RFC 3867
Payment Application Programmers Interface (API) for v1.0 Internet Open Trading Protocol (IOTP)
Pages: 106
Informational
Informational
Part 2 of 4 – Pages 12 to 34
2. Message Flow
The following lists all functions of the IOTP Payment API: o Brand Compilation Related API Functions "Find Accepted Payment Brand" identifies the accepted payment brands for any indicated currency amount. "Find Accepted Payment Protocol" identifies the accepted payment protocols for any indicated currency amount (and brand) and returns payment scheme specific packaged content for brand selection purposes. This function might be used in conjunction with the aforementioned function or called without any brand identifier. "Get Payment Initialization Data" returns additional payment scheme specific packaged content for payment processing by the payment handler. "Inquire Authentication Challenge" returns the payment scheme specific authentication challenge value. "Check Authentication Response" verifies the returned payment scheme specific authentication response value. "Change Process State" is used (here only) for abnormal termination. (cf. Payment Processing Related API Functions). o Brand Selection Related API Functions "Find Payment Instrument" identifies which instances of a payment instrument of a particular payment brand are available for use in a payment. "Check Payment Possibility" checks whether a specific payment instrument is able to perform a payment.
"Authenticate" forwards any payment scheme specific authentication
data to the IOTP Payment Bridge for processing.
"Change Process State" is used (here only) for abnormal termination.
(cf. Payment Processing Related API Functions).
o Payment Processing Related API Functions
"Start or Resume Payment Consumer/Payment Handler" initiate or resume
a payment transaction. There exist specific API functions for the
two trading roles Consumer and Payment Handler.
"Continue Process" forwards payment scheme specific data to the
Existing Payment Software and returns more payment scheme specific
data for transmission to the counter party.
"Change Process State" changes the current status of payment
transactions. Typically, this call is used for termination or
suspension without success.
o General Inquiry API Functions
"Remove Payment Log" notifies the IOTP Payment Bridge that a
particular entry has been removed from the Payment Log of the IOTP
Application Core.
"Payment Instrument Inquiry" retrieves the properties of Payment
Instruments.
"Inquire Pending Payment" reports any abnormal interrupted payment
transaction known by the IOTP Payment Bridge.
Payment Processing Related Inquiry API Functions
"Check Payment Receipt" checks the consistency and validity of IOTP
Payment Receipts, received from the Payment Handler or returned by
"Inquire Process State" API calls. Typically, this function is
called by the Consumer during the final processing of payment
transactions. Nevertheless, this check might be advantageous both
for Consumers and Payment Handlers on failure resolution.
"Expand Payment Receipt" expands the Packaged Content of IOTP Payment
Receipts as well as payment scheme specific payment receipts into a
form which can be used for display or printing purposes.
"Inquire Process State" responds with the payment state and the IOTP
Payment Receipt Component. Normally, this function is called by the
Payment Handler for final processing of the payment transaction.
"Start Payment Inquiry" prepares the remote inquiry of the payment
transaction status and responds with payment scheme specific data
that might be needed by the Payment Handler for the Consumer
initiated inquiry processing.
"Inquire Payment Status" is called by the Payment Handler on Consumer
initiated inquiry requests. This function returns the payment scheme
specific content of the Inquiry Response Block.
"Continue Process" and "Change Process State" (cf. Payment Processing
Related API Calls)
o Other API Functions
"Manage Payment Software" enables the immediate activation of the
Existing Payment Software. Further user input is under control of
the Existing Payment Software.
"Call Back" provides a general interface for the visualization of
transaction progress by the IOTP Application Core.
The following table shows which API functions must (+), should (#),
or might (?) be implemented by which Trading Roles.
API function Consumer Payment Handler Merchant
------------ -------- --------------- --------
Find Accepted Payment Brand +
Find Accepted Payment Protocol #
Find Payment Instrument +
Get Payment Initialization Data +
Check Payment Possibility +
Start Payment Consumer +
Start Payment Payment Handler +
Resume Payment Consumer #
Resume Payment Payment Handler #
Continue Process + +
Inquire Process State + + ?
Change Process State + + ?
Check Payment Receipt + ?
Expand Payment Receipt # ?
Remove Payment Log ? ? ?
Inquire Authentication Challenge ?
Authenticate +
Check Authentication Response ?
Payment Instrument Inquiry ?
Inquire Pending Payment # #
Start Payment Inquiry ?
Inquire Payment Status ?
Manage Payment Software # ? ?
Call Back #
Table 1: Requirements on API Functions by the Trading Roles
The next sections sketch the relationships and the dependencies
between the API functions. They provide the informal description of
the progress alternatives and depict the communication and
synchronization between the general IOTP Application Core and the
payment scheme specific modules.
