Multiple ALTO Resources Query Using Multipart Message
draft-zhang-alto-multipart-03
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| Authors | Jingxuan Zhang , Y. Richard Yang | ||
| Last updated | 2020-03-09 | ||
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draft-zhang-alto-multipart-03
ALTO WG J. Zhang
Internet-Draft Tongji University
Intended status: Standards Track Y.R. Yang
Expires: 10 September 2020 Yale University
9 March 2020
Multiple ALTO Resources Query Using Multipart Message
draft-zhang-alto-multipart-03
Abstract
Many ALTO use cases involve multiple ALTO information resources like
different network maps, cost maps and property maps to achieve their
own specific goals. To make the ALTO client query them one by one is
not only inefficient but also error-prone. The inconsistent
responses can be performed because of the unstable communication
environment, and finally conduct the unexpected traffic optimization.
Further more, some ALTO information resources may have correlation,
which means one's input parameters may depends on another one's
response. To address those issues, some advanced query schema is
required. This document proposes an ALTO extension to support the
multiple ALTO resources query in the single request using the HTTP
multipart message and the existing JSON query languages.
Requirements Language
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 [RFC2119].
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on 10 September 2020.
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Copyright Notice
Copyright (c) 2020 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents (https://trustee.ietf.org/
license-info) in effect on the date of publication of this document.
Please review these documents carefully, as they describe your rights
and restrictions with respect to this document. Code Components
extracted from this document must include Simplified BSD License text
as described in Section 4.e of the Trust Legal Provisions and are
provided without warranty as described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminologies . . . . . . . . . . . . . . . . . . . . . . . . 4
2.1. Resource Query Entry . . . . . . . . . . . . . . . . . . 4
2.2. Resource Response Entry . . . . . . . . . . . . . . . . . 4
2.3. Resource Response Entry Body . . . . . . . . . . . . . . 4
3. Use Cases . . . . . . . . . . . . . . . . . . . . . . . . . . 4
3.1. Simple Batch Query . . . . . . . . . . . . . . . . . . . 4
3.2. Properties Constrained Query . . . . . . . . . . . . . . 5
3.3. Path Vector Query . . . . . . . . . . . . . . . . . . . . 5
4. Requirements . . . . . . . . . . . . . . . . . . . . . . . . 5
5. Design Space of Multipart Resource in ALTO . . . . . . . . . 6
6. Multipart Query Resource . . . . . . . . . . . . . . . . . . 7
6.1. Media Type . . . . . . . . . . . . . . . . . . . . . . . 7
6.2. HTTP Method . . . . . . . . . . . . . . . . . . . . . . . 7
6.3. Capabilities . . . . . . . . . . . . . . . . . . . . . . 7
6.4. Accept Input Parameters . . . . . . . . . . . . . . . . . 7
6.5. Uses . . . . . . . . . . . . . . . . . . . . . . . . . . 8
6.6. Response . . . . . . . . . . . . . . . . . . . . . . . . 8
7. Protocol Errors . . . . . . . . . . . . . . . . . . . . . . . 8
7.1. Partial Error . . . . . . . . . . . . . . . . . . . . . . 8
7.2. Entire Error . . . . . . . . . . . . . . . . . . . . . . 9
8. Incremental Update Integration . . . . . . . . . . . . . . . 9
9. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . 10
9.1. IRD Example . . . . . . . . . . . . . . . . . . . . . . . 10
9.2. Example 1: Simple Batch Query . . . . . . . . . . . . . . 11
9.3. Example 2: Properties Constrained Query . . . . . . . . . 13
9.4. Example 3: Path Vector Query . . . . . . . . . . . . . . 15
10. Compatibility . . . . . . . . . . . . . . . . . . . . . . . . 17
10.1. Compatibility with Legacy ALTO Clients/Servers . . . . . 17
10.2. Compatibility with Existing Protocol Extensions . . . . 18
11. Misc Considerations . . . . . . . . . . . . . . . . . . . . . 18
11.1. Return ALTO Information Resources over HTTP/2 . . . . . 18
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11.2. Support Incremental Update . . . . . . . . . . . . . . . 18
11.3. Anonymous Resources . . . . . . . . . . . . . . . . . . 19
12. Security Considerations . . . . . . . . . . . . . . . . . . . 19
13. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 19
13.1. application/alto-* Media Types . . . . . . . . . . . . . 19
14. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 21
15. References . . . . . . . . . . . . . . . . . . . . . . . . . 21
15.1. Normative References . . . . . . . . . . . . . . . . . . 21
15.2. Informative References . . . . . . . . . . . . . . . . . 21
Appendix A. Figures . . . . . . . . . . . . . . . . . . . . . . 22
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 22
1. Introduction
Application-Layer Traffic Optimization (ALTO) protocol [RFC7285] and
its extensions already define several types of information resources,
like Network Map, Cost Map and Property Map, to expose useful network
information to applications. However, many applications do not only
use a single information resource to perform their traffic
optimization. Retrieving multiple ALTO information resources is very
common in many ALTO use cases.
