{:toc:2-5}
STOMP is a simple interoperable protocol designed for asynchronous message passing between clients via mediating servers. It defines a text based wire-format for messages passed between these clients and servers.
STOMP has been in active use for several years and is supported by many message brokers and client libraries. This specification defines the STOMP 1.1 protocol and is an update to STOMP 1.0.
Please send feedback to the stomp-spec@googlegroups.com mailing list.
STOMP arose from a need to connect to enterprise message brokers from scripting languages such as Ruby, Python and Perl. In such an environment it is typically logically simple operations that are carried out such as 'reliably send a single message and disconnect' or 'consume all messages on a given destination'.
It is an alternative to other open messaging protocols such as AMQP and implementation specific wire protocols used in JMS brokers such as OpenWire. It distinguishes itself by covering a small subset of commonly used messaging operations rather than providing a comprehensive messaging API.
More recently STOMP has matured into a protocol which can be used past these simple use cases in terms of the wire-level features it now offers, but still maintains its core design principles of simplicity and interoperability.
STOMP is a frame based protocol, with frames modelled on HTTP. A frame consists of a command, a set of optional headers and an optional body. STOMP is text based but also allows for the transmission of binary messages. The default encoding for STOMP is UTF-8, but it supports the specification of alternative encodings for message bodies.
A STOMP server is modelled as a set of destinations to which messages can be sent. The STOMP protocol treats destinations as opaque string and their syntax is server implementation specific. Additionally STOMP does not define what the delivery semantics of destinations should be. The delivery, or "message exchange", semantics of destinations can vary from server to server and even from destination to destination. This allows servers to be creative with the semantics that they can support with STOMP.
A STOMP client is a user-agent which can act in two (possibly simultaneous) modes:
-
As a producer, sending messages to a destination on the server via a
SENDframe -
As a consumer, sending a
SUBSCRIBEframe for a given destination and receiving messages from the server asMESSAGEframes.
STOMP 1.1 is designed to be backwards compatible with STOMP 1.0 while introducing several new features not present in STOMP 1.0:
-
protocol negotiation to allow for interoperability between clients and servers supporting successive versions of STOMP
-
heartbeats to allow for reliable detection of disconnecting clients and servers
-
NACKframes for negative acknowledgment of message receipt -
Support for virtual hosting
The main philosophies driving the design of STOMP are simplicity and interoperability.
STOMP is designed to be a lightweight protocol that is easy to implement both on the client and server side in a wide range of languages. This implies, in particular, that there are not many constraints on the architecture of servers and many features such as destination naming and reliability semantics are implementation specific.
In this specification we will note features of servers which are not explicitly defined by STOMP 1.1. You should consult your STOMP server's documentation for the implementation specific details of these features.
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC 2119.
Implementations may impose implementation-specific limits on unconstrained inputs, e.g. to prevent denial of service attacks, to guard against running out of memory, or to work around platform-specific limitations.
The conformance classes defined by this specification are STOMP clients and STOMP servers.
STOMP is a frame based protocol which assumes a reliable 2-way streaming network protocol (such as TCP) underneath. The client and server will communicate using STOMP frames sent over the stream. A frame's structure looks like:
COMMAND
header1:value1
header2:value2
Body^@The frame starts with a command string terminated by a newline. Following the
command are one or more header entries in <key>:<value> format. Each header
entry is terminated by a newline. A blank line indicates the end of the
headers and the beginning of the body. The body is then followed by the null
byte (0x00). The examples in this document will use ^@, control-@ in ASCII,
to represent the null byte. The null byte can be optionally followed by
multiple newlines. For more details, on how to parse STOMP frames, see the
Augmented BNF section of this document.
All commands and header names referenced in this document are case sensitive.
The commands and headers are encoded in UTF-8. All frames except the CONNECT
and CONNECTED frames will also escape any colon or newline octets found in
the resulting UTF-8 encoded headers.
Escaping is needed to allow header keys and values to contain those frame
header delimiting octets as values. The CONNECT and CONNECTED frames do not
escape the colon or newline octets in order to remain backward compatible with
STOMP 1.0.
