Copyright ©2003 W3C®(MIT, ERCIM, Keio), All Rights Reserved. W3C viability, trademark, document use and software licensing rules apply.
This document describes an abstract feature and a concrete implementation of it for optimizing the transmission and/or wire format of SOAP messages.
This section describes the status of this document at the time of its publication. Other documents may supersede this document. The latest status of this document series is maintained at the W3C.
This is the first W3C Working Draft of the SOAP Message Transmission Optimization Mechanism document. It has been produced by the XML Protocol Working Group (WG), which is part of the Web Services Activity.
Discussion of this document takes place on the public xml-dist-app@w3.org mailing list (public archive) under the email communication rules in the XML Protocol Working Group Charter .
Patent disclosures relevant to this specification may be found on the Working Group's patent disclosure page.
This is a public W3C Working Draft. It is a draft document and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use W3C Working Drafts as reference material or to cite them as other than "work in progress". A list of all W3C technical reports can be found at http://www.w3.org/TR/.
1. Introduction
2. Abstract Transmission Optimization Feature
3. Inclusion Mechanism
4. HTTP Transmission Optimization Feature
A. References
B. Change Log (Non-Normative)
1. Introduction
1.1 Notational Conventions
1.2 Relation to other specifications
2. Abstract Transmission Optimization Feature
2.1 Introduction
2.2 Abstract Transmission Optimization Feature Name
2.3 Abstract Transmission Optimization Feature Properties
2.4 Abstract Transmission Optimization Feature Processing
2.4.1 Sending a message
2.4.2 Receiving a message
2.4.3 Transmitting a message
3. Inclusion Mechanism
3.1 Introduction
3.2 Inclusion element
3.2.1 Include element
3.2.2 href attribute
3.3 MIME Multipart/Related Serialization
3.3.1 Introduction
3.3.2 Serialization of a SOAP message
3.3.3 Deserializing a SOAP message
4. HTTP Transmission Optimization Feature
4.1 Introduction
4.2 HTTP Transmission Optimization Feature Name
4.3 Implementation
4.3.1 Sending a SOAP message
4.3.2 Receiving a SOAP message
A. References
B. Change Log (Non-Normative)
The first part of this document (2. Abstract Transmission Optimization Feature) describes an abstract feature for optimizing the transmission and/or wire format of a SOAP message by selectively re-encoding portions of the message, while still presenting an XML Infoset to the SOAP application.
This Abstract Transmission Optimization Feature is intended to be implemented by SOAP bindings, however nothing precludes implementation as a SOAP module.
The usage of the Abstract Transmission Optimization Feature is a hop-by-hop contract between a SOAP node and the next SOAP node in the SOAP message path, providing no normative convention for optimization of SOAP transmission through intermediaries. Additional specifications could in principle be written to provide for optimized multi-hop facilities provided herein, or in other ways that build on this specification (e.g. by providing for transparent passthrough of optimized messages).
The second part (3. Inclusion Mechanism) describes an Inclusion Mechanism implementing part of the Abstract Transmission Optimization Feature in a binding-independant way. The third part (4. HTTP Transmission Optimization Feature) uses this Inclusion Mechanism for implementing the Abstract Transmission Optimization Feature for an HTTP binding.
This document represents a transmission optimization mechanism which was inspired by a similar mechanism in the PASWA document (see [PASWA]). The WG plans to work later on the other parts of that document (assigning media types to binary data in XML infosets and including representations of Web resources in SOAP messages) and to publish other drafts which will include such mechanisms.
The keywords "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 [RFC 2119].
