ILL Protocol Basics

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ILL Protocol Basics

• Presentation by
• Randy Menakes
• Ameritech Library Services

Access Tutorial on ISO ILL Protocol 28
October 1999
2
Special thanks to

• Barbara Shuh
• ILL ASMA
• Joe Zeeman
• CGI Group

3
Multiple systems and user interfaces
National Library of Canada
British Library
Document Supplier

OCLC
Consortium Partner
4
Scattered and duplicated data
National Library of Canada
British Library
Document Supplier

OCLC
Consortium Partner
5
Standardized systems
National Library of Canada
British Library
Document Supplier

OCLC
Consortium Partner
6
Consolidated data
National Library of Canada
British Library
Document Supplier

OCLC
Consortium Partner
7
Fundamental Protocol Concepts

• ILL Protocol defined in ISO 10160/10161
• Peer-to-peer
• Predictable data / Predictable behavior
• Protocol Machine
• Finite State Machine
• Confirmed vs. Unconfirmed Services

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21 ILL Services

• ILL Request
• Forward
• Forward-Notification
• Shipped
• ILL-Answer
• Conditional-Reply
• Cancel
• Cancel-Reply
• Received
• Recall
• Returned

• Checked-In
• Overdue
• Renew
• Renew-Answer
• Lost
• Damaged
• Message
• Status-Query
• Status-Or-Error-Report
• Expiry

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Logical Model of ILL Protocol Machines
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Events, Actions and States

• Events things that come in from outside the
  ILLPM
• service primitives
• APDUs
• timer events
• Actions things that get sent outside the ILLPM
• service primitives
• APDUs
• State depends on last event and action
• determines next legal action

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Time Sequences

• Communication is not instantaneous
• Delay between one system sending a message and
  the other system receiving it
• Further delay while receiving system processes
  message and generates response
• Messages can cross
• Protocol needs to accommodate crossing messages

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Simple Transaction
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More Complex Transaction
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User Roles

• Requester
• Responder
• Intermediary

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Requester and Responder Roles
Lender
Borrower
Staff (lending library)
Staff (borrowing library)
ILL Responder Protocol Machine
ILL Requester Protocol Machine
ILL APDU
Communications Service, (e.g., TCP, SMTP, etc.)
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Intermediary
Requester (Borrowing Library)

Responder (Lending Library)
ILL APDU
ILL Requester Protocol Machine
ILL APDUs
Intermediary (e.g., British Library)
ILL Responder Protocol Machine
ILL Intermediary Protocol Machine
ILL APDUs (sub-transaction)
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ILL Transactions

• Single complete Interlending cycle
• Initiated only by a Requester
• 3 Types
• Simple
• Chained
• Partitioned

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Simple Transaction
Lender
Borrower
Staff (lending library)
Staff (borrowing library)
ILL Responder Protocol Machine
ILL Requester Protocol Machine
ILL APDU
Communications Service, (e.g., TCP, SMTP, etc.)
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Chained Transaction
Requester (Borrowing Library)

Responder (Lending Library)
ILL APDU
ILL Requester Protocol Machine
ILL APDUs
Intermediary (e.g., British Library)
ILL Responder Protocol Machine
ILL Intermediary Protocol Machine
ILL APDUs (sub-transaction)
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Partitioned Transaction
Requester (Borrowing Library)

Responder (Lending Library)
ILL Requester Protocol Machine
1. ILL- Request
3. Renew
Intermediary (Centralized ILL Utility)
ILL Intermediary Protocol Machine
ILL Responder Protocol Machine
2. ILL- Request (sub-transaction)
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Service Types

• Loan
• Copy-non-returnable
• Locations
• Estimate
• Responder-specific

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20 ILL APDUs

• ILL Request
• Forward Notification
• Shipped
• ILL-Answer
• Conditional-Reply
• Cancel
• Cancel-Reply
• Received
• Recall
• Returned

• Checked-In
• Overdue
• Renew
• Renew-Answer
• Lost
• Damaged
• Message
• Status-Query
• Status-Or-Error-Report
• Expired

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Transaction forwarding
Requester (Borrowing Library)

Responder (Lending Library)
ILL APDU
ILL Requester Protocol Machine
ILL-Request
Forward- Notification
Intermediary (e.g., British Library)
ILL Responder Protocol Machine
ILL Intermediary Protocol Machine
ILL-Request
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ILL-Request

• Initial Service
• Mandatory for all transactions

ILL Request
ILL-REQUEST
Responder
Requester
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ILL-ANSWER
Conditional? Retry. Unfilled. Locations-pr
ovided. Will-Supply. Hold-placed. Estimate.
ILL-ANSWER
ILL-ANSWER
Responder
Requester
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SHIPPED

• For loans or copies
• Optional if Simple Transaction

Shipped
SHIPPED
Responder
Requester
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ILL Transaction Identification

• Uniquely identified (transaction-id)
• Allows sub-transactions to be related to the
  parent
• Allows multiple transactions to be related
  together
• Transaction ID components
• initial requester id
• transaction group qualifier
• transaction qualifier
• sub-transaction qualifier

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Initial Transaction ID
ILL-Request goes out to first potential provider

• Transaction ID components
• initial requester id OONL
• transaction group qualifier 12345
• transaction qualifier 1
• sub-transaction qualifier

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Initial Transaction ID
Unfilled by the first potential lender, the
ILL-Request goes out to next potential provider

• Transaction ID components
• initial requester id OONL
• transaction group qualifier 12345
• transaction qualifier 2
• sub-transaction qualifier

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Initial Transaction ID
Unfilled by the second potential lender, the
ILL-Request goes out to a third potential provider

• Transaction ID components
• initial requester id OONL
• transaction group qualifier 12345
• transaction qualifier 3
• sub-transaction qualifier

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Initial Transaction ID
This potential provider is an intermediary, who
sends the request to a potential lender (chained)

• Transaction ID components
• initial requester id OONL
• transaction group qualifier 12345
• transaction qualifier 3
• sub-transaction qualifier 1

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Protocol States

• Requester states
• Responder states
• Terminal states
• Intermediary states

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Requester States

• RENEW/OVERDUE
• OVERDUE
• NOT-RECEIVED/ OVERDUE
• RECALL
• RETURNED
• LOST
• (italics terminal state)

• IDLE
• PENDING
• NOT-SUPPLIED
• CONDITIONAL
• CANCEL-PENDING
• CANCELLED
• SHIPPED
• RECEIVED

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Responder States

• IDLE
• IN-PROCESS
• FORWARD
• NOT-SUPPLIED
• CONDITIONAL
• CANCEL-PENDING
• CANCELLED

• SHIPPED
• RENEW-PENDING
• RENEW/OVERDUE
• OVERDUE
• RECALL
• CHECKED-IN
• LOST

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Expiry Timer

• Maintained by the responder
• Expiry time specified in ILL-Request
• When expiry occurs, protocol machine
  automatically raises Expiry event at both
  requester and responder.
• Expired APDU is sent only by the Responder
• Requester uses the Cancel APDU

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What is carried in APDUs

• Predictable data in a predictable structure
• Externals
• OIDs (Object Identifiers)
• Extensions

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How data is structured and transferred

• ASN.1 (Abstract Syntax Notation 1) Abstract -
  independent of any particular computer system or
  programming language
• Transfer syntax - BER (Basic Encoding Rules)