Technical Jig

debugging ssl certificates jvm option

2011-08-05T12:33:00.000-07:00

-Djavax.net.debug=ssl,handshake,trustmanager

Session Tracking in Java

2010-08-17T14:03:00.000-07:00

Maintaining client sessions is the ability for servers to associate multiple stateless http requests within a single session context. Often, implementing session seems to be magic, but an actual mechanism exists by which this is implemented.

The main requirement for maintaing client sessions is the server's ability to associate one request with a previous request. In order to do this, a session id must be generated and passed back from the server to client. The client will then pass this session id in subsequent requests to associate these with the previous request. The main difference between the various methods of maintaing a session is the form of the session id, such as the way the session id is generated or how it is stored on the client and/or on the server.

Java web servers provide a default implementation using Http Session. However, there are several other ways. The server

1) Using HttpSession

Generation: web server

Client Location: cookies or url
Server Location: web server

Java web servers by default can maintain http sessions by generating at request a session id, or the JSESSION_ID. Once the session has been established, the Java web developer can save any type of information in the new session when processing the request. The web server is responsible for storing this session and any saved information without any additional coding. Once the request has been processed, a JSESSION ID is passed back to the browser as a cookie. The browser saves the cookie. On subsequent requests to the same web server, the cookie is passed back to the server, and the web server picks up the session cookie and retrieves the JSESSION ID. Once the session id has been identified, the session associated with the id is set on the request.

2) Encrypt and Decrypt

Generation: servlet

Client Location: cookies
Server Location: N/A

When the client makes a request with a particular user-specific id, the server can generate the session id from this user id. The user id

3) Memcached

Generation: servlet

Client Location: cookies
Server Location: N/A

LDAP Modify - Changing your password

2010-07-27T10:51:00.000-07:00

File contents: mod_attribute.ldif

dn: uid=mtan,ou=People,dc=mlbam,dc=com

changetype: modify

replace: userPassword

userPassword: {clear text password}

ldapmodify -x -h ldap01.mlbam.com -p 389 -D "uid=mtan,ou=People,dc=mlbam,dc=com" -f /Users/tan/mod_attribute.ldif -W

Enter LDAP Password:

Enter your current password.

Possible outcomes:

additional info: invalid password syntax: no numeric character

This indicates your password must contain a numeric character

additional info: invalid password syntax: dictionary word match

This indicates your new password contains a dictionary word, which is not allowed.

additional info: invalid password syntax: no special character

This indicates your new password must contain a special character.

SASL/EXTERNAL authentication started

ldap_sasl_interactive_bind_s: Unknown authentication method (-6)

additional info: SASL(-4): no mechanism available:

You should use the -x option for simple authentication.

Mule 2.x Start Error

2009-09-29T14:12:00.000-07:00

Message:

Root Exception stack trace:

oracle.xml.parser.schema.XSDException: Duplicated definition for: 'identifiedType'

at oracle.xml.parser.v2.XMLError.flushErrorHandler(XMLError.java:418)

at oracle.xml.parser.v2.XMLError.flushErrors1(XMLError.java:284)

Solution:

The Mule 2.x app does not contain the correct Spring library. Please include the spring-context-2.5.jar

Always go to the Source

2009-08-20T14:54:00.001-07:00

Java Performance Diagnosis Tools

2009-07-29T14:32:00.000-07:00

prstat / prstat -mLp

the last number of each column is the NLWP (number light weight processes aka threads) that are currently active.
prstat -mLp will show the current threads for one process. The last column is the LWPID (light weight process ID)
LWPID’s increment by one, hence the highest LWPID indicates how many threads have been launched since process creation.

ps -fLp

indicates how many threads have been launched since process creation.

truss -f -p /

new system calls for one thread

/usr/jdk/jdk1.6.0_10/bin/jstatd -J-Djava.security.policy=jstatd.all.policy -p 52074

starts an rmi server on the local host to be able to monitor application running on this host

/usr/jdk/jdk1.6.0_10/bin/jps -q

determines the running java processes

References:

http://prefetch.net/blog/index.php/2008/01/16/monitoring-garbage-collection-with-jstat/

Curl Command

2009-07-29T07:32:00.000-07:00

curl -x (proxy.host):(proxy.port) http://www.google.com

Heap Dump

2009-05-21T09:52:00.001-07:00

jmap -dump:format=b,file=heap.bin 518

Mule 1.x: Spring Integration

2009-02-11T12:06:00.000-08:00

Integrating a Spring configuration file into a Mule configuration has been the most frustrating thing in the world... well at least for me.

Mule provides documentation for using Spring with Mule 1.x in the following URL:
http://www.mulesource.org/display/MULEUSER/Using+Spring+as+a+Component+Factory

However, after following these instructions, there are a couple of things that were left undocumented for the spring application context xml to be integrated successfully. The following are these undocumented notes:

The Spring application context xml file should not include a XML schema definition. It should specify the Mule-specific DTD.

Example Spring XML:

<beans xmlns="http://www.springframework.org/schema/beans" xsi="http://www.w3.org/2001/XMLSchema-instance" schemalocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.5.xsd">

......
</beans>

In order for the Spring XML file to be read successfully by the Mule Server, the above Spring XML file must modified to use the DTD file, and not the XML Schema as follows:

<!DOCTYPE beans PUBLIC "-//MuleSource //DTD mule-configuration XML V1.0//EN"
"http://mule.mulesource.org/dtds/spring-beans.dtd">
<beans>
.......
</beans>

If you do not do this, the Mule server will throw the following exception and cause you frustration beyond belief (jk):

nested exception is org.xml.sax.SAXParseException: : XML-20149: (Error) Element 'beans' used but not declared.
When specifying the <contianer-context> element, remember to define it at the appropriate place in the mule configuration xml.
```
<!ELEMENT mule-configuration (description?,environment-properties?,mule-environment-properties?,container-context*,security-manager?,
transaction-manager?,agents?,connector*,endpoint-identifiers?,transformers?,global-endpoints?,
         interceptor-stack*,model*)
```
From the above DTD element, the container-context element should be after the mule-environment-properties element and before any connector, transformer, and model elements.