Using the current ALTO framework defined in [RFC7285], the ALTO
client can only query multiple ALTO information resources one by one.
It is not only inefficient but also error-prone. Because of the
network delay between different requests and the frequent change of
ALTO information resources, the responses received by the ALTO client
may be inconsistent.
Further more, some ALTO information resources have known
dependencies, which means the ALTO client may need one's response to
decide another one's query input parameters.
To be summarized, we need the multipart query service for three
reasons:
* Clients may want to query multiple ALTO information resources in a
single request to reduce the network latency.
* Clients may want to query multiple ALTO resources consistently,
which means the server should guarantee the responses of all
resources are generated at the same time.
* Some use cases need to query multiple ALTO resources with a joint
relationship.
This document defines a new ALTO services for: (1) querying multiple
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ALTO resources in a single request/response, and (2) supporting
general-purpose JSON query languages to resolve the relational query.
2. Terminologies
Besides the terms defined in [RFC2045], [RFC2046], [RFC2387], and
[RFC7285], this document also uses the following additional terms:
2.1. Resource Query Entry
A Resource Query Entry indicates the ResoureQuery object (see
Section 6.4) for an individual resource in the accept input
parameters of the Multipart Query resource.
2.2. Resource Response Entry
A Resource Response Entry indicates the entry of an individual part
of the multipart response message, including the MIME headers and the
body content.
2.3. Resource Response Entry Body
A Resource Response Entry Body indicates the body content of a
Resource Response Entry.
3. Use Cases
The following use cases can benefit from the multipart query service.
3.1. Simple Batch Query
The simplest use case is to query a batch of ALTO resources in a
single request.
Although the ALTO client can perform ALTO requests for multiple
times, it is not only inefficient but also inconsistent.
For example, the ALTO server provides a network map resource A and a
dependent cost map resource B. Both resources may change frequently.
Assume the ALTO client queries the network map first, and it gets the
revision A1. When the client queries the cost map, the network map
may be already changed from A1 to A2, and the client receives cost
map B2 which depends on A2 not A1. So the responded cost map B2 is
not consistent with the previous network map A1.
This case requires the ALTO server to provide a way for the ALTO
client to query multiple ALTO resources in a single transaction.
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3.2. Properties Constrained Query
Beyond the simple batch query, there are also some another use cases
requiring a new service for relational query. For example, Some
clients may need to query an endpoint property map first, and find
endpoints with some properties fitting some conditions. And then
they query the endpoint cost of these endpoints.
In this case, the endpoint cost query depends on the result of the
property map query. Although the ALTO client can cache the whole
property map in its local storage, it is still not efficient and may
conduct the consistency issue if the property map changes frequently.
So it requires a new service to provide multiple dependent resources
efficiently and consistently.
A general multipart query service benefits the ALTO client in two
aspects:
* It allows the ALTO client to specify the boolean test to reduce
the transmission of the useless data from the ALTO server.
* It compounds multiple ALTO information resources in a single
response to reduce the communication times. Thus, the
transmission latency can be reduced.