This specification uses a number of namespace prefixes throughout; they are listed in Table 1. Note that the choice of any namespace prefix is arbitrary and not semantically significant (see XML Infoset [XML InfoSet]).
| Prefix | Namespace | Notes |
|---|---|---|
| env | "http://www.w3.org/2003/05/soap-envelope" | A normative XML Schema [XML Schema Part 1], [XML Schema Part 2] document for the "http://www.w3.org/2003/05/soap-envelope" namespace can be found at http://www.w3.org/2003/05/soap-envelope. |
| xbinc | "http://www.w3.org/2003/06/soap/features/binary-inclusion" | The namespace of the 3. Inclusion Mechanism. |
This specification has currently no well-defined relation with the [SOAP 1.2 Attachment Feature] specification. However, it may be expected that this specification will supersede the [SOAP 1.2 Attachment Feature] specification once this specification has reached a stable state.
Even if this specification does not target specificaly attachments to a SOAP message, it is expected that it will fulfill all attachment feature requirements described in [SOAP 1.2 Attachment Feature].
The implementation of the abstract feature as a binding feature for an HTTP binding is intended to enhance the SOAP HTTP binding described in [SOAP Part 2] SOAP HTTP Binding or an updated version of it.
This document has been produced in conjunction with the development of requirements, embodied in the requirements document [SOAP Attachment Requirements]. The requirements document is a work in progress. No reconciliation of this document and the requirements document has been done for this publication. It is expected that this document and the requirements document will iteratively evolve over time.
The Abstract Transmission Optimization Feature enables SOAP bindings to optimize the transmission and/or wire format of a SOAP message by selectively re-encoding portions of the message, whilst still presenting an XML Infoset to the SOAP application.
The Abstract Transmission Optimization Feature also enables SOAP applications to provide hints about what part of a SOAP message could be re-encoded in an efficient way. However, it is up to the implementation to decide if and how it will optimize the transmission of a given SOAP message.
This Abstract Transmission Optimization Feature is identified by the URI:
"http://www.w3.org/2003/06/soap/features/abstract-optimization".
The Abstract Transmission Optimization Feature defines the set of properties described in Table 2.
| Property Name | Property Description |
|---|---|
http://www.w3.org/2003/06/soap/features/abstract-optimization/OptimizationCandidates |
A list containing zero or more (pointers to) element information items within the SOAP envelope candidate for being transmitted in an optimized way. The manner in which such identification is represented in the node is at the discretion of the implementation. |
Note: Among the possible choices for identifying element
information items in the
http://www.w3.org/2003/06/soap/features/abstract-optimization/OptimizationCandidates
are XPaths relative to the Envelope element
information item, or pointers to the internal implementation
of the elements in question. Indeed the list may be implicit in the
content of the envelope itself. For example, any information item
with contents that happen to be the canonical form of some base64
binary value can be implicitly included in the list if desired.
| Editorial note: HR | |
| Does "enabling" an Abstract Feature make sense for a SOAP node? If this is not the case, another property should be created for reflecting the fact that the Abstract Transmission Optimization Feature is enabled or not. | |
| Editorial note: HR per Noah's remark | |
Do we allow the optimization of only base64 binary content or do we
allow to generalize the http://www.w3.org/2003/06/soap/features/abstract-optimization/OptimizationCandidates
as a list of (type, node) pairs? This would allow for binary
transmission of integers, floats, and so on.
| |
To send a SOAP message using the Abstract Transmission Optimization
Feature, an application MUST enable the Abstract Transmission
Optimization Feature. In addition it SHOULD define the value of the
http://www.w3.org/2003/06/soap/features/abstract-optimization/OptimizationCandidates property.
When sending a SOAP message with the Abstract Transmission
Optimization Feature enabled, a SOAP node using a binding
implementing the Abstract Transmission Optimization Feature SHOULD
optimize the transmission of all the SOAP message element
information items listed in the value of the
http://www.w3.org/2003/06/soap/features/abstract-optimization/OptimizationCandidates
property.
