1 Introduction

The Patrons Account Information API (PAIA) is a HTTP based programming interface to access library patron information, such as loans, reservations, and fees. Its primary goal is to provide patron access for discovery interfaces and other third-party applications to integrated library system, as easy and open as possible.

1.1 Synopsis

PAIA defines six methods in PAIA core and three methods in PAIA auth. Each method is defined with an HTTP verb and an entity that the method acts on:

PAIA core	PAIA auth
GET patron: general patron information	POST login: get access token
GET items: current loans, reservations, …	POST logout: invalidate access token
POST request: new reservation, delivery, …	POST change: modify credentials
POST renew: existing loans, reservations, …
POST cancel: requests, reservations, …
GET fees: paid and open charges

1.2 Status of this document

This specification has been created collaboratively based on use cases and taking into account existing related standards and products of integrated library systems (ILS), such as NISO Circulation Interchange Protocol (NCIP), SIP2, [X]SLNP,¹ DLF-ILS recommendations, and VuFind ILS.

Updates and sources can be found in a public git repository at http://github.com/gbv/paia. The master file paia.md is written in Pandoc’s Markdown. HTML version of the specification and PAIA ontology in RDF/Turtle and in RDF/XML are generated from the master file with makespec. The text of the specification can be distributed freely under the terms of CC-BY-SA.

1.3 How to contribute

Implement a PAIA server for your library system - either directly to the core, or as wrapper above existing protocols (SIP2, SLNP, NCIP), or based on screen-scraping.
Urge libraries to implement a public PAIA server for their patrons.
Implement a PAIA client that makes use of patron account information - for instance a mobile app or a web application.
Comment on the specification and point to errors.
Suggest useful apps and mashups that make use of PAIA.

1.4 Conformance requirements

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 RFC 2119.

A PAIA server MUST implement PAIA core and it MAY implement PAIA auth. If PAIA auth is not implemented, another way SHOULD BE documented to distribute patron identifiers and access tokens. A PAIA server MAY support only a subset of methods but it MUST return a valid response or error response on every method request, as defined in this document.

2 General

PAIA consists of two independent parts:

PAIA core defines six basic methods to look up loaned and reserved items, to request and cancel loans and reservations, and to look up fees and general patron information.
PAIA auth defines three authentification methods (login, logout, and password change) to get access tokens, required by PAIA core.

Each method is accessed at an URL with a common base URL for PAIA core methods and common base URL for PAIA auth methods. A server SHOULD NOT provide additional methods at these base URLs and it MUST NOT propagate additional methods at these base URLs as belonging to PAIA.

In the following, the base URL https://example.org/core/ is used for PAIA core and https://example.org/auth/ for PAIA auth.

Authentification in PAIA is based on OAuth 2.0 (RFC 6749) with bearer tokens (RFC 6750) over HTTPS (RFC 2818). For security reasons, PAIA methods MUST be requested via HTTPS only. A PAIA client MUST NOT ignore SSL certificate errors; otherwise access token (PAIA core) or even password (PAIA auth) are compromised by the client.

2.1 Request and response format

Each PAIA method is identified by a URL and HTTP verb GET or POST. Method calls expect a set of request parameters and return a JSON object. Request parameters and JSON response of PAIA core can be mapped to RDF.

The special request parameter access token can be sent either as an HTTP query parameter or in an HTTP request header.

For POST methods a request body MUST be included in JSON format in UTF-8. A Content-Type request header MUST be sent with application/json; charset=utf-8 or application/json. A PAIA auth server SHOULD additionally accept URL encoded HTTP POST request bodies with content type application/x-www-form-urlencoded. Request encoding ISO-8859-1 MAY be supported in addition to UTF-8 for these requests.

Clients SHOULD include an approriate User-Agent request header with client name and version.

The HTTP response content type of a PAIA response is a JSON object (HTTP header Content-Type: application/json) in UTF8, optionally wrapped as JSONP (HTTP header Content-Type: application/javascript). The charset SHOULD be included as part of the Content-Type header (application/json; charset=utf-8 or application/javascript; charset=utf-8)

Every request parameter and every response field is defined with

the name of the parameter/field
the ocurrence (occ) of the parameter/field being one of
- 0..1 (optional, non repeatable)
- 1..1 (mandatory, non repeatable)
- 1..n (mandatory, repeatable)
- 0..n (optional, repeatable)
the data type of the parameter/field.
a short description

Simple parameter names and response fields consist of lowercase letters a-z only.