C style string literal escapes are used to encode any colons and newlines that are found within the UTF-8 encoded headers. When decoding frame headers, the following transformations MUST be applied:
\n(octet 92 and 110) translates to newline (octet 10)\c(octet 92 and 99) translates to:(octet 58)\\(octet 92 and 92) translates to\(octet 92)
Undefined escape sequences such as \r (octet 92 and 114) MUST be treated as
a fatal protocol error. Conversely when encoding frame headers, the reverse
transformation MUST be applied.
Only the SEND, MESSAGE, and ERROR frames can have a body. All other
frames MUST NOT have a body.
The STOMP 1.0 specification included many example frames with padding in the headers and many servers and clients were implemented to trim or pad header values. This causes problems if applications want to send headers that SHOULD not get trimmed. In STOMP 1.1, clients and servers MUST never trim or pad headers with spaces.
To prevent malicious clients from exploiting memory allocation in a server, servers MAY place maximum limits on:
- the number of frame headers allowed in a single frame
- the maximum length of header lines
- the maximum size of a frame body
If these limits are exceeded the server SHOULD send the client an ERROR
frame and disconnect the client.
Since messaging systems can be organized in store and forward topologies, similar to SMTP, a message may traverse several messaging servers before reaching a consumer. The intermediate server MAY 'update' header values by either prepending headers to the message or modifying a header in-place in the message.
If the client receives repeated frame header entries, only the first header entry SHOULD be used as the value of header entry. Subsequent values are only used to maintain a history of state changes of the header. For example, if the client receives:
MESSAGE
foo:World
foo:Hello
^@The value of the foo header is just World.
A STOMP client initiates the stream or TCP connection to the server by sending
the CONNECT frame:
CONNECT
accept-version:1.1
host:stomp.github.org
^@If the server accepts the connection attempt it will respond with a
CONNECTED frame:
CONNECTED
version:1.1
^@The server can reject any connection attempt. The server SHOULD respond back
with an ERROR frame listing why the connection was rejected and then close
the connection. STOMP servers MUST support clients which rapidly connect and
disconnect. This implies a server will likely only allow closed connections
to linger for short time before the connection is reset. This means that a
client may not receive the ERROR frame before the socket is reset.
STOMP servers SHOULD handle a STOMP frame in the same manner as a CONNECT
frame. STOMP 1.1 clients SHOULD continue to use the CONNECT command to
remain backward compatible with STOMP 1.0 servers.
Clients that use the STOMP frame instead of the CONNECT frame will only
be able to connect to STOMP 1.1 servers but the advantage is that a protocol
sniffer/discriminator will be able to differentiate the STOMP connection from
an HTTP connection.
STOMP 1.1 clients MUST set the following headers:
-
accept-version: The versions of the STOMP protocol the client supports. See Protocol Negotiation for more details. -
host: The name of a virtual host that the client wishes to connect to. It is recommended clients set this to the host name that the socket was established against, or to any name of their choosing. If this header does not match a known virtual host, servers supporting virtual hosting MAY select a default virtual host or reject the connection.
STOMP 1.1 clients MAY set the following headers:
-
login: The user id used to authenticate against a secured STOMP server. -
passcode: The password used to authenticate against a secured STOMP server.
STOMP 1.1 servers MUST set the following headers:
version: The version of the STOMP protocol the session will be using. See Protocol Negotiation for more details.
STOMP 1.1 servers MAY set the following headers:
-
session: A session id that uniquely identifies the session. -
server: A field that contains information about the STOMP server. The field MUST contain a server-name field and MAY be followed by optional comment feilds delimited by a space character.The server-name field consists of a name token followed by an optional version number token.
server = name ["/" version] *(comment)Example:
server:Apache/1.3.9
From STOMP 1.1 and onwards, the CONNECT frame MUST include the
accept-version header. It SHOULD be set to a comma separated list of
incrementing STOMP protocol versions that the client supports. If the
accept-version header is missing, it means that the client only supports
version 1.0 of the protocol.
The protocol that will be used for the rest of the session will be the highest protocol version that both the client and server have in common.
