rrdFilter module

The rrdFile Javascript module implements a set of classes that can be used to extract information from RRD archives loaded as binary file objects.

Overview

The rrdFilter module is allows filters to be applied to DSs (datasources).

(These classes should have almost idential instantiations to their rrdFile module equivilents.)

Filters can either be a list of DSs to filter out (*FilterDS), or a user-created and customized filter object (*FilterOp - for example, mathematical functions like summing and averaging DSs).

Clases included in this module:

RRDRRAFilterDS
RRDFilterDS
RRDDSFilterOp
RRDRRAFIlterOp
RRDFilterOp.

Class RRDRRAFilterDS

This class filters out a subset of DSs from an RRA identified by index or name.

The constructor has two arguments: rrd_rra (the RRA) and ds_list (the list of DSs to filter).

This class implements the following methods:

Method	Description
getIdx()	Return which RRA it is in the RRD file.
getNrRows()	Return the number of rows in the RRA.
getNrDSs()	Return the number of DSs in the RRD file.
getStep()	Return the number of seconds between rows.
getCFName()	Return the Consolidation Function used by the RRA.
getEl(r,d)	Return the value for the d-th DS in the r-th row.
getElFast(r,d)	Return the low-precision value for the d-th DS in the r-th row.

Class RRDFilterDS

This class filters out a subset of DSs from an RRD identified by index or name.

This class implements the following methods:

Method	Description
getMinSteps()	Return the base interval in seconds that was used to feed the RRD file.
getLastUpdate()	Return the timestamp of the last update.
getNrDSs()	Return the number of Data Sources present in the RRD file.
getDSNames()	Return the names of the Data Sources present in the RRD file.
getDS(id)	If id is a number, return an object of type RRDDS holding the information about the id-th Data Source. If id is a string, return an object of type RRDDS holding the information about the Data Source with the requested name.
getNrRRAs()	Return the number of Round Robin Archives present in the RRD file.
getRRAInfo(n)	Return an object of type RRDRRAInfo holding the information about the n-th Round Robin Archive.
getRRA(n)	Return an object of type RRDRRA that can be used to access the values stored in the n-th Round Robin Archive.

Class RRDDSFilterOp

This class filters DSs from an RRD by using a user-provided filter object.

This object must implement the following interface:

getName() - Symbolic name give to this function
getDSName() - list of DSs used in computing the result (names or indexes)
computeResult(val_list) - val_list contains the values of the requested DSs (in the same order)

For example, a summing function:

function SumDS(ds1,ds2){

this.getName() = function() {return ds1+"+"+ds2}

this.getDSName = function() {return [ds1,ds2]}

this.computeResult = function(val_list) {return val_list[0]+val_list[1]}}

This class has three arguments: rrd_file, op_object (the filter object) and my_idx (index of new DS in case old one was modified by a filter).

This class implements the following methods:

Method	Description
getIdx()	Return which DS it is in the RRD file.
getName()	Return the name of the data source.
getType()	Return the type of the data source.
getMin()	Return the minimum and maximum value the data source can contain. If either is not defined, undefined is returned.
getMax()
getRealDSList()	Returns which DSs is being used in the Filter.
ComputeResult()	Return the computed result of the filter object on the DSs.

Class RRDRRAFilterDS

This class filters out a subset of DSs from an RRA using by a filter object.

The constructor has two arguments: rrd_rra (the RRA) and ds_list (the list of DS filters).

This class also implements the following methods:

Method	Description
getIdx()	Return which RRA it is in the RRD file.
getNrRows()	Return the number of rows in the RRA.
getNrDSs()	Return the number of DSs in the RRD file.
getStep()	Return the number of seconds between rows.
getCFName()	Return the Consolidation Function used by the RRA.
getEl(r,d)	Return the value for the d-th DS in the r-th row.
getElFast(r,d)	Return the low-precision value for the d-th DS in the r-th row.

Class RRDFilterOp

This class filters all of the DSs in an RRD by an accompning list of filters - one filter for each DS.

Its arguments are: rrd_file and op_obj_list (list of ds filtersr;list length must be the same as the number of DSs in the RRD).

This class implements the following methods:

Method	Description
getMinSteps()	Return the base interval in seconds that was used to feed the RRD file.
getLastUpdate()	Return the timestamp of the last update.
getNrDSs()	Return the number of Data Sources present in the RRD file.
getDSNames()	Return the names of the Data Sources present in the RRD file.
getDS(id)	If id is a number, return an object of type RRDDS holding the information about the id-th Data Source. If id is a string, return an object of type RRDDS holding the information about the Data Source with the requested name.
getNrRRAs()	Return the number of Round Robin Archives present in the RRD file.
getRRAInfo(n)	Return an object of type RRDRRAInfo holding the information about the n-th Round Robin Archive.
getRRA(n)	Return an object of type RRDRRA that can be used to access the values stored in the n-th Round Robin Archive.

This module is part of the javascriptRRD package hosted at http://javascriptrrd.sourceforge.net.
It is licensed under the MIT license.