Repeatable response fields are encoded as JSON arrays, for instance:

{ "fee" : [ { ... }, { ... } ] }

Hierarchical JSON structures in this document are referenced with a dot (.) as separator. For instance the subfield/parameter item of the doc element is referenced as doc.item and refers to the following JSON structure:

{ "doc" : [ { "item" : "..." } ] }

2.2 Special request parameters

The following special request parameters can be added to any request as URL query parameters:

callback: A JavaScript callback method name to return JSONP instead of JSON. The callback MUST only contain alphanumeric characters and underscores. If a callback is given, the response content type MUST be application/javascript.
suppress_response_codes: If this parameter is present, all responses MUST be returned with a 200 OK status code, even error responses.

2.3 Access tokens and scopes

All PAIA methods, with login from PAIA auth as the only exception, require an access token as a special request parameter. The access token is a so called bearer token as described in RFC 6750. The access token can be sent either as a URL query parameter or in an HTTP header. For instance the following requests both get information about patron 123 with access token vF9dft4qmT:

curl -H "Authorization: Bearer vF9dft4qmT" https://example.org/core/123
curl -H https://example.org/core/123?access_token=vF9dft4qmT

An access token is valid for a limited set of actions, referred to as scope. The following scopes are possible for PAIA core:

read_patron: Get patron information by the patron method.
read_fees: Get fees of a patron by the fees method.
read_items: Get a patron’s item information by the items method.
write_items: Request, renew, and cancel items by the request, renew, and cancel methods.

For instance a particular token with scopes read_patron and read_items may be used for read-only access to information about a patron, including its loans and requested items but not its fees.

A PAIA server SHOULD send the following HTTP headers with every response:

X-OAuth-Scopes: A space-separated list of scopes, the current token has authorized
X-Accepted-OAuth-Scopes: A space-separated list of scopes, the current method checks for

For PAIA auth an additional scope is possible:

change_password: Change the password of a patron with the PAIA auth change method.

A PAIA core server SHOULD NOT include the change_password scope in the X-OAuth-Scopes header because the scope is limited to PAIA auth. A PAIA auth server MAY send X-OAuth-Scopes and X-Accepted-OAuth-Scopes headers with both PAIA auth scopes and PAIA core scopes.

2.4 Error response

Two classes of errors must be distinguished:

Document errors

Unknown document URIs and failed attempts to request, renew, or cancel a document do not result in an error response. Instead they are indicated by the doc.error response field, which SHOULD contain a human-readable error message. Form and type of document error messages are not specified, so clients SHOULD use these strings for display only.

For instance the following response, returned with HTTP status code 200, could result from a request for an item given by an unknown URI:

{
  "doc": [ {
    "item": "http://example.org/some/uri",
    "error": "item URI not found"
  } ]
}

Request errors

Malformed requests, failed authentication, unsupported methods, and unexpected server errors such as backend downtime etc. MUST result in an error response. An error response is returned with an HTTP status code 4xx (client error) or 5xx (server error) as defined in RFC 2616, unless the request parameter suppress_response_codes is given.

The following section only covers request errors.

The response body of a request error is a JSON object with the following fields (compatible with OAuth error response):

name	occ	data type	description
error	1..1	string	alphanumerical error code
code	0..1	nonnegative integer	HTTP status error code
error_description	0..1	string	Human-readable error description
error_uri	0..1	string	Human-readable web page about the error

The code field is REQUIRED with request parameter suppress_response_codes in PAIA core. It SHOULD be omitted with PAIA auth requests to not confuse OAuth clients.