For example, if the client sends:
CONNECT
accept-version:1.0,1.1,2.0
host:stomp.github.org
^@The server will respond back with the highest version of the protocol that it has in common with the client:
CONNECTED
version:1.1
^@If the client and server do not share any common protocol versions, then the
server SHOULD respond with an ERROR frame similar to:
ERROR
version:1.2,2.1
content-type:text/plain
Supported protocol versions are 1.2 2.1^@A client MAY send a frame not in this list, but for such a frame a
STOMP 1.1 server MAY respond with an ERROR frame.
The SEND frame sends a message to a destination in the messaging system. It
has one REQUIRED header, destination, which indicates where to send the
message. The body of the SEND frame is the message to be sent. For example:
SEND
destination:/queue/a
content-type:text/plain
hello queue a
^@This sends a message to a destination named /queue/a. Note that STOMP treats
this destination as an opaque string and no delivery semantics are assumed by
the name of a destination. You should consult your STOMP server's
documentation to find out how to construct a destination name which gives you
the delivery semantics that your application needs.
The reliability semantics of the message are also server specific and will
depend on the destination value being used and the other message headers
such as the transaction header or other server specific message headers.
SEND supports a transaction header which allows for transactional sends.
SEND frames SHOULD include a
content-length header and a
content-type header if a body is present.
An application MAY add any arbitrary user defined headers to the SEND frame.
User defined headers are typically used to allow consumers to filter
messages based on the application defined headers using a selector
on a SUBSCRIBE frame. The user defined headers MUST be passed through
in the MESSAGE frame.
If the server cannot successfully process the SEND frame for any reason,
the server MUST send the client an ERROR frame and disconnect the client.
The SUBSCRIBE frame is used to register to listen to a given destination.
Like the SEND frame, the SUBSCRIBE frame requires a destination header
indicating the destination to which the client wants to subscribe. Any
messages received on the subscribed destination will henceforth be delivered
as MESSAGE frames from the server to the client. The ack header controls
the message acknowledgement mode.
Example:
SUBSCRIBE
id:0
destination:/queue/foo
ack:client
^@If the server cannot successfully create the subscription,
the server MUST send the client an ERROR frame and disconnect the client.
STOMP servers MAY support additional server specific headers to customize the delivery semantics of the subscription. Consult your server's documentation for details.
An id header MUST be included in the frame to uniquely identify the subscription within the
STOMP connection session. Since a single connection can have multiple open
subscriptions with a server, the id header allows the client and server to
relate subsequent ACK, NACK or UNSUBSCRIBE frames to the original
subscription.
The valid values for the ack header are auto, client, or
client-individual. If the header is not set, it defaults to auto.
When the ack mode is auto, then the client does not need to send the
server ACK frames for the messages it receives. The server will assume the
client has received the message as soon as it sends it to the client.
This acknowledgment mode can cause messages being transmitted to the client
to get dropped.
When the ack mode is client, then the client MUST send the server
ACK frames for the messages it processes. If the connection fails before a
client sends an ACK for the message the server will assume the message has
not been processed and MAY redeliver the message to another client. The ACK
frames sent by the client will be treated as a cumulative ACK. This means the ACK operates on the message specified in the ACK frame
and all messages sent to the subscription before the ACK-ed message.
When the ack mode is client-individual, the ack mode operates just
like the client ack mode except that the ACK or NACK frames sent by the
client are not cumulative. This means that an ACK or NACK for a
subsequent message MUST NOT cause a previous message to get acknowledged.
The UNSUBSCRIBE frame is used to remove an existing subscription. Once the
subscription is removed the STOMP connections will no longer receive messages
from that destination. It requires that the id header matches the id
value of previous SUBSCRIBE operation. Example:
UNSUBSCRIBE
id:0
^@ACK is used to acknowledge consumption of a message from a subscription
using client or client-individual acknowledgment. Any messages received
from such a subscription will not be considered to have been consumed until
the message has been acknowledged via an ACK or a NACK.
ACK has two REQUIRED headers: message-id, which MUST contain a value
matching the message-id for the MESSAGE being acknowledged and
subscription, which MUST be set to match the value of the subscription's
id header. Optionally, a transaction header MAY be specified, indicating
that the message acknowledgment SHOULD be part of the named transaction.
ACK
subscription:0
message-id:007
transaction:tx1
^@NACK is the opposite of ACK. It is used to tell the server that the
client did not consume the message. The server can then either send the
message to a different client, discard it, or put it in a dead letter queue.
