like; this would be generated by a web browser:

GET /path/to/myscript.php?argument1=value HTTP/1.1
Host: www.mysite.ca
Connection: close
User-agent: Mozilla/5.0
Accept-language:en
Referer: http://whateverIwant.ca  

The browser normally sets the Referer to be the "current" page when the HTTP request is initiated by clicking the link to /path/to/myscript.php. So it tells you the last page the user could have been looking at. You can set the Referer to be anything you want with a Firefox plugin.

So, there. I know a little more about PHP. I wonder how this distinction would look in Java/JSP/Tomcat, hmm! I am much more comfortable with servlets, contexts, and web applications!

January 28, 2011

Syntax highlighter

The tool, Syntax Highlighter looks really awesome. I would like to try it out on this blog. I am having trouble getting it working, but here is a start. UPDATE: Okay, I got it working! I had the path to the script wrong; the one I copied from the instructions was a relative path, assuming you had downloaded the scripts and were hosting them on your own server. I am linking directly to Gorbatchev's hosted version. If I continue to use this service I will likely send him some a donation.

Example:

  /** this is a comment */
 this is some code

January 20, 2011

Can't even articulate this one

I just spent about 1.5 hours (YES!!! I love it when I have time for programming. But it does suck when you get tripped up for extended periods of time. But it is necessary.) trying to figure out why my web app wouln't deploy. I got it working, but I am not sure why.

THe problem was that my context.xml was not getting updated. When I did a clean, dist, deploy, it worked. But when I only did a dist, deploy, it was not working.

The file was in my tomcat_home/conf/Catalina/localhost/webapp.xml. I have no idea how my ANT is accessing this file; I can't pick it out of the xml. All I know is I have to Clean if I want this to get updated. I think. Actually, I may have had to fix the xml manually???

????

Oh well. Perhaps some light will be shed on this at a later time, when I am older and wiser.

January 18, 2011

BUILD FAILED - ${tomcat.home} not found

BUILD FAILED - ${tomcat.home} not found

When I was first learning how to use ANT, I got this error while I was trying to get my environment set up. And then I fixed it! Unfortunately, I had written down the error with the intention of blogging about it in case I ever ran into it again, but, I forgot how I solved it, and couldn't remember how to reproduce the problem.

Today, I remain uncertain about whether the "tomcat.home" notation is local to the developers I learned these conventions from, or, if it's a convention used more generally by hundreds of Tomcat + ANT + Eclipse + Java/JSP + Subversion developers.

Fortunately (ha?) I ran into the problem again. It didn't take me nearly as long to fix it this time, and, I am lucky to have the time and opportunity this time around to blog about it before I forget.

Without further ado: The reason I got the error is that I had my build file pointing to the wrong configuration files folder.

That is, in build dot xml, the folder value in the following line was wrong:

(ugh, why is it so hard to include code snippets in a blog entry?? That was a rhetorical question. UPDATE: Problem solved!)

Wooo! I had 2 cups of coffee today, (which is 1 more than usual) and it doesn't feel like it was enough.

December 28, 2010

SequelPro

My current favourite MySQL GUI client is SequelPro. I am accustomed to using MySQL at the command line, but if all you want to do is browse your data and review the database structure, I prefer usng SequelPro. Even better -- free download! (at the time of this writing)

http://www.sequelpro.com/

The reason for this blog entry is that I have needed to install this program several times (computer at home, computer at work, laptop) and I want to be sure I remember the link. I am considering donating some cash for this nice software.

November 13, 2010

MySQL installation

Over the last decade, I have installed MySQL dozens of times on dozens of computers using several different operating systems. However, when the time comes that I need to do it again, I can never freaking remember how to do it quickly and easily. Often, I find myself reading about building make files and setting up aliases through unix-style filesystems. I am aware that I have done this successfully many times, and I wish it could just "stay" done so that I do not have to expend this effort over and over. However, as I change jobs and change computers over time, it seems any optimization is unlikely.

Therefore, for my notes I supply this link that helped me perform an installation today. Perhaps it will help to jog memory next time.

