Internet DRAFT - draft-efimchick-remotelaboratorycontrolprotocol
draft-efimchick-remotelaboratorycontrolprotocol
INTERNET-DRAFT Evgeny Efimchick, Andrey Lyamin
Intended Status: Proposed Standard (NRU ITMO, Saint-Petersburg, Russia)
Expires: July 18, 2013 March 18, 2013
Remote Laboratory Control Protocol
draft-efimchick-remotelaboratorycontrolprotocol-00
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Copyright and License Notice
Copyright (c) 2013 IETF Trust, Evgeny Efimchick, Andrey Lyamin. All
rights reserved.
Abstract
This protocol is intended to provide the interaction between servers
of virtual or remote laboratories and educational information systems
that use virtual or remote laboratories in educational process.
Table of Contents
1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2 RLCP-compatible VL . . . . . . . . . . . . . . . . . . . . . . . 3
2.1 RLCP-VL Structure . . . . . . . . . . . . . . . . . . . . . 3
2.2 RLCP-VL workflow . . . . . . . . . . . . . . . . . . . . . . 4
3 RLCP description . . . . . . . . . . . . . . . . . . . . . . . . 6
3.1 RLCP request header . . . . . . . . . . . . . . . . . . . . 6
3.2 RLCP response header . . . . . . . . . . . . . . . . . . . . 7
3.3 RLCP request body . . . . . . . . . . . . . . . . . . . . . 8
3.4 RLCP response body . . . . . . . . . . . . . . . . . . . . . 10
3.5 RLCP url . . . . . . . . . . . . . . . . . . . . . . . . . 11
3.6 RLCP request/response header fields . . . . . . . . . . . . 11
4 Security Considerations . . . . . . . . . . . . . . . . . . . . 11
5 IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 12
6 References . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 12
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1 Introduction
This protocol is intended to provide the interaction between servers
of virtual or remote laboratories and educational information systems
that use virtual or remote laboratories in educational process.
The Virtual Laboratory (VL) is an electronic environment that allows
to create and investigate models of real phenomena. VL can be a
useful tool in the distance learning technologies. It is difficult to
develop VLs, but they provide numerous opportunities for education,
especially in technical and natural science.
Remote laboratories provides interaction with real laboratory plant
but VL is actually kind of remote laboratories where real laboratory
plant is replaced by its virtual model. Remote Laboratory Control
Protocol describes rules of interaction of both remote and virtual
laboratories.
The Remote Laboratory Control Protocol (RLCP) was proposed in Saint-
Petersburg National Research University of Information Technologies,
Mechanics and Optics (NRU ITMO) to simplify the development and use
of VLs. RLCP, its implementation and examples of RLCP-compatible VLs
are described in scientific journals. [1], [2], [3]
2 RLCP-compatible VL
2.1 RLCP-VL Structure
The RLCP-compatible VLs (RLCP-VL) have a strictly defined structure
as shown in Fig. 1.
_______________ _______________ _______________
| | | | | |
| HTML-page | | | | |
| |-----| RLCP client |-----| Data base |
| of task frame | | | | |
|_______ _______| |_______ _______| |_______________|
| |
| |
| |
_______|_______ _______|_______
| | | |
| Virtual | | |
| laboratory | | RLCP server |
| plant | | |
|_______________| |_______________|
Figure 1 RLCP-VL structure
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2.2 RLCP-VL workflow
An assessment process with RLCP-VL may vary depending on RLCP client,
but its general principles can be described. RLCP-VL workflow is
presented on Fig. 2.
When a user starts an assessment using VL, RLCP client sends to the
user a page that contains task description and interactive element -
an applet that represents the VL plant. This page is called task
frame. The task frame can be selected from a task bank by RLCP client
or constructed by using RLCP server. In the latter case, the client
creates an RLCP request to RLCP server of VL, which specifies
instructions for the formation of tasks.
RLCP server sends back data required to construct the task frame.
While solving problem a user can send one or more requests for the
intermediate calculations if such behavior is allowed by concrete VL.
In this case after each inspection the task frame will be modified in
accordance with inspection results.
