Header (Javadocs [I2P+ 2.13.0+] - API Version 0.9.70+)

java.lang.Object
- org.rrd4j.core.Header

All Implemented Interfaces:
RrdUpdater<Header>
```
public class Header
extends Object
implements RrdUpdater<Header>
```
Class to represent RRD header. Header information is mainly static (once set, it cannot be changed), with the exception of last update time (this value is changed whenever RRD gets updated).
Normally, you don't need to manipulate the Header object directly - Rrd4j framework does it for you.
This header contains metadata about the RRD file.

Field Summary

Fields
Modifier and Type	Field and Description
`(package private) static String`	`DEFAULT_SIGNATURE` Default signature string for RRD files created by RRD4J.
`(package private) static String`	`RRDTOOL_VERSION1` Version identifier for RRDTool version 1 compatibility.
`(package private) static String`	`RRDTOOL_VERSION3` Version identifier for RRDTool version 3 compatibility.
`(package private) static String`	`SIGNATURE` RRD4J signature string used to identify RRD4J files.
`(package private) static int`	`SIGNATURE_LENGTH` Length of the RRD signature string.

Constructor Summary
Constructors
Constructor and Description
Header(RrdDb parentDb, DataImporter reader)
Header(RrdDb parentDb, RrdDef rrdDef)

Constructors
Constructor and Description
`Header(RrdDb parentDb, DataImporter reader)`
`Header(RrdDb parentDb, RrdDef rrdDef)`