In addition, the SOAP node binding MAY optimize the transmission of
other SOAP message element information items not
listed in the value of the
http://www.w3.org/2003/06/soap/features/abstract-optimization/OptimizationCandidates
property. In particular, if the
http://www.w3.org/2003/06/soap/features/abstract-optimization/OptimizationCandidates
property is not defined or if it has an empty value, the SOAP node
binding MAY optimize the transmission of any SOAP message
element information item.
| Editorial note: HR | |
Do we allow the optimization of the Envelope ,
Header , Body
element information items, or of a full Header
Block?
| |
| Editorial note: HR | |
| If the binding used does not implement the Abstract Transmission Optimization Feature there are several options which can be followed: fault; send the message ignoring the request for using the Abstract Optimization Feature; send the message including the request for using the Abstract Transmission Optimization Feature (allows an intermediary implementing it to use its implementation). | |
When receiving a SOAP message using an implementation of the Abstract Transmission Optimization Feature, a SOAP node MUST fault if it does not support the implementation used or the Abstract Transmission Optimization Feature.
When receiving a SOAP message using an implementation of the Abstract Transmission Optimization Feature, a SOAP node binding MUST be capable of reconstructing the original SOAP message infoset. However, implementations are free to reconstruct only those portions actually needed for processing, or to present information from the message in a form convenient for efficient processing. For example, a value sent in an optimized form (e.g. binary) MAY be made available in that form as well as in the character form mandated by the Infoset.
When receiving a SOAP message using an implementation of the
Abstract Transmission Optimization Feature, a SOAP node binding
MUST enable the Abstract Transmission Optimization Feature. In
addition, the SOAP node binding SHOULD/MAY set the value of the
http://www.w3.org/2003/06/soap/features/abstract-optimization/OptimizationCandidates property to reflect the SOAP
message parts whose transmission was optimized in the incoming
message.
| Editorial note: HR | |
We should decide on a SHOULD or on a MAY. In addition, the
http://www.w3.org/2003/06/soap/features/abstract-optimization/OptimizationCandidates
property is not very meaningful on the receiver side. We may
create another property for reflecting element information
items whose transmission was effectively optimized (an
efficient implementation will provide this property to allow
efficient retrieval of the optimized element information
items).
| |
The usage of the Abstract Transmission Optimization Feature is a hop-by-hop contract between a SOAP node and the next SOAP node in the SOAP message path. Therefore, no specific rules exist for a SOAP intermediary implementing the Abstract Transmission Optimization Feature.
However a SOAP intermediary implementing the Abstract Transmission Optimization Feature MUST still follow the rules related to the usage of an implementation of the Abstract Transmission Optimization Feature when receiving the message (see 2.4.2 Receiving a message) and those related to the usage of an implementation of the Abstract Transmission Optimization Feature when sending the message (see 2.4.1 Sending a message). In addition, it MUST follow the rules for relaying SOAP messages (see [SOAP Part 1] Relaying SOAP Messages).
The Inclusion Mechanism expands upon the Abstract Transmission Optimization Feature by describing parts of an implementation of this feature. This specification does not describe a full implementation but is intended to provide support for building a full implementation of the Abstract Transmission Optimization Feature. In particular, this specification does not specify the use of any transport for the SOAP message. A full implementation based on this specification is describe in 4. HTTP Transmission Optimization Feature.
The Inclusion Mechanism is divided into two parts, the first one
describing an xbinc:Include element information
item for including external data of any type in an XML
Infoset or document.
The second part describes a serialization of a SOAP message optimized
for transmission. This serialization uses the
xbinc:Include element information item and a
MIME Multipart/Related ([RFC 2387]) packaging for
encapsulating the SOAP message.
The xbinc:Include element information item
is used for logically including generic data into an XML infoset.
The full XML infoset can be build by replacing the
xbinc:Include element information item by
the base64 encoded value of the data referred to in the
href attribute information item.
The xbinc:Include element information item
has:
A [local name] of Include .
A [namespace name] of "http://www.w3.org/2003/06/soap/features/binary-inclusion".
Zero element information item in its [children] property.
One or more attribute information items in its [attributes] property. Among these MUST be the following:
href attribute information item
(see 3.2.2 href attribute).
