Web Services Internationalization Usage Scenarios

2.1.1 Discovery

Discovery of Web services can be done in many ways. For example, the system administrators on either end of the transaction may just discuss their objectives or exchange Web service description files (WSDL). Other options include a UDDI registry or other automated mechanism.

The Web service description forms the service contract for the service. It contains the information about how to invoke the service and what, if any, response to expect. This information is called the message exchange pattern. The message exchange pattern includes the data structures passed to the service itself and the data structures returned (if any). It may also describe headers that contain the contextual information, either required or optional, that the service may need for features such as quality-of-service, security, transactionality, and so forth.

Each service or set of services may provide a variety of ways to be invoked, with different URLs, ports, and other information distinguishing the various invocations. Each specific collection (single way of invoking a Web service), consisting of a URL, request and response is called a binding.

The Web service description is typically generated by the provider and is subsequently parsed by the requester in order to configure the requester to invoke the service. In some cases the Web service description may also be used to generate the service.

2.1.2 Request

The request goes through several stages:

1. The caller invokes the service in the requester agent somehow.

2. The requester agent formulates the SOAP message that will invoke the service. It uses the WSDL to create and populate the message body and any headers, attachments, and so forth as set out in the description.

3. The SOAP message is dispatched over the transport (typically HTTP, but not always so) to the URL in the WSDL. This generally represents the provider agent, but may also involve an intermediary server which forwards the request.

4. The provider agent receives and decodes the message. This may result in an error, in which case a SOAP Fault message may be generated as a response.

5. If the SOAP message is decoded successfully, recognized, and valid for a service supported by the provider agent (that is, it was not in error), the provider agent attempts to invoke the service itself.

   Note that invoking the service may result in an error (if, for example, the service isn't currently available) and also that the service itself might result in an error.

2.1.3 Response

Not all services generate a response, either when an error is encountered or with a successful result. If the message exchange pattern calls for a response, then the following steps apply:

1. The service returns its result(s) to the provider agent. This may, as noted above, be a successful result or an error.

2. The provider agent formulates the SOAP message that will be the response. The results of the service are used to build any message body and the provider agent fills in any additional header information. If the service generated an error, then the response message will take the form of a SOAP Fault.

3. The SOAP message is then returned over the transport to the requester agent. Note that from the perspective of the provider agent, this may be an intermediary.

4. The requester agent receives the response and decodes it.

5. The results are passed or made available to the client process.

3.1.1 Relationship of Locale to Natural Language

There is not yet an Internet standard for locale identifiers. However, there is one for natural language identifiers, RFC3066. Since these language identifiers can imply a locale and in the absence of a standard for locale interchange, language identifiers are often used by software as the source for locale identification. Language and locale are distinct properties and should not be used interchangeably, but there is a relationship between these parameters in the area of resource selection and localization.

The danger of using one for the other lies in the distinction between them. A language preference controls only the language of the textual content, while locale objects are used to control culturally affected (software) behavior within the system. For example, making the assumption that the language parameter ja (Japanese) means the data should be presented in the locale-determined format for Japan could be a mistake if the requester actually lives and works in Australia.

The language parameter may be available in several places. In HTTP, there is an Accept-Language header field which can be used (see the HTTP Accept-Language section for more information). MIME has a Content-Language header which contains a language identifier (see the MIME Tags section for more information). In XML, there is an attribute which can be defined for elements called xml:lang. xml:lang marks all the contents and attribute values of the corresponding element as belonging to the language identified. What that means for processing those contents varies from application to application.

Here are some examples:

<p xml:lang="en">The quick brown fox jumps over the lazy dog.</p>
<p xml:lang="en-GB">What colour is it?</p>
<p xml:lang="en-US">What color is it?</p>
<sp who="Faust" desc='leise' xml:lang="de">
  <l>Habe nun, ach! Philosophie,</l>

  <l>Juristerei, und Medizin</l>
  <l>und leider auch Theologie</l>
  <l>durchaus studiert mit heißem Bemüh'n.</l>
</sp>

For more detailed information on the behavior of xml:lang, see the XML specification.

3.1.2 I-025: Specifying and Exchanging International Preferences in Web Services

Web service and provider implementations, like Web based applications, face the problem of language and locale negotiation.

Most Web based application environments have established proprietary standards for performing language and locale negotiation and provide greater or lesser support for managing this form of personalization and content management.

Web services, in contrast, must allow disparate systems to interoperate in a consistent, non-proprietary manner. This design allows systems to invoke each other without regard to the internal architecture of any part of the system. It is helpful to think of a Web service as an remote procedure call ("RPC"), even though many Web services do not use the SOAP-RPC pattern. Unlike Web applications that can store user preferences in a session-like object hidden from the requester, Web service interoperability requires a shared model, if processing is to produce consistency between expectations and result.

Some of the problems inherent in dealing with locale negotiation and identifiers in Web services include:

Web Service Description Scenario A: A method is implemented in the Java programming language which takes a java.util.Locale argument. A Web service description is generated from this method via reflection of the Java class so that the method can be deployed as a Web service. The implementation of the Java java.util.Locale class is exposed in the Web service description and requests must be submitted with field values appropriate for Java, which may be difficult or impossible for non-Java clients to provide.

Description Scenario B: The same method is implemented taking a single string argument instead. The programmer creating the method writes logic to translate the string into the appropriate internal locale object. This logic may be substantial and must be repeated or shared for each locale-affected method. There is no way to associate the string argument with locale functionality in the provider, locale or language identifiers available in the transport, or to describe the parameter fully and consistently in directories. A system invoking the service might not be able to create a string in the expected format. The provider may not be able to validate the information appropriately.

Description Scenario C: A existing or "legacy" function or method which obtains its locale information from the runtime environment is deployed as a Web service. Existing locale negotiation mechanisms, such as Accept-Language in many application servers, rely on the container (formerly an Application server, but in this case the service provider) to populate this information. The service provider cannot know that this information is needed. The Web service description doesn't have a mechanism for describing this environment setting and the results from the service are limited to the runtime default locale of the provider or service host.

Scenario A, Different Locale Identifiers:: Sender sends a request to a provider and wants a specific locale and uses its identifier for that. The provider is running on a different platform and doesn't produce the same result as the sender expects.

Scenario A₁, Different Locale Semantics: Sender sends a request to a provider, expecting a result in a specific locale-affected format. The provider has a locale with the same ID, but the specific operation is different from the sender's implementation and the results don't match. These differences are generally subtle, but may vary widely depending on the specifics of the implementation. For example: collation or formatting dates as a string often display subtle variation from one platform to another.