In other words, this is a very good link explaining how to get a mySQL server up running quickly and easily on your mac.

http://www.bos89.nl/install-mysql-on-mac-osx/

September 26, 2010

CoRD - Remote Desktop Client

I am in love with this great Remote Desktop Client, CoRD.

For many years, I only used Microsoft's Remote Desktop Client. It made sense when I was a Windoze user. And when I switched to Mac I simply used the same software, downloaded the Mac version.

But this morning I got really fed up. See, version 2 of the Microsoft Remote Desktop Client tries to "save" my credentials in an application window. This is a huge pain because I have a half dozen servers I need to access, and the software forces me to erase the user and domain name from the previous session each time. Also, I have a crappy memory and I really do like seeing the Server's actual login prompt to help me jog my memory, instead of being forced to enter the credentials in the application-specific menu each time. Version 1 of the software was better because it did send you to the server's local login screen, but unfortunately I can't download it; I can only find Version 2. Luckily, I had an older computer with Version 1, so I have been using that for several months.

But today I got fed up. I should be able to remote in from my new computer. So after a bit of Googling, I discovered CoRD and now I am happy and in love. :)

September 17, 2010

JESS

If I lived in a fantasy world and I had spare time, I would build a little application using JESS to get some experience with rule-based systems.

http://www.jessrules.com/

In the real world, a 30-second blog entry will have to suffice. ;)

September 04, 2010

Keener - class project

The first day of class isn't until Tuesday, but I have already been fantasizing a little bit about the term project. My supervisor tells me the project will be "to build an eLearning system" (as I understood, sort of jokingly about the broadness of the project description but quite serious about the room for creativity and freedom.)

I would like to contribute something to do with agent programming with hopes of experiencing some game theoretic concepts.

I am looking forward to our first project meeting to learn what my team members will be interested in incorporating into our collective endeavor.

Agents, Concept maps, the ecological approach... I have always wanted to try and build something in Second Life to take advantage of the immersive environment. Reward functions, storyline progression... looking forward to seeing where this will go!

August 12, 2010

create jar file

I am always forgetting this.

To create a jar file, go

jar -cf myfile.jar *.class

(see javacoffeebreak.com)

The "c" means you are CREATING a new jar. The "f" means output to file instead of output to terminal. (see Oracle's resources for more option descriptions.)

August 04, 2010

Apache virtual hosts

I should start using delicious or something for all these links I wish to keep.

Here is a good one for Apache virtual hosts. I need to know how to do this for my job, but I don't do it frequently enough to memorize the syntax nor techniques.

http://www.unix-girl.com/geeknotes/apache_virtual_host_conf.html

July 23, 2010

Subversion errors

I had to move my Subversion repository to a new server. After I set it up, I could Browse the repo just fine, and do checkouts. Unfortunately, whenever I tried to Commit anything (via HTTP), I was getting these Subversion errors:

Permission denied
svn: Commit failed (details follow):
svn: Can't open file '/mysvnrepo/db/txn-current-lock': Permission denied

Permission denied
svn: Commit failed (details follow):
svn: Could not open the requested SVN filesystem

Permission denied
svn: Commit failed (details follow):
svn: Can't make directory '/mysvnrepo/dav/activities.d': Permission denied

I solved them by executing the following command (which I explain below):

cd /
sudo chown -R www:www mysvnrepo
chmod -R 664 *

The first line -- you have to change to the parent directory that holds your SVN repo.
The second line -- the "sudo" part of the command is when you want to invoke administrator power to let you perform this command (which otherwise would give you an Operation Not Permitted error). The "chown" command means you are going to change some file permissions. The -R means "recursive", i.e. apply the changes to everything downward in the directory hierarchy. The "www:www" means owner/group. If you don't know what yours are, check your Apache's httpd.conf file. Finally, "mysvnrepo" is the name of the folder that contains all of the back-end SVN stuff in it.
The third line gives read/execute to Owner and Group and Read to everyone else.

I love you, StackOverflow. Why didn't you exist when I was a young programmer? heh

July 09, 2010

Adventures with ANT, Part 8

Okay, I fixed my web.xml problem. All I had to do was go into the correct version of the XML file, add a carriage return and save. Maybe the system was looking at the timestamp on the file.