3.3. Path Vector Query
Another use case requiring the multiple resource query is the
relational query between the on-demand generated resources. A
straightforward example is the path vector query demonstrated in
[I-D.ietf-alto-path-vector].
[I-D.ietf-alto-path-vector] introduces an extension of ALTO to
provide path vector information by cost map and unified property map
[I-D.ietf-alto-unified-props-new]. The client using path vector
extension will usually query cost map and a dynamically generated
property map sequentially. It is even hard to cache the full data of
resources, because both the cost map and the property map are on-
demand generated by the query input here. Thus, the only way to
reduce the time consumption is to compound the two resources.
4. Requirements
From the use cases described in Section 3, there are three additional
requirements for ALTO protocol:
MPQ-Req1: The ALTO protocol SHOULD allow the client to query
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multiple ALTO resources in a single request, and return the result
in a single response.
It is the basic requirement to provide the query for the compound
resources. Even simple cases can benefit if this requirement is
realized.
MPQ-Req2: The ALTO protocol SHOULD provide general filter schema for
any ALTO resources.
Current filter schema in ALTO protocol only supports the simple
boolean test of numerical comparison. And the boolean filtered
query is only supported by the cost map and the endpoint cost
resource. It is not enough for the general cases. Even simple
property map may require more general filter schema.
MPQ-Req3: The ALTO protocol SHOULD support relational query for
mulitple joint resources.
Some ALTO resources are relational and cannot be used
individually. The path vector query is such an example. In these
use cases, the support of relational query for multiple joint
resources is very helpful.
5. Design Space of Multipart Resource in ALTO
This document discusses the solution of how to apply "multipart/*"
(see [RFC2045] and [RFC2046]) response to the ALTO protocol.
There are three cases applying Multipart response to ALTO:
Multipart Request and Multipart Response: In this case, an ALTO
client can start a single request using Multipart encoding to
query a batch of resources.
Single Request and Fixed-Layout Multipart Response: In this case, an
ALTO server receives a non-Multipart request, e.g., the filtered
costmap request or the endpoint cost request, but returns a
Multipart response. The ALTO server MUST export the layout of the
Multipart response in the IRD. A special example can be found in
[I-D.ietf-alto-path-vector].
Single Request and Flexible-Layout Multipart Response: This case
extends the previous case to allows the Multipart response with
flexible layout. The ALTO server receives the unified query
request and generate the layout of the response based on the
request. The ALTO client can even use general-purpose query
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language like XQuery [W3CXQUERY] and JSONiq [JSONIQ] for general
query process and relational joint query.
The application about Multipart request to the single object response
is out of the scope of this document.
6. Multipart Query Resource
6.1. Media Type
"multipart/related" [RFC2387].
6.2. HTTP Method
An ALTO Multipart Query resource is requested using the HTTP POST
method.
6.3. Capabilities
The capabilities are defined by an object of type
MultipartQueryCapabilities:
object {
JSONString query-langs<0..*>;
} MultipartQueryCapabilities;
where "query-langs" is an array of JSONString to indicate which query
languages are supported by this resource.
6.4. Accept Input Parameters
The input parameters for a Multipart Query request are supplied in
the entity body of the POST request. This document specifies the
input parameters with a data format indicated by the media type
"application/alto-multipartquery+alto", which is a JSON object of
type ReqMultipartQuery:
object {
ResourceQuery resources<1..*>;
[JsonString query-lang;]
} ReqMultipartQuery;
object {
JsonString resource-id;
[JsonValue input;]
} ResourceQuery;
with fields:
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resources: List of ResourceQuery objects for which resources are to
be queried and how to query them. Each ResourceQuery object MUST
include the "resource-id" field to indicate which resource is to
be queried. If the queried resource requires the POST method, the
"input" field MUST be specified. The value of the "input" field
MUST be either a JSONString or a JSONObject. When its value is a
JSONObject, its format MUST be as the accept input parameters of
its resource. When its value is a JSONString, it MUST be a
program written in the query language specified by the "query-
lang" field.
query-lang: Optional. The value of the "query-lang" field MUST be
one of values in the "query-langs" capability. If this field is
not specified in the request, the ALTO client SHOULD NOT use any
query language in the "input" field.