The response header of a request error MUST include a WWW-Authenticate header field to indicate the need of providing a proper access token. The field MAY include a short name of the PAIA service with a “realm” parameter:

WWW-Authentificate: Bearer
WWW-Authentificate: Bearer realm="PAIA Core"

The following error responses are expected:²

error	code	description
not_found	404	Unknown request URL or unknown patron. Implementations SHOULD first check authentication and prefer error `invalid_grant` or `access_denied` to prevent leaking patron identifiers.
not_implemented	501	Known but unsupported request URL (for instance a PAIA auth server server may not implement `http://example.org/core/change`)
invalid_request	405	Unexpected HTTP verb (all but GET, POST, HEAD)
invalid_request	400	Malformed request (for instance error parsing JSON, unsupported request content type, etc.)
invalid_request	422	The request parameters could be parsed but they don’t match the request method (for instance missing fields, invalid values, etc.)
invalid_grant	401	The access token was missing, invalid, or expired
insufficient_scope	403	The access token was accepted but it lacks permission for the request
access_denied	403	Wrong or missing credentials to get an access token
internal_error	500	An unexpected error occurred. This error corresponds to a bug in the implementation of a PAIA auth/core server
service_unavailable	503	The request couldn’t be serviced because of a temporary failure
bad_gateway	502	The request couldn’t be serviced because of a backend failure (for instance the library system’s database)
gateway_timeout	504	The request couldn’t be serviced because of a backend failure

For instance the following response could result from a request with malformed URIs

{
  "error": "invalid_request",
  "code": "422",
  "error_description": "malformed item identifier provided: must be an URI",
  "error_uri": "http://example.org/help/api"
}

2.5 Data types

The following data types are used to define request and response format:

string

A Unicode string. Strings MAY be empty.

nonnegative integer

An integer number larger than or equal to zero.

boolean

Either true or false. Note that omitted boolean values are not false by default but unknown!

date

A date value in YYYY-MM-DD format.

money

A monetary value with currency (format [0-9]+\.[0-9][0-9] [A-Z][A-Z][A-Z]), for instance 0.80 USD.

email

A syntactically correct email address.

URI

A syntactically correct URI.

account state

A nonnegative integer representing the current state of a patron account. Possible values are:

active
inactive
inactive because account expired
inactive because of outstanding fees
inactive because account expired and outstanding fees

A PAIA server MAY define additional states which can be mapped to 1 by PAIA clients. In JSON account states MUST be encoded as numbers instead of strings.

service status

A nonnegative integer representing the current status in fulfillment of a service. In most cases the service is related to a document, so the service status is a relation between a particular document and a particular patron. Possible values are:

no relation (this applies to most combinations of document and patron, and it can be expected if no other state is given)
reserved (the document is not accessible for the user yet, but it will be)
ordered (the document is being made accessible for the user)
held (the document is on loan by the patron)
provided (the document is ready to be used by the patron)
rejected

A PAIA server MUST NOT define any other service status. In JSON service status MUST be encoded as numbers instead of strings.

document

A key-value structure with the following fields

name	occ	data type	description
status	1..1	service status	status (0, 1, 2, 3, 4, or 5)
item	0..1	URI	URI of a particular copy
edition	0..1	URI	URI of a the document (no particular copy)
requested	0..1	URI	URI that was originally requested
about	0..1	string	textual description of the document
label	0..1	string	call number, shelf mark or similar item label
queue	0..1	nonnegative integer	number of waiting requests for the document or item
renewals	0..1	nonnegative integer	number of times the document has been renewed
reminder	0..1	nonnegative integer	number of times the patron has been reminded
duedate	0..1	date	date of expiry of the service status (most times loan)
cancancel	0..1	boolean	whether an ordered or provided document can be canceled
canrenew	0..1	boolean	whether a document can be renewed
error	0..1	string	error message, for instance if a request was rejected
storage	0..1	string	location of the document
storageid	0..1	URI	location URI

For each document at least an item URI or an edition URI MUST be given. Together, item and edition URI MUST uniquely identify a document within the set of documents related to a patron.

The response fields label, storage, storageid, and queue correspond to properties in DAIA.

An example of a document (with status 5=rejected) serialized in JSON is given below. In this case an arbitrary copy of a selected document was requested and mapped to a particular copy that turned out to be not accessible:

{
   "status":    5,
   "item":      "http://example.org/items/barcode1234567",
   "edition":   "http://example.org/documents/9876543",
   "requested": "http://example.org/documents/9876543",
   "error":     "sorry, we found out that our copy is lost!"
}

See documents in RDF for a mapping in RDF.

