Representation of a GattServer attribute. More...

#include <GattAttribute.h>

Public Types
typedef ble::attribute_handle_t	Handle_t
	Representation of an attribute handle. More...

Public Member Functions
	GattAttribute (const UUID &uuid, uint8_t *valuePtr=nullptr, uint16_t len=0, uint16_t maxLen=0, bool hasVariableLen=true)
	Construct an attribute. More...

Handle_t	getHandle () const
	Get the attribute's handle in the ATT table. More...

const UUID &	getUUID () const
	Get the UUID of the attribute. More...

uint16_t	getLength () const
	Get the current length of the attribute value. More...

uint16_t	getMaxLength () const
	Get the maximum length of the attribute value. More...

uint16_t *	getLengthPtr ()
	Get a pointer to the current length of the attribute value. More...

void	setHandle (Handle_t id)
	Set the attribute handle. More...

uint8_t *	getValuePtr ()
	Get a pointer to the attribute value. More...

bool	hasVariableLength () const
	Check whether the length of the attribute's value can change throughout time. More...

void	allowRead (bool allow_read)
	Allow or disallow read operation from a client. More...

bool	isReadAllowed () const
	Indicate if a client is allowed to read the attribute. More...

void	setReadSecurityRequirement (Security_t requirement)
	Set the security requirements of the read operations. More...

Security_t	getReadSecurityRequirement () const
	Return the security level required by read operations. More...

void	allowWrite (bool allow_write)
	Allow or disallow write operation from a client. More...

bool	isWriteAllowed () const
	Indicate if a client is allowed to write the attribute. More...

void	setWriteSecurityRequirement (Security_t requirement)
	Set the security requirements of the write operations. More...

Security_t	getWriteSecurityRequirement () const
	Return the security level required by write operations. More...

Static Public Attributes
static const Handle_t	INVALID_HANDLE = 0x0000
	Invalid attribute handle. More...

Detailed Description

Representation of a GattServer attribute.

Attributes are the building block of GATT servers: services are attributes, characteristics are groups of attributes and characteristic descriptors are attributes, too.

Typed values

Attributes are typed values composed of a type and its associated value. The attribute type identifies the attribute purpose. A UUID read by the client during the discovery of the GATT server models the attribute type. The value of the attribute is an array of bytes; its length may be fixed or variable.

As an example, a primary service is declared by an attribute with the type 0x2800, and the value of the attribute is the UUID of the service.

Attribute Access

The GATT server is an array of attributes in which a unique index identifies each of the attributes within the array. That index is called the attribute handle, and clients use it to access to attributes within the server.

Note: Attributes do not contain information related to their permissions, grouping or semantic. Higher level specifications define these concepts.

Definition at line 60 of file gatt/GattAttribute.h.

Member Typedef Documentation

◆ Handle_t

typedef ble::attribute_handle_t Handle_t

Representation of an attribute handle.

Each attribute in a GattServer has a unique handle that clients can use to identify the attribute. The underlying BLE stack usually generates and assigns handles to attributes.

Definition at line 69 of file gatt/GattAttribute.h.

Constructor & Destructor Documentation

◆ GattAttribute()

GattAttribute	(	const UUID &	uuid,
		uint8_t *	valuePtr = `nullptr`,
		uint16_t	len = `0`,
		uint16_t	maxLen = `0`,
		bool	hasVariableLen = `true`
	)

Construct an attribute.

Application code uses attributes to model characteristic descriptors and characteristics values.

Parameters

[in]	uuid	The type of the attribute.
[in]	valuePtr	Pointer to the memory buffer, which contains the initial value of the attribute. The constructor does not make a copy of the attribute buffer; as a consequence, the memory buffer must remain valid during the lifetime of the attribute.
[in]	len	The length in bytes of this attribute's value.
[in]	maxLen	The length in bytes of the memory buffer containing the attribute value. It must be greater than or equal to `len`.
[in]	hasVariableLen	Flag that indicates whether the attribute's value length can change throughout time.

Example

// declare a value of 2 bytes within a 10 bytes buffer
const uint8_t attribute_value[10] = { 10, 50 };
GattAttribute attr = GattAttribute(
   0x2A19, // attribute type
   attribute_value,
   2, // length of the current value
   sizeof(attribute_value), // length of the buffer containing the value
   true // variable length
);

Note: By default, read and write operations are allowed and does not require any security.

Definition at line 114 of file gatt/GattAttribute.h.

Member Function Documentation

◆ getHandle()

Handle_t getHandle ( ) const

Get the attribute's handle in the ATT table.