If this is not the case, the Mule Server will throw the following exception:

SAXParseException: : XML-20148: (Error) Invalid element 'container-context' in content of 'mule-configuration', expected elements '[connector, endpoint-identifiers, transformers, global-endpoints, interceptor-stack, model]'.

It will indicate the mule-configuration DTD element that does not even contain the container-context element, which may be quite confusing.

So, it seems most of these are related to DTD and XML schema definitions.

Esper

2009-01-23T13:54:00.001-08:00

Oracle SQL: Calculating on a Running Window

2009-01-05T08:10:00.001-08:00

select t1me, m1n, m1n_1, m1n_2, m1n_3, m1n_4, m1n+m1n_1+m1n_2+m1n_3+m1n_4 fiveminspan from
(select
trunc(record_timestamp,'MI') t1me,
count(*),
LEAD(count(*), 0, -1) OVER (ORDER BY trunc(record_timestamp,'MI') ASC) m1n,
LEAD(count(*), 1, -1) OVER (ORDER BY trunc(record_timestamp,'MI') ASC) m1n_1,
LEAD(count(*), 2, -1) OVER (ORDER BY trunc(record_timestamp,'MI') ASC) m1n_2,
LEAD(count(*), 3, -1) OVER (ORDER BY trunc(record_timestamp,'MI') ASC) m1n_3,
LEAD(count(*), 4, -1) OVER (ORDER BY trunc(record_timestamp,'MI') ASC) m1n_4
from REP_OWNER.BAM_MEDIA_REPORT where
record_timestamp > TO_DATE('03/30/2008', 'MM/DD/YYYY') and
record_timestamp < TO_DATE('09/29/2008', 'MM/DD/YYYY')
group by trunc(record_timestamp,'MI')
order by count(*) desc)

Lesson of the Day: Data Integrity

2008-07-30T14:48:00.000-07:00

Often, one needs to make sure that the data of one service/application is not inappropriately saved/cached in another service/application. This ensures the integrity of the data.

A single service/application may be responsible for providing a particular type of data. This data should not be cached or saved in another application. In this way, all data of this type is solely accessed from this application/service. All applications/services requesting this data would have to always retrieve it from this single service/application. Typically, however, other applications/services may reference data within this single application with an identifier or id which can be used and passed to the single service to access the actual original data. Therefore, data the actual data would not be replicated by the other services/application.

If the actual data were to be saved/cached in another application/service in order that the original service does not have to be called and thus improve performance, data integrity cannot be ensured. The data would then inadvertently be saved in two locations. If the data needs to change, one would have to update these two locations to ensure the integrity of the data.

This is a basic notion of application design.

Therefore, one needs to be careful in caching actual data that can be accessed from another service as opposed to simply saving the reference to the data which can be used for accessing the data in the originating service/application.

Database Views

2008-05-21T07:31:00.001-07:00

Views should be created if a query is required for accessing data from multiple tables and multiple rows of multiple tables.

CORE3282: Crash occurred in function

2008-05-01T08:10:00.000-07:00

[01/May/2008:11:05:23] fine ( 6208): Successfully initialized web application environment for virtual server [https-bamws]
[01/May/2008:11:05:35] info ( 6208): CORE3282: stdout: WebappClassLoader: Additional JARs have been added : 'hibernate-3.2.3.jar'
[01/May/2008:11:05:39] info ( 6208): WEB2798: [] ServletContext.log(): WEB3945: Scratch dir for the JSP engine is: /opt/sunone/https-mtan/ClassCache/https-bamws/default-webapp
[01/May/2008:11:05:39] info ( 6208): WEB2798: [] ServletContext.log(): WEB3947: IMPORTANT: Do not modify the generated servlets
[01/May/2008:11:05:44] catastrophe ( 6208): CORE3260: Server crash detected (signal SIGSEGV)
[01/May/2008:11:05:44] info ( 6208): CORE3262: Crash occurred in function pblock*NVPairs::dup()const from module /opt/sunone/bin/https/lib/libns-httpd40.so

Scenario:

I removed all jars from WEB-INF/lib with rm -r *, populated it with a new lib directory, restarted the server and the above error occurred. Restarting the server every time still caused this same error.

I tried to remove all references to this web app in the server.xml file, but the error still occurred.

Cause:

This could have been possibly caused by the removal of jars that while the server was still running. Perhaps, an artifact of the jar remained after subsequent restarts and would continuously cause the crash on the server.

Solution:

I removed the hibernate-3.2.3.jar from this lib directory and the web server now starts without error.

NoSuchMethodError: javax.xml.parsers.DocumnentBuilderFactory.getSchema()

2008-04-28T09:37:00.001-07:00

java.lang.NoSuchMethodError: javax.xml.parsers.DocumentBuilderFactory.getSchema()Ljavax/xml/validation/Schema;
at com.sun.org.apache.xerces.internal.jaxp.DocumentBuilderImpl.(Unknown Source)
at com.sun.org.apache.xerces.internal.jaxp.DocumentBuilderFactoryImpl.newDocumentBuilder(Unknown Source)

Cause: You are using a different version of the DocumentBuilderFactory class

Solution:

This version of the javax.xml.parsers.DocumentBuilderFactory is used by the xercesImpl.jar and is defined in the jaxp-api.jar

This class is defined in the following jars:
xml-apis.jar
xmlParserAPIs.jar
xercesImpl-2.8.1.jar
jaxp-api.jar

In addition, this class is also include in the JVM. The JVM implementation of this class does not define a getSchema() method.