6.5. Uses
An array with the resource ID(s) of resource(s) which this multipart
query resource can compound. The used resource can be any available
ALTO resources except for the multipart query resource. If the
"uses" field is not specified, all the available ALTO resources can
be queried except for the multipart query resource.
6.6. Response
The response of multipart query resource is a multipart message.
Each part of this multipart message is the response of a queried
resource in the request.
7. Protocol Errors
At the top level, the request of ALTO Multipart Query resource may
conduct two types of errors: Partial Error and Entire Error.
7.1. Partial Error
The Partial Error only occurs when the value of the "resource-id"
field or the "input" field is invalid.
When the Partial Error occurs, the ALTO server MUST still return the
response in the media type "multipart/related". For the resource
query entry with an error, the ALTO server MUST specify the "Content-
Type" of its resource response entry as "application/alto-
error+json", and include the ALTO error message in its resource
response entry body. For the resource query entry without any error,
the ALTO server MUST perform its query request normally.
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The value of the "resource-id" field is invalid when this resource id
is not defined by the Information Resource Directory. In this case,
the ALTO server MUST return the E_INVALID_FIELD_VALUE error.
The validation of each "input" field of the multipart query input
parameters depends on the queried resource:
* If the "input" field of the multipart query input parameters is
neither a JSONObject nor a JSONString, the ALTO server SHOULD
return the E_INVALID_FIELD_TYPE error, unless a future protocol
extension supports the non-JSONObject input parameters.
* If the "input" field of the multipart query input parameters is a
JSONObject, the ALTO server MUST validate the value using its
queried resource and return the corresponding error if it has.
* If the "input" field of the multipart query input parameters is a
JSONString:
- If the "query-lang" is not specified, the ALTO server MUST
return the E_INVALID_FIELD_TYPE error.
- If the "query-lang" is specified, the ALTO server MUST execute
this JSONString as a program written in the "query-lang". If
the execution failed, the ALTO server MUST return the
E_INVALID_FIELD_VALUE error. If the execution succeed but the
result fails to pass the validation of the queried resource,
the ALTO server MUST return the E_INVALID_FIELD_VALUE error and
attach the error message returned by the queried resource into
the "message" field of the ALTO error message.
The syntax error is an Entire Error.
7.2. Entire Error
Any other invalid request will conduct the Entire Error.
When the Entire Error occurs, the ALTO server MUST return the error
response in the media type "application/alto-error+json" instead of
"multipart/related". The process of the Entire Error is as defined
in Section 8.5 of [RFC7285].
8. Incremental Update Integration
This document defines a compatible incremental update process for
Multipart Query resource with [I-D.ietf-alto-incr-update-sse].
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An ALTO server's IRD can export an Update Stream service defined in
[I-D.ietf-alto-incr-update-sse] including the Resource ID of a
Multipart Query resource in the "uses" field. When an ALTO client
subscribe the incremental update for this Multipart Query resource,
the ALTO server sends the whole Multipart response message back at
the first data update message. Then the ALTO server subscribe all
nodes in this multipart resource tree automatically. Once data
updated later, the ALTO server publishes the update for each node
individually.
