IOC and HLA folder structures.

Software packages are classified by cram into various package types. Package types are nothing more than a name and two folders but there are these kinds of package types

• EPICS IOC software packages
• HLA software packages
• Tools/script - This category also includes scripts like cram.

IOC folder structures.

IOC software packages are those that have multiple instances of the same software package in the same facility. A version of an EPICS IOC software package typically has this folder structure.

The source code for the IOC is typically in an app folder which gets compiled into a bin folder. Each IOC instance has a folder in the iocBoot folder - the folder name is identical to the IOC name. Each iocBoot folder has a st.cmd that contains the boot commands for that IOC. These are mostly identical - typically, only the msi macro expansions vary from IOC to IOC but this need not be the case. Some IOC software packages can have multiple executables that cater to completely different hardware; however, the folder structure even in these cases is as shown here.

Each site/facility has a release folder where the various versions of the IOC software packages are kept. This is sometimes referred to as iocTop and has the following folder structure.

Each site/facility has a startup folder where the various initial startup scripts/boot images are kept. This is a fixed location and is often used in DHCP or /etc/init.d configuration. This is sometimes referred to as iocCommon.

For EPICS IOC software packages, cram uses two soft links to control a master release and a IOC specific release.

• In iocTop, there is a softlink called current that points to the current master release for this software package.
• In iocCommon, for each IOC, there is a soft link called iocSpecificRelease that typically points to the current master release. However, to use a release other than the current master release for an IOC, the iocSpecificRelease changes from pointing to the current master release and points directly to the appropriate release.

HLA folder structures.

HLA applications have a simpler folder structure. HLA applications do not have multiple instances like EPICS IOCs. Each facility typically has only one instance of the software package. For this reason, a single softlink is sufficient to switch releases. This softlink has the same name as the name of the package.

Tools/script folder structures.

cram is also used to manage the various scripts that are used our facilities. For example, cram itself is one such software package. Typically, a site specific folder called tools/script is added to the PATH to facilitate running scripts like cram from the command line. In a fashion similar to the HLA apps, the tools/script folder also contains a release folder where the various software package versions are maintained. In a fashion similar to the HLA apps, there is a softlink with the same name as the package name that points to the current version of the software package. Individual scripts are softlinks to <package name>/<script name>. For example, cram points to multi_site_build/cram.

Note that the folder structure for tools/script is identical to the folder structure for HLA applications.