The only jar that contains an implementation of the DocmentBuilderFactory with the getSchema() method defined is the jaxp-api.jar. In order for this implementation to be used instead of the JVM's implementation or the other jar's implementation, you must either endorse this jar or put this jaxp-api.jar at the top of the classpath.

NoClassDefFoundError: com/sun/org/apache/xerces/internal/dom/DocumentImpl

2008-04-28T08:20:00.001-07:00

java.lang.NoClassDefFoundError: com/sun/org/apache/xerces/internal/dom/DocumentImpl
at java.lang.ClassLoader.defineClass0(Native Method)
..........
at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:302)
at com.sun.xml.messaging.saaj.soap.SOAPPartImpl.(SOAPPartImpl.java:63)
at com.sun.xml.messaging.saaj.soap.ver1_1.SOAPPart1_1Impl.(SOAPPart1_1Impl.java:29)
at com.sun.xml.messaging.saaj.soap.ver1_1.Message1_1Impl.getSOAPPart(Message1_1Impl.java:52)
at

Cause: Missing a class
Solution:
There are two versions of the xercesImpl.jar that define the different classes in different packages. These packages are the following:

com.sun.org.apache
org.apache

The DocumentImpl class is defined in the following packages of each corresponding jar:
com.sun.org.apache.exerces.internal.dom
org.apache.xerces.dom

The jar that contains the DocumentImpl of the NoClassDefFoundError is contained in the first jar. Please include this jar in the classpath before the second version of the jar.

Reference:
http://mail-archives.apache.org/mod_mbox/xerces-j-users/200407.mbox/%3C40F0D3AD.3050201@sun.com%3E

Mule Error: Application does not seem to be starting or is hanging

2008-04-21T09:40:00.000-07:00

Error:
Launching a JVM...
Error [125] in bind() call!
err:: Address already in use
Socket transport failed to init.
Transport dt_socket failed to initialize, rc = -1.
FATAL ERROR in native method: No transports initialized
JVM exited while loading the application.
------------------------------------------------------------------------
The JVM is being launched with a debugger enabled and could possibly be
suspended. To avoid unwanted shutdowns, timeouts will be disabled,
removing the ability to detect and restart frozen JVMs.
------------------------------------------------------------------------

The logs display the above error.

This indicates that the port for debugging is already in use, and not the actual mule application's port.

Change the debug port in the wrapper.conf.

wrapper.java.additional.5=-Xrunjdwp:transport=dt_socket,address=5295,server=y,suspend=y

CSS

2008-04-08T21:23:00.000-07:00

So, I'm creating a website and I'm noting some things down about CSS I'm learning from an actual site. Cool dudes.

CSS Styles

position: relative |

color: #ABC123
background-color: #ABC123
font:
font-size: XXXpx | XXX
width: XXXpx
margin: XXXpx
margin-bottom: XXXpx
margin-right:
padding:
text-align: center |
border: XXX

Lesson of the Day

2008-03-31T12:21:00.000-07:00

"We learn something new everyday!" As a tribute to this saying...

We have this large million of records table. An audit table exists to record every single update or deletion of a row in this table. We were thinking of creating an index on this audit table where no indexes existed before. However, every update/deletion would require an update of this new index, therefore, slowing the performance of write operations on this table.

Lesson of the Day: Indexes, although improves the performance of read operations, leads to more overheard if this table is often updated.

I know i'm dumb..

Flex Error: ReferenceError: Error #1065

2008-03-29T08:26:00.000-07:00

This error often refers to missing assets in the swf file that is expected to be there. For example, if you get the following error:

Variable ExampleView__embed_mxml__assets_png_example_picture_png_1012766830 is not defined.

It refers to a missing asset in an mxml file called ExampleView attempting to reference a png file as in the VBox below:

<mx:VBox backgroundImage="@Embed(source='/assets/png/example_picture.png')" width="100%"

In this instance, you must remember to include these assets into the compiled swf files.

Flash Global Security Settings: Windows vs. Macs

2008-03-14T22:42:00.000-07:00

There seems to be a slight difference between how global security settings are set on Windows and Macs browsers. To note, when you set the global security settings, they are set "globally" for the machine and not for the particular browser where the security setting was set.

On Macs, you can just specify the swf file in the global security settings. The swf file will load successfully and any external interface registered functions can be successfully called.

On Windows, however, specifying the swf file in the global security settings will allow the swf file to load correctly. But, this does not allow registered external interface functions to be called. It will cause the following js error:

Error calling method on NPObject! [plugin exception: Error in Actionscript. Use a try/catch block to find error.].

In order for external interface functions to be called, you must also specify the folder/file where the swf file is located.

CVS Commands

2008-03-12T08:26:00.000-07:00

Creating a New Tag from an Existing Tag
cvs -d :ext:{user}@{host}:/{cvs directory} -q rtag -r {existing tag} {new tag} {cvs directory}

java.lang.UnsatisfiedLinkError: create_stmt_c_copy

2008-02-28T11:04:00.000-08:00

Googling this, this is a result of old oracle jars. Update your oracle jars to the latest or the right version. This should fix this error.

Mule Error: ObjectNotFoundException Object " null" not found in container

2008-02-28T10:19:00.000-08:00

This error is not a very descriptive message. What is actually happening in the mule app is that the UMO is attempting to be created, however, it is throwing an error during its creation. The UMO is never then added to the container and therefore cannot be found in the container.