The href attribute information item is used
to refer to the external data logically included by the
xbinc:Include element information item
containing it.
The href attribute information item has the
following XML infoset properties:
A [local name] of href .
A [namespace name] which has no value.
A [specified] property with a value of "true".
The type of the href attribute information
item is xs:anyURI. The value of the
href attribute information item is a URI
that refers to the data logically included by the
xbinc:Include element information item
containing it.
The MIME Multipart/Related serialization provides part of an implementation of the Abstract Transmission Optimization Feature by describing how to serialize a SOAP infoset in an optimized way inside a MIME Multipart/Related packaging. This serialization uses the 3.2 Inclusion element element for linking the main SOAP message with element information items serialized in a compact form.
For transmitting a SOAP message for which the Abstract Transmission Optimization Feature is enabled, the MIME Multipart/Related serialization helps optimizing the transmission of the message by allowing to transmit in a compact form parts of the SOAP message. The SOAP message is serialized into a MIME Multipart/Related ([RFC 2387]) packaging: one body part, the root, containing an XML representation of the SOAP envelope, while other body parts contain the parts of the SOAP message transmitted in a compact form.
Unless otherwise stated, serializing a SOAP message infoset with the MIME Multipart/Related serialization MUST be semantically equivalent to performing the following steps separately, and in the order given.
Create a MIME Multipart/Related packaging.
Create a list of the element information items
whose transmission is to be optimized. This list SHOULD
contain all the element information items of the
SOAP message pointed to in the
http://www.w3.org/2003/06/soap/features/abstract-optimization/OptimizationCandidates
property. This list MAY contain other element information
items of the SOAP message.
Add a serialization of the content of each element information item in the list in a body part of the MIME Multipart/Related packaging.
| Editorial note: HR | |
| How do we set the Content-type? | |
Modify the SOAP message infoset by replacing the content of
each element information item in the list by an
xbinc:Include element information item
referring to the body part of the MIME Multipart/Related
packaging containing its serialization.
Serialize the resulting SOAP message infoset, using XML 1.0, in the root object of the MIME Multipart/Related packaging.
| Editorial note: HR | |
| Do we allow only an XML 1.0 serialization? | |
When receiving a SOAP message using the MIME Multipart/Related serialization, deserializing MUST, at least logically, provide access to the reconstructed SOAP message infoset.
The reconstruction of the SOAP message infoset from the data contained in the MIME Multipart/Related packaging MUST be semantically equivalent to performing the following steps separately, and in the order given.
Extract the SOAP message from the root object of the MIME Multipart/Related packaging and deserialize it to an infoset representation.
Extract and deserialize each other body part of the MIME Multipart/Related packaging.
Find every xbinc:Include element information
item in the SOAP message infoset.
For each xbinc:Include element information
item, find the body part of the MIME Multipart/Related
packaging which is referred to by the href
attribute information item of the
xbinc:Include element information item.
Replace the xbinc:Include element information
item by the base64-encoded value of the referred to
body part.
When reconstructing a SOAP message infoset, the implementation:
SHOULD generate an "env:Sender" SOAP fault with a subcode of
xbinc:MissingHRef if an xbinc:Include
element information item does not contain a
href attribute information item.
SHOULD generate an "env:Sender" SOAP fault with a subcode of
xbinc:NotFoundHRef if no body part of the MIME
Multipart/Related packaging matches the href
attribute information item of an
xbinc:Include element information item.
The HTTP Transmission Optimization Feature is a binding-level feature implementing the Abstract Transmission Optimization Feature in an HTTP binding. This HTTP Transmission Optimization Feature uses the 3. Inclusion Mechanism as the basis of its implementation.
This HTTP Transmission Optimization Feature builds upon the current HTTP binding (see [SOAP Part 2] SOAP HTTP Binding), enhancing it with the support of the Abstract Transmission Optimization Feature. In all aspects not described in this section, the rules of the HTTP binding are not modified.
