org.snmp4j.agent.mo.MOColumn Maven / Gradle / Ivy
/*_############################################################################
_##
_## SNMP4J-Agent 2 - MOColumn.java
_##
_## Copyright (C) 2005-2014 Frank Fock (SNMP4J.org)
_##
_## Licensed under the Apache License, Version 2.0 (the "License");
_## you may not use this file except in compliance with the License.
_## You may obtain a copy of the License at
_##
_## http://www.apache.org/licenses/LICENSE-2.0
_##
_## Unless required by applicable law or agreed to in writing, software
_## distributed under the License is distributed on an "AS IS" BASIS,
_## WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
_## See the License for the specific language governing permissions and
_## limitations under the License.
_##
_##########################################################################*/
package org.snmp4j.agent.mo;
import org.snmp4j.agent.*;
import org.snmp4j.smi.*;
import org.snmp4j.agent.request.SubRequest;
import org.snmp4j.mp.SnmpConstants;
/**
* The MOColumn class represents columnar SMI objects. It
* represents all instances of a table's column not only a single instance
* (cell).
*
* Objects represented by MOColumn cannot be modified via SNMP,
* thus MOColumn supports read-only maximum access only.
*
* @see MOMutableColumn
* @author Frank Fock
* @version 2.4
*/
public class MOColumn implements Comparable {
private int columnID;
private int syntax;
private MOAccess access;
private MOTable table;
/**
* Creates a read-only column object with the given column and syntax.
*
* @param columnID
* the column ID which is ID the last sub-identifier of the corresponding
* OBJECT-TYPE definition.
* @param syntax
* the syntax of the objects in this column. See {@link SMIConstants} for
* possible values.
*/
public MOColumn(int columnID, int syntax) {
this.columnID = columnID;
this.syntax = syntax;
this.access = MOAccessImpl.ACCESS_READ_ONLY;
}
/**
* Creates a column object with the given column, syntax, and maximum access.
* Since MOColumn only supports read-only columns the only
* reasonable values for access are 'not-accessible' and
* 'read-only'. Generally this constructor should not be called directly.
*
* @param columnID
* the column ID which is ID the last sub-indentifer of the corresponding
* OBJECT-TYPE definition.
* @param syntax
* the syntax of the objects in this column. See {@link SMIConstants} for
* possible values.
* @param access
* the maximum access of the column.
*/
public MOColumn(int columnID, int syntax, MOAccess access) {
this.columnID = columnID;
this.syntax = syntax;
if (access == null) {
throw new NullPointerException("Access must be specified");
}
this.access = access;
}
public void setColumnID(int columnID) {
this.columnID = columnID;
}
public void setSyntax(int syntax) {
this.syntax = syntax;
}
public void setAccess(MOAccess access) {
this.access = access;
}
/**
* Sets the table instance this columnar object is contained in. This method
* should be called by {@link MOTable} instance to register the table with
* the column.
* @param table
* the MOTable instance where this column is contained in.
*/
public void setTable(MOTable> table) {
this.table = table;
}
public int getColumnID() {
return columnID;
}
public int getSyntax() {
return syntax;
}
public MOAccess getAccess() {
return access;
}
public MOTable getTable() {
return table;
}
@SuppressWarnings("unchecked")
public V getValue(MOTableRow row, int column) {
return (V) row.getValue(column);
}
/**
* Tests if the supplied row is volatile or persistent. If volatile then
* the row will not be saved when the table is saved to persistent storage.
*
* @param row
* a row of the table where this column is part of.
* @param column
* the column index of this column in row.
* @return
* true if row should not be
*/
public boolean isVolatile(MOTableRow row, int column) {
return false;
}
/**
* Return the restore value for this column and the given row.
* @param rowValues
* a row of the table where this column is part of.
* @param column
* the column index of this column in row.
* @return
* the restored value. By default this is rowValues[column].
* @since 2.4
*/
public Variable getRestoreValue(Variable[] rowValues, int column) {
return rowValues[column];
}
/**
* Return the content of this column's value of the given row for persistent storage.
* @param row
* a row of the table where this column is part of.
* @param column
* the column index of this column in row.
* @return
* the value to be stored persistently for this row and column.
* @since 2.4
*/
public Variable getStoreValue(MOTableRow row, int column) {
return row.getValue(column);
}
/**
* Compares this managed object column by its ID with another column.
* @param column
* another MOColumn.
* @return int
* a negative integer, zero, or a positive integer as this column ID
* is less than, equal to, or greater than the specified object's column
* ID.
*/
public int compareTo(Object column) {
return columnID - ((MOColumn)column).getColumnID();
}
public String toString() {
return this.getClass().getName()+"[columnID="+getColumnID()+",syntax="+
getSyntax()+"]";
}
@SuppressWarnings("unchecked")
public void get(SubRequest subRequest, MOTableRow row, int column) {
if (getAccess().isAccessibleForRead()) {
V value = getValue(row, column);
if (value != null) {
subRequest.getVariableBinding().setVariable((V) value.clone());
}
else {
subRequest.getVariableBinding().setVariable(Null.noSuchInstance);
}
subRequest.completed();
}
else {
subRequest.getStatus().setErrorStatus(SnmpConstants.SNMP_ERROR_NO_ACCESS);
}
}
}