net.percederberg.mibble

Class MibType

java.lang.Object

net.percederberg.mibble.MibType

Direct Known Subclasses:

BitSetType, BooleanType, ChoiceType, ElementType, IntegerType, NullType, ObjectIdentifierType, RealType, SequenceOfType, SequenceType, SnmpType, StringType, TypeReference

public abstract class MibType
extends java.lang.Object

The base MIB type class. There are two categories of MIB types extending this class, primitive ASN.1 type and SNMP macro types. The primitive types are used in SNMP for transferring data on the wire. The SNMP macro types are used in the MIB files for adding additional information to the primitive types or values, such as descriptions and similar. Most of the SNMP macro types only support object identifier values, and can only be used at the top level. The primitive types support whatever values are appropriate for the specific type, and are normally used inside the SNMP macro types in a MIB file.

The best way to extract the specific type information from a MIB type is to check the type instance and then cast the MibType object to the corresponding subtype. Each subtype have very different properties, which is why the API in this class is rather limited. The example below shows some skeleton code for extracting type information.

    if (type instanceof SnmpObjectType) {
        objectType = (SnmpObjectType) type;
        ...
    }

Another way to check which type is at hand, is to query the type tags with the hasTag() method. In this way it is possible to distinguish between types using the same or a similar primitive ASN.1 type representation (such as DisplayString and IpAddress). This should normally be done in order to create a correct BER- or DER-encoding of the type. The example below illustrates how this could be done.

    tag = type.getTag();
    if (tag.getCategory() == MibTypeTag.UNIVERSAL) {
        // Set BER and DER identifier bits 8 & 7 to 00
    } else if (tag.getCategory() == MibTypeTag.APPLICATION) {
        // Set BER and DER identifier bits 8 & 7 to 01
    }
    ...
    if (!type.isPrimitive()) {
        // Set BER and DER constructed bit
    }

Since:

2.0

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	MibType(java.lang.String name, boolean primitive) Creates a new MIB type instance.

Method Summary

Methods

Modifier and Type	Method and Description
MibType	createReference() Creates a type reference to this type.
MibType	createReference(java.util.ArrayList<?> values) Creates a constrained type reference to this type.
MibType	createReference(Constraint constraint) Creates a constrained type reference to this type.
java.lang.String	getComment() Returns the type comment.
java.lang.String	getName() Returns the type name.
MibTypeSymbol	getReferenceSymbol() Returns the type reference symbol.
MibTypeTag	getTag() Returns the type tag.
boolean	hasReferenceTo(java.lang.String name) Checks if this type referenced the specified type symbol.
boolean	hasReferenceTo(java.lang.String module, java.lang.String name) Checks if this type referenced the specified type symbol.
boolean	hasTag(int category, int value) Checks if this type has a specific type tag.
boolean	hasTag(MibTypeTag tag) Checks if this type has a specific type tag.
abstract MibType	initialize(MibSymbol symbol, MibLoaderLog log) Initializes the MIB type.
abstract boolean	isCompatible(MibValue value) Checks if the specified value is compatible with this type.
boolean	isPrimitive() Checks if this type represents a primitive type.
void	setReferenceSymbol(MibTypeSymbol symbol) Sets the type reference symbol.
void	setTag(boolean implicit, MibTypeTag tag) Sets the type tag.
java.lang.String	toString() Returns a string representation of this object.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

MibType

protected MibType(java.lang.String name,
       boolean primitive)

Creates a new MIB type instance.

Parameters:

name - the type name

primitive - the primitive type flag

Method Detail

initialize

public abstract MibType initialize(MibSymbol symbol,
                 MibLoaderLog log)
                            throws MibException

Initializes the MIB type. This will remove all levels of indirection present, such as references to types or values. No information is lost by this operation. This method may modify this object as a side-effect, and will return the basic type.

NOTE: This is an internal method that should only be called by the MIB loader.

Parameters:

symbol - the MIB symbol containing this type

log - the MIB loader log

Returns:

the basic MIB type

Throws:

MibException - if an error was encountered during the initialization

Since:

2.2

createReference

public MibType createReference()
                        throws java.lang.UnsupportedOperationException

Creates a type reference to this type. The type reference is normally an identical type, but with the primitive flag set to false. Only certain types support being referenced, and the default implementation of this method throws an exception.

NOTE: This is an internal method that should only be called by the MIB loader.

Returns:

the MIB type reference

Throws:

java.lang.UnsupportedOperationException - if a type reference couldn't be created

Since:

2.2

createReference

public MibType createReference(Constraint constraint)
                        throws java.lang.UnsupportedOperationException

Creates a constrained type reference to this type. The type reference is normally an identical type, but with the primitive flag set to false. Only certain types support being referenced, and the default implementation of this method throws an exception.

NOTE: This is an internal method that should only be called by the MIB loader.