3 PAIA core

Each API method of PAIA core is accessed at a URL that includes the URI escaped patron identifier.

3.1 patron

purpose

Get general information about a patron

HTTP verb and URL

GET https://example.org/core/{uri_escaped_patron_identifier}

scope

read_patron

response fields

name	occ	data type	description
name	1..1	string	full name of the patron
email	0..1	email	email address of the patron
expires	0..1	date	date of patron account expiry
status	0..1	account state	current state (0, 1, 2, or 3)

mapping to RDF

see patrons in RDF

Additional fields such as address may be added in a later revision.

Example

GET /core/123 HTTP/1.1
Host: example.org
Accept: application/json
Authorization: Bearer a0dedc54bbfae4b

HTTP/1.1 200 OK
Content-Type: application/json; charset=utf-8
X-Accepted-OAuth-Scopes: read_patron
X-OAuth-Scopes: read_patron, read_fees, read_items, write_items

{
  "name": "Jane Q. Public", 
  "email": "jane@example.org",
  "expires": "2013-05-18",
  "status": 0
}

3.2 items

purpose

Get a list of loans, reservations and other items related to a patron

HTTP verb and URL

GET https://example.org/core/{uri_escaped_patron_identifier}/items

scope

read_item

response fields

name	occ	data type	description
doc	0..n	document	list of documents (order is irrelevant)

mapping to RDF

see documents in RDF

In most cases, each document will have an item URI for a particular copy, but users may also have requested an edition.

3.3 request

purpose

Request one or more items for reservation or delivery.

HTTP verb and URL

POST https://example.org/core/{uri_escaped_patron_identifier}/request

scope

write_item

request parameters

name	occ	data type	description
doc	1..n		list of documents requested
doc.item	0..1	URI	URI of a particular item
doc.edition	0..1	URI	URI of a particular edition
doc.storage	0..1	string	Requested pickup location
doc.storageid	0..1	URI	Requested pickup location

response fields

name	occ	data type	description
doc	1..n	document	list of documents (order is irrelevant)

mapping to RDF

see documents in RDF

The response SHOULD include the same documents as requested. A client MAY also use the items method to get the service status after request.

3.4 renew

purpose

Renew one or more documents usually held by the patron. PAIA servers MAY also allow renewal of reserved, ordered, and provided documents.

HTTP verb and URL

POST https://example.org/core/{uri_escaped_patron_identifier}/renew

scope

write_item

request parameters

doc	1..n		list of documents to renew
doc.item	0..1	URI	URI of a particular item
doc.edition	0..1	URI	URI of a particular edition

response fields

name	occ	data type	description
doc	1..n	document	list of documents (order is irrelevant)

mapping to RDF

see documents in RDF

The response SHOULD include the same documents as requested. A client MAY also use the items method to get the service status after renewal.

3.5 cancel

purpose

Cancel requests for items.

HTTP verb and URL

POST https://example.org/core/{uri_escaped_patron_identifier}/cancel

scope

write_item

request parameters

name	occ	data type
doc	1..n		list of documents to cancel
doc.item	0..1	URI	URI of a particular item
doc.edition	0..1	URI	URI of a particular edition

response fields

name	occ	data type	description
doc	1..n	document	list of documents (order is irrelevant)

mapping to RDF

see documents in RDF

3.6 fees

purpose

Look up current fees of a patron.

HTTP verb and URL

GET https://example.org/core/{uri_escaped_patron_identifier}/fees

scope

read_fees

response fields

name	occ	data type	description
amount	0..1	money	Sum of all fees. May also be negative!
fee	0..n		list of fees
fee.amount	1..1	money	amount of a single fee
fee.date	0..1	date	date when the fee was claimed
fee.about	0..1	string	textual information about the fee
fee.item	0..1	URI	item that caused the fee
fee.edition	0..1	URI	edition that caused the fee
fee.feetype	0..1	string	textual description of the type of fee
fee.feeid	0..1	URI	URI of the type of fee

mapping to RDF

see fees in RDF

If given, fee.feetype MUST NOT refer to the individual fee but to the type of fee. A PAIA server MUST return identical values of fee.feetype for identical fee.feeid. The default value of fee.feeid is:

http://purl.org/ontology/dso#DocumentService if fee.item or fee.edition is set,
http://purl.org/ontology/service#Service otherwise (experimental!).