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`(package private) void`	`appendXml(XmlWriter writer)` Appends header information to XML writer.
`void`	`copyStateTo(Header header)` copyStateTo.
`(package private) String`	`dump()` Returns a string representation of the header information.
`int`	`getArcCount()` Returns the number of archives defined in the RRD.
`int`	`getDsCount()` Returns the number of datasources defined in the RRD.
`String`	`getInfo()` Info string (everything after the signature prefix).
`long`	`getLastUpdateTime()` Returns the last update time of the RRD.
`RrdAllocator`	`getRrdAllocator()` Required to implement RrdUpdater interface.
`RrdBackend`	`getRrdBackend()` Returns the underlying storage (backend) object which actually performs all I/O operations.
`String`	`getSignature()` Returns RRD signature.
`long`	`getStep()` Returns primary RRD time step.
`int`	`getVersion()` Return the RRD version.
`(package private) boolean`	`isRrd4jHeader()` True if the header matches RRD4J or JRobin format.
`void`	`setInfo(String info)` Override the info portion of the RRD signature.
`(package private) void`	`setLastUpdateTime(long lastUpdateTime)` Sets the last update time of the RRD.
`(package private) void`	`validateHeader()` InvalidRrdException if the header is not a valid RRD4J/RRD file.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Field Detail
  - DEFAULT_SIGNATURE
```
static final String DEFAULT_SIGNATURE
```
    Default signature string for RRD files created by RRD4J.
    See Also:
    Constant Field Values
  - RRDTOOL_VERSION1
```
static final String RRDTOOL_VERSION1
```
    Version identifier for RRDTool version 1 compatibility.
    See Also:
    Constant Field Values
  - RRDTOOL_VERSION3
```
static final String RRDTOOL_VERSION3
```
    Version identifier for RRDTool version 3 compatibility.
    See Also:
    Constant Field Values
  - SIGNATURE
```
static final String SIGNATURE
```
    RRD4J signature string used to identify RRD4J files.
    See Also:
    Constant Field Values
  - SIGNATURE_LENGTH
```
static final int SIGNATURE_LENGTH
```
    Length of the RRD signature string.
    See Also:
    Constant Field Values
- Constructor Detail
  - Header
```
Header(RrdDb parentDb,
       DataImporter reader)
throws IOException
```
    Throws:
    IOException
  - Header
```
Header(RrdDb parentDb,
       RrdDef rrdDef)
throws IOException
```
    Throws:
    IOException
- Method Detail
  - appendXml
```
void appendXml(XmlWriter writer)
        throws IOException
```
    Appends header information to XML writer.
    Parameters:
    writer - the XML writer to append to
    Throws:
    IOException - if an I/O error occurs
  - copyStateTo
```
public void copyStateTo(Header header)
                 throws IOException
```
    copyStateTo.
    Copies object's internal state to another Header object.
    Specified by:
    copyStateTo in interface RrdUpdater<Header>
    Parameters:
    header - a RrdUpdater object.
    Throws:
    IOException - if any.
  - dump
```
String dump()
     throws IOException
```
    Returns a string representation of the header information.
    Returns:
    a string containing header information
    Throws:
    IOException - if an I/O error occurs
  - getArcCount
```
public int getArcCount()
                throws IOException
```
    Returns the number of archives defined in the RRD.
    Returns:
    Number of archives defined
    Throws:
    IOException - Thrown in case of I/O error
  - getDsCount
```
public int getDsCount()
               throws IOException
```
    Returns the number of datasources defined in the RRD.
    Returns:
    Number of datasources defined
    Throws:
    IOException - Thrown in case of I/O error
  - getInfo
```
public String getInfo()
               throws IOException
```
    Info string (everything after the signature prefix).
    Returns:
    the info string (everything after the signature prefix)
    Throws:
    IOException - if an I/O error occurs
  - getLastUpdateTime
```
public long getLastUpdateTime()
                       throws IOException
```
    Returns the last update time of the RRD.
    Returns:
    Timestamp (Unix epoch, no milliseconds) corresponding to the last update time.
    Throws:
    IOException - Thrown in case of I/O error
  - getRrdAllocator
```
public RrdAllocator getRrdAllocator()
```
    Required to implement RrdUpdater interface. You should never call this method directly.
    Specified by:
    getRrdAllocator in interface RrdUpdater<Header>
    Returns:
    Allocator object
  - getRrdBackend
```
public RrdBackend getRrdBackend()
```
    Returns the underlying storage (backend) object which actually performs all I/O operations.
    Specified by:
    getRrdBackend in interface RrdUpdater<Header>
    Returns:
    I/O backend object
  - getSignature
```
public String getSignature()
                    throws IOException
```
    Returns RRD signature. Initially, the returned string will be of the form Rrd4j, version x.x.
    Returns:
    RRD signature
    Throws:
    IOException - Thrown in case of I/O error
  - getStep
```
public long getStep()
             throws IOException
```
    Returns primary RRD time step.
    Returns:
    Primary time step in seconds
    Throws:
    IOException - Thrown in case of I/O error
  - getVersion
```
public int getVersion()
               throws IOException
```
    Return the RRD version.
    Returns:
    RRD version
    Throws:
    IOException - if any.
  - isRrd4jHeader
```
boolean isRrd4jHeader()
```
    True if the header matches RRD4J or JRobin format.
    Returns:
    true if the header matches RRD4J or JRobin format
  - setInfo
```
public void setInfo(String info)
             throws IOException
```
    Override the info portion of the RRD signature.
    Parameters:
    info - the new info string, or null/empty to clear it
    Throws:
    IOException - if an I/O error occurs
  - setLastUpdateTime
```
void setLastUpdateTime(long lastUpdateTime)
                throws IOException
```
    Sets the last update time of the RRD.
    Parameters:
    lastUpdateTime - the last update time (Unix epoch)
    Throws:
    IOException - if an I/O error occurs
  - validateHeader
```
void validateHeader()
             throws IOException
```
    InvalidRrdException if the header is not a valid RRD4J/RRD file.
    Throws:
    InvalidRrdException - if the header is not a valid RRD4J/RRD file
    IOException

Class Header

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

DEFAULT_SIGNATURE

RRDTOOL_VERSION1

RRDTOOL_VERSION3

SIGNATURE

SIGNATURE_LENGTH

Constructor Detail

Header

Header

Method Detail

appendXml

copyStateTo

dump

getArcCount

getDsCount

getInfo

getLastUpdateTime

getRrdAllocator

getRrdBackend

getSignature

getStep

getVersion

isRrd4jHeader

setInfo

setLastUpdateTime

validateHeader