9. Examples
9.1. IRD Example
Assume the root IRD is like the following:
{
"meta": {
"path-vector": {
"cost-mode": "array",
"cost-metric": "ane-path"
},
"num-routingcost": {
"cost-mode": "numerical",
"cost-metric": "routingcost"
},
"num-hopcount": {
"cost-mode": "numerical",
"cost-metric": "hopcount"
}
},
"resources": {
"my-default-networkmap": {
"uri": "http://alto.example.com/networkmap",
"media-type": "application/alto-networkmap+json"
},
"my-default-costmap": {
"uri": "http://alto.example.com/costmap",
"media-type": "application/alto-costmap+json",
"capabilities": {
"cost-type-names": [ "num-routingcost" ]
},
"uses": [ "my-default-networkmap" ]
},
"my-filtered-costmap": {
"uri": "http://alto.example.com/costmap/filtered",
"media-type": "application/alto-costmap+json",
"accepts": "application/alto-costmapfilter+json",
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"capabilities": {
"cost-type-names": [ "num-hopcount" ]
},
"uses": [ "my-default-networkmap" ]
},
"endpoint-path-vector": {
"uri": "http://alto.exmaple.com/endpointcost",
"media-type": "application/alto-endpointcost+json",
"accepts": "application/alto-endpointcostparams+json",
"capabilities": {
"cost-constraints": true,
"cost-type-names": [ "path-vector" ],
},
"property-map": "propmap-availbw"
},
"propmap-availbw-delay": {
"uri": "http://alto.exmaple.com/propmap/availbw",
"media-type": "application/alto-propmap+json",
"accepts": "application/alto-propmapparams+json",
"capabilities": {
"domain-types": [ "ane" ],
"prop-types": [ "availbw" ]
}
},
"propmap-location": {
"uri": "http://alto.exmaple.com/propmap/location",
"media-type": "application/alto-propmap+json",
"accepts": "application/alto-propmapparams+json",
"capabilities": {
"domain-types": [ "pid" ],
"prop-types": [ "country", "state" ]
}
},
"multipart-query": {
"uri": "http://alto.example.com/multipart",
"media-type": "multipart/related",
"accepts": "application/alto-multipartquery+json",
"capabilities": {
"query-langs": [ "xquery", "jsoniq" ]
}
}
}
}
9.2. Example 1: Simple Batch Query
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POST /multipart HTTP/1.1
Host: alto.example.com
Accept: multipart/related, application/alto-error+json
Content-Lenght: [TBD]
Content-Type: application/alto-multipartquery+json
{
"resources": [
{
"resource-id": "my-default-networkmap"
},
{
"resource-id": "my-default-costmap"
}
]
}
HTTP/1.1 200 OK
Content-Lenght: [TBD]
Content-Type: multipart/related; boundary=simple-batch-query
--simple-batch-query
Content-Type: application/alto-networkmap+json
{
"meta": {
"vtag": {
"resource-id": "my-default-networkmap",
"tag": "75ed013b3cb58f896e839582504f622838ce670f"
}
},
"network-map": {
"PID1" : {
"ipv4" : [
"192.0.2.0/24",
"198.51.100.0/25"
]
},
"PID2" : {
"ipv4" : [
"198.51.100.128/25"
]
},
"PID3" : {
"ipv4" : [
"0.0.0.0/0"
],
"ipv6" : [
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"::/0"
]
}
}
}
--simple-batch-query
Content-Type: application/alto-costmap+json
{
"meta": {
"dependent-vtags": [
{
"resource-id": "my-default-networkmap",
"tag": "75ed013b3cb58f896e839582504f622838ce670f"
}
],
"cost-type": {
"cost-mode": "numerical",
"cost-metric": "routingcost"
}
},
"cost-map": {
"PID1": { "PID1": 1, "PID2": 5, "PID3": 10 },
"PID2": { "PID1": 5, "PID2": 1, "PID3": 15 },
"PID3": { "PID1": 20, "PID2": 15 }
}
}
9.3. Example 2: Properties Constrained Query
NOTE: In this example, we use the "`" block to express the raw string
with unescaped characters like "\n" and "\"". It is not valid HTTP
body, but only used to better present. When the request is sent to
the ALTO server, the "`" block should be escaped.
