org.snmp4j.agent.mo.MOColumn Maven / Gradle / Ivy
/*_############################################################################
_##
_## SNMP4J-Agent 3 - MOColumn.java
_##
_## Copyright (C) 2005-2021 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 {@code MOColumn} class represents columnar SMI objects. It
* represents all instances of a table's column not only a single instance
* (cell).
*
* Objects represented by {@code MOColumn} cannot be modified via SNMP,
* thus {@code MOColumn} supports read-only maximum access only.
*
* @author Frank Fock
* @version 2.6
* @see MOMutableColumn
*/
public class MOColumn implements Comparable> {
private int columnID;
private int syntax;
private MOAccess access;
@SuppressWarnings("rawtypes")
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 {@code MOColumn} only supports read-only columns the only
* reasonable values for {@code 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-identifier 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 {@code MOTable} instance where this column is contained in.
* @param
* the {@link MOTableRow} type supported by the table.
*/
@SuppressWarnings("rawtypes")
public void setTable(MOTable> table) {
this.table = table;
}
public int getColumnID() {
return columnID;
}
public int getSyntax() {
return syntax;
}
public MOAccess getAccess() {
return access;
}
@SuppressWarnings("rawtypes")
public MOTable getTable() {
return table;
}
/**
* Gets the value of the specified column from the provided row. The optional
* {@code subRequest} parameter provides information on the currently processed
* SNMP request if the value retrieval is trigger by a SNMP command.
*
* @param row
* the row with the value to be returned.
* @param column
* the column index pointing to the column to return in the above row.
* @param subRequest
* an optional sub-request on which behalf this value retrieval is executed.
*
* @return the value as a pointer to the cell value or {@code null} if such a value does not exist.
* @since 2.6
*/
@SuppressWarnings("unchecked")
public V getValue(MOTableRow row, int column, SubRequest subRequest) {
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 {@code row}.
*
* @return {@code true} if {@code row} will not be persistently stored.
*/
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 {@code row}.
*
* @return the restored value. By default, this is {@code 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 {@code row}.
*
* @return the value to be stored persistently for this {@code row} and {@code 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 {@code 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(MOColumn column) {
return columnID - column.getColumnID();
}
public String toString() {
return this.getClass().getName() + "[columnID=" + getColumnID() + ",syntax=" +
getSyntax() + "]";
}
/**
* Process a get sub-request for the specified table row and column.
*
* @param subRequest
* the GET sub-request to execute.
* @param row
* the row that contains the value to return in the GET response PDU.
* @param column
* the column index of the value to return in {@code subRequest}
*/
public void get(SubRequest subRequest, MOTableRow row, int column) {
if (getAccess().isAccessibleForRead()) {
Variable value = getValue(row, column, subRequest);
if (value != null) {
subRequest.getVariableBinding().setVariable((Variable) value.clone());
} else {
subRequest.getVariableBinding().setVariable(Null.noSuchInstance);
}
subRequest.completed();
} else {
subRequest.getStatus().setErrorStatus(SnmpConstants.SNMP_ERROR_NO_ACCESS);
}
}
}