Scenario A₂, Fallback Produces Different Results: Sender requests a specific locale. Provider's fallback produces wildly different results. For example, zh-Hant, the RFC3066 language tag for Chinese written in the Traditional Han script might fall back to zh which represents generic Chinese and, on many systems, implies the use of the Simplified Han script.

The following graphics show some Chinese language tags and the resulting locale object in various systems. Note the differences in interpretation:

Here are two additional examples, one for Serbian and another for Azerbaijani:

Scenario B: Sender sends a request to a provider, expecting results in in a specific locale-affected format. The sender uses its own locale identifiers. The provider and/or service is on an incompatible platform and cannot interpret the request. For example, converting Microsoft Windows's LCID identifier to Java's java.util.Locale.

Scenario C: Sender wants a specific format or set of processing rules for a specific item or set of items. The provider is running on a different platform, so the semantics differ. For example, the sender expects the Java SHORT date format, but the provider is written in the C# language.

Scenario D: Sender wants a specific format and sends a picture string or other very specific identifier. The provider and sender must agree on picture string semantics. For example, they must agree on what the picture string symbols stand for. Even in the presence of such an agreement, the underlying data in the different locale models may not match, such as the particular abbreviation for a month name.

Scenario E: Sender wants a specific locale and the provider doesn't support it. This isn't fatal to or detected by the receiving process, which returns data in an unexpected format or with unexpected results. For example, the date May 6, 2004 might be returned in a locale-formatted string as 06/05/2004 and be interpreted by a U.S. English end user as June 5, 2004.

Scenario F: Scenario E, except that it is detected by or fatal to the service. It may be difficult to interpret why the service failed. For example, the date returned in Scenario E might have been 13/05/2004, which is clearly in the wrong format for a U.S. user, but the receiving service may not be able to correct for the problem

Scenario G: Sender requests results that contain human readable text. The provider returns all languages available.

3.1.3 Locales in Web Service Descriptions

Web service descriptions should consider how to communicate language or locale choices in a consistent manner. In the sections that follow, specific patterns are recommended as good canonical references. However experience shows that a specific implementation may require additional contextual information not conveyed with a simple language tag. Generally this type of additional information should be encoded into the message body (that is, as part of the application's design, not as part of the Web services infrastructure). This expresses specific implementation decisions as part of the service's signature: you might require additional or different data in future versions. Some of the examples below show this type of information exchanged in headers and some of the complications that may arise from this.

In the examples below, adoption of a generic method for exchanging "international contextual information" would allow implementations to better model the natural language and locale processing choices offered by the services.

Implementers should consider adding a language tag to any operation fault elements to show what language to expect fault messages to be generated in.

In all cases, descriptive text should be tagged with its actual content language using the xml:lang attribute (where permitted). Consideration should be given to providing documentation within services in alternate languages when the service is expected to be utilized by users such as those in other countries or who speak other languages.

3.1.4 Locales in SOAP

Some applications of Web services require a locale in order to meet end user expectations. An example of this is any process that returns human readable text messages (many more examples exist and some are given below).

Software developers generally get their messages from language resources using an API provided by the programming environment. This functionality is implemented in many ways, but the pattern for writing the logic is always similar: the language and locale preferences are not included in the parameter list of the service itself because the processing environment (JVM, OS, .NET framework, etc.) maintains this information as metadata about the process or user.

A SOAP Processor implementation might provide accessible natural language or locale preference information, received either in the transport (such as HTTP Accept-Language) or in SOAP headers defined for a particular binding of a service.

For example, a .NET SOAP Processor might set the service's thread default CultureInfo using a language tag. A J2EE implementation might populate the javax.servlet.ServletRequest class's Locale property with a java.util.Locale constructed from the ISO639 and ISO3166 fields embedded in a language tag. And so forth.

3.1.5 Faults, Errors, and Human Readable Text

Fault message "text" elements must be labelled with an appropriate language identifier, as defined in XML 1.0. That is, an xml:lang tag containing an RFC3066 (or its successor) language identifier. If the transport provides the user's language preference (such as HTTP Accept-Language), then that language or set of languages should be preferred, followed by the SOAP Processor machine's local language preference.

Ideally there should always be a "message of last resort" included in the fault. In many cases this message may be in English, but consideration should be given to the likely users of the system, including the administrators trying to puzzle out the error. Numeric (or ASCII-only alpha-numeric) error codes should be considered for inclusion in all fault messages. This may provide valuable reference when the text of the message itself is in a language not understood by the recipient.

When designing specifications intended for interoperability between vendors or implementations, consideration should be given to enumerating the possible faults in advance so that reference numbers can be universally and consistently referenced by disparate implementations.

3.2.1 Textual vs. Binary Representations

In many traditional applications, the distinction between locale-independent and locale-dependent datatypes is also a distinction between binary and textual representations.

As an example, a floating-point number is represented in some binary format internal to an application. It is converted to a textual format when displayed to the user, and appropriate localization is applied to the formatting. For example, it would use a comma rather than a decimal point for many European locales.

Because XML is an inherently textual format, the XML Schema Datatypes also are textual. Nevertheless, most of them were carefully designed to be locale-independent, and are intended to be used in a locale-independent manner.

As an example, the XML Schema Datatype date uses the format YYYY-MM-DD from [ISO8601]. This format is similar (and in some cases even identical) to some actual formats used in some locales. The format is unambiguous and can be understood by a human reading the XML file. Although it is the appropriate format in some locales and not in others, it can be understood to be a locale-independent format. By contrast, if XML Schema had chosen a format that is not used in any locale, such as just numbering days since a well-defined day, it would have made the format much more difficult for humans to work with, without any benefits.

3.2.2 Locale-Dependent XML Schema Datatypes

While most datatypes in XML Schema are locale-independent, there are a few that are locale-dependent, and therefore should be avoided. These are all the datatypes that start with 'g', namely gYearMonth, gYear, gMonthDay, gDay, and gMonth, and the duration datatype.

The semantics of these datatypes are bound to the Gregorian calendar. As an example, a field of type gMonth with a value set to 5 refers to the month of May in the Gregorian calendar. This concept cannot be converted to calendars that do not have their months aligned with the months of the Gregorian calendar, such as the Islamic, Hebrew, or Ethiopic calendars.

As another example, a gMonthDay field with value of 09-12 refers to September 12^th in the Gregorian calendar. This date may coincide with the first or the second day of the month Meskerem in the Ethiopian calendar depending on the year.

On the other hand, the semantics of the other date- and time-related XML Schema datatypes are not bound to the Gregorian calendar, although they rely on the Gregorian calendar for their lexical form. For example, the date 2004-09-12 can not only be converted to September 12, 2004 (using the Gregorian calendar), but also to the first day in the month Meskerem in the year 1997 in the Ethiopic calendar (the Ethiopic New Year).