If a fee was caused by a document (fee.item or fee.edition), the value of fee.feeid SHOULD be a class URI from the Document Service Ontology.

4 PAIA auth

PAIA auth defines three methods for authentication based on username and password. These methods can be used to get access tokens and patron identifiers, which are required to access PAIA core methods. There MAY be additional or alternative ways to distribute and manage access tokens and patron identifiers.

There is no strict one-to-one relationship between username/password and patron identifier/access token, but a username SHOULD uniquely identify a patron identifier. A username MAY even be equal to a patron identifier, but this is NOT RECOMMENDED. An access token MUST NOT be equal to the password of the same user.

A PAIA auth server acts as OAuth authorization server (RFC 6749) with password credentials grant, as defined in section 4.3 of the OAuth 2.0 specification. The access tokens provided by the server are so called OAuth 2.0 bearer tokens (RFC 6750).

A PAIA auth server MUST protect against brute force attacks (e.g. using rate-limitation or generating alerts). It is RECOMMENDED to further restrict access to PAIA auth to specific clients, for instance by additional authorization.

4.1 login

The PAIA auth login method is the only PAIA method that does not require an access token as part of the query.

purpose

Get a patron identifier and access token to access patron information

URL

POST https://example.org/auth/login (in addition a PAIA auth server MAY support HTTP GET requests)

request parameters

name	occ	data type
username	1..1	string	User name of a patron
password	1..1	string	Password of a patron
grant_type	1..1	string	Fixed value set to “password”
scope	0..1	string	Space separated list of scopes

If no scope parameter is given, it is set to the default value read_patron read_fees read_items write_items for full access to all PAIA core methods (see access tokens and scopes).

The response format is a JSON structure as defined in section 5.1 (successful response) and section 5.2 (error response) of OAuth 2.0. The PAIA auth server MAY grant different scopes than requested for, for instance if the account of a patron has expired, so the patron should not be allowed to request and renew new documents.

response fields

name	occ	data type	description
patron	1..1	string	Patron identifier
access_token	1..1	string	The access token issued by the PAIA auth server
token_type	1..1	string	Fixed value set to “Bearer” or “bearer”
scope	1..1	string	Space separated list of granted scopes
expires_in	0..1	nonnegative integer	The lifetime in seconds of the access token

Example of a successful login request

POST /auth/login
Host: example.org
Accept: application/json
Content-Type: application/json
Content-Length: 85

{
  "username": "alice02",
  "password": "jo-!97kdl+tt",
  "grant_type": "password"
}

HTTP/1.1 200 OK
Content-Type: application/json; charset=utf-8
Cache-Control: no-store
Pragma: no-cache

{
  "access_token": "2YotnFZFEjr1zCsicMWpAA",
  "token_type": "Bearer",
  "expires_in": 3600,
  "patron": "8362432",
  "scope": "read_patron read_fees read_items write_items"
}

Example of a rejected login request

HTTP/1.1 403 Forbidden
Content-Type: application/json; charset=utf-8
Cache-Control: no-store
Pragma: no-cache
WWW-Authenticate: Bearer realm="PAIA auth example"

{
  "error": "access_denied",
  "error_description": "invalid patron or password"
}

4.2 logout

purpose

Invalidate an access token

URL

POST https://example.org/auth/logout (in addition a PAIA auth server MAY support HTTP GET requests)

request parameters

name	occ	data type	description
patron	1..1	string	patron identifier

response fields

name	occ	data type	description
patron	1..1	string	patron identifier

The logout method invalidates an access token, independent from the previous lifetime of the token. On success, the server MUST invalidate at least the access token that was used to access this method. The server MAY further invalidate additional access tokens that were created for the same patron.

4.3 change

purpose

Change password of a patron

URL

POST https://example.org/auth/change

scope

change_password

request parameters

name	occ	data type	description
patron	1..1	string	Patron identifier
username	1..1	string	User name of the patron
old_password	1..1	string	Password of the patron
new_password	1..1	string	New password of the patron

response fields

name	occ	data type	description
patron	1..1	string	patron identifier

The server MUST check

the access token
whether username and password match
whether the user identified by username has scope change_password

A PAIA server MAY reject this method and return an error response with error code access_denied (403) or error code not_implemented (501). On success, the patron identifier is returned.