In general, user's answer is treated as a description of a system
with sets of inputs and outputs. This system is constructed in
accordance with the task by means of the VL plant. Knowledge of the
correct answer can be represented as pairs of test sets of input and
output data. It is necessary to get reaction of the described system
on the given set of input data and to compare it with the
corresponding set of output data in order to assess the answer. The
correct answer is indicated when system reaction meets expected set
of output data.
A user sends the response with control elements of the task frame to
RLCP client. RLCP client prepares the RLCP request that consists of
user's response, validation data sets and other parameters for
checking, and sends it to RLCP server. RLCP server checks user's
response using given parameters, and returns the result to RLCP
client. After receiving the response RLCP client can save
assessment's result and make it available to the user.
When user starts assignment using VL, RLCP client sends the user to a
page that contains the job description and an interactive element -
an applet that represents a virtual plant. This page is called a task
frame. The task frame can be selected from a task bank by RLCP
client or constructed using RLCP server. In the latter case, the
client creates RLCP request to RLCP server of VL, which specifies
instructions for the formation of task. RLCP server sends back data
required to construct task.
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User RLCP client RLCP-VL server
| | |
| | |
_ _ _
| | | | | |
| | Request for | | | |
| | laboratory task | | | |
| |------------------->| | Request for variant| |
| | | | (RLCP request) | |
| | | |------------------->| |
| | | | | |
| | | | Variant data | |
| | | | (RLCP response) | |
| | Task frame | |<-------------------| |
| |<-------------------| | | |
| | | | | |
_______|_|____________________|_|____________________|_|______
| || | | | | | |
| loop || | Request for | | | | |
|_____/ | | intermediate | | | | |
| | | inspection | | Request for | | |
| | |------------------->| | intermediate | | |
| | | | | inspection | | |
| | | | | (RLCP request) | | |
| | | | |------------------->| | |
| | | | | | | |
| | | | | Result of | | |
| | | | | intermediate | | |
| | | | | inspection | | |
| | | | | (RLCP response) | | |
| | | Modified task frame| |<-------------------| | |
| | |<-------------------| | | | |
|_______|_|____________________|_|____________________|_|______|
| | | | | |
| | Solution | | Request for | |
| |------------------->| | solution checking | |
| | | | (RLCP request) | |
| | | |------------------->| |
| | | | | |
| | | | Result of | |
| | | | solution checking | |
| | | | (RLCP response) | |
| | | |<-------------------| |
| | | | | |
|_| |_| |_|
| | |
Figure 2 RLCP-VL workflow
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In general, the user answer is treated as description of system with
a set of inputs and outputs. This system is constructed in accordance
with the task of the objects and relations of the domain by means of
virtual plant . Knowledge of the correct answer can be represented as
pairs of test sets of input and output data. We need to get a
reaction of described system in a given set of input data and compare
it with the corresponding set of output data due to assess the
correctness of the answer . The coincidence of the system reaction
with an expected set of output data will indicate the correct answer.
User sends a response with the controls of task frame to RLCP client.
RLCP client prepares RLCP request consists of the user's response,
the validation data sets and other parameters for checking, and sends
it to RLCP server. RLCP server checks the user's response, based on
the given parameters, and returns the result to RLCP client. After
receiving a response RLCP client can save the check results and make
them available to the user.
3 RLCP description
RLCP provides a connection between RLCP server and RLCP client. RLCP
client can request data to construct the task frame, checking results
of user's answer or results of the intermediate calculations from
RLCP server. For each type of the request and its corresponding
response a format of RLCP requests and responses exists. This format
is called RLCP method. RLCP has the following methods:
- Generate, intended to transmit data for the construction of the
task frame;
- Calculate, which is designed to transfer results of the
intermediate calculations;
- Check, designed to transmit results of the checking based on the
test sets of input and output data.
RLCP is based on TCP. Stages of RLCP interaction between RLCP client
and RLCP-VL server are given below:
- RLCP Client establishes TCP connection with RLCP-VL server,
- RLCP Client sends RLCP request to RLCP-VL server through this
connection,
- RLCP Client receives response from RLCP-VL server,
- RLCP Client closes connection.
All requests and responses contain a header and body. Header and body
is divided by empty line.
3.1 RLCP request header
The request header contains the name of a request method in capital
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letters and a set of service fields. There are two required service
fields that are listed in table 1. Optional service fields might be
added to the request due to particular VL needs.