3.2.3 Examples

    TYPE            : EXAMPLE
    ---------------- ---------------------------
    date            : 2003-05-31
    time            : 13:20:00
    dateTime        : 2003-05-31T13:20:00+09:00
    double          : 1267.43233E12
    integer         : 2678967543233

    TYPE            : EXAMPLE
    ---------------- ---------------------------
    duration        : P1Y2M3D
    gYearMonth      : 2003-05
    gYear           : 2003
    gMonthDay       : 05-25
    gDay            : 25
    gMonth          : 05

4.1.1 The Travel Application

This section uses examples from the travel industry to illustrate all four patterns.

4.1.2 Locale Neutral

In the Locale Neutral pattern, the service executes in the same locale-independent way regardless of how it is deployed, invoked or configured. Locale neutral services generally do not provide culturally sensitive processing or deal with human-readable natural language text.

An example of this would be a service that returns flight arrival time using the XML Schema datatype xsi:dateTime. This data type is expressed in a universal format. It is then up to the requester to decide if and how to process or format the results.

This means that the strings embedded in the SOAP message produced from the service's results are intended to be machine readable and that data processed by the service does not need to be handled in a culturally sensitive way. The requester might format the value for display to human end user, but this is not part of the service's lifecycle.

Locale neutral services, being the default, do not generally need to announce their locale in their service contracts, although information about the locale or language preference of the requester may still be useful to the service or provider (for example in generating fault messages for diagnostic purposes).

4.1.3 Client Influenced

In the Client Influenced pattern, the service provides a specific set of localized behaviors which are tailored according to the locale preferences of the requester.

The service must provide a way for the requester to communicate the preferences, and, if there is a response, it should communicate the actual value used to perform the processing.

This pattern's name uses the term 'influenced' because the provider and service may not have all possible languages, locales, or sets of preferences available as resources. The service might perform language negotiation and 'fall-back' to a more general set of preferences or use its own preferences if the preferences requested cannot be satisfied.

<flight>
  <airline>XA</airline>
  <flight>116</flight>
  <restrictions xml:lang="en">Change requires
     USD100.00 fee. Bags limited to two plus one
     carry on.
  </restrictions>
  <departs>
    <code>SFO</code>
    <name xml:lang="en">San Francisco</name>
    <date>2004-04-15</date>
    <time>16:45-0800</time>
  </departs>
  <arrives>
    <code>AER</code>
    <name xml:lang="ru">Сочи</name>
    <date>2004-04-17</date>
    <time>23:45+0300</time>
  </arrives>
</flight>

4.1.4 Service Determined

In the Service Determined pattern, the service provides a specific localized set of behaviors determined prior to the request.

That is, the service does something in a culturally specific or locale affected way and the locale used in this processing is inherent in how the service is implemented, installed, deployed, or configured. The major difference between this pattern and the client influenced pattern is that the service and provider do not perform language negotiation for whatever reason.

For example, the service might use the default locale of the system where the provider is running.

It may also be a configuration option of the service, provider, or provider agent. One example of this would be a service that provides several bindings, each with a separate locale.

The preferences of the requester therefore do not influence how the service executes and may not influence aspects of the service such as the language of messages returned and so forth.

<wsdl:message name="flightCheck0In">
<wsdl:part name="arg0" type="xsd:date"/>
<wsdl:part name="arg1" type="xsd:string"/>
<wsdl:part name="arg2" type="xsd:int"/>
</wsdl:message>

	<wsdl:message name="flightCheck0Out">
<wsdl:part name="Result0" type="xsd:decimal"/>
<wsdl:part name="Result1" type="xsd:string"/>
</wsdl:message>

4.1.5 Data Driven

In the Data Driven pattern, the service's performance depends on the locale of the data (or, more usually, the data source or back-end system) itself, rather than the requester, provider or the service itself.

As an example, a service dealing with flight schedules will use the time zones of the respective departure and arrival locations for departure and arrival times, rather than some server-related time zone or the time zone preference of the client. The ISO 8601 format used by XML Schema might express times using the [RFC822] UTC offset for each time zone, rather than attempting to use a single time zone in the messages.

As another example, a service that queries a database might return data sorted or selected based on the database's configuration, rather than an external setting (such as the requester or service locale).

4.2.1 I-009: One Way Messages

One-way messages that do not have a response may still have language-related issues.

1. Service A is defined to receive a message from Requester A and deliver to Requester B via Service B. An example of this would be similar to a mail server, message queue, or messaging broker triggered by a Web service.

2. Requester A calls Service A.

3. Service B is unable to complete its message transaction and generates a fault.

Service B should return a message in a language that matches Requester B's language preference (so that the administrator of that system can use it). In addition, if Requester A's preferences are available to Requester B (that is, Service A got the preferences as part of its input or via an external mechanism such as the transport), then Requester A's language preference should be included in the SOAP fault reason text.

  <env:Reason>
      <env:Text xml:lang="fr-FR">erreur en français</env:Text>
      <env:Text xml:lang="de-DE">Verarbeitungsfehler</env:Text>
      <env:Text xml:lang="en-US">Processing error</env:Text>
  </env:Reason>>

4.2.2 I-018: Data Associated with a Default Attribute

Default attributes can cause difficulties in Web services, since they often do not travel with their corresponding values. For example, a provide deploys a Web service that returns currency values as a single numeric field, without identifying the currency. For example, the underlying function could assume that all currency amounts are returned using the Euro currency, whose ISO 4217 currency code is EUR. Responses from this service are used by multicurrency services; since the default currency type of 'Euro' doesn't accompany the numeric values, these other services may make assumptions about which currency applies to those values. This could cause problems with incorrect monetary values going out to requesters.

A solution to the above problem is to include the currency value in the message body which corresponds to the numeric value. This solution, however, may not be viable for service providers that are wrapping existing functions or which generate the Web service description via introspection. In these cases, the service provider may need to associate a 'default attribute' with the messages generated by the underlying service. This would allow requesters to recover the currency information.

The following example demonstrates multiple currency data transmission in a SOAP message and the currency code being provided in a separate element along with the value. A currency data structure such as the one shown below is one suitable solution for internationalized Web services.