5 PAIA Ontology

The information expressed by PAIA core responses in JSON, can also be expressed in RDF. The PAIA Ontology defines an RDF ontology for this purpose.

PAIA Ontology reuses classes and properties from other ontologies and defines a small set of additional classes, properties, and individuals to express information about patrons in RDF, documents in RDF, and fees in RDF.

RDF Serializations of PAIA Ontology are available in RDF/Turtle (paia.ttl) and in RDF/XML (paia.owl).

5.1 Ontology metadata

The URI namespace of PAIA ontology is http://purl.org/ontology/paia#. The namespace prefix paia is recommended. The URI of PAIA ontology as a whole is http://purl.org/ontology/paia.

@prefix paia: <http://purl.org/ontology/paia#> .
@base         <http://purl.org/ontology/paia> .

@prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> .
@prefix owl:  <http://www.w3.org/2002/07/owl#> .
@prefix dct:  <http://purl.org/dc/terms/> .
@prefix vann: <http://purl.org/vocab/vann/> .

<> a owl:Ontology ;
    dct:title "PAIA Ontology" ;
    rdfs:label "PAIA" ;
    vann:preferredNamespacePrefix "paia" ;
    vann:preferredNamespaceUri "http://purl.org/ontology/paia#" .

@prefix cc:   <http://creativecommons.org/ns#> .
@prefix xsd:  <http://www.w3.org/2001/XMLSchema#> .
@prefix voaf: <http://purl.org/vocommons/voaf#> .

<>
    dct:description "An ontology to express library patron information, such as loans, reservations, and fees."@en ;
    dct:modified "2014-06-30"^^xsd:date ;
    owl:versionInfo "1.0.2" ;
    cc:license <http://creativecommons.org/licenses/by/3.0/> ;
    dct:creator "Jakob Voß" 
    .

5.2 PatronAccount

A patron account, as returned by the PAIA core method patron is represented by an instance of the class paia:PatronAccount. Every patron account is also an instance of sioc:User (and therefore also of foaf:OnlineAccount) and an instance of particip:Role. The date of expiration can be expressed with particip:endDate. The patron identifier is given with [foaf:AccountName].

A patron account belongs to a person or another foaf:Agent, connected to with sioc:account_of and foaf:account. The full name of a patron is given with foaf:name and its email address can be given with foaf:mbox.

@prefix sioc:     <http://rdfs.org/sioc/ns#> .
@prefix foaf:     <http://xmlns.com/foaf/0.1/> .
@prefix particip: <http://purl.org/vocab/participation/schema#> .

paia:PatronAccount a owl:Class ;
    rdfs:label "PatronAccount"@en ;
    rdfs:subClassOf sioc:User, foaf:OnlineAccount, particip:Role ;
    rdfs:seeAlso
        sioc:account_of, foaf:account, particip:endDate, 
        foaf:name, foaf:mbox 
.

An instance of paia:patronAccount is assumed to be active, unless it is also an instance of paia:InactivePatronAccount.

paia:InactivePatronAccount a owl:Class ;
    rdfs:label "InactivePatronAccount"@en ;
    rdfs:subClassOf paia:PatronAccount 
.

Reasons for inactivation can be given with property paia:inactiveBecause. The inactivation reasons paia:AccountExpired and paia:OutstandingFees SHOULD be linked to.

paia:inactiveBecause a rdfs:Property ;
    rdfs:label "inactiveBecause"@en ; 
    rdfs:domain paia:InactivePatronAccount
. 

paia:AccountExpired a rdfs:Resource ; 
    rdfs:label "AccountExpired"@en
.
paia:OutstandingFees a rdfs:Resource ;
    rdfs:label "OutstandingFees"@en
.

5.3 Items in RDF

Lists of documents, as returned by the PAIA core methods items, request, renew, and cancel, are represented as sets of document service events.