Table 1. Required header service fields
__________ ____________________________________________________
| | | |
| Name | Description | Example |
|__________|___________________________|________________________|
| | | |
| url | Contains an URL of | url:rlcp://test:test@ |
| | RLCP-VL server | 127.0.0.1:3000 |
|__________|___________________________|________________________|
| | | |
| content- | Contains a size of | content-length:12345 |
| length | RLCP request in bytes | |
|__________|___________________________|________________________|
Example of RLCP request is given below:
CHECK
url:rlcp://test:test@127.0.0.1:3000
content-length:12345
3.2 RLCP response header
RLCP response header consists of a response status and a set of
service fields.
Response status is a numeric code. Response codes are listed in table
2.
There is only required service field in response header: content-
length. It contains size of RLCP response in bytes. In addition, one
optional service field is defined. It is called 'url' and contains
url of the RLCP server when response code is 300. Optional service
fields might be added to the response due to particular VL needs.
Example of RLCP response header is given below:
200
content-length:12345
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Table 2. Response codes
__________ ___________________________________________________
| | |
| Code | Description |
|__________|___________________________________________________|
| | |
| 100 | The request is still processing |
|__________|___________________________________________________|
| | |
| 200 | The request is successfully processed |
| | and response contains results |
|__________|___________________________________________________|
| | |
| 300 | The requested resource is temporary moved |
|__________|___________________________________________________|
| | |
| 400 | Incorrect request |
|__________|___________________________________________________|
| | |
| 401 | Incorrect input data sets |
|__________|___________________________________________________|
| | |
| 402 | Authentication error |
|__________|___________________________________________________|
| | |
| 403 | Unsupported method |
|__________|___________________________________________________|
| | |
| 404 | Required service field was not found |
|__________|___________________________________________________|
| | |
| 405 | Required service field value was not found |
|__________|___________________________________________________|
| | |
| 500 | The requested resource is temporary unavailable |
|__________|___________________________________________________|
| | |
| 501 | Request method is supported by protocol |
| | but it is not supported by this particular server |
|__________|___________________________________________________|
3.3 RLCP request body
The body of RLCP request is presented as an XML-document and its
structure depends on RLCP method. Common to all methods DTD-
description of the request body is given below:
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<!ELEMENT Request (Conditions, Instructions?, PreGenerated?)>
<!ELEMENT Conditions (ConditionForCalculating | ConditionForChecking
+ | ConditionForGenerating)>
<!ELEMENT ConditionForChecking (Input, Output)>
<!ATTLIST ConditionForChecking
id CDATA # REQUIRED
Time CDATA # REQUIRED
>
<!ELEMENT ConditionForCalculating (Input)>
<!ELEMENT ConditionForGenerating (Input)>
<!ELEMENT PreGenerated (Text, Code, Instructions)>
<!ELEMENT Instructions (# PCDATA)>
<!ELEMENT Output (# PCDATA)>
<!ELEMENT Input (# PCDATA)>
<!ELEMENT Text (# PCDATA)>
<!ELEMENT Code (# PCDATA)>
Description of RLCP request elements.
Request
The root element of the message.
Request/Conditions
The element that contains conditions for processing the request.
It may contain one or more elements, depending on the request
method.
Request/Conditions/ConditionForCalculating
The element that contains conditions to perform the intermediate
calculations. The element is allowed in the request of the
Calculate method. The condition itself enclosed in the nested
comment of the child element called Input.
Request/Conditions/ConditionForGenerating
The element that contains conditions for the generating data to
construct the task frame online. The element is allowed in the
request of the Generate method. The condition itself lies in the
nested comment of the child element called Input.
Request/Conditions/ConditionForChecking
The element that contains conditions to validate user's solution
in the form of a pair of input and output data. There may be
several such elements. The element is allowed in the request of
the Check method, contains a set of input data in the nested
comment of the child element Input, a corresponding set of output
data in the nested comment of child element Output and an
identifier and a time limit (in milliseconds) to perform checks in
the id and Time attributes respectively.
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Request/Instructions
The user's answer that is received from the VL plant. The element
is allowed in the requests of the Check and Calculate methods.