2.1. Authentication Documentation Exchange
This section describes how the functions in this document are used
together to process authentication.
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Authenticator Inquire Authentication Challenge(Alg1*) -> IPB
Inq. Auth. Challenge Response(Alg1,Ch1) <- IPB
. . .
Inquire Authentication Challenge(Algn*) -> IPB
Inq. Auth. Challenge Response(Algn,Chn) <- IPB
Create and transmit Authentication Request Block
Authenticatee Authenticate(Alg1, Ch1) -> IPB
AuthenticateResponse(...) <- IPB
. . .
Authenticate(Algm, Chm) -> IPB
AuthenticateResponse(Res) <- IPB
Create and transmit Authentication Response Block
Authenticator Check Authentication Response(Algm,Chm,Res)->IPB
Check Auth. Response() <-IPB
Create and transmit Authentication Status Block
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Figure 2. Authentication Message Flows
1. (Authenticator Process) None, one or multiple IOTP Payment Bridges
(IPB) are requested for one or multiple authentication challenge
values ("Inquire Authentication Challenge"). Each value is
encapsulated in an IOTP Authentication Request Component. In
addition, the IOTP Application Core may add payment scheme
independent authentication methods. All of them form the final
IOTP Authentication Request Block, which describes the set of
authentication methods being supported by the authenticator and
from which the Authenticatee has to choose one method.
Note that the interface of the API function is limited to the
response of exactly one algorithm per call. If the IOTP
Application Core provides a choice of algorithms for input, this
choice should be reduced successively by the returned algorithm
({Alg(i+1)*} is subset of {Algi*}).
During the registration of new Payment Instruments, the IOTP
Payment Bridge notifies the IOTP Application Core about the
supported authentication algorithms.
2. On the presence of an IOTP Authentication Block within the
received IOTP message, the Authenticatee's IOTP Application Core
checks whether the IOTP transaction type in the current phase
actually supports the authentication process.
For each provided Authentication Request Component, the IOTP
Application Core analyzes the algorithms' names, the transaction
context, and optionally user preferences in order to determine the
system components which are capable to process the authentication
request items. Such system components might be the IOTP
Application Core itself or any of the registered IOTP Payment
Bridges.
Subsequently, the IOTP Application Core requests the responses to
the supplied challenges from the determined system components in
any order. The authentication trials stop with the first
successful response, which is included in the IOTP Authentication
Response Block.
Alternatively, the IOTP Application might ask for a user
selection. This might be appropriate, if two or more
authentication algorithms are received that require explicit user
interaction, like PIN or chip card insertion.
The Authenticatee's organizational data is requested by an IOTP
Authentication Request Block without any content element. On
failure, the authentication (sequence) might be retried, or the
whole transaction might be suspended or cancelled.
3. (Authenticator Process) The IOTP Application Core checks the
presence of the IOTP Authentication Response Component in the
Authentication Response Block and forwards its content to the
generator of the associated authentication challenge for
verification ("Check Authentication Response").
On sole organizational data request, its presence is checked.
Any verification must succeed in order to proceed with the
transaction.
2.2. Brand Compilation
The following shows how the API functions are used together so that
the Merchant can (1) compile the Brand List Component, (2) generate
the Payment Component, and (3) adjust the Order Component with
payment scheme specific packaged content.
*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+* Merchant For each registered IOTP Payment Bridge | Find Accepted Payment Brand() -> IPB | Find Accepted Payment Brand Response (B*) <- IPB | Find Accepted Payment Protocol(B1) -> IPB | Find Accepted Payment Protocol Res.(P1*) <- IPB | . . . | Find Accepted Payment Protocol(Bn) -> IPB | Find Accepted Payment Protocol Res.(Pn*) <- IPB Create one Brand List Component, ideally sharing common Brand, Protocol Amount, Currency Amount, and Pay Protocol Elements Create Trading Protocol Options Block On brand independent transactions | Create Brand Selection Component, implicitly | Get Payment Initialization Data(B1,P1) -> IPB | Get Payment Initialization Data Res.() <- IPB | Optionally | | Inquire Process State() -> IPB | | Inquire Process State Response(State) <- IPB | Create Offer Response Block Transmit newly created Block(s) Consumer Consumer selects Brand (Bi)/Currency/Protocol (Pj) from those that will work and generates Brand Selection Component - at least logically On brand dependent transaction | Transmit Brand Selection Component Merchant On brand dependent transaction | Get Payment Initialization Data(Bi,Pj) -> IPB | Get Payment Initialization Data Res.() <- IPB | Optionally | | Inquire Process State() -> IPB | | Inquire Process State Response(State) <- IPB | Create Offer Response Block | Transmit newly created Block *+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+* Figure 3. Brand Compilation Message Flows 1. The Merchant's commerce server controls the shopping dialog with its own mechanisms until the Consumer checks out the shopping cart and indicates the payment intention. The notion shopping subsumes any non-IOTP based visit of the Merchant Trading Role's (which subsumes Financial Institutes) web site in order to negotiate the content of the IOTP Order Component. The subsequent processing switches to the IOTP based form by the activation of the Merchant's IOTP aware application.