<wsdl:definitions name="currencyExample" targetNamespace="http://www.example.com/wsdl/currencyExample/">
  <wsdl:types>
    <xsd:schema targetNamespace="http://www.example.com/package/">
    <xsd:import namespace="http://schemas.xmlsoap.org/soap/encoding/"/>
    <xsd:import namespace="http://www.example.com/something/"/>
        <xsd:complexType name="currencyExample$Price">
            <xsd:all>
            <xsd:element name="c" minOccurs="0" nillable="true" type="n4:Currency"/>
            <xsd:element name="value" minOccurs="0" nillable="true" type="soapenc:double"/>
            </xsd:all>
        </xsd:complexType>
    </xsd:schema>
    <xsd:schema targetNamespace="http://www.example.com/something/">
        <xsd:complexType name="Currency">
            <xsd:all>
            <xsd:element name="currencyCode" minOccurs="0" nillable="true" type="xsd:string"/>
            </xsd:all>
        </xsd:complexType>
    </xsd:schema>
</wsdl:types>

   <?xml version='1.0' encoding="UTF-8" ?>
  <env:Envelope xmlns:env="http://www.w3.org/2002/06/soap-envelope" >
   <env:Header>
   </env:Header>
   <env:Body>
    <c:purchase>
     <c:apple>
        <price>
		        <currency>
            <currencyCode>USD</currencyCode>
          </currency>
          <value>4.56</value>
        </price>
     </c:apple>
     <c:orange>
        <price>
		        <currency>
            <currencyCode>JPY</currencyCode>
          </currency>
          <value>442</value>
        </price>
     </c:orange>
     <c:peach>
      <price>
		      <currency>
          <currencyCode>EUR</currencyCode>
        </currency>
        <value>3.97</value>
      </price>
     </c:peach>
    </c:purchase>
   </env:Body>
  </env:Envelope>

Adding parameters to the SOAP body requires design changes to the service interface and possibly to the implementation. Adding default values into SOAP headers does not affect the service interface and often can be done statically for a particular resource. This may be an acceptable solution when presenting data from legacy systems through Web services. For example, this could be used for adapting a legacy retail or banking system which conducts all transactions in a single currency to provide data to an international system, however there are many potential issues with this design (see section 4.4.1 Pandora's box: Using Non-internationalized Data Structures).

   <?xml version='1.0' ?>
   <env:Envelope xmlns:env="http://www.w3.org/2002/06/soap-envelope" >
    <env:Header>
     <example:SomeInternationalization xmlns:example="http://example.org/2002/11/21/example">
      <example:Currency>JPY</example:Currency>
     </example:SomeInternationalization>
    </env:Header>
   <env:Body>
    <c:purchase>
     <c:apple>
      <c:price>123</c:price>
     </c:apple>
     <c:orange>
      <c:price>3250</c:price>
     </c:orange>
     <c:peach>
      <c:price>3612</c:price>
     </c:peach>
     </c:purchase>
    </env:Body>
   </env:Envelope>

4.2.3 I-013: Conflicts Between Requester's Expectations and Service's Locale

In some cases, the locale in which the service provider is executing could affect how parameters sent are evaluated and lead to faults that the requester does not expect or does not understand.

1. Service A is defined on Provider A, running in a Finnish locale, which queries a company's credit records.

2. Requester A is running in a French locale. The Requester is doing a monthly audit to verify local customer credit. To request the credit information from the Finnish provider in manageable chunks, the requester makes multiple requests in which is requests that the customer records fall into a range.

   If one were to write the query in SQL, it might take the form: SELECT * WHERE (LASTNAME >= low) AND (LASTNAME < high) iterating over the variables low and high.

3. The first iteration sends a low value of "A" and a high value of "B".

4. Requester A compares the results with its list of customers in that range. The audit is missing many customer records, since the Finnish provider doesn't consider names beginning with either "Å" or "Ä" to be less than "B" but the French requester expects this.

4.3.1 I-004: Producing Fault Reasons in All Available Languages

In the absence of language negotiation, the service provider may need to produce fault messages in all available languages.

A service provider detects an error in a request. The provider generates a response containing a SOAP Fault. In the absence of language negotiation, the provider must return several, if not all, available languages. The provider cannot know what languages (resources) are installed, since most programming environments do not provide functionality that enumerates which languages are actually installed.

If the service provider wishes to return all languages available, it must request every possible installed locale in turn in order to poll whether the string is available in that language. Since resources are often sparsely populated, this suggests significant a processing overhead to loop over all possible locales, loading resources in turn.

If the service provider returns a significant portion of the languages available, the size of the Fault message may also be adversely affected.

Solaris 8: 42
Redhat Linux 497
SuSE Linux 9.0: 227
Java JDK 1.4.2: 150
Microsoft .NET: 120

4.3.2 I-005: Language Matching for Fault Reason Messages

The service requester needs to select a matching language from the list of fault reasons returned by the service provider. Language tag matching and language ranges are described by RFC3066[RFC3066]. Since the xml:lang value associated with the Reason Text element may not be empty, the requester may be unable to match any of the returned text elements to its current end user language.

RFC3066 language tag matching and SOAP Reason Text elements do not provide for a default message: there is only a list of different language messages. So the requester must choose some reasonable default from the list of messages provided.

<env:faultReason>
 <env:Text xml:lang="en-US">Processing error</env:Text>
 <env:text xml:lang="cs">Chyba zpracování</env:Text>
</env:faultReason>

If the requester prefers en-GB, then neither string will match directly for the current requester language preference. Although it is apparent to a human that en-US is a reasonable match for en-GB, automated processes are not permitted to make the assumption that languages with common prefixes are mutually understandable.

If the requester prefers ja, then selecting the best fallback is even more difficult, since there is no matching language. How can an implementation choose which message to display?

4.3.3 I-008: Locale Sensitive Formatted Data in SOAP Fault Messages

A service or service provider substitutes locale-sensitive data into text messages when generating fault reasons.

A service generates a fault during invocation, resulting in a SOAP Fault being returned to the requester. In order to properly present values in the Reason element of the Fault, the locale must be known and locale information must be available. For example:

• "The date provided, 12 November 2201, was too late."

• "The argument 12345.678 was too large."

• "The argument 12345,678- was too small."

The service or provider should format the substitutions in each message according to the language and locale of the target audience (typically the requester), which is not necessarily the same as the locale of the provider or service.

If locale or language preference information is not available from the requester, it may not be possible to generate a message in the user's preferred language. In these cases, the message should follow the language preference of the provider or service host.

4.4.1 Pandora's box: Using Non-internationalized Data Structures

A data structure may be provided without international considerations. This may happen, for instance, when a service was originally designed and targeted for a specific local market and later converted to a Web service.

Use and adoption of locale-affected and non-internationalized data structures generally requires a firm understanding of the conventions being adopted and careful implementation. It is generally poor practice in Web services, since the goal of having a Web services infrastructure is usually interoperablity without deep knowledge of the underlying implementation decisions.

This is an example of a user's daily activity provided in Japanese 12 hour time scheme.