The exact behavior is server specific.
NACK takes the same headers as ACK: message-id (mandatory),
subscription (mandatory) and transaction (OPTIONAL).
NACK applies either to one single message (if the subscription's ack mode
is client-individual) or to all messages sent before and not yet ACK'ed
or NACK'ed.
BEGIN is used to start a transaction. Transactions in this case apply to
sending and acknowledging - any messages sent or acknowledged during a
transaction will be handled atomically based on the transaction.
BEGIN
transaction:tx1
^@The transaction header is REQUIRED, and the transaction identifier will be
used for SEND, COMMIT, ABORT, ACK, and NACK frames to bind them to
the named transaction.
Any started transactions which have not been committed will be implicitly
aborted if the client sends a DISCONNECT frame or if the TCP connection
fails for any reason.
COMMIT is used to commit a transaction in progress.
COMMIT
transaction:tx1
^@The transaction header is REQUIRED and MUST specify the id of the transaction to
commit!
ABORT is used to roll back a transaction in progress.
ABORT
transaction:tx1
^@The transaction header is REQUIRED and MUST specify the id of the transaction to
abort!
A client can disconnect from the server at anytime by closing the socket but there is no guarantee that the previously sent frames have been received by the server. To do a graceful shutdown, where the client is assured that all previous frames have been received by the server, the client SHOULD:
-
send a
DISCONNECTframe with areceiptheader set. Example:DISCONNECT receipt:77 ^@
-
wait for the
RECEIPTframe response to theDISCONNECT. Example:RECEIPT receipt-id:77 ^@
-
close the socket.
Clients MUST NOT send any more frames after the DISCONNECT frame is sent.
Some headers MAY be used, and have special meaning, with most frames.
The SEND, MESSAGE and ERROR frames SHOULD include a content-length
header if a frame body is present. If a frame's body contains NULL octets, the
frame MUST include a content-length header. The header is a byte count for
the length of the message body. If a content-length header is included, this
number of bytes MUST be read, regardless of whether or not there are null
characters in the body. The frame still needs to be terminated with a null
byte.
The SEND, MESSAGE and ERROR frames SHOULD include a content-type
header if a frame body is present. It SHOULD be set to a mime type which
describes the format of the body to help the receiver of the frame interpret
it's contents. If the content-type header is not set, the receiver SHOULD
consider the body to be a binary blob.
The implied text encoding for mime types starting with text/ is UTF-8. If
you are using a text based mime type with a different encoding then you
SHOULD append ;charset=<encoding> to the mime type. For example,
text/html;charset=utf-16 SHOULD be used if your sending an html body in
UTF-16 encoding. The ;charset=<encoding> SHOULD also get appended to any
non text/ mime types which can be interpreted as text. A good example of
this would be a UTF-8 encoded XML. It's content-type SHOULD get set to
application/xml;charset=utf-8
All STOMP clients and servers MUST support UTF-8 encoding and decoding. Therefore, for maximum interoperability in a heterogeneous computing environment, it is RECOMMENDED that text based content be encoded with UTF-8.
Any client frame other than CONNECT MAY specify a receipt
header with an arbitrary value. This will cause the server to acknowledge
receipt of the frame with a RECEIPT frame which contains the value of this
header as the value of the receipt-id header in the RECEIPT frame.
SEND
destination:/queue/a
receipt:message-12345
hello queue a^@The server will, on occasion, send frames to the client (in addition to the
initial CONNECTED frame). These frames MAY be one of:
MESSAGE frames are used to convey messages from subscriptions to the
client. The MESSAGE frame will include a destination header indicating
the destination the message was sent to. It will also contain a message-id
header with a unique identifier for that message. The subscription header
will be set to match the id header of the subscription that is receiving
the message. The frame body contains the contents of the message:
MESSAGE
subscription:0
message-id:007
destination:/queue/a
content-type:text/plain
hello queue a^@MESSAGE frames SHOULD include a
content-length header and a
content-type header if a body is present.
MESSAGE frames will also include all user defined headers that were present
when the message was sent to the destination in addition to the server
specific headers that MAY get added to the frame. Consult your server's
documentation to find out the server specific headers that it adds to
messages.
