SMPTE ST 2032-3-2007 Media Dispatch Protocol (MDP) Basic Target Pull Profile Specification.pdf

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1、 Copyright 2007 by THE SOCIETY OF MOTION PICTURE AND TELEVISION ENGINEERS 595 W. Hartsdale Ave., White Plains, NY 10607 (914) 761-1100 Approved December 14, 2007 Table of Contents Page Foreword . 2 Introduction . 2 1 Scope 3 2 Conformance Notation 3 3 Normative References 3 4 Acronyms and Definition

2、s . 3 5 Background (Informative). 4 6 Summary of Profile (Informative) . 4 7 Properties in Manifest Documents 4 8 Use of Protocol in a Transaction. 5 8.1 Capabilities 5 8.2 Initiation and Negotiation 5 8.3 Transfer. 6 8.3.1 General . 6 8.3.2 Transfer endpoint 6 8.3.3 Properties of transferred files

3、6 8.3.4 Timescale 6 8.3.5 Priorities 6 8.4 Notification of Initiation of Transfer . 6 8.5 Status Check. 6 8.6 Pause and Resume 7 8.7 Completion 7 8.8 Termination . 7 9 Required Protocols 7 9.1 HTTP. 7 9.2 HTTP/TLS . 8 9.3 Other Protocols . 8 10 Integrity Check 8 10.1 Requesting Integrity Check 8 10.

4、2 Performing Integrity Check 8 10.3 Required Hash Types 8 Page 1 of 8 pages SMPTE 2032-3-2007SMPTE STANDARD Media Dispatch Protocol (MDP) Basic Target Pull Profile Specification SMPTE 2032-3-2007 Page 2 of 8 pages Foreword SMPTE (the Society of Motion Picture and Television Engineers) is an internat

5、ionally-recognized standards developing organization. Headquartered and incorporated in the United States of America, SMPTE has members in over 80 countries on six continents. SMPTEs Engineering Documents, including Standards, Recommended Practices and Engineering Guidelines, are prepared by SMPTEs

6、Technology Committees. Participation in these Committees is open to all with a bona fide interest in their work. SMPTE cooperates closely with other standards-developing organizations, including ISO, IEC and ITU. SMPTE Engineering Documents are drafted in accordance with the rules given in Part XIII

7、 of its Administrative Practices. SMPTE Standard 2032-3 was prepared by Technology Committee S22 on Committee on Television Systems Technology. Introduction This section is entirely informative and does not form an integral part of this document. The Media Dispatch Protocol (MDP) is a means of orche

8、strating the delivery of media files over IP networks. It defines a standard mechanism for implementations to initiate a delivery, to negotiate the details of the delivery, to provide information about the progress of the delivery, and to provide a confirmation of the outcome of the delivery. MDP al

9、lows organizations to transfer files at agreed times, using agreed transfer protocols, and using an agreed set of secure technologies (where appropriate). However, the protocol is not overly prescriptive in regards to which protocols or technologies shall be used; rather it provides a framework whic

10、h allows organizations to choose those that best suit their own needs. MDP is a multi-part standard: Part 1, the MDP protocol specification, defines the logical messages, data structures and data dictionary of MDP. Part 2, an MDP mapping specification, defines a representation of the messages and st

11、ructures defined in Part 1. Part 3, of which this document is part, defines subsets of the protocol and rules on the use of these subsets. Part 4, the MDP Engineering Guideline, introduces and describes MDP and how it can be used in particular scenarios. SMPTE 2032-3-2007 Page 3 of 8 pages 1 Scope T

12、his standard defines the MDP Basic Target Pull Profile. This specifies a subset of the MDP protocol defined in SMPTE 2032-1, in which the name and size of all files is known to the initiating agent before the transaction is initiated, the target agent initiates the file transfers, and all transfers

13、use a pull-mode protocol. The standard specifies the sequence of messages that shall or may be used in a transaction, how certain properties shall be set in the manifest document, how the file transfers shall be initiated, and which transfer protocols an agent shall support. 2 Conformance Notation N

14、ormative text is text that describes elements of the design that are indispensable or contains the conformance language keywords: “shall“, “should“, or “may“. Informative text is text that is potentially helpful to the user, but not indispensable, and can be removed, changed, or added editorially wi