In the example that I encountered this error message, the creation of the com.bamnetworks.reporting.DataReporter fails to be created, because of a misconfiguration in the database and the reporting config.

SWFObject not working

2008-02-11T10:13:00.000-08:00

Please ensure that the div in which the flash embed object will be written to is defined before the inclusion of the external javascript file that defines the SWFObject

Otherwise, it will not be able to write to a div tag that does not yet exist.

Example:

...

<div id="flash_videoplayer"><strong>You need to upgrade your
Flash Player</strong> This is replaced by the Flash content. Place your alternate
content here and users without the Flash plugin or with Javascript
turned off will see this. Content here allows you to leave out <code>noscript</code>
tags. Include a link to <a href="swfobject.html?detectflash=false">bypass the detection</a> if you wish.</div>

...

<script type="text/javascript" src="js/flvplayer_2.js">

==========
The above flvplayer_2.js file contains the code below:

var swfObject = new SWFObject("FlvPlayer2.swf", "flvPlayer2", flv_width, flv_height, "9");
swfObject.addParam("allowScriptAccess", "always");
swfObject.addParam("allowFullScreen", "true");
swfObject.addParam("salign", "tl");
swfObject.addParam("menu", "false");
swfObject.addParam("wmode", "transparent");
swfObject.write("flash_videoplayer");

Removing a CVS tag

2008-02-07T09:39:00.000-08:00

The following commands will allow you to execute the cvs command without having to be in a cvs directory:

export CVS_RSH=ssh
cvs -d :ext:{user}@{host name or IP}:/source/cvs -q rtag -d {tag} {absolute location to module}

example:
cvs -d :ext:mtan@172.16.100.123:/source/cvs -q rtag -d MLB_
QA bamnet/tiers/web/axis2/modules/appaccount/auth-service

Axis2 Container Error: Processing Operations Modules ClassNotFoundException Error in loading message receiver

2008-01-16T09:29:00.000-08:00

Error:
org.apache.axis2.deployment.DeploymentException: ClassNotFoundException Error in l
oading message receiver tier.ws.migration.axis2.MLBUserWSInOutMessageReceiver; nested exception is:
java.lang.ClassNotFoundException: tier.ws.migration.axis2.MLBUserWSInOutMessageRec
eiver at org.apache.axis2.deployment.ServiceBuilder.populateService(ServiceBuilder.java:
329)

Cause:
You are attempting to use a service compiled in JDK 1.5 in a Axis2 container running under JDK 1.4.

Solution:
Compile the service using JDK 1.4

References:
http://www.mail-archive.com/axis-user@ws.apache.org/msg21397.html
http://issues.apache.org/jira/browse/AXIS2-1670

Decompressing a tgz file

2008-01-14T10:02:00.001-08:00

gzcat (file.tgz) | tar xvf -

or

tar -xzvf (file.tgz)

Sun Java System Web Server 6.1 - Proxying

2007-12-19T15:01:00.000-08:00

We are currently inquiring about the use of directives as a way to proxy requests from one url to another server. Proxies can be used for different use cases. For one, if you would like to simply redirect requests from a legacy web service to a new web service, you could want to use proxies.

There are three options available to proxy requests. Each provide a partial solution for proxying but none provide a full one. They are listed below in order of complexity.

A) Using the NameTrans 'redirect' directive.

The documentation indicates that this directive can redirect URLs coming into the web server to another web server at a particular path. It is configured in the following way:

Steps:
1) Make a copy of the obj.conf in the same folder and rename the file as desired. This file will contain the NameTrans directive to redirect the requests.
2) Add the following directive to the new copy of the obj.conf before the NameTrans ntrans-j2ee directive, like below:

<Object name="default">
AuthTrans fn="match-browser" browser="*MSIE*" ssl-unclean-shutdown="true"
NameTrans fn=redirect from=/ws/services/ url=http://dev-a.services.bamnetworks.com:52070/ws/services/
NameTrans fn="ntrans-j2ee" name="j2ee"
...

3) Configure a new virtual server class (VSCLASS) in server.xml.
4) Configure the new virutal server class to use the new obj.conf like below:

<VSCLASS id="vsclass2" objectfile="obj2.conf" >

5) Add the web application instance on which requests will be proxied under this virtual server class.

Disadvantages:
1) Redirect Response code: This directive actually will return a response code of 301 Permanently Moved back to the client requesting the server. The client is responsible for automatically redirecting to the new URL. This is however not default behavior of web service clients, but is for web browsers.

Note: We tried to use this solution for redirecting our web service clients but the generated client does not automatically redirect to the new URL given this HTTP response code.

2) Cross-browser issues: This directive does not solve cross-browser issues either. Although the browser will redirect automatically to a web service, it will not be able to accept incoming data from a domain different from the domain of the current page making the HTTP requests.

B) Using the Reverse Proxy Plug-in.

Actionscript Arrays displayed as objects using typeof operator

2007-12-10T07:26:00.000-08:00

The typeof operator applied to an Array object does not display as "array". It still displays as "object".

How to Retrieve FlashVars Data in ActionScript 3.0

2007-12-03T07:55:00.000-08:00

You would like to retrieve variables from the embed Flash object as in the following example:

root.loaderInfo.parameters

References: How to Retrieve FlashVars Data in ActionScript 3.0

Struts Error Message - ???en.ProfileProperty.error.message???

