Cactus applications are comprised of the Flesh and Cactus Computational Toolkit, distributed by the Cactus team, along with thorns distributed openly or privately by research groups around the world. Typically these thorns are distibuted using a source code versioning system.

To faciliate assembling full Cactus applications, including associated tools, and the sharing of configurations between colleagues, we have revamped the Cactus language for specificing thorn locations as part of thornlists, as well as the GetCactus tool for assembling components (now called GetComponents).

Our new language for specifying Cactus thorns is called the Component Retrieval Language (CRL). The CRL is independent of Cactus and can be used to specify locations of any kinds of components. Wilth Cactus, CRL files (thornlists) can now include the Cactus flesh, parameter files, group configuration files, visualization tools etc.

A new script, GetComponents, has been developed to assemble components based on a CRL file. GetComponents, while developed for Cactus use cases, will work with any CRL file

Notable capabilities of CRL/GetComponents include

  • anonymous and authenticated access
  • support for cvs, svn, mercurial, git, darcs, http
  • mobility of CRL files, which can now be shared (authentication information is not stored in the CRL file itself)
  • support for multiple CRL files makes it possible to integrate shared and personal thornlists easily
  • component lists can be remote (URL)

More information about GetComponents is provided on its home page, summaries relevant for Cactus work are provided below


GetComponents is available from the Cactus web page ` wget chmod 755 GetComponents`

Up-to-date documentation for GetComponents can be seen by executing ./GetComponents --man but basically the synthax is GetComponents [options] [file] or GetComponents [options] [URL] where options are

−−help brief help message
−−man full documentation
−−verbose print all system commands as they are executed
−−debug print all commands to be executed and exit
−−anonymous use anonymous checkout for all components
−−update process all updates
−−root override root directory

Component Retrieval Language (CRL)

The simplest way to understand the CRL language is too look at a good example, e.g. the component list for the Einstein Toolkit includes a range of different repositories.

Formally, the CRL file must have the following syntax:

  1. The first (non‐comment) line must be ’!CRL_VERSION = 1.0’
  2. It will be split up in to multiple sections, with each section corresponding to a repository. The order of the sections is irrelevant.
  3. Each section will contain multiple directives beginning with a !. Required directives are: !TARGET, !TYPE, !URL, and !CHECKOUT. Optional directives are: !ANONYMOUS_USER, !ANONYMOUS_PASSWORD, !LOCAL_PATH, !REPOSITORY_PATH, and !AUTHORIZATION_URL. The shortened directives !ANON_USER, !ANON_PASS, !LOC_PATH, !REPO_PATH, and !AUTH_URL are also recognized.
  4. !TARGET MUST be the first directive for each section. It will specify the directory, in which the components for the current repository will be placed. !TARGET may contain predefined constants i.e. $ROOT, which could represent the root directory for all of the components.
  5. !TYPE specifies the tool used to checkout the components. Currently, cvs, svn, git, http, https, ftp, and hg (mercurial) are supported. 5. !URL specifies the location of the repository for anonymous checkout. !URL may contain variables $1, $2, etc, which will correspond to the directories in the path given by !CHECKOUT. For example, if !URL =$2/trunk and !CHECKOUT = foo/bar, !URL will be interpreted as 6. !AUTH_URL will specify a different location for an authenticated checkout. If both !AUTH_URL and !URL are defined, !AUTH_URL will take precedence.
  6. !CHECKOUT specifies the components to checkout from the repository. !CHECKOUT can contain a path through multiple directories, in which case they must be separated by a /. If there are multiple components to be checked out from a single repository, they should be separated by a newline. Any trailing whitespace or comments will be ignored.
  7. !NAME specifies an alternate name for the component to be checked out. That means that if !TARGET is foo, !CHECKOUT is bar, and !NAME is foobar, the resulting directory tree will be foo/foobar.
  8. !ANON_USER and !ANON_PASS will specify the login credentials for an anonymous cvs checkout from the repository.
  9. !REPO_PATH will specify the location of the item to be checked out within a repository. It can consist of a file path, or $1 or $2, and will essentially serve as a prefix to the checkout path when the script is looking for the checkout item.
  10. Each directive will be followed by optional whitespace, an =, optional whitespace, the corresponding argument, and more optional whitespace. The end of an argument will be indicated by the ! preceding the next directive. The argument may be enclosed in quotes (\” or\ ’), in which case the argument will be taken literally and no variable substitution will occur.
  11. Extra newlines may be inserted between sections for greater clarity, and any comments will be preceded by a #.
  12. There is an optional section that will contain any definitions i.e. $ROOT. These definitions will be preceded by !DEFINE, and then follow the syntax for the directives. Definitions may only be defined once.