2. The IOTP Application Core inquires for the IOTP level trading
parameters (Consumer's shopping identifier, payment direction,
initial currency amounts, discount rates, Merchant's and Delivery
Handler's Net Locations, Non-Payment Handler's Organizational
Data, initial order information, ....).
3. The registered IOTP Payment Bridges are inquired by the IOTP
Application Core about the accepted payment brands ("Find
Accepted Payment Brand"). Their responses provide most of the
attribute values for the compilation of the Brand List
Component's Brand Elements. The IOTP Application Core might
optionally match the returned payment brands with Merchant's
general preferences.
The IOTP Application Core must provide any wallet identifiers, if
they are required by the IOTP Payment Bridges which signal their
need by specific error codes (see below). Any signaled error
that could not be immediately solved by the IOTP Application Core
should be logged - this applies also to the subsequent API calls
of this section. In this case, the IOTP Application Core creates
an IOTP Error Block (hard error), transmits it to the Consumer,
and terminates the current transaction.
4. The IOTP Application Core interrogates the IOTP Payment Bridges
for each accepted payment brand about the supported payment
protocols ("Find Accepted Payment Protocol"). These responses
provide the remaining attribute values of the Brand Elements as
well as all attribute values for the compilation of the Brand
List Component's Protocol Amount and Pay Protocol Elements.
Furthermore, the organisational data about the Payment Handler is
returned. The IOTP Application Core might optionally match the
returned payment brands with Merchant's general preferences.
Alternatively, the IOTP Application Core might skip the calls of
"Find Accepted Payment Brands" (cf. Step 3) and issue the "Find
Accepted Payment Protocol" call without any Brand given on the
input parameter list. In this case, the IOTP Payment Bridge
responds to the latter call with the whole set of payment schemes
supported w.r.t. the other input parameters.
5. The steps 3 and 4 are repeated during IOTP Value Exchange
transactions - these steps are omitted in the previous figure.
6. The IOTP Application Core compiles the Brand List Component(s)
and the IOTP Trading Protocol Options Block. It is recommended
that the "equal" items returned by IOTP Payment Bridge function
calls are shared due to the extensive linking capabilities within
the Brand List Component. However, the compilation must consider
several aspects in order to prevent conflicts - sharing detection
might be textual matching (after normalization):
o Packaged Content Elements contained in the Brand List Component
(and subsequently generated Payment and Order Components) might
be payment scheme specific and might depend on each other.
o Currently, IOTP lacks precise rules for the content of the
Packaged Content Element. Therefore, transaction / brand /
protocol / currency amount (in)dependent data might share the
same Packaged Content Element or might spread across multiple
Packaged Content Elements.
o The Consumer's IOTP Application Core transparently passes the
Packaged Content Elements to the IOTP Payment Bridges which
might not be able to handle payment scheme data of other
payment schemes, accurately.
The rules and mechanisms of how this could be accomplished are
out of the scope of this document. Furthermore, this document
does not define any further restriction to the IOTP
specification.
7. The IOTP Application Core determines whether the IOTP message can
be enriched with an Offer Response Block. This is valid under
the following conditions:
o All payment alternatives share the attribute values and
Packaged Content Elements of the subsequently generated IOTP
Payment and Order Components.
o The subsequently generated data does not depend on any IOTP
BrandSelInfo Elements that might be reported by the consumer
within the TPO Selection Block in the brand dependent variant.
If both conditions are fulfilled, the IOTP Application Core might
request the remaining payment scheme specific payment
initialization data from the IOTP Payment Bridge ("Get Payment
Initialization Data") and compile the IOTP Offer Response Block.
Optionally, the IOTP Application Core might request the current
process state from the IOTP Payment Bridge and add the inferred
order status to the IOTP Offer Response Block. Alternatively,
IOTP Application might determine the order status on its own.
As in step 6, the rules and mechanisms of how this could be
accomplished are out of the scope of this document.
8. The IOTP Application Core compiles the IOTP TPO Message including
all compiled IOTP Blocks and transmits the message to the
Consumer. The IOTP Application Core terminates if an IOTP Offer
Response Block has been created.