Note: The GattServer sets the attribute's handle when services are inserted.

Returns: The attribute's handle.

Definition at line 144 of file gatt/GattAttribute.h.

◆ getUUID()

const UUID & getUUID ( ) const

Get the UUID of the attribute.

The UUID identifies the type of the attribute.

Returns: The attribute.

Definition at line 156 of file gatt/GattAttribute.h.

◆ getLength()

uint16_t getLength ( ) const

Get the current length of the attribute value.

Returns: The current length of the attribute value.

Definition at line 166 of file gatt/GattAttribute.h.

◆ getMaxLength()

uint16_t getMaxLength ( ) const

Get the maximum length of the attribute value.

The maximum length of the attribute value.

Definition at line 176 of file gatt/GattAttribute.h.

◆ getLengthPtr()

uint16_t * getLengthPtr ( )

Get a pointer to the current length of the attribute value.

Attention: note Do not use this function.

Returns: A pointer to the current length of the attribute value.

Definition at line 188 of file gatt/GattAttribute.h.

◆ setHandle()

void setHandle ( Handle_t id )

Set the attribute handle.

Attention: The GattServer uses this function internally. Application code must not use it.

Parameters

[in] id The new attribute handle.

Definition at line 201 of file gatt/GattAttribute.h.

◆ getValuePtr()

uint8_t * getValuePtr ( )

Get a pointer to the attribute value.

Returns: A pointer to the attribute value.

Definition at line 211 of file gatt/GattAttribute.h.

◆ hasVariableLength()

bool hasVariableLength ( ) const

Check whether the length of the attribute's value can change throughout time.

Returns: true if the attribute value has a variable length and false otherwise.

Definition at line 222 of file gatt/GattAttribute.h.

◆ allowRead()

void allowRead ( bool allow_read )

Allow or disallow read operation from a client.

Parameters

allow_read Read is allowed if true.

Definition at line 231 of file gatt/GattAttribute.h.

◆ isReadAllowed()

bool isReadAllowed ( ) const

Indicate if a client is allowed to read the attribute.

Returns: true if a client is allowed to read the attribute.

Definition at line 240 of file gatt/GattAttribute.h.

◆ setReadSecurityRequirement()

void setReadSecurityRequirement ( Security_t requirement )

Set the security requirements of the read operations.

Parameters

requirement The security level required by the read operations.

Definition at line 249 of file gatt/GattAttribute.h.

◆ getReadSecurityRequirement()

Security_t getReadSecurityRequirement ( ) const

Return the security level required by read operations.

Returns: The security level of the read operations.

Definition at line 258 of file gatt/GattAttribute.h.

◆ allowWrite()

void allowWrite ( bool allow_write )

Allow or disallow write operation from a client.

Parameters

allow_write Write is allowed if true.

Definition at line 267 of file gatt/GattAttribute.h.

◆ isWriteAllowed()

bool isWriteAllowed ( ) const

Indicate if a client is allowed to write the attribute.

Returns: true if a client is allowed to write the attribute.

Definition at line 276 of file gatt/GattAttribute.h.

◆ setWriteSecurityRequirement()

void setWriteSecurityRequirement ( Security_t requirement )

Set the security requirements of the write operations.

Parameters

requirement The security level required by the write operations.

Definition at line 285 of file gatt/GattAttribute.h.

◆ getWriteSecurityRequirement()

Security_t getWriteSecurityRequirement ( ) const

Return the security level required by write operations.

Returns: The security level of the write operations.

Definition at line 294 of file gatt/GattAttribute.h.

Field Documentation

◆ INVALID_HANDLE

const Handle_t INVALID_HANDLE = 0x0000

static

Invalid attribute handle.

Definition at line 74 of file gatt/GattAttribute.h.

Public Types

Public Member Functions

Static Public Attributes

Detailed Description

Member Typedef Documentation

◆ Handle_t

Constructor & Destructor Documentation

◆ GattAttribute()

Member Function Documentation

◆ getHandle()

◆ getUUID()

◆ getLength()

◆ getMaxLength()

◆ getLengthPtr()

◆ setHandle()

◆ getValuePtr()

◆ hasVariableLength()

◆ allowRead()

◆ isReadAllowed()

◆ setReadSecurityRequirement()

◆ getReadSecurityRequirement()

◆ allowWrite()

◆ isWriteAllowed()

◆ setWriteSecurityRequirement()

◆ getWriteSecurityRequirement()

Field Documentation

◆ INVALID_HANDLE