Parameters:

constraint - the type constraint

Returns:

the MIB type reference

Throws:

java.lang.UnsupportedOperationException - if a type reference couldn't be created with constraints

Since:

2.2

createReference

public MibType createReference(java.util.ArrayList<?> values)
                        throws java.lang.UnsupportedOperationException

Creates a constrained type reference to this type. The type reference is normally an identical type, but with the primitive flag set to false. Only certain types support being referenced, and the default implementation of this method throws an exception.

NOTE: This is an internal method that should only be called by the MIB loader.

Parameters:

values - the type value symbols

Returns:

the MIB type reference

Throws:

java.lang.UnsupportedOperationException - if a type reference couldn't be created with value constraints

Since:

2.2

isCompatible

public abstract boolean isCompatible(MibValue value)

Checks if the specified value is compatible with this type. A value is compatible if it has a type that matches this one and a value that satisfies all constraints.

Parameters:

value - the value to check

Returns:

true if the value is compatible, or false otherwise

isPrimitive

public boolean isPrimitive()

Checks if this type represents a primitive type. The primitive types are the basic building blocks of the ASN.1 type system. By defining new types (that may be identical to a primitive type), the new type looses it's primitive status.

Returns:

true if this type represents a primitive type, or false otherwise

Since:

2.2

hasTag

public boolean hasTag(MibTypeTag tag)

Checks if this type has a specific type tag. This method will check the whole type tag chain.

Parameters:

tag - the type tag to search for

Returns:

true if the specified type tag was present, or false otherwise

Since:

2.2

See Also:

hasTag(int, int)

hasTag

public boolean hasTag(int category,
             int value)

Checks if this type has a specific type tag. This method will check the whole type tag chain.

Parameters:

category - the tag category to search for

value - the tag value to search for

Returns:

true if the specified type tag was present, or false otherwise

Since:

2.2

See Also:

hasTag(MibTypeTag)

hasReferenceTo

public boolean hasReferenceTo(java.lang.String name)

Checks if this type referenced the specified type symbol. This method should be avoided if possible, as it is much better to rely on type tags to distinguish between two types with the same base type (such as DisplayString and IpAddress).

Parameters:

name - the type symbol name

Returns:

true if this type was a reference to the symbol, or false otherwise

Since:

2.2

See Also:

hasTag(int, int), hasTag(MibTypeTag), getReferenceSymbol(), SnmpTextualConvention.findReference(MibType)

hasReferenceTo

public boolean hasReferenceTo(java.lang.String module,
                     java.lang.String name)

Checks if this type referenced the specified type symbol. This method should be avoided if possible, as it is much better to rely on type tags to distinguish between two types with the same base type (such as DisplayString and IpAddress).

Parameters:

module - the type symbol module (MIB) name

name - the type symbol name

Returns:

true if this type was a reference to the symbol, or false otherwise

Since:

2.2

See Also:

hasTag(int, int), hasTag(MibTypeTag), getReferenceSymbol(), SnmpTextualConvention.findReference(MibType)

getName

public java.lang.String getName()

Returns the type name.

Returns:

the type name, or an empty string if not applicable

Since:

2.2

getTag

public MibTypeTag getTag()

Returns the type tag. The type tags consist of a category and value number, and are used to identify a specific type uniquely (such as IpAddress and similar). Most (if not all) SNMP types have unique tags that are normally inherited when the type is referenced. Type tags may also be chained together, in which case this method returns the first tag in the chain.

Returns:

the type tag, or null if no type tag has been set

Since:

2.2

setTag

public void setTag(boolean implicit,
          MibTypeTag tag)

Sets the type tag. The old type tag is kept to some extent, depending on if the implicit flag is set to true or false. For implicit inheritance, the first tag in the old tag chain is replaced with the new tag. For explicit inheritance, the new tag is added first in the tag chain without removing any old tag.

NOTE: This is an internal method that should only be called by the MIB loader.

Parameters:

implicit - the implicit inheritance flag

tag - the new type tag

Since:

2.2

getReferenceSymbol

public MibTypeSymbol getReferenceSymbol()

Returns the type reference symbol. A type reference is created whenever a type is defined in a type assignment, and later referenced by name from some other symbol. The complete chain of type references is available by calling getReference() recursively on the type of the returned type symbol.

In general, this method should be avoided as it is much better to rely on type tags to distinguish between two types with the same base type (such as DisplayString and IpAddress).

Returns:

the type reference symbol, or null if this type never referenced another type

Since:

2.2

See Also:

getTag(), SnmpTextualConvention.findReference(MibType)

setReferenceSymbol

public void setReferenceSymbol(MibTypeSymbol symbol)

Sets the type reference symbol. The type reference is set whenever a type is defined in a type assignment, and later referenced by name from some other symbol.

NOTE: This is an internal method that should only be called by the MIB loader.

Parameters:

symbol - the referenced type symbol

Since:

2.2

getComment

public java.lang.String getComment()

Returns the type comment.

Returns:

the type comment, or null if no comment was set

Since:

2.9

toString

public java.lang.String toString()

Returns a string representation of this object.

Overrides:

toString in class java.lang.Object

Returns:

a string representation of this object