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POST /multipart HTTP/1.1
Host: alto.example.com
Accept: multipart/related, application/alto-error+json
Content-Lenght: [TBD]
Content-Type: application/alto-multipartquery+json
{
"query-lang": "jsoniq",
"resources": [
{
"resource-id": "propmap-location"
},
{
"resource-id": "my-default-costmap",
"input": `
let $propmap := collection("propmap-location")
.("property-map")
return {
"cost-type": {
"cost-mode": "numerical",
"cost-metric": "hopcount"
},
"pids": {
"srcs": [
for $pid in keys($propmap)
where $propmap.$pid.country eq "US"
return substring-after($pid, "PID:")
],
"dsts": [
for $pid in keys($propmap)
where $propmap.$pid.country eq "CA"
return substring-after($pid, "PID:")
]
}
}
`
}
]
}
HTTP/1.1 200 OK
Content-Lenght: [TBD]
Content-Type: multipart/related; boundary=prop-const-query
--prop-const-query
Content-Type: application/alto-propmap+json
{
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"property-map": {
"pid:PID1": {
"country": "US",
"state": "CA"
},
"pid:PID2": {
"country": "US",
"state": "CT"
},
"pid:PID3": {
"country": "CA",
"state": "QC"
},
"pid:PID4": {
"country": "CA",
"state": "NT"
},
"pid:PID5": {
"country": "FR"
}
}
}
--prop-const-query
Content-Type: application/alto-costmap+json
{
"meta": {
"cost-type": {
"cost-mode": "numerical",
"cost-metric": "hopcount"
}
},
"cost-map": {
"PID1": {
"PID3": 5,
"PID4": 7
},
"PID2": {
"PID3": 8,
"PID4": 4
}
}
}
9.4. Example 3: Path Vector Query
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POST /multipart HTTP/1.1
Host: alto.example.com
Accept: multipart/related, application/alto-error+json
Content-Lenght: [TBD]
Content-Type: application/alto-multipartquery+json
{
"query-lang": "jsoniq",
"resources": [
{
"resource-id": "endpoint-path-vector",
"input": {
"cost-type": {
"cost-mode": "array",
"cost-metric": "ane-path"
},
"endpoints": {
"srcs": [ "ipv4:192.0.2.2" ],
"dsts": [ "ipv4:192.0.2.89",
"ipv4:203.0.113.45" ]
}
}
},
{
"resource-id": "propmap-availbw",
"input": `
let $propmap := collection("endpiont-path-vector")
.("endpoint-cost-map")
return {
"entities": [
distinct-values(flatten(
for $src in keys($propmap)
let $dsts := $propmap.$src
return flatten(
for $dst in keys($dsts)
return $dsts.$dst
)
))
],
"properties": [ "availbw" ]
}
`
}
]
}
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HTTP/1.1 200 OK
Content-Length: [TBD]
Content-Type: multipart/related; boundary=path-vector-query
--path-vector-query
Content-Type: application/alto-endpointcost+json
{
"meta": {
"cost-type": {
"cost-mode": "array",
"cost-metric": "ane-path"
}
},
"endpoint-cost-map": {
"ipv4:192.0.2.2": {
"ipv4:192.0.2.89": [ "ane:L001", "ane:L003", "ane:L004" ],
"ipv4:203.0.113.45": [ "ane:L001", "ane:L004", "ane:L005" ],
"ipv6:2001:db8::10": [ "ane:L001", "ane:L005", "ane:L007" ]
}
}
}
--path-vector-query
Content-Type: application/alto-propmap+json
{
"property-map": {
"ane:L001": { "availbw": 50 },
"ane:L003": { "availbw": 48 },
"ane:L004": { "availbw": 55 },
"ane:L005": { "availbw": 60 },
"ane:L007": { "availbw": 35 }
}
}
10. Compatibility
10.1. Compatibility with Legacy ALTO Clients/Servers
The multipart query service is a new ALTO service using the new media
type. So the legacy ALTO client cannot identify this service from
the IRD of the ALTO server supporting it. And the legacy ALTO server
also cannot interpret the request of a multipart query service sent
by the ALTO client.
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10.2. Compatibility with Existing Protocol Extensions
The multipart query service can use any ALTO resources exchanging
JSON data in request/response mechanism. So all the known ALTO
extensions like ALTO Calendar [I-D.ietf-alto-cost-calendar], Multi-
Cost [RFC8189] and the Path Vector [I-D.ietf-alto-path-vector]
extension, which does not change the request/response mechanism, are
compatible with the multipart query service.