Example: My schedule

Time       : To do
---------- : -----------------------
GOZEN 8:00 : Breakfast
GOGO  0:00 : Lunch
GOGO  7:00 : Dinner
GOZEN 0:00 : Go to bed

GOZEN means "before noon", and generally corresponds to AM. GOGO means "after noon", and generally corresponds to PM. The problem is GOGO 0:00 is noon rather than 0:00 AM, and GOZEN 0:00 is midnight rather than 0:00 PM. This is confusing and conversion to an internationally known time format may fail.

4.4.2 I-019: Locale Dependent Datatypes

A sender wishes to send locale dependent data to a receiver. The receiver needs to process the locale dependent data correctly.

As an example, if a Japanese sender sends dates to a Japanese receiver, the Japanese sender may wish to send the data in a Japanese date format as required for government records, such as H13-5-31(H stands for the Heisei era; see Appendix C Heisei).

<?xml version='1.0' ?>
   <env:Header>
    <example:WSinternationalization
       xmlns:example="http://example.org/2002/11/21/WS-I18N">
     <example:dataTypePreference>
      <ja:JDate xmlns:ja="http//example.org/2003/12/3/ja">EYY-MM-DD</WS-I18N:JDate>
     </example:dataTypePreference>
    </example:WSinternationalization>
   </env:Header>
   <env:Body>
     ...
     <JDate:birthDate>H13-05-31</JDate:birthDate>
@@Note: We need to figure out how to properly present this data type
     ...
   </env:Body>

Wherever possible it is best to avoid locale dependent data types. Otherwise, the sender and receiver must agree in advance on the data formating and semantics.

Many locale- or region-specific data types such as telephone number, address elements, post code, forms of address, etc. can be modeled as strings with patterns. It is the responsibility of the application on either end to validate, interpret, and format the data properly.

WSDL and SOAP can be used to constrain locale- or region-specific data fields.

Applies to: WSDL, SOAP, or Localizable datatype

4.4.3 Existing Web Services

If a Web service is created from a specific agent which is not internationalized and later the agent is internationalized, then the service itself may have to be redeployed because the parameter list, headers, or other information have changed. The developer of the agent is responsible for supplying the fields, logic, and semantics that will be used to achieve international capabilities.

The international considerations in doing this include:

• What information is needed to enable international operation.

• What fields and format are needed to collect that data.

• Fallbacks, validation and whether the items are optional or not.

If the two versions of the service vary in their approach or don't supply a suitable mechanism then the service itself may have changed enough....

Scenario A: There is a Service A which is not internationalized. Some senders start using this service. Later a new version is created that is internationalized, B. Service B cannot simply replace Service A because the service signature has changed. Service A must remain deployed until all users have switched.

Scenario B: There is a Service A which is not internationalized. Later a new internationalized version, Service B, is created that is internationalized but which uses the same fields and required values as Service A. Senders that used Service A may be switched to Service B without warning. Now the behavior may differ... (users expecting Service A may get different results than they expect).

Scenario C: There is a Service A which is not internationalized. Later a new version is created that adds optional fields to enable internationalized behavior and this new service is deployed as Service B, replacing Service A. Existing senders to Service A do not notice the change, but new senders can use the optional fields to get internationalized results. This may be a way to avoid the problems with Service B, but may be difficult to maintain over time.

Scenario D: Service B is deployed in place of Service A. The new service either generates faults (to deprecate the original invocation) or acts as an intermediary that invokes the original Service A at some new location. Service B can then record senders that are using the original service as a way of assisting in migration.

4.5.1 SOAP Documents and the MIME Charset Parameter

Scenario Definition: A SOAP interaction is based on SOAP 1.1. The documents exchanged use the Content-Type 'text/xml' without a charset parameter. The default character encoding for the 'text/xml' media type is US-ASCII, so omitting the charset parameter may result in failure or data loss.

The charset parameter must be supplied in order to ensure correct interoperability.

A provider or requester is using SOAP 1.2, which uses the Content-Type 'application/soap+xml'. If the charset parameter for that media type is omitted using 'application/soap+xml' then the SOAP document will be examined for its character encoding using the rules provided in XML.

4.5.2 Character Encoding of Attachments

Frequently Web services have attachments. Since attachments are not part of the SOAP document, they can be in a different encoding. In order for an attachment to be processed correctly, the encoding must be identified for the processing application.

The SOAP processor (either in the provider, in the case of receiving a SOAP request, or in the requester's client when receiving a response) must handle the attachment correctly. For textual data types, this means providing a correct charset parameter in the MIME type when generating the SOAP message. It also means that the recipient of an attachment must provide this information to the ultimate processor (such as the service or the client). Loss of the encoding may result in corruption of the data or having to guess.

If the receipt of the attachment and its processing are separated in some manner, it may be important to provide the encoding of the attachment as part of the actual SOAP message type. This way the text can be processed without access to the MIME header information.

For example, a Web service takes the title of an article and retrieves the full text of the article as an attachment. The database contains articles in many languages and character encodings from sources around the world. The articles are in plain text, with no internal encoding identifier, but when stored in the database, the encoding is inserted as a related parameter. The return SOAP message contains an attribute with the encoding.

MIME-Version: 1.0
Content-Type: Multipart/Related; boundary=MIME_boundary; type=text/xml;
         start="<article123456@samplerepository.co.uk>"
Content-Description: Sample SOAP envelope with attachment in ISO-8859-15.

--MIME_boundary
Content-Type: text/xml; charset=UTF-8
Content-Transfer-Encoding: 8bit
Content-ID: <article123456@samplerepository.co.uk>

<?xml version="1.0" encoding="UTF-8" ?>
   <env:Envelope xmlns:env="http://www.w3.org/2002/06/soap-envelope" >
    <env:Header>
    </env:Header>
    <env:Body>
      <encExample:articleRetriever>
        <articleTitle xml:lang="fr">Voici le titre</articleTitle>
        <articleEncoding>ISO-8859-15</articleEncoding>
        <articleSize unit="byte">14355</articleSize>
      </encExample:articleRetriever>
<!-- ... -->
     <att:SecondaryPartBag>
	http://samplerepository.co.uk/retrieval/database/article123456
     </att:SecondaryPartBag>
    </env:Body>
   </env:Envelope>

--MIME_boundary
Content-Type: text/plain; charset=ISO-8859-15
Content-Transfer-Encoding: 8bit
Content-ID: <article123456@samplerepository.co.uk>

...plain text article in ISO-8859-15...

--MIME_boundary--

Note that the SOAP message itself is in the UTF-8 encoding, which is different from the attachment's encoding of ISO-8859-15.

4.5.3 Unsupported Charset in Request Scenario

A requester sends a SOAP document in an encoding that the provider does not support. The provider should fail and return a fault.