9. The Consumer performs the Brand Selection Steps (cf. Section 2.3)
and responds with a TPO Selection Block if no IOTP Offer Response
Block has been received. Otherwise, the following step is
skipped.
10. On brand dependent transactions, the IOTP Application Core
requests the remaining payment scheme specific payment
initialization data from the IOTP Payment Bridge ("Get Payment
Initialization Data"), compiles the IOTP Offer Response Block,
transmits it to the Consumer, and terminates. Like Step 7, the
IOTP Application Core might access the current process state of
the IOTP Payment Bridge for the compilation of the order status.
Any error during this process raises an IOTP Error Block.
2.3. Brand Selection
This section describes the steps that happen mainly after the
Merchant's Brand Compilation (in a brand independent transaction).
However, these steps might partially interlace the previous process
(in a brand dependent transaction).
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Merchant Merchant generates Brand List(s) containing
Brands, Payment Protocols and Currency Amounts
On brand independent transactions
| Merchant generates Offer Response Block
Consumer Compile set(s) of Brands B/Protocols P
for each set
| Find Payment Instrument(B, P, C) -> IPB
| Find Payment Instrument Response (PI*) <- IPB
Consumer selects Brand/Currency/Payment Instrument
from those that will work and generates Brand
Selection Component
For the Selection
| Get Payment Initialization Data(B,C,PI,P) -> IPB
| Get Payment Initialization Data Response()<- IPB
On brand dependent transaction
| Generate and transmit TPO Selection Block
Merchant On brand dependent transaction
| Merchant checks Brand Selection and generates
| and transmits Offer Response Block
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Figure 4. Brand Selection Message Flows
1. The Merchant's commerce server controls the shopping dialog with
its own mechanisms until the Consumer checks out the shopping cart
and indicates his payment intention. The subsequent processing
switches to the IOTP based form by the activation of the
Merchant's IOTP aware application.
2. The IOTP Application Core compiles the IOTP Trading Protocol
Options Block which contains the IOTP Brand List Component(s)
enumerating Merchant's accepted payment brands and payment
protocols and initiates the Brand Selection process.
3. This first IOTP message activates the Consumer's IOTP aware
application, e.g., the Web browser invokes a helper application
(e.g., Java applet or external application). Its IOTP Application
Core
o infers the accepted payment brands, payment protocols, payment
direction, currencies, payment amounts, any descriptions etc.,
and their relationships from the IOTP message,
o determines the registered IOTP Payment Bridges,
o compiles one or multiple sets of brand and protocol such that
the join of all sets describes exactly the payment alternatives
being offered by the Merchant.
o inquires payment (protocol) support and the known payment
instruments from each registered IOTP Payment Bridge for each
compiled set ("Find Payment Instrument"). However, some IOTP
Payment Bridges may refuse payment instrument distinction.
The payment protocol support may differ between payment
instruments if the IOTP Payment Bridge supports payment instrument
distinction.
These API calls are used to infer the payment alternatives at the
startup of any payment transaction (without user unfriendly
explicit user interaction).
The IOTP Application Core must provide wallet identifiers, if they
are requested by the IOTP Payment Bridges which signal their need
by specific error codes (see below).
It is recommended that the IOTP Application Core manages wallet
identifiers. But for security reasons, it should store pass
phrases in plain text only in runtime memory. Developers of IOTP
Payment Bridges and payment software modules should provide a thin
and fast implementation - without lengthy initialization processes
- for this initial inquiry step.
4. The IOTP Application Core verifies the Consumer's payment
capabilities with the Merchant's accepted payment brands and
currencies,
o displays the valid payment instruments and payment instrument
independent payment brands (brand and protocol) together with
their purchase parameters (payment direction, currency,
amount), and
o requests the Consumer's choice or derives it automatically from
any configured preferences. Any selection ties one IOTP
Payment Bridge with the following payment transaction.
The handling and resolution of unavailable IOTP Payment Bridges
during the inquiry in Step 3 is up to the IOTP Application Core.
It may skip these IOTP Payment Bridges or may allow user supported
resolution.
Furthermore, it may offer the registration of new payment
instruments when the Consumer is asked for payment instrument
selection.
5. The IOTP Application Core interrogates the fixed IOTP Payment
Bridge whether the payment might complete with success ("Check
Payment Possibility"). At this step, the IOTP Payment Bridge may
issue several signals, e.g.,
o payment can proceed immediately,
o required peripheral inclusive of some required physical payment
instrument (chip card) is unavailable,
o (non-IOTP) remote party (e.g., issuer, server wallet) is not
available,
o wallet identifier or pass phrase is required,
o expired payment instrument (or certificate), insufficient
funds, or
o physical payment instrument unreadable.