Request/PreGenerated
Data for the construction of the task frame that is previously
obtained by using the request of the Generate method. The element
contains data to display to a user in the nested comment of the
child element called Text, data intended to substitute as the
applet parameter of the VL plant in the nested comment of the
child element called Code, additional instructions for checking
that are intended only for RLCP server in the nested comment of
the child element called Instructions. The element is allowed in
the requests of the Check and Calculate methods.
3.4 RLCP response body
The body of RLCP response is presented as an XML-document and its
structure depends on RLCP method. Common to all the methods DTD of
the response body and its description is given below:
<!ELEMENT Response (CalculatingResult | CheckingResult+ |
GeneratingResult)>
<!ELEMENT CheckingResult (#PCDATA)>
<!ATTLIST CheckingResult
id CDATA #REQUIRED
Time CDATA #REQUIRED
Result CDATA #REQUIRED
>
<!ELEMENT CalculatingResult (Text,Code)>
<!ELEMENT GeneratingResult (Text,Code,Instructions)>
<!ELEMENT Text (#PCDATA)>
<!ELEMENT Code (#PCDATA)>
<!ELEMENT Instructions (#PCDATA)>
Description of RLCP response elements.
Response
The root element of the message.
Response/CheckingResult
The container element for the checking result of the single
checking condition that contains the pair of the test sets of
validation input and output data. The element contains the literal
output data in the nested comment, checking result (a number in
the interval (0, 1)) in the attribute called Result, identifier of
the pair of input and output data in the attribute called id,
elapsed time (in milliseconds) in the attribute called Time. The
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element is allowed in the response of the Check method.
Response/CalculatingResult
The container element for the results of the intermediate
calculations. It contains the data intended to display to a user
in the nested comment of the child element called Text, data
intended to substitute as the applet parameter of the VL plant in
the nested comment of the child element called Code. The element
is allowed in the response of the Calculate method.
Response/GeneratingResult
The container element for data to construct the task frame. It
contains the data that is should be displayed to a user in the
nested comment of the child element called Text, data that should
be substituted as an parameter of the applet of the VL plant in
the nested comment of the child element called Code, additional
checking instructions for RLCP server in the nested comment of the
child element called Instructions. The element is allowed in the
response of the Generate method.
3.5 RLCP url
RLCP url format is:
rlcp://[login:password@](Server_IP-address|Server_domain_name):Port
Elements in square brackets are optional. Elements in round brackets
separated by vertical bar are mutually exclusive. Login and password
must contain only characters from A-z and 0-9 ranges. RLCP url length
is limited to 255 characters.
3.6 RLCP request/response header fields
Header fields format is:
field_name:field_value
Each field occupies one line. Header fields may be listed in any
order, but must be used no more than once. Field names are not case
sensitive.
4 Security Considerations
Security is not generally a problem in normal operation, however,
only authenticated requests should be processed by RLCP-VL server, if
particular server does not support anonymous connections. Malformed
requests should not be processed, instead response with 4xx status
code should be returned. If content-type field value and actual
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message size does not match the lesser amount of bytes should read.
No encryption considerations is represented in this memo.
5 IANA Considerations
No assignments by the IANA are required.
6 References
[1] Lyamin A.V., Vashenkov O.E. VIRTUAL LABORATORY: MULTI-STYLE CODE
EDITOR // 23rd ICDE World Conference on Open Learning and Distance
Education including the 2009 EADTU Annual Conference. -
Maastricht,The Netherlands, on 7-10 June 2009. - URL:
http://www.ou.nl/icde2009.
[2] Lyamin A.V., Vashenkov O.E. Virtual environment and instruments
for student olympiad on cybernetics // Proceedings of 8th IFAC
Symposium on Advances in Control Education. - Kumamoto, JAPAN, 2009.
[3] Efimchik E.A., Lyamin A.V. RLCP-Compatible Vitual Laboratories //
The International Conference on E-Learning and E-Technologies in
Education (ICEEE 2012) Technical University of Lodz, Poland Sept. 24-
26, 2012 Proceedings. - Lodz, Poland, 2012.
Authors' Addresses
Evgeny Efimchick, Andrey Lyamin
197101, Russia, Saint Petersburg,
Kronverkskiy pr., 49,
National Research University
of Information Technologies, Mechanics and Optics,
Distance Learning Center
EMail: efimchick@cde.ifmo.ru
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