Thursday, May 19, 2016

How do I enable rndc on Mac OS X El Capitan (10.11.5)

So I was trying to figure out how to enable rndc on El Capitan so I could dump the DNS cache to check name resolution. I could run the command from the command line, but alas it would indicate that it was not listening on port 953. I tried the alternate port 54, but again to no avail. As it turns out, I needed to modify the named.conf file controls section to get it to work. The named.conf file is located at /Library/Server/named/named.conf. You will need to modify it as the super user using sudo.

Note: I have the Apple Server Application installed

sudo nano /Library/Server/named/named.conf


The existing file should have a controls section that looks similar to the one below.

controls {
        inet ::1 port 54 allow {
                "any";
        } keys {
                "rndc-key";
        };
};

I added the following inet 127.0.0.1 allow {localhost;};. So now the configuration looks like:

controls {
        inet 127.0.0.1 allow {localhost;};
        inet ::1 port 54 allow {
                "any";
        } keys {
                "rndc-key";
        };
};


You will need to restart named service using the following commands.

sudo launchctl stop org.isc.named
sudo launchctl start org.isc.named

You should be able to use rndc. To check, you can issue the following command:

sudo rndc status

version: 9.9.7-P3 
CPUs found: 8
worker threads: 8
UDP listeners per interface: 4
number of zones: 100
debug level: 0
xfers running: 0
xfers deferred: 0
soa queries in progress: 0
query logging is OFF
recursive clients: 0/0/1000
tcp clients: 0/100
server is up and running

Thursday, March 24, 2016

JSF 2.2 Tip of the Day: Using Hibernate Validators with JSF

Introduction

Hibernate validators offer a plethora of validators to make your development work much easier. Some of the common ones that are used are @NotNull, @NotBlank, and @NotEmpty. To take advantage of these validators, and avoid some misconceptions, a little information needs to be provided.

@NotNull

Everyone likes this particular annotation, and it can be a real life saver. However something that often catches developers using it on JSF is that JSF treats empty form fields as empty strings. This is not the same as null. So if you want JSF to capture these values and treat them as null values, you need to tell JSF to do so. This is accomplished by adding the following context parameter to the web.xml file.
    <context-param>
         <param-name>javax.faces.INTERPRET_EMPTY_STRING_SUBMITTED_VALUES_AS_NULL</param-name>
         <param-value>true</param-value>
    </context-param>
Once this is added to the context, all blanks will be treated as null values. Be mindful of any side effects created from this change.

@NotEmpty

This validator causes a lot of confusion. The value can not be null, but can be any character including whitespace, e.g. You can enter a space, and it will accept it.

@NotEmpty

This is the most useful annotation from my standpoint. This makes sure that the input is not null, and is not an empty string like white spaces. This is really what I think most developers are really after anyway. They want to make sure that users fill in form fields.

Code

The code for this project can be found on Github, and includes some additional bonus code such as using locales, and custom messages. The code can be found here: jsf-hibernate-validator.


Tuesday, March 22, 2016

JSF 2.2 Tip of the Day: Using ValueExpressions and VariableMapper to set EL using a PhaseListener

The title seems like a mouthful, and it is. I had some code which I used to demonstrate how to set EL values using a PhaseListener. I was going to delete the code when I decided that it was the second time someone in a short span of time asked me the same question, and I should post how to do it.

The use of a PhaseListener to set EL values seems to the casual observer like Voodoo magic. You will see the EL expressions on the page, and they magically seem to populate. In some ways it is like a classical interceptor which can make your code really seem magical, and lead to confusion. This approach though has its place, and if used correctly can solve a lot of issues. One example is determining if a <ui:include src="XXX" rendered="#{EL_VARIABLE_HERE}" /> should render.

It can also be used to set the src value on the fly. An always popular question on how to resolve.

The project can be found on GitHub here: jsf-ve-phaselistener

So the output looks like a nice set of name value pairs using the Greek alphabet as variable names.



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