@prefix bibo: <http://purl.org/ontology/bibo/> .
@prefix daia: <http://purl.org/ontology/daia/> .
@prefix frbr: <http://purl.org/vocab/frbr/core#> .
@prefix ssso: <http://purl.org/ontology/ssso#> .
@prefix dso:  <http://purl.org/ontology/dso#> .

The final mapping to RDF will probably include the following core concepts:

Document

An abstract work, a specific edition, or an item. Probably an instance of bibo:Document or frbr:Item.

Document service

An instance of a library service connected to a patron and a document. Document services are returned by the PAIA core method items. This entity is an instance of daia:Service and ssso:Service.

Service status

The current state of a (document) service is defined as an instance of a subclass of ssso:ServiceEvent from the Simple Service Status Ontology (SSSO), which are:

ssso:ReservedService: document service status 1 (reserved)
ssso:PreparedService: document service status 2 (ordered)
ssso:ExecutedService: document service status 3 (held)
ssso:ProvidedService: document service status 4 (provided)
ssso:RejectedService: document service status 4 (rejected)

The specific type of service on an item can be indicated by a subclass of dso:DocumentService from the Document Service Ontology (DSO) or by classes from a yet-to-be-created library service ontology (libso). By now the particular service types are:

dso:Loan (borrow to use at home for a limited time)
dso:Presentation (view/use within the boundaries of a library)
dso:Interloan (get a document/copy mediated from another library)
dso:OpenAccess (get directed to the location of a publicly available document)

5.4 Fees in RDF

A fee, as returned by the method fees, is an amount of money that has to be paid by a patron for some reason. Each fee is represented by the following properties of a ssso:ServiceEvent instance:

dc:date (or a more specific sub property) for fee.date
schema:price and schema:priceCurrency for fee.amount
dc:description for fee.about
Maybe schema:itemOffered to connect to a document or document service (item and/or edition).

The type of fee is represented by a class from the Document Service Ontology or by another subclass of class ServiceEvent from the Simple Service Status Ontology. All URIs returned in fee.feeid SHOULD be resolvable as Linked Open Data.

6 Glossary

access token: A confidential random string that must be sent with each PAIA request for authentication.
document: A concrete or abstract document, such as a work, or an edition.
item: A concrete copy of a document, for instance a particular physical book.
PAIA auth server: HTTP endpoint that implements the PAIA auth specification, so all PAIA auth methods can be accessed at a common base URL.
PAIA core server: HTTP endpoint that implements the PAIA core specification, so all PAIA core methods can be accessed at a common base URL.
patron: An account of a library user
patron identifier: A Unicode string that identifies a library patron account.

7 Security Considerations

Security of OAuth 2.0 with bearer tokens relies on correct application of HTTPS. It is known that SSL certificate errors are often ignored just because of laziness. It MUST be clear to all implementors that this breaks the chain of trust and is as secure as sending access tokens in plain text.

To limit the risk of spoiled access tokens, PAIA servers SHOULD put limits on the lifetime of access tokens and on the number of allowed requests per minute among other security limitations.

It is also known that several library systems allow weak passwords. For this reason PAIA auth servers MUST follow appropriate security measures, such as protecting against brute force attacks and blocking accounts with weak passwords or with passwords that have been sent unencrypted.

8 Informative parts

This non-normative section contains additional examples and explanations to illustrate the semantics of PAIA concepts and methods and usage.

8.1 Transitions of service states

Six service status data type values are possible. One document can have different status for different patrons and for different times. The following table illustrates reasonable transitions of service status with time for a fixed patron. For instance some document held by another patron is first requested (0 → 1) with PAIA method request, made available after return (1 → 4), picked up (4 → 3), renewed after some time with PAIA method renew (3 → 3) and later returned (3 → 0).

transition →	0	1: reserved	2: ordered	3: held	4: provided	5: rejected
0	=	`request`	`request`	loan	`request`	`request`
1: reserved	`cancel`	=	available	loan	available	patron inactive, document lost …
2: ordered	`cancel`	/	=	loan	available	patron inactive, document lost …
3: held	return	/	/	`renew`	/	/
4: provided	not picked up	/	/	loan	=	patron inactive, …
5: rejected	time passed	patron active	patron active	/	patron active	=

Transitions marked with “/” may also be possible in special circumstances: for instance a book ordered from the stacks (status 2) may turn out to be damaged, so it is first repaired and reserved for the patron meanwhile (status 1). Transitions for digital publications may also be different. Note that a PAIA server does not need to implement all service status. A reasonable subset is to only support 0, 1, 3, and 5.