15、thout affecting interoperability. Informative text does not contain any conformance keywords. All text in this document is, by default, normative, except: the Introduction, any section explicitly labeled as “Informative“ or individual paragraphs that start with “Note:” The keywords “shall“ and “shal

16、l not“ indicate requirements strictly to be followed in order to conform to the document and from which no deviation is permitted. The keywords, “should“ and “should not“ indicate that, among several possibilities, one is recommended as particularly suitable, without mentioning or excluding others;

17、or that a certain course of action is preferred but not necessarily required; or that (in the negative form) a certain possibility or course of action is deprecated but not prohibited. The keywords “may“ and “need not“ indicate courses of action permissible within the limits of the document. The key

18、word “reserved” indicates a provision that is not defined at this time, shall not be used, and may be defined in the future. The keyword “forbidden” indicates “reserved” and in addition indicates that the provision will never be defined in the future. A conformant implementation according to this do

19、cument is one that includes all mandatory provisions (“shall“) and, if implemented, all recommended provisions (“should“) as described. A conformant implementation need not implement optional provisions (“may“) and need not implement them as described. 3 Normative Reference The following standard co

20、ntains provisions which, through reference in this text, constitute provisions of this standard. At the time of publication, the edition indicated was valid. All standards are subject to revision, and parties to agreements based on this standard are encouraged to investigate the possibility of apply

21、ing the most recent edition of the standard indicated below. SMPTE 2032-1-2007, Media Dispatch Protocol (MDP) Protocol Specification 4 Acronyms and Definitions The full glossary of acronyms and definitions used in the MDP specification is given in the MDP protocol specification (SMPTE 2032-1). It is

22、 not repeated here to avoid any divergence of meaning. SMPTE 2032-3-2007 Page 4 of 8 pages 5 Background (Informative) The MDP protocol standard (SMPTE 2032-1) defines the complete set of messages and data structures available to MDP agents. An MDP profile standard defines a subset of these messages

23、and structures, and specifies rules for their use during a transaction. It allows the complexity of an agent implementation to be appropriate to the delivery scenario. Two agents that correctly implement the same profile, and also the same MDP mapping standard, will be able to interoperate correctly

24、. A pair of agents can determine, via the capabilities document defined in the protocol whether they implement a compatible profile, prior to initiating a transaction. This profile provides a suitable subset of features for the common “target pull“ scenario. In this scenario, the initiator agent has

25、 available all relevant information about the files to be transferred, the target agent is responsible for initiating all file transfers, and all transfers use a pull-mode protocol 6 Summary of Profile (Informative) A transaction compliant with this profile has the following characteristics: The nam

26、e and size of all files is known to the initiating agent before the transaction is initiated. The target agent initiates all file transfers. All transfers use a pull-mode protocol. A simple negotiation procedure is used in which the initiator agent sends a manifest document containing all the file a

27、nd transferoption and transferwith elements. The target agent then sends a manifest document accepting or rejecting each transferwith element. The target agent sends a manifest document to notify that the first transfer has started. An agent may request a capabilities document from the other agent,

28、which replies synchronously. The initiator agent may request a manifest document from the target agent, which replies synchronously. The initiator agent may request pause and resume of transfers. Annex A of the MDP protocol specification (SMPTE 2032-1) includes a figure showing an example of the mes

29、sages sent in a transaction compliant with this profile. Agents supporting this profile are able to initiate file transfers using HTTP GET and HTTP/TLS GET. 7 Properties in Manifest Documents The profile property of the manifest element shall have the value “basic target pull”. The usecase property

30、of the manifest element shall have the value “target pull”. The direction property of all transferoption elements shall have the value PULL. The sender property shall be present in all transferoption elements. SMPTE 2032-3-2007 Page 5 of 8 pages The receiver property shall not be present. The contro

31、ller property of all transferoption elements shall have the same value as the target property of the manifest element. The pathname, size and mimetype properties shall be present in all file elements. 8 Use of Protocol in a Transaction 8.1 Capabilities An agent may send a qry_requestcapabilities que

32、ry to another agent at any time. Note: Typically this will be done before the initiation of a transaction. The agent receiving the query shall respond with an rpl_capabilities or rpl_error reply. The agent should provide as complete a list of capabilities as possible in an rpl_capabilities reply. 8.