2007-11-15T13:26:00.001-08:00

error
???en.ProfileProperty.error.message???

environment
You have a Struts web application. The error messages are configured through the applicationResoources.properties file. Whenever these properties file is changed, the error messages may now be configured differently and will result in the above unrecognizable error message. This seems to be happening in only this particular error message. Other messages are working correctly.

possible causes:
The following Struts configuration files may be related to the misconfiguration:

struts-config.xml
applicationResources.xml

solution
You may either include dom.jar or xml-apis.jar in your classpath.

Flash verus Java: Differences

2007-10-26T21:30:00.000-07:00

As a Java developer, moving to Flash should not be too difficult of a task. Actionscript 3.0 contains many features of the Java language, but also has tremendous amount of other features related to animations that Java does not have. It is these latter features that will require a slower learning curve for a Java developer. Here are couple of important similarities and differences that I have encountered related to the design, structure and syntax of the Actionscript language as I was reading a book. These differences are more oriented toward a Java developer moving to Actionscript as opposed to a Flash developer moving to Java.

Conceptual Differences

1. Variable declaration

Variables in Actionscript do not have a type, as opposed to Java where all variables must be assigned a type. Although one could stipulate that assigning a Java variable as a java.lang.Object could simulate an untyped Actionscript variable, the same can be done to an Actionscript variable. Although, the variable of a type Object is still a typed variable. The difference lies in the fact that an untyped Actionscript variable can be assigned a primitive data type value or an Object type, where in Java it would not be possible for a single variable to be assigned both a primitive data type and an Object at the same time.

2. Function declaration

Despite the syntactical differences, there are also two conceptual differences in function/method declarations between Actionscript and Java.

(1) The first difference is that functions do not need to declare a return type. This is to support older versions of Actionscript.

(2) The second is that functions can declare initial values for its parameters in Actionscript. Initialized parameters of a function are not required to be passed to the function, while uninitialized parameters of a function are required to be passed. Whether they will cause compile errors is something i do not yet know.

3. Function passed as value

One of the more powerful features in Actionscript is the ability to assign a variable to a reference to a function. This is quite a powerful feature in Actionscript and perhaps provides a short cut for coding.

This feature is actually used for event handling and animation, the forte of Actionscript.

4. Nested Functions

Functions can be declared within another function.

5. Package-level, Source-File-Level, And Global Functions

One can create functions within a package (package-level). Package-level functions are accessible only within the package.

Source-file-level functions are rarely used because they can be replaced with private static functions within a package.

Global functions are defined in the unnamed package and are accessible by any class or package without an import.

All these are not concepts within Java. In Java, all functions are always associated with a class.

6. Protected and default access-control modifiers.

The protected and default access modifiers of Actionscript and Java have different definitions. The protected modifier in Java allows classes within the same package and any subclasses to access the class or variable on which the protected modifier has been declared, while in Actionscript, the protected modifier allows only subclasses to access the class or variable. Therefore, the Actionscript modifier is more restrictive, but in my opinion, makes more sense.

The default modifier in Java, which is designated with no keyword but aka package-private, only allows classes within the same package to access the class or variable, while, in Actionscript, the default or internal modifier allows classes within the same package and subclasses to access the class or variable. Essentially, the internal modifier has the same access control as in Java's protected modifier.

8. Overloading Methods in Subclasses

9. No Abstract Classes

10. Reflection replaced with built-in operators.

11. Arrays are different in Actionscript.

Arrays in Actionscript are not associated with a particular class or type as in Java. So, there is only one array type in Actionscript as opposed to Java where there can be an infinite number of array types according to the type the array has been declared with. This single array type in Actionscript is used to hold all types within the same array.

The array in Actionscript is also dynamically sized and therefore will never throw an error if the initial capacity of the array has been exceeded when attempting to add new elements beyond the size of the array. In Java, an array is always initialized with an initial capacity and cannot be changed after instantiation. Instead, the ArrayList can be used in place of the fixed-sized array.

Unlike the Java array, the Actionscript array has methods used for modifying its contents. Both array types allow you to directly modify its contents using the bracket notation. However, the Actionscript array defines modification methods, listed in the following: push, unshift, splice, shift, pop, concat, delete. This allows the array to be used as a stack.

One other trivial but nice feature of the Actionscript array is that it prints out as a comma-delimited list of element values. No more weird string representations of arrays! (Athough in Java 1.5, there is a new method that prints out Arrays nicely, Arrays.toString()).

12. Dynamic Actionscript

An entirely different concept in Actionscript is the ability to dynamically create or add new instance variables and methods to classes or dynamically create new classes. There is no analogous concept in Java.

Only Actionscript classes that have been defined as

13. Actionscript Lookup Tables versus Java Collections Map

The Java Collections framework has revolutionalized the way Java developers use data structures in their programs. The lead designer of the Collections Framework, Joshua Bloch, who also wrote a highly acclaimed and one of the most useful Java programming books, called Effective Java, is a prominent Java architect among the Java community. His framework has won an award for Best Java Class Library.

One of the collection classes in the framework is a Map. There is not equivalent class in Actionscript. Instead, the ability to dynamically add instance variables to a dynamic object replaces the Map concept.

Feature Differences

1. Setter / Getter functions

2. Constants and the final modifier for instance variables.

3. The switch statement is more powerful in Actionscript.

The Java switch statement only allows the primitive data types to used as values in the switch statement. One of the complaints in Java is that you cannot use Strings or perhaps Objects within the switch statement. Fortunately, in Actionscript, you can! However, there is fine print related with this feature. In a switch statement, it uses a strict equality operator on determining equality of the switch values.

4. Actionscript has additional operators that Java does not have. Some are quite powerful.

Some of these additional operators include those that backwards-compatible for older versions of Actionscript. These will not be included here as they should not be used in new code.