11. Misc Considerations
11.1. Return ALTO Information Resources over HTTP/2
HTTP/2 [RFC7540] provides new features like streams and multiplexing
that can essentially improve the web interface communication latency.
As the deployment of HTTP/2, it is valuable to consider how to
transit the ALTO information resources over HTTP/2.
The multipart query service defined in this document includes two
parts: the multiple-resource query schema and the multipart response
schema.
By leveraging HTTP/2 multiplexing in the scope of this document, the
multipart response schema can be replaced with sending multiple
HTTP/2 streams using HTTP/2 server push. Each stream only needs to
include a single ALTO information resource. The benefit is that the
Server can include additional meta information in the HTTP HEADERS
frame of each stream. And the Client can parse each ALTO information
resource in parallel.
However, the multiple-resource query schema is required to be reused
to keep the consistent request semantics. The Server requires the
Client to send the multiple-resource query request in a single HTTP/2
stream. It will enforce the Server to generate the response to
different ALTO information resources based on the same database
snapshot.
11.2. Support Incremental Update
Because the response body entry of the multipart query resource is
not a single JSON object, it may not be compatible with the current
incremental update representation used in
[I-D.ietf-alto-incr-update-sse].
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11.3. Anonymous Resources
Some use cases may need the server generates "anonymous" ALTO
resources for the on-demand information. The "anonymous" ALTO
resources usually cannot appear alone but need to bind with some
"non-anonymous" ALTO resources.
12. Security Considerations
Allow the ALTO clients to upload the query language script may not be
safe. The code injection and many potential attacks can be
conducted. The security issue should be discussed and considered.
To avoid the attacks like the code injection, this document
recommends the following approaches:
Database Isolation: Some clients may attempt to access the secure
database inside the server. Isolate the data into the different
databases can reduce the risk of the information leak.
Application Container Isolation: Attackers may inject harmful code
into the input query programs to attempt to access the system
control. To avoid this, each query process is recommended to be
isolated using the application container.
Resource Limit: Even attackers cannot get the permission to crack
the data or the system, they can still inject some heavy-load
programs to consume the server resources. Thus, limiting the
memory usage and execution time of each query process is highly
recommended.
13. IANA Considerations
13.1. application/alto-* Media Types
This document registers an additional ALTO media type, listed in
Table 1.
+-------------+--------------------------+---------------+
| Type | Subtype | Specification |
+=============+==========================+===============+
| application | alto-multipartquery+json | Section 6.4 |
+-------------+--------------------------+---------------+
Table 1: Additional ALTO Media Type.
Type name: application
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Subtype name: This document registers multiple subtypes, as listed
in Table 1.
Required parameters: n/a
Optional parameters: n/a
Encoding considerations: Encoding considerations are identical to
those specified for the "application/json" media type. See
[RFC8259].
Security considerations: Security considerations related to the
generation and consumption of ALTO Protocol messages are discussed
in Section 15 of [RFC7285].
Interoperability considerations: This document specifies formats of
conforming messages and the interpretation thereof.
Published specification: This document is the specification for
these media types; see Table 1 for the section documenting each
media type.
Applications that use this media type: ALTO servers and ALTO clients
either stand alone or are embedded within other applications.
Additional information: Magic number(s): n/a
File extension(s): This document uses the
mime type to refer to protocol messages and thus does not
require a file extension.
Macintosh file type code(s): n/a
Person & email address to contact for further information: See
Authors' Addresses section.
Intended usage: COMMON
Restrictions on usage: n/a
Author: See Authors' Addresses section.
Change controller: Internet Engineering Task Force
(mailto:iesg@ietf.org).
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14. Acknowledgements
15. References
15.1. Normative References
[RFC2045] Freed, N. and N. Borenstein, "Multipurpose Internet Mail
Extensions (MIME) Part One: Format of Internet Message
Bodies", RFC 2045, DOI 10.17487/RFC2045, November 1996,
<https://www.rfc-editor.org/info/rfc2045>.
