Snarl 5.0.9

Snarl is a monitoring tool for dynamic web applications.

Snarl dynamically creates and assembles URL’s and scans them at arbitrary intervals, performs predefined checks on URL content, size and timing, notifies a monitoring application via traps if a predefined error condition (event) has been met and delivers a snapshot of it’s current tests and result at any given time.

Snarl is build as a truly multi-threaded MIB module for net-snmp 5.0.3 and higher. its current monitoring status can be retrieved via the net-snmp daemons snmp request interface.

Configuration of the URL tests is done via a configuration file in a human readable format. all configurations can be hot updated. No data will be lost on reconfiguring a running Snarl.

Snarl is very humble. it can run on an average PC with average sized resources and still is able to monitor up to eight hundred web pages or even more.

Though the only limit should be machine capabilities, the amount of concurrent threads in Snarl has been limited to one thousand parallel monitoring tasks.

The lifetime of a thread is as long as one transaction, usually only a few concurrent threads exist in a typical monitoring environment. a mechanism inside Snarl keeps the amount of concurrent network connections as low as possible by desynchronizing network downloads. This is to account for limits imposed on most machines.

Snarl performs each monitoring test by downloading the content of the monitored URL and thereby causes a http server log file entry on the web server.

Consider this when you monitor web sites that pursue a business model where number of hits is important to the payor or customer.

Installation:

The `configure shell script attempts to guess correct values for various system-dependent variables used during compilation.

It uses those values to create a `Makefile in each directory of the package. It may also create one or more `.h files containing system-dependent definitions.

Finally, it creates a shell script `config.status that you can run in the future to recreate the current configuration, a file `config.cache that saves the results of its tests to speed up
reconfiguring, and a file `config.log containing compiler output (useful mainly for debugging `configure).

If you need to do unusual things to compile the package, please try to figure out how `configure could check whether to do them, and mail diffs or instructions to the address given in the `README so they can be considered for the next release.

If at some point `config.cache contains results you dont want to keep, you may remove or edit it.

The file `configure.in is used to create `configure by a program called `autoconf. You only need `configure.in if you want to change it or regenerate `configure using a newer version of `autoconf.

The simplest way to compile this package is:

1. `cd to the directory containing the packages source code and type `./configure to configure the package for your system.

If youre using `csh on an old version of System V, you might need to type `sh ./configure instead to prevent `csh from trying to execute `configure itself.

Running `configure takes awhile. While running, it prints some messages telling which features it is checking for.

2. Type `make to compile the package.

3. Optionally, type `make check to run any self-tests that come with the package.

4. Type `make install to install the programs and any data files and documentation.

5. You can remove the program binaries and object files from the source code directory by typing `make clean. To also remove the files that `configure created (so you can compile the package for a different kind of computer), type `make distclean.

There is also a `make maintainer-clean target, but that is intended mainly for the packages developers. If you use it, you may have to get all sorts of other programs in order to regenerate files that came with the distribution.