In any erroneous case, the user should be notified and offered
accurate alternatives. Most probably, the user might be offered
o to resolve the problem, e.g., to insert another payment
instrument or to verify the periphery,
o to proceed (assuming its success),
o to cancel the whole transaction, or
o to suspend the transaction, e.g., initiating a nested
transaction for uploading an electronic purse.
If the payment software implements payment instrument selection on
its own, it may request the Consumer's choice at this step.
If the check succeeds, it returns several IOTP Brand Selection
Info Elements.
6. The Steps 2 to 5 are repeated and possibly interlaced for the
selection of the second payment instrument during IOTP Value
Exchange transactions - this is omitted in the figure above.
7. The IOTP Brand Selection Component is generated and enriched with
the Brand Selection Info elements. This component is transmitted
to the Merchant inside a TPO Selection Block if the received IOTP
message lacks the IOTP Offer Response Block. The Merchant will
then respond with an IOTP Offer Response Block (following the
aforementioned compilation rules).
2.4. Successful Payment
An example of how the functions in this document are used together to
effect a successful payment is illustrated in the Figure 5. In the
figure 5, PS0, PS1, ..., and PSn indicate the nth PayScheme Packaged
Content data, and [ ] indicates optional.
(Technically, two payments happen during IOTP Value Exchange
transactions.)
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Consumer Start Payment Consumer(Amount,[PS0]...) -> IPB
Start Payment Cons. Res.([PS1], CS=Cont.) <- IPB
Create and transmit Payment Request Block
Payment Handler Start Payment Pay. Handler(Amount, [PS1]) -> IPB
Start Payment PH Response(PS2, CS=Cont.) <- IPB
Create and transmit Payment Exchange Block
Consumer Continue Process(PS2) -> IPB
Continue Process Response(PS3, CS=Cont.) <- IPB
... CONTINUE SWAPPING PAYMENT EXCHANGES UNTIL ...
Payment Handler Continue Process Response([PSn], CS=End) <- IPB
Request any local payment receipt
| Inquire Process State() -> IPB
| Inquire Proc. State Resp.(State, [Rcp.])<- IPB
Create and transmit Payment Response Block
Terminate transaction, actively
| Change Process State(State) -> IPB | Change PS Response(State=CompletedOK) <- IPB Consumer On receipt of final payment scheme data | Continue Process(PSn) -> IPB | Continue Process Response(CS=End) <- IPB Check Payment Receipt(Receipt) -> IPB Check Payment Receipt Response() <- IPB Request any local payment receipt | Inquire Process State() -> IPB | Inquire Proc. State Resp.(State, [Rcp.])<- IPB Terminate transaction, actively | Change Process State(State) -> IPB | Change PS Response(State=CompletedOk) <- IPB *+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+* Figure 5. Example Payment Message Flows 1. After Brand Selection and receipt of the IOTP Offer Response Block, the Consumer switches from communicating with the Merchant to communicating with the Payment Handler. This might be a milestone requiring the renewed Consumer's agreement about the payment transaction's continuation. Particularly, this is a good moment for payment suspension (and even cancellation), which will be most probably supported by all payment schemes. Simply, because the actual payment legacy systems have not yet been involved in the current transaction. Such an agreement might be explicit per transaction or automatic based on configured preferences, e.g., early acknowledgments for specific payment limits. It is assumed, that the transaction proceeds with minimal user (Consumer and Payment Handler) interaction and that its progress is controlled by the IOTP Application Core and IOTP Payment Bridge. 2. In order to open the actual payment transaction, the IOTP Application Core issues the "Start Payment Consumer" request towards the IOTP Payment Bridge. This request carries the whole initialization data of the payment transaction being referred to by the IOTP Payment Bridge for subsequent consistency checks: o payment brand and its description from the selected Brand Element of the IOTP Brand List Component, o payment instrument from preceding inquiry step,
o further payment parameters (currency, amount, direction,
expiration) from the selected Currency Amount element, Brand
List Component, and Payment Component of the IOTP Offer
Response Block,
o payment protocol from the selected IOTP Pay Protocol Element,
o order details contained in the IOTP Order Component which might
be payment scheme specific,
o payment scheme specific data inclusive of the payment protocol
descriptions from the IOTP Protocol Amount Element, and IOTP
Pay Protocol Element, and
o payment scheme specific data inclusive of the payment protocol
descriptions, in which the name attribute includes the prefix
as "Payment:" from the Trading Role Data Component.
Generally, the called API function re-does most checks of the
"Check Payment Possibility" call due to lack of strong
dependencies between both requests: There might be a significant
delay between both API requests.