33、2 Initiation and Negotiation It is assumed that the target agents message endpoint is already known to the initiator agent. The following sequence of steps shall be used for initiation of a transaction and negotiation of delivery details: 1. The initiator agent shall send a cmd_initiatingtransaction

34、 command to the target agents message endpoint. The manifest parameter of this command shall contain all proposed file, transferoption and transferwith elements for this transaction. The agent parameter shall specify the initiator agents message endpoint for the transaction. 2. The target agent shal

35、l either agree the initiation of the transaction with a cnf_ok, or shall send a cnf_error. 3. The target agent shall send a cmd_sendingmanifest command to the initiator agents message endpoint. The manifest parameter shall comply with each of the following: a) Each transferwith element shall have a

36、status property with value accepted or rejected. b) At most one transferwith element shall have its status property set to accepted for a given file. c) No other change shall be made with respect to the manifest document sent in step 1, other than to the status properties, and to the “updated” eleme

37、nts within transferwith elements. 4. The initiator agent shall acknowledge the details in the manifest document sent at step 3 with a cnf_ok, or shall send a cnf_error. In the latter case the initiator agent should terminate the transaction by sending a cmd_abortingtransaction command. 5. If no file

38、 element in the manifest document sent at step 3 contains a transferwith element whose status property has value accepted (all proposals were rejected), the target agent shall complete the transaction as in section 8.7. SMPTE 2032-3-2007 Page 6 of 8 pages 8.3 Transfer 8.3.1 General The target agent

39、shall initiate a transfer for each file that has a transferwith element whose status property has value accepted. Each transfer shall use the protocol specified by the protocol property of the relevant transferoption element. 8.3.2 Transfer endpoint The target agent shall perform each file transfer

40、by means of the URL generated by concatenating: the sender property of the appropriate transferoption element, the “/” character (if required syntactically), and the relativepath property of the relevant file element. 8.3.3 Properties of transferred files The name of each file transferred shall be t

41、he same as the filename part of the pathname property of the relevant file element. This is the final part of the pathname, after any string leading up to the final “/” character, if present, has been removed. The size of each file transferred shall be the same as the size property of the relevant f

42、ile element. 8.3.4 Timescale Each transfer shall start no earlier than the later of the times specified by the startafter property of the relevant file element, and the availablefrom property of the relevant transferoption element. 8.3.5 Priorities The priority property values of file elements shoul

43、d determine the order in which the corresponding file transfers are initiated within a transaction. The target agent should not initiate a transfer until it has attempted to initiate all transfers with lower priority values. A transfer without a priority property should not be initiated until after

44、all transfers with priority properties have been initiated. 8.4 Notification of Initiation of Transfer After initiating at least one transfer, the target agent shall send a cmd_sendingmanifest command to the initiator agents message endpoint. This should be sent as soon as possible after the first t

45、ransfer has started. The manifest parameter shall indicate which transfer(s) have started by means of the status property of each transferwith element. The initiator agent shall acknowledge the details in the manifest document sent with a cnf_ok, or shall send a cnf_error. In the latter case, the in

46、itiator agent should terminate the transaction by sending a cmd_abortingtransaction command. 8.5 Status Check The initiator agent may send a qry_requestmanifest query to the target agents message endpoint at any time after negotiation is completed and before the transaction is completed or terminate

47、d. The query shall not be sent at other times. SMPTE 2032-3-2007 Page 7 of 8 pages The target agent shall reply with an rpl_manifest, or an rpl_error. In the case that an rpl_manifest is sent, the manifest document payload shall indicate the status of the transaction when the reply is made: the stat

48、us property of each transferwith element shall indicate the current status of the file transfer, and the bytestransferred property of each file element shall indicate the current number of bytes that have been received for the file. The target agent shall not send a qry_requestmanifest query. 8.6 Pa

49、use and Resume The initiator agent may send a cmd_pausetransfers or cmd_resumetransfers command to the target agents message endpoint at any time after negotiation is completed and before the transaction is completed or terminated. The transfers to be paused or resumed shall be identified by the file_list parameter. If the file_list parameter is omitted then all transfers shall be paused or resumed. The target agent may pause or resume the transfer or transfers. It shall respond with a cnf_ok or a cnf_error. Note: The ini