5. Actionscript has built-in XML operators.

Syntactical Differences

1. Constructors

2. Overriding methods

3. void vs. null

Conceptual Similarities

1. Object-oriented programming

Actionscript 3.0 contains interfaces, classes, instance methods, static methods, instance variables, static variables.

Flash Questions

2007-10-23T11:26:00.000-07:00

1. Can two flash players embedded on the same page talk to each other?

2. Is it typical for flash players to be configured through a separate config file located on the machine?

3. NetStream is responsible for playing

Java To XML Technologies

2007-10-22T07:44:00.001-07:00

I am trying to find the most suitable Java to XML utility that will provide easy to read XML that defines a Java object. Here are some sample ones below:

1. XML Encoder

sample:

JFrame class

XML:

<?xml version="1.0" encoding="UTF-8"?>
<java version="1.0" class="java.beans.XMLDecoder">
<object class="javax.swing.JFrame">
<void property="name">
<string>frame1</string>
</void>
<void property="bounds">
<object class="java.awt.Rectangle">
<int>0</int>
<int>0</int>
<int>200</int>
<int>200</int>
</object>
</void>
<void property="contentPane">
<void method="add">
<object class="javax.swing.JButton">
<void property="label">
<string>Hello</string>
</void>
</object>
</void>
</void>
<void property="visible">
<boolean>true</boolean>
</void>
</object>
</java>
advantages:

completely comprehensive
part of the Java API

disadvantages:

verbose

2. JSX - Java Serialization to XML

sample XML:
N/A

advantages:

disadvantages:

not mature product
not free
no sample provided

3. XStream

sample:

Java:

public class Person {
private String firstname;
private String lastname;
private PhoneNumber phone;
private PhoneNumber fax;
// ... constructors and methods
}

public class PhoneNumber {
private int code;
private String number;
// ... constructors and methods
}

XML:

<person>
<firstname>Joe</firstname>
<lastname>Walnes</lastname>
<phone>
<code>123</code>
<number>1234-456</number>
</phone>
<fax>
<code>123</code>
<number>9999-999</number>
</fax>
</person>

advantages:

no mappings required

disadvantages:

4. Castor

References: Java Boutique Tutorial: Java To XML and Back Again with Castor XML

sample:

Java:

private List myList = new ArrayList();

public void setMyList(List myList) {
this.myList = myList;
}

public List getMyList() {
return this.myList;
}

public Person(String name, String email, String phone, List myList) {
this.name = name;
this.email = email;
this.phone = phone;
this.myList = myList;
}

XML:

<?xml version="1.0" encoding="UTF-8"?>
<person>
<myList xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:type="java:java.util.String">
List#1
</myList>
<myList xsi:type="java:java.util.String">
List#2
</myList>
<email>prokhorenko@gmail.com</email>
<name>Olexandr Prokhorenko</name>
<phone>123-555-1234</phone>
</person>

advantages:

comprehensive
mature product

disadvantages:

requires a mapping file

5. Java2XML

References: Java Boutique Tutorial: Java To XML and Back Again with Castor XML

sample:

Java:

public class HelloWorld
extends Thread
{
private int N;

private long sleep;

public HelloWorld(int N, long sleep)
{
this.N = N;
this.sleep = sleep;
}

public void run()
{
for (int i = 0; i < hw =" new"> XML:
<!-- Generated by Java2XML http://java2xml.dev.java.net/ -->
<java-source-program>
<java-class-file name="helloworld.java">
  <import module="java.util.*"/>
  <class name="HelloWorld" visibility="public">
      <superclass name="Thread"/>
      <field name="N" visibility="private">
<type primitive="true" name="int"/>
      </field>
      <field name="sleep" visibility="private">

          <type primitive="true" name="long"/>
      </field>
      <constructor visibility="public" name="HelloWorld">
          <formal-arguments>
              <formal-argument name="N">
                  <type primitive="true" name="int"/>
              </formal-argument>
              <formal-argument name="sleep">
                  <type primitive="true" name="long"/>

              </formal-argument>
          </formal-arguments>
          <assignment-expr op="=">
              <lvalue>
                  <field-access field="N">
                      <this/>
                  </field-access>
              </lvalue>
              <var-ref name="N"/>

          </assignment-expr>
          <assignment-expr op="=">
              <lvalue>
                  <field-access field="sleep">
                      <this/>
                  </field-access>
              </lvalue>
              <var-ref name="sleep"/>
          </assignment-expr>

      </constructor>
      <method name="run" visibility="public">
          <type name="void" primitive="true"/>
          <formal-arguments/>
          <block>
              <loop kind="for">
                  <init>
                      <local-variable name="i">
                          <type primitive="true" name="int"/>

                          <literal-number kind="interger" value="0"/>
                      </local-variable>
                  </init>
                  <test>
                      <binary-expr op="<">
                          <var-ref name="i"/>
                          <field-access field="N">
                              <this/>
                          </field-access>

                      </binary-expr>
                  </test>
                  <update>
                      <unary-expr op="++" post="true">
                          <var-ref name="i"/>
                      </unary-expr>
                  </update>
                  <block>
                      <send message="println">

                          <target>
                              <field-access field="out">
                                  <var-ref name="System"/>
                              </field-access>
                          </target>
                          <arguments>
                              <literal-string value=""Hello World""/>
                          </arguments>
                      </send>

                      <try>
                          <block>
                              <send message="sleep">
                                  <target>
                                      <var-ref name="Thread"/>
                                  </target>
                                  <arguments>
                                      <var-ref name="sleep"/>
                                  </arguments>

                              </send>
                          </block>
                          <catch>
                              <formal-argument name="e">
                                  <type name="InterruptedException"/>
                              </formal-argument>
                              <block>
                                  <send message="printStackTrace">
                                      <target>