The called API function may return further payment scheme specific
data being considered as payment specific initialization data for
the Payment Handler's IOTP Payment Bridge.
If the fixed Existing Payment Software implements payment
instrument selection on its own, it may request the Consumer's
choice at this step.
The IOTP Payment Bridge reports lack of capability quite similarly
to the "Check Payment Possibility" request to the IOTP Application
Core. The Consumer may decide to resolve the problem, to suspend,
or to cancel the transaction, but this function call must succeed
in order to proceed with the transaction.
Developers of payment modules may decide to omit payment
instrument related checks like expiration date or refunds
sufficiency, if such checks are part of the specific payment
protocol.
If the IOTP Payment Bridge requests wallet identifiers or pass
phrases anywhere during the payment process, they should be
requested by this API function, too. It is recommended that the
IOTP Application Core stores plain text pass phrases only in
runtime memory.
Finally, the IOTP Application Core generates the IOTP Payment
Request Block, inserts any returned payment scheme data, and
submits it to the Payment Handler's system.
3. The Payment Handler's IOTP Application Core opens the payment
transaction calling the "Start Payment Payment Handler" API
function. The payment brand, its description, payment protocol,
payment specific data, payment direction, currency and payment
amount are determined quite similar to the Consumer's IOTP
Application Core. Furthermore, the content of the IOTP Payment
Scheme Component and the IOTP Brand Selection Info Elements are
passed to this function.
On success, the Payment Handler's IOTP Payment Bridge responds
with payment scheme specific data. On failures, this non-
interactive server application has to resolve any problems on its
own or to give up aborting the payment transaction. However, the
Consumer may restart the whole payment transaction. Anyway, the
payment log file should reflect any trials of payments.
Eventually, the Payment Handler informs the Consumer about the
current IOTP Process State using the IOTP Payment Response or IOTP
Error Block.
Note that the "Start Payment Payment Handler" call might return
the Continuation Status "End" such that payment processing
proceeds with Step 7.
4. The IOTP Application Core verifies the presence of the Payment
Exchange Block in the IOTP message and passes the contained
payment scheme specific data to the fixed IOTP Payment Bridge
("Continue Process") which returns the next IOTP Payment Scheme
Component.
This Payment Scheme Component is encapsulated in an IOTP Payment
Exchange Block and transmitted to the Payment Handler.
5. The Payment Handler's IOTP Application Core verifies the presence
of the Payment Exchange Block and passes the contained payment
scheme specific data to the fixed IOTP Payment Bridge ("Continue
Process") which returns the next IOTP Payment Scheme Component for
encapsulation and transmission to the Consumer.
6. The payment process continues with IOTP Payment Exchange Block
exchanges, carrying the payment scheme specific data. Each party
(1) submits the embedded payment scheme specific data
transparently to the appropriate IOTP Payment Bridge calling the
"Continue Process" API function, (2) wraps the returned payment
scheme specific data into an IOTP Payment Exchange Block, and (3)
transmits this block to the counter party.
However, the processing of the payment scheme specific data may
fail for several reasons. These are signaled by specific error
codes which are transformed to IOTP Payment Response Blocks
(generated by Payment Handler) or IOTP Error Blocks (both parties
may generate them) and transmitted to the counter party.
7. Eventually, the Payment Handler's IOTP Payment Bridge recognizes
the termination of the payment transaction and reports this by the
continuation status "End" on the output parameter of "Continue
Process" (or "Start Payment Payment Handler"). Then, the IOTP
Application Core issues the "Inquire Process State" API call and
verifies whether an IOTP Payment Receipt Component has been
returned. The IOTP Application Core wraps the payment receipt,
the status response, and the optional payment scheme specific data
in an IOTP Payment Response Block and transmits this block to the
Consumer.
However, any of these API calls may fail or any response might be
incomplete (e.g., lack of payment receipt). Then, the Consumer
has to be notified about the failed processing by an IOTP Error
Block.
Finally, the Payment Handler terminates the payment transaction
with the "Change Process State" API call without awaiting any
further response from the Consumer. Further failures are not
reported to the Consumer.
Note that it might be possible that the Consumer's IOTP Payment
Bridge has returned the previous payment scheme specific data with
the continuation status "End". Even in the absence of this
knowledge - this status is not exchanged between the Consumer and
the Payment Handler - the Payment Handler must not supply any
further payment scheme specific data. Such data will be rejected
by the Consumer's IOTP Payment Bridge.
8. The Consumer passes the optional payment scheme specific data and
the payment receipt to the fixed IOTP Payment Bridge by "Continue
Process" and "Check Payment Receipt" API calls.
Afterwards, the IOTP Application Core issues the "Inquire Process
State" API call and verifies whether extensions to the payment
receipt have been returned.