I also learned that after I hit "build" I should look in the "dist" folder at my context.xml and web.xml to make sure they are the correct versions. Because this is the folder that gets uploaded to the production server.

July 08, 2010

Adventures with ANT, Part 7

Ugh, I messed up.

I deployed my latest (working) version of my app to production. I was perfect on localhost, so, it seemed logical to go live, right?

Stupidly, I deployed without checking the time. It was 4:24 p.m.. Every day I leave in a rush to go pickup my daughter from daycare. I do not have the luxury of working late. (but I love what I do and I wish I could)

Anyway, for some reason my dev web.XML went to production instead of the production copy. Obviously my build.XML is pointing to the wrong version, except that I double-checked the path and it is pointing to the correct version.

So I don't know what is going to happen. I have to trace the steps, but my day is jam-packed full of meetings tomorrow.

Sigh. It is very hard being both Management and Server Admin.

July 02, 2010

mysql connector

In my new local Tomcat environment, I was trying to set up some database connection pooling and I kept getting this error:

Cannot load JDBC driver class 'com.mysql.jdbc.Driver'

I solved it by adding the jar file for the MySql JDBC connector into this folder:

TOMCAT6_HOME/lib

Then you have to STOP and then re-START Tomcat so it can load up the new libraries.

This is something that my ANT didn't take care of!!!

lost MySQL admin password

I can't believe this happened to me because I am such a careful and organized person. But, I lost an admin password.

I created a MySQL database server on my local workstation for development purposes. Years went by where I did not do any development and I did not need to use my local database server. But now I am programming again and I need to run a local version of a system for work-in-progress. I require access to my local database server.

But the password I could have sworn I'd set wasn't working. I questioned whether I was actually connecting to the correct database server. (Who knows? Maybe I had 2 mysql servers installed on my workstation and forgot about one. It could happen!)

Anyway, the following link helped me get around my forgotten admin password.

http://lists.mysql.com/mysql/171366

I am summarizing the steps below in case the link above gets busted.

1) Stop the service
2) run mysqld_safe --skip-grant-tables &
3) mysql -u root mysql (i.e. log in with root and use the database, "mysql")
4) issue the following:
UPDATE user SET password=PASSWORD("newpassword") WHERE user="root";
FLUSH PRIVILEGES;
5) Log in again with your new credentials:
mysql -u root -p
Enter password: (new password)
USE DATABASE mysql;

You should be in!

June 28, 2010

Adventures with ANT, Part 6

In this entry, I share a trick about debugging ANT build.xml files.

Normally, when you run ANT in the command line, it can do the equivalent of System.out.print lines. Similarly, in your Eclipse environment, it prints status (ex. BUILD SUCCESSFUL) in the console.

If you want to debug, you can see values of your configurations by putting echos into your config file, like this:

Another good ANT tip -- if it gives you a "Bad Class Version" type error, do an ANT - Clean and try again. See, ANT usually only re-complies the files that have changed recently, not ALL files. But if you change your Java version somewhere in between, and then ANT compiles a subset of your project with this new version (but the rest of your files are still compiles in the old Java version) then you can get an error. So, since "ANT Clean" deletes all the class files, the next time you run ANT it will compile ALL your Java, this time everything with the same version, and the error will go away.

My ANT series

I am feeling a little odd about my Adventures with ANT series on this blog because these are more than "Technical How To's". The notes I write here are cultural conventions passed on through organizations and/or mentorship. It's not the only way to do things, and may not even be the best way of doing things. It feels kind of sacred to me. I'm very grateful and lucky to have had a mentor teach these things to me! (Thank you, GvdV, if you are reading this. :D)

And yet as I write it's coming out in a broken sort of way, not very well explained. There is no foresight or structure in my writing. I haven't done this knowledge justice!

But I'm writing this stuff down like crazy now, and may come back later to write something that is useful to someone other than myself. heh. This stuff is the Craft or the Art part of software development.

But for now it will remain scratch notes.

Adventures with ANT, Part 5

In this entry, I want to talk about creating local conf files for your development environment.

Recall this subtree from my other entry.