8.2 Digital documents

The handling of digital documents is subject to frequently asked questions. The following rules of thumb may help:

For most digital documents the concept of an item does not make sense and there is no URI of a particular copy. In this case the document.edition field should be used instead of document.item.
For some digital documents there may be no distinction between status provided and status held. The status provided should be preferred when the same document can be used by multiple patrons at the same time, and held should be used when the document can exclusively be used by the patron.

8.3 PAIA core extensions to non-document services

A future version of PAIA may be extended to support services not related to documents. For instance a patron may reserve a cabin or some other facility. The following methods may be added to PAIA core for this purpose:

services: List non-document services related to a patron - similar to method items.
servicetypes: Get a list of services that a patron may request, each with URI, name, and short description.

9 References

9.1 Normative References

Bradner, S. 1997. “RFC 2119: Key words for use in RFCs to Indicate Requirement Levels”. http://tools.ietf.org/html/rfc2119.
Crockford, D. 2006. “RFC 6427: The application/json Media Type for JavaScript Object Notation (JSON)”. http://tools.ietf.org/html/rfc4627.
Fielding, R. 1999. “RFC 2616: Hypertext Transfer Protocol”. http://tools.ietf.org/html/rfc2616.
D. Hardt. 2012. “RFC 6749: The OAuth 2.0 Authorization Framework”. http://tools.ietf.org/html/rfc6749.
Jones, M. and Hardt, D. 2012. “RFC 6750: The OAuth 2.0 Authorization Framework: Bearer Token Usage”. http://tools.ietf.org/html/rfc6750.
Rescorla, E. 2000. “RFC 2818: HTTP over TLS.” http://tools.ietf.org/html/rfc2818.
Voss, J. 2013. “Simple Service Status Ontology“. http://purl.org/ontology/ssso.

9.2 Informative References

3M. 2006. “3M Standard Interchange Protocol Version 2.00“. http://mws9.3m.com/mws/mediawebserver.dyn?6666660Zjcf6lVs6EVs66S0LeCOrrrrQ-.
ILS-DI. 2008. “DLF ILS Discovery Interface Task Group (ILS-DI) Technical Recommendation - revision 1.1“ http://old.diglib.org/architectures/ilsdi/.
Katz, D. 2013. “ILS Driver (VuFind 2.x)“. http://vufind.org/wiki/vufind2:building_an_ils_driver.
NISO. 2010. “NISO Circulation Interchange Protocol (NCIP) - Z39.83-1-2008 Version 2.01“. http://www.ncip.info/.
Styles, Rob, Wallace, Chris and Moeller, Knud. 2008. “Participation schema“. http://vocab.org/participation/schema.
Voss, J. 2012. “DAIA ontology“. http://purl.org/ontology/daia.
Voss, J. 2013. “Document Service Ontology“. http://gbv.github.io/dso/.

9.3 Revision history

The current version of this document was last modified at 2014-06-30 with revision f7d18b4.

Patrons Account Information API (PAIA)

Jakob Voß

2014-06-30 (version 1.0.2)

Table of Contents

1 Introduction

1.1 Synopsis

1.2 Status of this document

1.3 How to contribute

1.4 Conformance requirements

2 General

2.1 Request and response format

2.2 Special request parameters

2.3 Access tokens and scopes

2.4 Error response

2.5 Data types

3 PAIA core

3.1 patron

3.2 items

3.3 request

3.4 renew

3.5 cancel

3.6 fees

4 PAIA auth

4.2 logout

4.3 change

5 PAIA Ontology

5.1 Ontology metadata

5.2 PatronAccount

5.3 Items in RDF

5.4 Fees in RDF

6 Glossary

7 Security Considerations

8 Informative parts

8.1 Transitions of service states

8.2 Digital documents

8.3 PAIA core extensions to non-document services

9 References

9.1 Normative References

9.2 Informative References

9.3 Revision history