Finally, the transaction is terminated by calling the "Change
Process State" API function which verifies and synchronizes the
reported payment status with the local one and signals any
inconsistencies. Any Inconsistency and returned status text
should be displayed to the Consumer.
At this point, the payment transaction has already been closed by
the Payment Handler. Therefore, any failure has to be resolved
locally or out-of-band.
2.5. Payment Inquiry
In Baseline IOTP, Payment inquiries are initiated by the Consumer in
order to verify the current payment progress and process state at the
remote Payment Handler. In the figure 6, PS1 and PS2 indicate the
first and second PayScheme Packaged Content data, and [ ] indicates
optional.
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Consumer Start Payment Inquiry() -> IPB
Start Payment Inquiry Response([PS1]) <- IPB
Create and transmit Inquiry Request Trading Block
Payment Handler Inquire Payment Status([PS1]) -> IPB
Inquire Payment Status Res.(State, [PS2]) -> IPB
Create and transmit Inquiry Response Trading
Block
Consumer If Payment Scheme Data present
| Continue Process(PS2) -> IPB
| Continue Process Response(CS=End) <- IPB
Change Process State(State) -> IPB
Change Process State Response(State) <- IPB
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Figure 6. Remote Process State Inquiry
1. The Consumer might initiate a payment inquiry once the payment
transaction has been opened by the IOTP Application Core, i.e., at
any time after the initial submission of the IOTP Payment Request
Block. The IOTP Application Core requests any additional specific
payment scheme data from the IOTP Payment Bridge which has been
fixed during brand selection (cf. Section 2.3) using the "Start
Payment Inquiry" API request.
Erroneous API responses should be reported to the Consumer and
valid alternatives (typically retry and cancellation) should be
presented by the IOTP Application Core.
This request might perform the complete initialization, e.g.,
availability check of periphery or pass phrase supplement, and the
IOTP Payment Bridge reports lack of capability quite similarly to
the "Check Payment Possibility" request to the IOTP Application
Core.
If the IOTP Payment Bridge requests wallet identifiers or pass
phrases anywhere during the payment process, they should be
requested by this API function, too. It is recommended that the
IOTP Application Core store plain text pass phrases only in
runtime memory.
The IOTP Application Core encapsulates any Payment Scheme
Component in an IOTP Inquiry Request Block and submits the block
to the Payment Handler.
2. The Payment Handler analyses the IOTP Inquire Request Block, maps
the Transaction Identifier to payment related attributes (brand,
consumer and payment identifiers), determines the appropriate IOTP
Payment Bridge, and forwards the request to the this IOTP Payment
Bridge ("Inquire Payment Status"). The IOTP Application Core
transforms the response to an IOTP Inquiry Response Block and
transmits it to the Consumer.
3. On receipt of the respective IOTP Inquiry Response Block the
Consumer's IOTP Application Core submits any encapsulated payment
scheme specific data to the IOTP Payment Bridge for verification
("Continue Process").
4. The IOTP Application Core passes the reported payment status
(except textual descriptions) to the IOTP Payment Bridge ("Change
Process State") for verification purposes and payment status
change. The IOTP Payment Bridge reports any inconsistencies as
well as the final payment status to the IOTP Application Core.
Any additional information that might be of interest to the
Consumer has to be displayed by the IOTP Payment Bridge or
Existing Payment Software on their own.
2.6. Abnormal Transaction Processing
2.6.1. Failures and Cancellations
The IOTP specification distinguishes between several classes of
failures:
o Business and technical errors
o Error depths of transport, message and block level
o Transient errors, warnings, and hard errors.
Any IOTP Payment API has to deal with the receipt of failure
notifications by and failure responses. This proposal has borrowed
the basic mechanisms for error reporting between the IOTP Application
Core and the IOTP Payment Bridge from the actual protocol: Business
errors are reported by Status Components within IOTP Response Blocks while technical errors are signaled by Error Components within IOTP Error Blocks. Cancellations are mimicked as specific business errors which might be initiated by each trading party. Preferring slim interfaces, this IOTP Payment API introduces one additional Error Code value for business error indication - errors can be raised on every API call. On receipt of this value, the IOTP Application Core has to infer further details by the issuance of the API function call "Inquire Process State". *+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+* Any Party Issue some API request -> IPB Error Response(Error Code) <- IPB On "Business Error" response | Inquire Process State() -> IPB | Inquire P.S. Resp.(State, Receipt) <- IPB Analyze local process state and try to resolve with optional user interaction If Process State Change needed | Change Process State (State) -> IPB | Change Process State Response(State) <- IPB If counter party's notification required | Create Error or Cancel Block (, add to next | message, ) and transmit it to counter party *+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+* Figure 7. Error Response from IPB The specific Completion Codes "ConsCancelled", "MerchCancelled", and "PaymCancelled" - returned by "Inquire Process State" - determine that the IOTP Cancel Block has to be created instead of an IOTP Error Block. The rules for determining the required behavior of the IOTP Application Core are given in the IOTP specification. Note that any payment (intermediate) termination, i.e., failures, cancellations, and even successes are always reported to the IOTP Payment Bridge by the API function "Change Process State". This API function does both status changes and consistency checking / synchronization. Any suspicion of inconsistency should be reported by the IOTP Payment Bridge for display by the IOTP Application Core.
