application types?

[jjacott]

What applications/platforms do you find in the typical PCI environment?

Java? .net? C++/C#?

Windows? Solaris? Linux?

[jbhall56]

It depends on whether we are talking processor, acquirer, merchant, etc.

Merchants can be all across the board.

The "Big Box" types typically are going to have some sort of customized POS solution. It may have originally started out as something from Micros, IBM, NCR, etc. but has been customized into something that no longer looks like what it was originally. In the back office, you will find financial and inventory management software like SAP, Oracle or some similar ERP solution(s).

For middle-market merchants, you are more likely to find standard POS solutions from Micros, IBM, NCR, etc. There may be some modifications, but they are likely made by the vendor on the merchant's behalf. Back office solutions may also be SAP, Oracle, Peoplesoft, JD Edwards, etc. You may also find Microsoft Great Plains Dynamics or other PC-based ERP solutions.

Small merchants may have no POS solution beyond the VeriFone type of stand-alone card devices. They may have a VeriPhone that integrates with a PC-based POS. Or they may have the Cherry-type keyboard that has the card swipe built into the keyboard that integrates with some sort of PC-based POS. Back office software may be anything from Great Plains to QuickBooks to the good, old manual bookkeeping method.

On the processor and acquirer side of things, they may have a certain amount of custom software along with an SAP, Peoplesoft, Oracle, etc. for financial and other business applications. They may have all custom written software.

As you can see, it varies widely.

[jbhall56]

Forgot to address the language/OS pieces of your question.

Pick any or all of your suggestions. Add in Python, Perl, CGI, COBOL (yes, it's not dead yet), assembler and some of the older languages as well as the appropriate online application generators.

On the OS side of the equation, there's some move back to mainframes (zOS, AIX, iOS - OS/400) for load balancing and capacity capability. Bring in FreeBSD, Fedora Core and ubuntu for open source solutions (i.e., "free'). Plus all of the OSes you mention.

Don't forget about virtualization, particularly if you are talking about ISPs/ASPs. Most will be using VMware ESX, but XEN and Virtual Iron are gain market share. Any ISP/ASP using virtualization will also likely be using automated provisioning which takes most, if not all, of the human equation out of setting up a virtual server.

I really don't think you can make any blanket statements about any languages or OSes.