Snarl is a monitoring tool for dynamic web applications.
Version: 5.0.9Snarl is a monitoring tool for dynamic web applications.
Operating System: Linux
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 daemon's 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.
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 don't 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 package's source code and type `./configure' to configure the package for your system.
If you're 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 package's 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.