*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+* Any Party Error Block or Cancel Block Received If Change Process State required | Change Process State (State) -> IPB | Change Process State Response(State) <- IPB *+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+*+* Figure 8. Error Notification from counter party Not every failure might be visible at the IOTP layer, e.g., the processing of payment transactions might temporarily be hampered by intermediate failures at the payment scheme or protocol transport layer which might be resolved by the actual components. However, final failures or cancellations have to be reported at the IOTP layer. E.g., communication time-outs and heavily faulty communication channels may disable the transaction. Any system component may implement time-out recognition and use the aforementioned API mechanisms for the notification of process state changes. But, time-outs may happens while communicating with both the counter party and local system components, like chip card readers or IOTP Payment Bridges. Anyway, the Consumer's IOTP Application Core should notify the Consumer about the resolution alternatives, i.e., retry, suspension, and cancellation.2.6.2. Resumption
Payment transaction resumption may apply at different steps of a payment transaction: o The Consumer's and Payment Handler's view of the transaction might not be synchronized: Due to different time-out values the payment transaction may not have been suspended by the counter party. Any "Resume Payment ..." API function responds with an Error Code on non-suspended payment transaction that signals a business error. Afterwards the IOTP Application Core has to issue the "Inquire Process State" API call for further analysis of the process state. o One IOTP message sent by one party might not be processed successfully or even received by the counter party. This needs to be handled by the actual payment scheme. It is expected that the IOTP Application Core will not recognize anything.
o IOTP does not provide any specific signal for payment resumption.
On receipt of every IOTP Payment Exchange Block, the IOTP
Application Core has to decide whether this Block belongs to a
pending transaction or to a suspended transaction that should be
resumed. The IOTP Application Core might call the "Inquire
Process State" API function to update any lack of knowledge.
Any "Resume Payment" API function responds with an Error Code on
non-suspended payment transaction that signals a business error.
Similar, the "Continue Process" API function should report
business errors on non-pending payment transactions.
o The payment transaction may not have been created at the Payment
Handler (early suspension and failed data transmission). In that
case, the IOTP Application Core should respond with a business
error that signals the repetition of the payment transaction (by
the Consumer).
Any "Resume Payment", "Continue Process" or "Inquire Process
State" API function should return with an Error Code
"AttValIllegal" on non-existent payment transaction whereby the
further Error Attribute "Names" denote the payment identifier.
o The IOTP Application Core should always request fresh payment
scheme specific data on resumption - for synchronization purposes
with the Existing Payment Software. Old data in the cache that
has not been sent to the counter party should not be accessed.
If the Consumer does not reconnect within an acceptable amount of
time, the Payment Handler's system may perform local failure
resolution in order to close the transaction and to retain resources
for other transactions ("Change Process State"). If the Consumer
reconnect afterwards, an IOTP Payment Response or IOTP Error Block
could be generated.
2.7. IOTP Wallet Initialization
At startup or on explicit user request the IOTP Application Core
should check its IOTP Payment Bridges' internal status by searching
for pending payment transactions.
1. The IOTP Application Core interrogates the registered IOTP Payment
Bridges about pending payment transactions. The IOTP Application
Core may store indicators for pending transactions and use them
for driving any subsequent inquiry ("Inquire Pending Payment").
2. If one or more IOTP Payment Bridges report the presence of pending
transactions, the IOTP Application Core may try to suspend
("Change Process State") or resume (only Consumer: "Resume Payment
Consumer") the pending transactions (on user request).
The IOTP Payment Bridge may deny the processing of any new payment
transactions until the pending transactions have been processed.
Such denials are signaled by the error code "Business Error".
2.8. Payment Software Management
The IOTP Application Core provides only a simple and generic
interface for the registration of new payment methods / instruments
("Manage Payment Software"). It receives the initial user request
and defers the actual registration to the corresponding IOTP Payment
Bridge.
The IOTP Application Core may also activate the Existing Payment
Software for further payment instrument and wallet administration.
(page 34 continued on part 3)