4.5.4 Unsupported Charset in Response Scenario

A requester receives a response. The response is encoded using a character encoding not supported requester. This is an unrecoverable error. Web services providers and requesters should agree in advance on the collection of encodings that will be used in the transactions. Ideally all transactions will use a Unicode encoding, such as UTF-8, since all XML processors are required to handle this encoding.

4.5.5 Unsupported Characters

Some encodings have more characters than are included in Unicode or use Private Use characters. SOAP messages sent using these problematic characters may result in transient failure or odd results. These characters should be avoided wherever possible or some mutually agreed upon private solution should be adopted. Note that this is rare problem.

4.5.6 Legacy Application Use of non-Unicode Character Encodings

One use of Web services is to wrap existing or legacy systems. These systems may use a legacy (non-Unicode) encoding internally or in their API. Although the service provider supports Unicode for sending and receiving SOAP messages, the underlying system does not. This may lead to:

4.5.7 Variability in Transcoding Scenario

Note that the XML Japanese Profile [XML-JP] describes that using legacy encodings such as Shift_JIS cannot provide complete interoperability in information interchange; there are differences among platforms in the mapping tables they use for this and similar encodings.

4.7.1 I-020: Correlation of Data Between Services in Different Languages

Clients requesting from the intermediary service can have different international preferences. Therefore the intermediary service must be careful with its algorithms for determining when to reuse responses that it receives from its providers. Proper tracking of source data locale and requester locale is required. Also, correlation and/or aggregation of data may prove difficult if sound internationalization principles are not used.

4.7.2 I-007: Interaction of Optional Locale and Language Negotiation and Chained Services

If caching does not take international preferences into account, it is possible that cached responses in the wrong language, format, or locale could be returned.

Alternatively, in scenario I-020, the intermediary service caches fault reasons and other data returned from its providers in each of the languages and cultural conventions that are requested of it, tracking the locales of each result.

Requesters of the intermediary service identify the desired locale of expected results. With locale negotiation, the intermediary service can provide results and/or fault reasons that match the requester's international preferences.

4.7.3 I-012: Caching

Chained services are a form of intermediary services. A (source) provider defines a service that has a requirement for a language or locale preference. Another (intermediary) service provider, defines the same service and invokes the first service to utilize its capabilities.

The source provider defines an optional header containing a language request field. If the intermediary service does not also define the optional header, then when it receives a request it cannot communicate the requester's preferences to the source provider. The intermediary service might indicate its own international preference(s) to the source provider or none, accepting default values. Unless, the description of the intermediary's service declares its policy on addressing international preferences, its users may have incorrect expectations of the results.

4.7.4 Caching with Locale Information in SOAP Headers

In a variation of the above scenarios, a SOAP header can be used for locale negotiation between each layer of requester, intermediary and service. An example is a Web service wrapper to a legacy client/server application.

If the intermediary strips off optional headers (either from the requester of its service or the response from its providers), some of the contextual information necessary to interpret the response may be lost.

4.8.1 Character encoding conversion scenario

An environment exists in which a legacy application invokes a service. The receiving service and the legacy requester are not necessarily using the same character encoding scheme. An intermediary site receives the sender's message and, using data in the message's SOAP header, converts the message's character data to the encoding of the ultimate receiver, the service.

A requester sends a SOAP message with an attachment that uses a character encoding and character set of its local process. The ultimate receiver of the message is a service which can only process UTF-8 encoded data. An intermediary provider examines message headers before forwarding the messages to the service's provider. If the character encoding is not UTF-8, the intermediary converts the data, modifies the character encoding attribute of the message, removes the header, and forwards the message.

<?xml version="1.0" encoding="ISO-8859-1" ?>
<env:Envelope xmlns:env="http://www.w3.org/2003/05/soap-envelope">
  <env:Header>
    <WS-I18N:convertData
       xmlns:WS-I18N="http://example.org/2002/11/21/WS-I18N"
       env:role="http://www.w3.org/2003/05/soap-envelope/role/next">
       <WS-I18N:senderEncoding>ISO-8859-1</WS-I18N:senderEncoding>
    </WS-I18N:convertData>
  </env:Header>
  <env:Body>
     . . .[legacy ISO-8859-1 data]
  </env:Body>
</env:Envelope>

<?xml version="1.0" encoding="UTF-8" ?>
<env:Envelope xmlns:env="http://www.w3.org/2003/05/soap-envelope">
  <env:Body>
     . . .[UTF-8 data]
  </env:Body>
</env:Envelope>

4.9.1 Searching for Web Services Using UDDI

With respect to internationalization, there are four primary scenarios that will be discussed below:

1. How do I search for services using my language to perform the search?

2. How do I search for services that are specific to my region?

3. How do I search for services that can handle my locale or language preference needs?

4. How do I describe a service that handles multiple locales or languages?

4.9.2 I-026 Searching for Service Descriptions Using My Language

I-026.1 Searching for Service Descriptions using my language

It states in the UDDI Version 3.0.1[UDDI] specification in the section on Introduction to Internationalization:

"1.8.4 Use of Multiple Languages and Multiple Scripts Multinational businesses or businesses involved in international trading at times require the use of possibly several languages or multiple scripts of the same language for describing their business. The UDDI specification supports this requirement through two means, first by specifying the use of XML with its underlying Unicode representation, and second by permitting the use of the xml:lang attribute for various items such as names, addresses, and document descriptions to designate the language in which they are expressed. "

Using xml:lang and multiple entries, a service provider can publish text information about their service in multiple languages. The name, description, address, and personName UDDI elements MAY be adorned with the xml:lang attribute to indicate the language in which their content is expressed. The policyDescription element contains a description of the effect of the policy implementation. This element can be adorned with the xml:lang attribute and can appear multiple times to allow for localized versions of the policy description. Providers are encouraged to do this for target language markets that their service may support.

Entity names in UDDI can also provide an Alternate Name in RFC2277 default language, readable in English. This provides a fallback mechanism to allow a search to identify services even if the named contents may be in a script that is not readable by the entity doing the search.

The scenario would be as follows:

1. Service provider publishes service information using UDDI in the provider's default language. The first entity name in a list is considered to be in the primary name and language.

2. Service provider, or other entity, adds localized duplicate content to the UDDI entries for the service.

3. Service requester makes a request for service listings, first setting the primary language for searching using the UDDI Subscription API. The language is indicated by setting the xml:lang attribute on query key entities.

4. The UDDI application returns services that match the query in the given xml:lang language, matching languages according to the language matching rules defined in RFC3066???.

Here are some examples from the UDDI Version 3.0.1 specification.