                                          <var-ref name="e"/>
                                      </target>
                                      <arguments/>
                                  </send>
                              </block>
                          </catch>
                      </try>
                  </block>
              </loop>

          </block>
      </method>
      <method name="main" visibility="public" static="true">
          <type name="void" primitive="true"/>
          <formal-arguments>
              <formal-argument name="args">
                  <type name="String" dimensions="1"/>
              </formal-argument>
          </formal-arguments>

          <block>
              <local-variable name="hw">
                  <type name="HelloWorld"/>
                  <new>
                      <type name="HelloWorld"/>
                      <arguments>
                          <literal-number kind="interger" value="10"/>
                          <literal-number kind="interger" value="1000"/>
                      </arguments>

                  </new>
              </local-variable>
              <send message="start">
                  <target>
                      <var-ref name="hw"/>
                  </target>
                  <arguments/>
              </send>
          </block>

      </method>
  </class>
</java-class-file>
</java-source-program>
 advantages:
comprehensive
mature product
free

disadvantages:
complicated XML
6.  Jato

References: Javaworld Article: Jato: The new kid on the open source block

disadvatages:

fairly new product

7.  JiBX

advantages

disadvantages:

requires binding file to define the XML

JAXRPC Error - java.lang.ClassCastException

2007-10-16T13:13:00.000-07:00

error
java.lang.ClassCastException
at com.sun.xml.rpc.client.StubBase._postSendingHook(StubBase.java:231)
at com.sun.xml.rpc.client.StreamingSender._send(StreamingSender.java:324)
at com.bamnetworks.services.boc.csp.client.impl.jaxrpc.generated.CspWsInterface_Stub.getPlanSummary(CspWsInterface_Stub.java:86)
at com.bamnetworks.services.boc.csp.client.CspClient.getMnCollegescholarshipInterface(CspClient.java:63)

environment
JAXRPC client resides inside Axis2 container.
The following jars are included in the Axis2 service lib: saaj-api.jar and saaj-impl.jar.

However, the Axis2 container also contains the following jar: axis2_saaj-1.1.jar

possible causes:
The above two jars are conflicting with each other. What is happening is that the axis2 saaj implementation of the message factory is being used instead of the sun saaj implementation of the message factory.

Therefore, the axis2 saaj implementation is creating messages that the JAX-RPC client is not expecting. It is expecting Message objects of a different type.

Axis2 saaj Message class: org.apache.axis2.saaj.SOAPMessageImpl
Sun saaj Message class: com.sun.xml.messaging.saaj.soap.MessagingImpl

It is this discrepancy in the classes that is causing the above ClassCastException. Within the StubBase it is expecting the type to be of the Sun implementation, but instead is getting the Axis 2 implementation.

solution

solution 1) Setting a system property and moving jars to the Axis 2 container lib

Move the saaj-impl.jar and FastInfoSet.jar to the Axis2 container lib from the Axis2 service's lib.

Then, within the code, set a system property that indicates which message factory should be used to construct SOAP messages for web services before the JAX-RPC client operation is called, as in the following code:

System.setProperty("javax.xml.soap.MessageFactory", "com.sun.xml.messaging.saaj.soap.ver1_1.SOAPMessageFactory1_1Imp");

solution 2) Keep the JAXRPC jars in the service lib directory and modify the JAXRPC stub to use the correct MessageFactory.

This is particularly a hacky way of embedding a JAXRPC client within a Axis2 service, but this seems to be the only way to do without including the JAXRPC client jars in the Axis2 container lib.

In this solution, you need to modify the JAXRPC stub to

a) Create a custom MessageContext that extends from com.sun.xml.rpc.soap.message.SOAPMessageContext

In this custom class, override the methods called createMessage(useFastInfoset, acceptFastInfoset) and createMessage(useFastInfoset, acceptFastInfoset) to use the com.sun.xml.messaging.saaj.soap.ver1_1.SOAPMessageFactory1_1Impl() as the MessageFactory.

b) Create a custom ClientTransport that extends from HttpClientTransport.

In this custom class, override the readResponse() method.

Detecting Broken Images with Javascript

2007-10-12T08:18:00.000-07:00

An awesome link to determine whether the image is broken within the page. The following is exact copy from the link in the References below. Please refer to the link below.

<script language="javascript">

</script>

(If you feel that an exact copy of the code in this blog violates your rights, please tell me and I will take this code down. The link below will still remain. Thanks!)

References:
http://talideon.com/weblog/2005/02/detecting-broken-images-js.cfm

Cool Recommended New Technologies

2007-10-10T08:19:00.000-07:00

Testlink - http://testlink.org/wordpress/

Axis2 Client Error - NullPointerException at ClientUtils.inferIntTransport

2007-09-24T08:00:00.000-07:00

error
java.lang.NullPointerException
at org.apache.axis2.description.ClientUtils.inferInTransport(ClientUtils.java:85)
at org.apache.axis2.description.OutInAxisOperationClient.execute(OutInAxisOperation.java:253)

environment
Attempting to connect to a web service using an Axis2 client.

possible causes:
You are missing a jar in your classpath.

solution
The missing jar is the commons-httpclient.jar. Add this jar to your classpath.

