Not a day goes by without a blogathon on the advantages of "free software" vs. nefarious proprietary information technology (IT) suppliers. There are even constant debates about the degrees of freedom within the OSS world. But the real meaningful OSS freedom for users, independent software vendors (ISVs), software as a service (SaaS) providers and original equipment manufacturers (OEMs) is the freedom of choice that OSS has brought to the middle of the IT stack. Because of that freedom, OSS has grown most rapidly in the most boring and non-controversial place in the industry, the midstack. (Actually one could argue that print servers are the most boring category in the IT market but midstack software is a close second.)

To be clear, by midstack software I mean the software that "glues" together application logic and data to users and devices via browsers, portals and other interfaces, human or otherwise. I refer to the following:

• application, web and portal server software
• the classic middleware categories of the transaction monitor (TM), message-oriented middleware (MOM), and MOM's modern day equivalent, the enterprise service bus (ESB)
• the most modern midstack category-integration servers for data or logic-and its first cousin, the business process management (BPM) platform
• all related adapters and connectors, including software that connects mainframe and AS/400-family data and applications to desktops and browsers
  

Much of it is cross-industry but an increasing set is industry-specific. I used to call midstack software "middleware" but the term has been hijacked by IBM, Oracle and others to mean a lot of software that isn't in the middle of anything. Despite the efforts of the large IT-supplier PR machines, I do not mean business intelligence (BI) software such as Oracle's Hyperion Essbase, collaboration software products such as IBM Lotus Notes, or development tools from any supplier. I mean midstack.

Midstack software is deployed for load balancing, integration, transaction management, and other "services" functionality to enable intra- and inter-organizational interoperability. In this ebizQ.net feature article, I am going to overview the categories of mid-stack software in OSS terms. This article is the first in a monthly series that will look at each type of mid-stack software individually in more detail.