<businessEntity>
    ...
  <name xml:lang="zh">黄河花店</name>
  <name xml:lang="en">Huang He Hwa Dian</name>
    ...
</businessEntity>

<businessEntity>
  ...
  <name xml:lang="zh">康柏電腦股份有限公司</name>
  <name xml:lang="en">Compaq Computer Taiwan Limited</name>
  ...
</businessEntity>

<businessEntity>
  ...
  <name xml:lang="ja">日本生花店</name>
  <name xml:lang="ja">ニッポンセイカテン</name>
  <name xml:lang="en">NIPPON FLOWERS </name>
  <name xml:lang="en">NF</name>
  <name xml:lang="ja">nippon seikaten</name>
  ...
</businessEntity>

When searching for services, requesters can hunt for names and descriptions by using the UDDI API to pass an optional collection of string values and potentially qualified with xml:lang attributes. Since "exactMatch" is the default behavior, the value supplied for the name argument must be an exact match. If the "approximateMatch" findQualifier is used together with an appropriate wildcard character in the name, then any businessService data contained in the specified businessEntity (or across all businesses if the businessKey is omitted or specified as empty) with a matching name value will be returned. Matching occurs using wildcard matching rules. Each name may be marked with an xml:lang adornment. If language markup is specified, the search results report a match only on those entries that match both the name value and language criteria. The match on language is a leftmost case-insensitive comparison of the characters supplied. This allows one to find all services whose name begins with an "A" and are expressed in any dialect of French, for example. Values which can be passed as language criteria are required to obey the rules governing the xml:lang attribute (that is, they must be valid language tags or ranges).

UDDI does not specify the use of variant find scenarios to allow alternatives such as accent-insensitive matching. To aid in search retrieval, developers creating a service discovery engine under UDDI may consider alternative match mechanisms.

4.9.3 I-027: Searching for Services Specific to a Region

The UDDI Version 3.0.1 specification states in its introduction to internationalization that UDDI provides features that enable Web service providers to describe the geographical location of different aspects of a business or service, that is, where it offers its products and services, where it is located, or even where it has stores, warehouses, or other branches. This is done through categoryBags and keyedReferences.

"The optional categoryBag element allows businessEntity structures to be categorized according to published categorization systems. For example, a businessEntity might contain UNSPSC product and service categorizations that describe its product and service offering and ISO 3166 geographical regions that describe the geographical area where these products and services are offered. "

"As within an identifierBag , a keyedReference contains the three attributes tModelKey, keyName and keyValue. The required tModelKey refers to the tModel that represents the categorization system, and the required keyValue contains the actual categorization within this system. The optional keyName can be used to provide a descriptive name of the categorization. Omitted keyNames are treated as empty keyNames. A keyName MUST be provided in a keyedReference if its tModelKey refers to the general_keywords category system. "

"For example, in order to categorize a businessEntity as offering goods and services in California, USA, using the corresponding ISO 3166 tModelKey within the UDDI Business Registry, one would add the following keyedReference to the businessEntity's categoryBag: "

<keyedReference
    tModelKey="uddi:ubr.uddi.org:categorization:geo3166-2"
    keyName="California, USA"
    keyValue="US-CA" />

The use of geographic categorization for services is useful for taxes, import, export, and acknowledgment of available location-specific physical services such as shipping, export, manufacturing, labor, etc.

The problems involved in identifying the actual geographical or political entity that apply to a service or implementation are not dealt with on the level of ISO 3166 country codes or UDDI directory standards and mechanisms for handling geographic location and applicability of services needs further study.

4.12.1 Locale-Neutral Natural Language Text Search

Most search engines do not understand language, but do understand patterns and proximity. Patterns refer to wildcards and whitespace for full-text search. However, many asian languages have no concept of whitespace in most full text, and therefore may use a scheme where every character can be considered to be a word.

<elementtype name="Product">
        <model>
            <sequence>
              ...
         <element type="<ShortDescription.html>" occurs="*"/>
         <element type="<LongDescription.html>" occurs="*"/>
              ...

    <elementtype name="ShortDescription">
         <model>
                  <string/>
         </model>
         <attdef name="lang" datatype="xmllang" prefix="xml">
              <default>en</default>
         </attdef>
    </elementtype>

 <Product Type="Good" SchemaCategoryRef="C43171803">
      <ProductID>154723-005</ProductID>
      <Manufacturer PartnerRef="Acme Tools"></Manufacturer>
                       . . .
      <ShortDescription xml:lang="en">Wrench</ShortDescription>
      <ShortDescription xml:lang="en_GB">Spanner</ShortDescription>
      <ShortDescription xml:lang="da">fladnoegle</ShortDescription>
      <ShortDescription xml:lang="es-ES">llave abierta</ShortDescription>
      <ShortDescription xml:lang="es-MX">llave inglesa</ShortDescription>
      <ShortDescription xml:lang="fr-FR">clef à fourche</ShortDescription>
      <ShortDescription xml:lang="de">Gabelschluessel</ShortDescription>
      <ShortDescription xml:lang="it">chiave a forchetta</ShortDescription>
      <ShortDescription xml:lang="ja">変化</ShortDescription>
      <ShortDescription xml:lang="ko">스패너</ShortDescription>
      <ShortDescription xml:lang="nl">vorkvormige sleutel</ShortDescription>
      <ShortDescription xml:lang="pt-PT">chave fixa</ShortDescription>
      <ShortDescription xml:lang="pt-BR">chave de boca</ShortDescription>
      <ShortDescription xml:lang="zh-CN">扳子</ShortDescription>
      <ShortDescription xml:lang="zh-TW">板鉗</ShortDescription>
                       . . .
    </Product>

4.12.2 Language-specific Natural Language Text Search

Most search engines that have any linguistic characteristics are tuned to a specific language such as English, German, or French. This allows techniques, such as stemming and ignoring stop-words to operate according to the unique characteristics of the language it is operating in.

    en:      422 Saint Jerome Street
    fr:        Rue De 422 Saints Jerome
    es:      Calle De 422 Santos Jerome
    de:      422 Heiliger Jerome Straße
    ja:        422 人の聖者のJerome の通り

Client ==> <query xml:lang="lang0"> ==> service ==> <query xml:lang="lang0".
                                    ^== look-up service
                                    v
                                    ==> <query xml:lang="lang1">
                                    ==> <query xml:lang="lang2">
                                    :
                                    ==> <query xml:lang="langN">

4.13.1 I-021: Data Formatting for End User on Receiver Side

Data is formatted for an end user by the receiver according to the end user's preferences and the system conventions.

The receiver may format data in order to display the data in a user interface. Locale sensitive data formatting functions are widely provided by internationalization functionality of operating systems, programming languages, or applications such as word processors and middleware. Therefore, an application may be able to format most locale neutral data using built-in internationalization functions. The details of data formatting vary across different systems and there may be dependencies on the data provided or on third-party data sources. Therefore, Web services do not guarantee identical presentation of the same data on different systems.