Classpath Problem - javax.xml.stream.FactoryConfigurationError: Provider com.bea.xml.stream.MXParserFactory not found

2007-09-21T15:17:00.000-07:00

error
com.bea.xml.stream.MXParserFactory not found

environment
The following xml jars are in my classpath:
xerces.jar - org.apache.*, org.w3c.dom.html.*, org.w3c.dom.ls.*
xercesImpl.jar - com.sun.org.apache.*

possible causes:
You do not have a StAX implementation in your classpath.

solution
You must provide an implementation of StAX in your classpath.

references
http://forums.java.net/jive/thread.jspa?messageID=117971

Secure Copy

2007-09-20T12:59:00.000-07:00

Copy local file to remote location:

scp <local-file-path>/<file-name> <username>@<server-name>:<location-from-home-dir>

Copy remote file to local location:

scp <username>@<server-name>:~/<path-to-file>/<file-name> <local-directory-location>

Mule Logging - How to specify a different location for the mule logs

2007-09-20T10:50:00.000-07:00

bin/mule script

Create and export an environment variable pointing to your desired log location.

export LOG_DIR=/data/logs/your-desired-log-location

conf/wrapper.conf file

Refer to the environment variable exported in the mule script in the wrapper.logfile property in the wrapper.conf configuration file.

#********************************************************************
# Wrapper Logging Properties
#********************************************************************
......
# Log file to use for wrapper output logging.
wrapper.logfile=%LOG_DIR%/%MULE_APP%.log
......

Running an SSH Tunnel in the background

2007-09-13T07:40:00.000-07:00

nohup ssh -v -L <local.port>:<destination.ip>:<destination.port> username@<remote.ip>

Note: You cannot use an alias for the ssh command or else it will not work. You must use the ssh command directly in the nohup command.

Mule Error: Remote Debugging a Mule Server

2007-09-07T12:21:00.001-07:00

The article given in Remote Debugging a Mule Server does not work on some operating systems. You must include each JVM option on a separate line as in the following example.

# uncomment this line to debug remotely, the application will wait for the external debugger to connect
# IMPORTANT: change the wrapper.java.additional. parameter to be the actual consecutive number,
# depending on the number of additional parameters above
wrapper.java.additional.4=-Xdebug
wrapper.java.additional.5=-Xnoagent
wrapper.java.additional.6=-Djava.compiler=NONE
wrapper.java.additional.7=-Xrunjdwp:transport=dt_socket,server=y,suspend=y,address=5005

References:
http://mule.codehaus.org/display/MULE/Remote+Debugging+a+Mule+Server
http://www.mail-archive.com/user@mule.codehaus.org/msg04986.html

Migrating from Mule 1.3.3 to Mule 1.4.1

2007-09-07T11:16:00.001-07:00

1. Change the MULE_HOME to point to the Mule 1.4.1 home directory.

2. Update the 'mule' script in the bin folder with the Mule 1.4.1 version.

XML Error: NoClassDefFoundError: org/w3c/dom/ranges/DocumentRange

2007-08-30T12:27:00.001-07:00

error
java.lang.NoClassDefFoundError: org/w3c/dom/ranges/DocumentRange

environment
The following xml jars are in my classpath:
xerces.jar - org.apache.*, org.w3c.dom.html.*, org.w3c.dom.ls.*
xercesImpl.jar - com.sun.org.apache.*

possible causes:
You are missing the DocumentRange class in your classpath.

solution
You may either include dom.jar or xml-apis.jar in your classpath.

Pivot Tables

2007-08-29T09:35:00.000-07:00

Example:

SELECT  *
FROM  (SELECT job,
     sum(decode(deptno,10,sal)) DEPT10,
     sum(decode(deptno,20,sal)) DEPT20,
     sum(decode(deptno,30,sal)) DEPT30,
     sum(decode(deptno,40,sal)) DEPT40
     FROM scott.emp
     GROUP BY job)
ORDER BY 1;

If you are pivoting over varchar fields, you can use the max or min aggregate function because these can operate on varchar fields.

Example:

SELECT language_id,
     max(decode(greeting,'hello', sal)) english,
     max(decode(greeting,'konichiwa',sal)) japanese,
     max(decode(greeting,'ni hao',sal)) chinese,
     max(decode(greeting,'ola',sal)) spanish
FROM language.phrases
GROUP BY language_id

References:
How does one code a matrix/crosstab/pivot report in SQL?
Pivot Table Techniques

Java XML Binding Frameworks

2007-08-28T08:07:00.001-07:00

Apache Axiom ~ AXis Object Model
Castor XML
JAXB ~ Java Architecture for XML Binding
JBind
JiBX
XMLBeans

Dom4j Schema Validation

2007-08-28T07:35:00.000-07:00

XML:

<?xml version="1.0"?>
<reportingConfig xmlns="http://services.bamnetworks.com/reporting/"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://services.bamnetworks.com/reporting/ reporting-config.xsd">
...
</reportingConfig>

XSD:

<?xml version="1.0" encoding="UTF-8"?>
<xsd:schema xmlns="http://www.w3.org/2001/XMLSchema"
targetNamespace="http://services.bamnetworks.com/reporting/"
xmlns:tns="http://services.bamnetworks.com/reporting/"
xmlns:xsd="http://www.w3.org/2001/XMLSchema"
elementFormDefault="qualified">
...
</xsd:schema>

Java code:

import org.dom4j.io.SAXReader;
import org.dom4j.Document;
....

SAXReader reader = new SAXReader(true);

reader.setFeature("http://apache.org/xml/features/validation/schema", true);

// set the validation feature to true to report validation errors
reader.setFeature("http://xml.org/sax/features/validation", true);

// set the validation/schema feature to true to report validation errors against a schema
reader.setFeature("http://apache.org/xml/features/validation/schema", true);

// set the validation/schema-full-checking feature to true to enable full schema, grammar-constraint checking
reader.setFeature("http://apache.org/xml/features/validation/schema-full-checking", true);

Document document = reader.read(reportingConfigURL);