1. Aspect oriented programming (AOP)

In the wikipedia example about AOP, transactions, security and logging represent cross-cutting concerns. If we need to change one of these (ex. security) – then it will be a major effort, since the concerns are tangled and the related methods appear scattered around all the code.

AOP attempts to solve this problem by allowing to express cross-cutting concerns in stand-alone modules called aspects. Aspects can contain
– advice – code joined to specified points in the program and
– inter-type declarations – structural members added to other classes.

Drawbacks: If a programmer makes a logical mistake in expressing crosscutting, it can lead to widespread program failure.
Conversely, another programmer may change the join points in a program in ways that the aspect writer did not anticipate, with unforeseen consequences.

2. HTTPS and MTU Path discovery

I recently encountered this interesting problem with HTTPS and MTU. It is explained entirely by Mark Maunder – ‘Routers treat HTTPS and HTTP traffic differently‘. I will just summarize it:
– HTTPS servers set the ‘Do not fragment’ IP flag
– if a server sends a big HTTPS packet and a router does not allow that packet size, then the router will not break that packet (see previous point).
– so the router will simply drop the packet and send back an ICMP (Internet Control Message Protocol) message telling the host to reduce the MTU size and resend the packet
– but if the network administrator decided to block all the ICMP traffic, then the host will never see the problem
– the solution in my case was to decrease the MTU size (1400)

The same issue described also here.

3. Information security standards

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Quick note about a problem with the cflayout tag – one of the Adobe’s attempts to play with the front-end. In my opinion – one of the places where ColdFusion no longer makes sense and should be replaced with a more robust alternative, like jQuery UI.

The problem: When using cflayout and cflayoutarea, if the content inside the cflayoutarea is dynamically redrawn, then the height of the layout area does not change. More details on the Adobe forum: https://forums.adobe.com/thread/565912

The solution:
Use the following styles:

<cflayout style="">
<cflayoutarea style="overflow-y:scroll; height: 450px;">

The drawback of this approach is that you need to hardcode the height of the layout area and accept the vertical scroll, but in some case this is exactly what you need.
The path to the solution was found on StackOverflow, as usual 🙂

Below is a simple ColdFusion application architecture using Apache as web server and Tomcat as JEE application server.

1. Request workflow

Apache: In the Apache configuration file we have a virtual host <VirtualHost host1:80> with DocumentRoot /var/www/theColdFusionApp
Apache receives the request – example: http://123.45.67.89:80.
Hosts file: In /etc/hosts the host host1 is associated with the IP: 123.45.67.89 host1
AJP module: If there is a non-CF request, Apache serves the request itself (ex. html, css, js, image). If there is a CFM request, the AJP module forwards it to Tomcat: ProxyPassMatch ^/(.*\.(cf[cm]|cfml))$ ajp://host1:8080/$1 (Apache config file)
Tomcat has an AJP connector on that port: <Connector port="8080" protocol="AJP/1.3"/>
and an engine to process the requests:

<Engine name="Catalina" defaultHost="host1">
 <Host name="host1"  appBase="webapps">
    <Context path="" docBase="/var/www/theColdFusionApp/"/>
 </Host>

Both entries above are in the Tomcat server.xml config file.
Application folders: In /var/www/theColdFusionApp we have both the CF files (WEB-INF and CFIDE folders) and the actual application folders. More details below.

2. Folder structure and configuration files

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