4.13.2 I-022: Data Formatting on Sender Side

Many applications produce human readable text as output. This makes it necessary for the service to format data for viewing by an end user on the receiver side. The service must choose which language message to return and the format of data inserted into the message. The language and locale preferences applied may or may not be the same and these variations could result in human readable messages that are perceived as flawed by the end user.

Clearly there are many possible (indeed acceptable) variations of the example texts. For example, one might quibble about the use of first vs. last name sorting in the list, but clearly the first list was not acceptable English alphabetical order. If one is quoting a name, like "Theatre Centre News", it might be left in the source orthography even if it differs from the publication target orthography. And so on. However, just as clearly, there limits on what is acceptable English (in this case), and 2003年3月20日, for example, is not.

4.13.3 Enumerated Values and Object Names

4.14.1 Times and Time Zones

Date and time handling in Web services is affected by time zones. However, there is no standard parameter to indicate the time zone alone. Locales are not useful for determining time zone because there can be many time zones within a given locale. Applications' needs with regard to time zone also differ.

For example, for a single timestamp the RFC 3339 UTC offset is sufficient. For processing dates (such as calculating a duration) you may need more information (such as daylight savings or summer time rules, if they apply).

Scenario A: A Web service returns the current time of a city listed as part of the request. The requester sends the name of a city (with an xml:lang attribute value) and the provider returns the current time in that city formatted in [ISO8601] format (hh:mm:ss).

Scenario B: A Web service takes a date/time value in ISO 8601 format (yyyymmddThhmm+hhmm) and the name of a city with an xml:lang attribute value, and returns the value converted to the specified city's time zone.

Scenario C: As a sub-process of a "meeting manager" service, a Web service inspects multiple appointment books looking for mutually available time slots. The requester provides a span of time in ISO 8601 format (yyyymmddThhmm+hhmm) using a start time and an end time. The inspected appointment books store information about their time zones. The service returns a series of time spans in the ISO 8601 format.

4.14.2 Calendars and Dates

A Web service is set up to calculate a calendar date and send it back to the requester. The value returned represents a specific date on the calendar, not a timestamp value as might be associated with a particular locale or time zone. The service may need to take in information such as the calendar type, year, and related descriptive information.

Scenario A: A service calculates the date for Easter, Passover, or Ramadan for any given year, returning a date value in ISO 8601 format. These religious holidays are partly based on astronomical events, such as lunar phases, as well as historical tables. They are not strictly calendar dependent in the way that many secular holidays, such as various national independence days or leader's birthdays are, nor are they predictable, for example, the fourth Thursday in November. Thus the need for a service to calculate the date might be necessary. The SOAP request would contain a holiday and a year in ISO 8601 format. In addition, some other data may be required, such as for Easter there may be a parameter specifying "Orthodox" or "Western". The Web service would in turn calculate the appropriate date and send a message back to the requester with the calculated date. Some other service may be used to convert the returned date value into a specified calendar type, such as the Japanese calendar.

Scenario B: A service calculates historical dates in different parts of the world and returns an equivalent ISO 8601 date to the requester. The SOAP request would contain a date and its country of origin. For example, a request might have the date 1812-08-26 and the origin "Russia". Russia was using a different calendar from places such as Italy or France at that time; what would appear as the same date was actually several days different. While this may look like it is part of the locale due to the country of origin, it should not be treated as such. Locales are typically associated with the end user, not with a piece of data, and a locale does not contain information on historical times.

Scenario C: A service calculates Chinese New Year for any non-Chinese calendar type. The SOAP request would include a parameter with the calendar type, such as "Gregorian", "Hebrew", or "Japanese Imperial". The locale is irrelevant to the calculation, since the requester may be looking for information unrelated to user preferences or system settings.

4.15.1 Modeling Tax, Customs, Legal, and Other Cross-Border and Cultural Considerations

Tax, customs, legal, and similar matters are usually country-specific. However, much of the types of processing involved are the same. For example, many tax calculations take a percentage or set of percentages of a given amount. A set of Web services can work together to provide information for many countries, avoiding code and process duplication.

There is more information needed in these types of processes than just the country identifier. Language information is crucial for legal documents, and important for other regime-type operations as well. For tax calculations, the currency of the incoming values as well as the currency of the result must be specified. Other cross-border services will likely require other types of information, such as address formats or some sort of legal status indicator.

Scenario A: Service A, specific to Country C, takes in the value of a sale, a language parameter, and the names of the city and the province. The currency is limited to Country C's official currency. Service A then calls a set of services, translating names into identifiers. Service B takes in a city id and a monetary value, then calculates city sales tax based on current tax tables it retrieves from other services; it returns the tax amount as a numeric value. Service C performs a similar function for taxes at the provincial level.

Service A then takes those monetary values and returns them with identifying tags for the city and provincial tax.

If Service A were to be used for multiple countries, there would have to be additional parameters, for example:

• a country identifier

• other regional identifiers, such as county, state, province, or region

• a currency identifier

There would have to be a function to handle currency calculations, possibly in a separate service. The additional tax regions need to be managed, again by separate services.

Scenario B: An application uses a Web service to send DVDs to rental customers around the world. DVDs contain a region code that limits where they can be played (according to the country they are intended for.) The Web service takes the country ID of of the customer and selects the right region code DVD to send.

Scenario C: A service takes a country ID, looks it up in a database, and return the driving rules for that country.

Configuration or business logic may have to be carefully designed in order to deal with these kinds of issues.

4.16.1 HTTP Accept-Language

The HyperText Transport Protocol (HTTP) is often used for Web service message transport. HTTP contains some header fields which are useful for identifying sender preferences and capabilities. One of those fields is Accept-Language.

Accept-Language takes one or more language identifiers in RFC3066 (or its succesor) format as its parameters. Each language identifier can have a quality value which gives a relative priority. Here is an example:

Accept-Language: zh-cn, fr-ch;q=0.8, fr;q=0.7

The above could be read as "Simplified Chinese is preferred, but Swiss French is acceptable, as are other types of French." There is more information about the handling of Accept-Language in the HTTP 1.1 specification.

A Web service requester using HTTP can include an Accept-Language field to indicate the languages preferred. The provider could then take that information and use it to return human-readable data in the appropriate language.

4.16.2 FTP

File Transfer Protocol (FTP) is a simple transport mechanism that can be used to transport Web service documents. The main international consideration in using FTP is to specify the representation type as I (Image), allowing 8-bit values to pass unchanged through the transfer.

File names, path names, and character encoding issues may intrude here, since the FTP specification provides limited guidance.

4.16.3 SMTP

4.16.4 IRIs, URIs, and fun stuff