[RFC2046] Freed, N. and N. Borenstein, "Multipurpose Internet Mail
Extensions (MIME) Part Two: Media Types", RFC 2046,
DOI 10.17487/RFC2046, November 1996,
<https://www.rfc-editor.org/info/rfc2046>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC2387] Levinson, E., "The MIME Multipart/Related Content-type",
RFC 2387, DOI 10.17487/RFC2387, August 1998,
<https://www.rfc-editor.org/info/rfc2387>.
[RFC7285] Alimi, R., Ed., Penno, R., Ed., Yang, Y., Ed., Kiesel, S.,
Previdi, S., Roome, W., Shalunov, S., and R. Woundy,
"Application-Layer Traffic Optimization (ALTO) Protocol",
RFC 7285, DOI 10.17487/RFC7285, September 2014,
<https://www.rfc-editor.org/info/rfc7285>.
[RFC7540] Belshe, M., Peon, R., and M. Thomson, Ed., "Hypertext
Transfer Protocol Version 2 (HTTP/2)", RFC 7540,
DOI 10.17487/RFC7540, May 2015,
<https://www.rfc-editor.org/info/rfc7540>.
15.2. Informative References
[I-D.ietf-alto-cost-calendar]
Randriamasy, S., Yang, Y., WU, Q., Lingli, D., and N.
Schwan, "Application-Layer Traffic Optimization (ALTO)
Cost Calendar", Work in Progress, Internet-Draft, draft-
ietf-alto-cost-calendar-19, 2 March 2020,
<http://www.ietf.org/internet-drafts/draft-ietf-alto-cost-
calendar-19.txt>.
[I-D.ietf-alto-incr-update-sse]
Roome, W. and Y. Yang, "ALTO Incremental Updates Using
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Server-Sent Events (SSE)", Work in Progress, Internet-
Draft, draft-ietf-alto-incr-update-sse-20, 20 February
2020, <http://www.ietf.org/internet-drafts/draft-ietf-
alto-incr-update-sse-20.txt>.
[I-D.ietf-alto-path-vector]
Gao, K., Lee, Y., Randriamasy, S., Yang, Y., and J. Zhang,
"ALTO Extension: Path Vector", Work in Progress, Internet-
Draft, draft-ietf-alto-path-vector-09, 3 November 2019,
<http://www.ietf.org/internet-drafts/draft-ietf-alto-path-
vector-09.txt>.
[I-D.ietf-alto-unified-props-new]
Roome, W., Randriamasy, S., Yang, Y., Zhang, J., and K.
Gao, "Unified Properties for the ALTO Protocol", Work in
Progress, Internet-Draft, draft-ietf-alto-unified-props-
new-10, 4 November 2019, <http://www.ietf.org/internet-
drafts/draft-ietf-alto-unified-props-new-10.txt>.
[JSONIQ] Robie, J., Fourny, G., Brantner, M., Florescu, D.,
Westmann, T., and M. Zaharioudakis, "JSONiq - the SQL of
NoSQL 1.0", JSONiq , 2015.
[RFC8189] Randriamasy, S., Roome, W., and N. Schwan, "Multi-Cost
Application-Layer Traffic Optimization (ALTO)", RFC 8189,
DOI 10.17487/RFC8189, October 2017,
<https://www.rfc-editor.org/info/rfc8189>.
[RFC8259] Bray, T., Ed., "The JavaScript Object Notation (JSON) Data
Interchange Format", STD 90, RFC 8259,
DOI 10.17487/RFC8259, December 2017,
<https://www.rfc-editor.org/info/rfc8259>.
[W3CXQUERY]
Robie, J., Chamberlin, D., Dyck, M., and J. Snelson,
"XQuery 3.0: An XML query language", W3C Recommendation,
W3C, 2014.
Appendix A. Figures
TODO: Put additional figures here if we have.
Authors' Addresses
Jingxuan Jensen Zhang
Tongji University
4800 Cao'An Hwy
Shanghai
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201804
China
Email: jingxuan.n.zhang@gmail.com
Yang Richard Yang
Yale University
51 Prospect Street
New Haven, CT
United States of America
Email: yry@cs.yale.edu
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