A RECEIPT frame is sent from the server to the client once a server has
successfully processed a client frame that requests a receipt. A RECEIPT
frame will include the header receipt-id, where the value is the value of
the receipt header in the frame which this is a receipt for.
RECEIPT
receipt-id:message-12345
^@The receipt body will be empty.
The server MAY send ERROR frames if something goes wrong. The error frame
SHOULD contain a message header with a short description of the error, and
the body MAY contain more detailed information (or MAY be empty).
ERROR
receipt-id:message-12345
content-type:text/plain
content-length:171
message: malformed frame received
The message:
-----
MESSAGE
destined:/queue/a
receipt:message-12345
Hello queue a!
-----
Did not contain a destination header, which is REQUIRED
for message propagation.
^@If the error is related to specific frame sent from the client, the server
SHOULD add additional headers to help identify the original frame that caused
the error. For example, if the frame included a receipt header, the ERROR
frame SHOULD set the receipt-id header to match the value of the receipt
header of the frame which the error is related to.
ERROR frames SHOULD include a
content-length header and a
content-type header if a body is present.
Heart-beating can optionally be used to test the healthiness of the underlying TCP connection and to make sure that the remote end is alive and kicking.
In order to enable heart-beating, each party has to declare what it can do
and what it would like the other party to do. This happens at the very
beginning of the STOMP session, by adding a heart-beat header to the
CONNECT and CONNECTED frames.
When used, the heart-beat header MUST contain two positive integers
separated by a comma.
The first number represents what the sender of the frame can do (outgoing heart-beats):
-
0 means it cannot send heart-beats
-
otherwise it is the smallest number of milliseconds between heart-beats that it can guarantee
The second number represents what the sender of the frame would like to get (incoming heart-beats):
-
0 means it does not want to receive heart-beats
-
otherwise it is the desired number of milliseconds between heart-beats
The heart-beat header is OPTIONAL. A missing heart-beat header MUST be
treated the same way as a "heart-beat:0,0" header, that is: the party cannot
send and does not want to receive heart-beats.
The heart-beat header provides enough information so that each party can
find out if heart-beats can be used, in which direction, and with which
frequency.
More formally, the initial frames look like:
CONNECT
heart-beat:<cx>,<cy>
CONNECTED
heart-beat:<sx>,<sy>For heart-beats from the client to the server:
-
if
<cx>is 0 (the client cannot send heart-beats) or<sy>is 0 (the server does not want to receive heart-beats) then there will be none -
otherwise, there will be heart-beats every MAX(
<cx>,<sy>) milliseconds
In the other direction, <sx> and <cy> are used the same way.
Regarding the heart-beats themselves, any new data received over the network
connection is an indication that the remote end is alive. In a given
direction, if heart-beats are expected every <n> milliseconds:
-
the sender MUST send new data over the network connection at least every
<n>milliseconds -
if the sender has no real STOMP frame to send, it MUST send a single newline byte (0x0A)
-
if, inside a time window of at least
<n>milliseconds, the receiver did not receive any new data, it CAN consider the connection as dead -
because of timing inaccuracies, the receiver SHOULD be tolerant and take into account an error margin
A STOMP session can be more formally described using the Backus-Naur Form (BNF) grammar used in HTTP/1.1 rfc2616.
LF = <US-ASCII new line (line feed) (octet 10)>
OCTET = <any 8-bit sequence of data>
NULL = <octet 0>
frame-stream = 1*frame
frame = command LF
*( header LF )
LF
*OCTET
NULL
*( LF )
command = client-command | server-command
client-command = "SEND"
| "SUBSCRIBE"
| "UNSUBSCRIBE"
| "BEGIN"
| "COMMIT"
| "ABORT"
| "ACK"
| "NACK"
| "DISCONNECT"
| "CONNECT"
| "STOMP"
server-command = "CONNECTED"
| "MESSAGE"
| "RECEIPT"
| "ERROR"
header = header-name ":" header-value
header-name = 1*<any OCTET except LF or ":">
header-value = *<any OCTET except LF or ":">This specification is licensed under the Creative Commons Attribution v2.5 license.