Crate serde_amqp
source · [−]Expand description
A serde implementation of AMQP1.0 protocol and the primitive types.
Serializing and deserializing data structures
Any type that implement serde::Serialize
and serde::Deserialize
trait can be serialized/deserialized with
the following convenience functions
Serialization:
Deserialization:
Primitive types
All primitive types defined in AMQP1.0 protocol can be found in mod primitives.
Described types
AMQP1.0 specification allows annotating any AMQP type with a descriptor::Descriptor
, thus creating a described type.
Though this can be constructed using described::Described
and Value
, a much easier way to define a custom described type is
to use the custom SerializeComposite
and DeserializeComposite
derive macros. Please be aware
that the "derive"
feature flag must be enabled.
You can read more about how to use the derive macros in the corresponding section.
Untyped AMQP1.0 values
Untyped AMQP1.0 values can be constructed as well as serialized/deserialized using Value
.
use serde_amqp::{
SerializeComposite, DeserializeComposite, Value, to_vec, from_slice,
described::Described, descriptor::Descriptor,
};
#[derive(Debug, SerializeComposite, DeserializeComposite)]
#[amqp_contract(code = "0x00:0x13", encoding = "list")]
struct Foo(Option<bool>, Option<i32>);
let foo = Foo(Some(true), Some(3));
let buf = to_vec(&foo).unwrap();
let value: Value = from_slice(&buf).unwrap();
let expected = Value::from(
Described {
descriptor: Descriptor::Code(0x13),
value: Value::List(vec![
Value::Bool(true),
Value::Int(3)
])
}
);
assert_eq!(value, expected);
Types that implements serde::Serialize
and serde::Deserialize
traits can also be converted into/from
Value
using the to_value
and from_value
functions.
WARNING enum
enum
in serde data model can be categorized as below.
use serde::{Serialize, Deserialize};
#[derive(Serialize, Deserialize)]
enum Enumeration {
UnitVariant,
NewTypeVariant(u32),
TupleVariant(bool, u64, String),
StructVariant { id: u32, is_true: bool },
}
AMQP1.0 protocol doesn’t natively support NewTypeVariant
, TupleVariant
or StructVariant
.
For the sake of completeness, serialization and deserialization for these variants are implemented as follows:
NewTypeVariant
is encoded/decoded as a map of one key-value pair with the variant index being the key and the single wrapped field being the value.TupleVariant
is encoded/decoded as a map of one key-value pair with the varant index being the key and a list of the fields being the value.StructVariant
is encoded/decoded as a map of one key-value pair with the variant index being the key and a list of the fields being the value.
Feature flag
default = []
Feature | Description |
---|---|
"derive" | enables SerializeComposite and DeserializeComposite |
"extensions" | enables extensions mod (see Extensions), added since “0.4.5” |
SerializeComposite
and DeserializeComposite
The macro provides three types of encodings:
"list"
: The struct will be serialized as a described list. A described list is an AMQP1.0 list with its descriptor prepended to the list itself. The deserialization will take either the"list"
or the"map"
encoded values."map"
: The struct will be serialized as a described map. A described map is an AMQP1.0 map with its descriptor prepended to the map. The deserialization will take either the"list"
or the"map"
encoded values."basic"
: The struct must be a thin wrapper (containing only one field) over another serializable/deserializable type. The inner struct will be serialized/deserialized with the descriptor prepended to the struct.
Details with the "list"
encoding
Optinal fields
If a field is not marked with "mandatory"
in the specification, the field can be an Option
. During serialization, the optional fields may be skipped completely or encoded as an AMQP1.0 null
primitive (0x40
). During deserialization, an AMQP1.0 null
primitive or an empty field will be decoded as a None
.
Fields with default values:
For fields that have default values defined in the specification, the field type must implement both the Default
and PartialEq
trait. During serialization, if the field is equal to the default value of the field type, the field will be either ignored completely or encoded as an AMQP1.0 null
primitive (0x40
). During deserialization, an AMQP1.0 null
primitive or an empty field will be decoded as the default value of the type.
Example of the derive macros
The "list"
encoding will encode the Attach
struct as a described list (a descriptor followed by a list of the fields).
/// 2.7.3 Attach
/// Attach a link to a session.
/// <type name="attach" class="composite" source="list" provides="frame">
/// <descriptor name="amqp:attach:list" code="0x00000000:0x00000012"/>
#[derive(Debug, DeserializeComposite, SerializeComposite)]
#[amqp_contract(
name = "amqp:attach:list",
code = "0x0000_0000:0x0000_0012",
encoding = "list",
rename_all = "kebab-case"
)]
pub struct Attach {
/// <field name="name" type="string" mandatory="true"/>
pub name: String,
/// <field name="handle" type="handle" mandatory="true"/>
pub handle: Handle,
/// <field name="role" type="role" mandatory="true"/>
pub role: Role,
/// <field name="snd-settle-mode" type="sender-settle-mode" default="mixed"/>
#[amqp_contract(default)]
pub snd_settle_mode: SenderSettleMode,
/// <field name="rcv-settle-mode" type="receiver-settle-mode" default="first"/>
#[amqp_contract(default)]
pub rcv_settle_mode: ReceiverSettleMode,
/// <field name="source" type="*" requires="source"/>
pub source: Option<Source>,
/// <field name="target" type="*" requires="target"/>
pub target: Option<Target>,
/// <field name="unsettled" type="map"/>
pub unsettled: Option<BTreeMap<DeliveryTag, DeliveryState>>,
/// <field name="incomplete-unsettled" type="boolean" default="false"/>
#[amqp_contract(default)]
pub incomplete_unsettled: Boolean,
/// <field name="initial-delivery-count" type="sequence-no"/>
pub initial_delivery_count: Option<SequenceNo>,
/// <field name="max-message-size" type="ulong"/>
pub max_message_size: Option<ULong>,
/// <field name="offered-capabilities" type="symbol" multiple="true"/>
pub offered_capabilities: Option<Array<Symbol>>,
/// <field name="desired-capabilities" type="symbol" multiple="true"/>
pub desired_capabilities: Option<Array<Symbol>>,
/// <field name="properties" type="fields"/>
pub properties: Option<Fields>,
}
/// 3.2.5 Application Properties
/// <type name="application-properties" class="restricted" source="map" provides="section">
/// <descriptor name="amqp:application-properties:map" code="0x00000000:0x00000074"/>
/// </type>
#[derive(Debug, Clone, SerializeComposite, DeserializeComposite)]
#[amqp_contract(
name = "amqp:application-properties:map",
code = "0x0000_0000:0x0000_0074",
encoding = "basic"
)]
pub struct ApplicationProperties(pub OrderedMap<String, SimpleValue>);
Extensions
The following type(s) are provided in the extensions
mod and require the extensions
feature
TransparentVec
- a thin wrapper aroundVec
that is serialized/deserialized as a sequence of elementsVec
is treated as an AMQPList
in the core spec
Re-exports
pub use serde;
pub use de::from_reader;
pub use de::from_slice;
pub use error::Error;
pub use ser::to_vec;
pub use value::Value;
Modules
Described<T>
typeDescriptor
type."derive"
.Read
traitFunctions
Value
as an instance of type T