Layered Queueing Network Documentation

• The LQN Tutorial is the best starting point.
• The User Manual for LQNS (Layered Queueing Network Solver User Manual) is essential for use of the solver tool

The original input language is defined informally by executable templates that you can edit, and formally by its grammar

• The LQN basic template is an ASCII input file for basic lqns, fully commented to explain the syntax.  (ASCII) (ASCII OUTPUT)
• The LQN activity template is an ascii input file for lqns with activities in the tasks, commented to explain the syntax.  (ASCII) (ASCII OUTPUT)
• The LQN Input Language defines the original input file format in BNF.

The XML input language as of 2005 is defined by:

• The XML LQN Input Language defines the XML input file schema.

You can convert the old to the new by the filter lqn2xml.

• The modeling of activity sequences within a task has been documented at length in Greg Frank's thesis. An extract of chapters 8 and 9 covers this topic. (PDF (1.4 MB))
• Two template files are heavily commented to explain the syntax, on two actual models
• Template for models with entries and phases only: RESERV-TEMPL.LQN
• Template for models with activities within entries, and internal parallel paths ACTIVITY-TEMPL.LQN

• The lqns manual page documents the run-time controls for the LQNS solver, which is the analytic solver based on mean value analysis and iteration. (ASCII MAN PAGE) (ANNOTATED OUTPUT FILE)
• Another substantial documentation of the LQNS solver is found in Greg Frank's PhD thesis PDF
• The lqsim man page documents the use of the simulation tool lqsim in place of the analytic solver LQNS. Lqsim employs our simulator parasol (which is similar to CSIM in many ways), and takes the same input file and model assumptions as LQNS. It is more accurate for activity flows which fork and join, expecially if the fork and join are in different tasks. It should be used if the LQNS iteration scheme fails to converge. (ASCII MAN PAGE)
• The Java-based editor jlqndef does not have a particular document at this time... the previous editor lqndef is quite buggy and is not supported.
• Two tools were written to support repetitive sequences of model runs with different parameter values, including extracting specified results into a table or a set of graphs. These run with the original modeling language only; for the XML syntax they are replaced by a new feature LQX integrated with the solver (documentation coming soon).
• The first is MultiSRVN, based on gawk. It has been superseded by SPEX. It utilizes a special language to identify the parameters to be changed. It does not support models with activities inside tasks, only phases. (POSTSCRIPT DOCUMENTATION)
• The new experiment-management tool is the Software Performance Experimenter, SPEX, which is based on PERL. It represents the parameters to be varied by character strings in-line in the model. It does support models with activities. (ASCII DOCUMENTATION)
• The XLQN template is an ascii input file for spex, fully commented to explain the syntax of spex (ASCII input) (ASCII OUTPUT for results template.res)

SPEX also has an iterative version which allows model parameters to be defined as functions of model outputs. ASCII DOCUMENTATION PART I  PART II

• A new component-based system builder is being tested.
• Layered queueing models are built by analyzing the flow of activities along scenarios. One approach is to create an activity graph which specifies the resource demands of operations along a scenario. It may be necessary to reduce this graph by counting loops and probabilities of branching, and by substituting in for abstract operations, and this can be tedious. The Activity Graph Reducer AGR does this. POSTSCRIPT
• For local execution, all the LQN tools are found in /home/artt/bin/, which must be in your path.