This HTTP Transmission Optimization Feature is identified by the URI:
"http://www.w3.org/2003/06/soap/features/http-optimization".
The HTTP Transmission Optimization Feature uses the 3. Inclusion Mechanism for implementing the Abstract Transmission Optimization Feature. It serializes the SOAP message using the 3.3.2 Serialization of a SOAP message and puts the resulting MIME Multipart/Related packaging in the HTTP body.
When sending a SOAP message for which the Abstract Transmission Optimization Feature is enabled, the HTTP Transmission Optimization Feature optimizes the transmission of the message by serializing it using the 3.3.2 Serialization of a SOAP message. Unless otherwise stated, serializing a SOAP message infoset into the HTTP body MUST be semantically equivalent to performing the following steps separately, and in the order given.
Serialize the SOAP Message into a MIME Multipart/Related packaging as described in 3.3.2 Serialization of a SOAP message.
Serialize the MIME Multipart/Related packaging into the HTTP body.
When receiving a SOAP message using the HTTP Transmission Optimization Feature, the HTTP binding MUST, at least logically, provide access to the reconstructed SOAP message infoset.
The reconstruction of the SOAP message infoset from the data contained in the HTTP Body MUST be semantically equivalent to performing the following steps separately, and in the order given.
Extract the MIME Multipart/Related packaging from the HTTP body.
Deserialize the SOAP message from the MIME Multipart/Related packaging as described in 3.3.3 Deserializing a SOAP message.
| Who | When | What |
|---|---|---|
| HR | 20030703 | Changed 1. Introduction paragraph 2 to include Noah's text on hop-by-hop contract. |
| HR | 20030703 | Changed 3.3.2 Serialization of a SOAP message bullet 4 as per Gudge suggestion (ie "the content" of each eii). Changed bullet 3 in the same way. |
| HR | 20030703 | Added Introductory text from Jacek relating document to PASWA and telling about future inclusion of PASWA related stuff. |
| HR | 20030701 | Added relation with requirements document. |
| HR | 20030630 | Added an URI table as in other specs, and a Notational Convention section. |
| HR | 20030630 | Named properties with URIs. |
| HR | 20030630 | Put all eii and aii names in monospace. |
| HR | 20030630 | Corrected specific typos found by Tony Graham. |
| HR | 20030620 | Split up HTTP implementation into an 3. Inclusion Mechanism and an 4. HTTP Transmission Optimization Feature using this 3. Inclusion Mechanism |
| HR | 20030620 | Added a link to other specification section (1.2 Relation to other specifications). |
| HR | 20030620 | Added a references section (A. References). |
| HR | 20030620 | Changed main title from "Optimization Mechanism" to "SOAP Message Transmission Optimization Mechanism". |
| HR | 20030620 | Changed abstract feature name from "Abstract Optimization Feature" to "Abstract Transmission Optimization Feature". |
| HR | 20030620 | Changed/removed all occurences of "Working Draft". |
| HR | 20030620 | Removed all colored-diff marks. |
| HR | 20030618 | Changed document's name from "Inclusion Mechanism" to "Optimization Mechanism", and changed abstract feature name and HTTP feature name. |
| HR | 20030618 | Corrected typos and other editorial errors. |
| HR | 20030618 | Added a publication date. |
| HR | 20030618 | Added an abstract. |
| HR | 20030618 | Improved general introduction (1. Introduction). |
| HR | 20030618 | Changed the presentation of the processing rules in 2.4.1 Sending a message, 2.4.2 Receiving a message. |
| HR | 20030618 | Shortened 2.4.3 Transmitting a message. |
| HR | 20030618 | Improved HTTP implementation introduction (4.1 Introduction). |
| HR | 20030618 |
Added a description of the Include element
information item and of the href
attribute information item.
|
| HR | 20030618 | Changed the presentation for sending a SOAP message through the HTTP binding. |
| HR | 20030618 | Improved the presentation for receiving a SOAP message through the HTTP binding. |