| Prev | Chapter 12. Kernel Documentation | Next |
|---|
This document describes how to develop internationalized OpenACS packages, including writing new packages with internationalization and converting old packages. Text that users might see is "localizable text"; replacing monolingual text and single-locale date/time/money functions with generic functions is "internationalization"; translating first generation text into a specific language is "localization." At a minimum, all packages should be internationalized. If you do not also localize your package for different locales, volunteers may use a public "localization server" to submit suggested text. Otherwise, your package will not be usable for all locales.
The main difference between monolingual and internationalized packages is that all user-visible text in an internationalized package are coded as "message keys." The message keys correspond to a message catalog, which contains versions of the text for each available language. Both script files (ADP/TCL) and APM parameters are affected.
Other differences include: all dates read or written to the database must use internationalized functions. All displayed dates must use internationalized functions. All displayed numbers must use internationalized functions.
For multilingual websites we recommend using the UTF8 charset. In order for AOLserver to use utf8 you need to set the config parameters OutputCharset and URLCharset to utf-8 in your AOLserver config file (use the etc/config.tcl template file). For sites running on Oracle you need to make sure that AOLserver is running with the NLS_LANG environment variable set to .UTF8. You should set this variable in the nsd-oracle run script (use the acs-core-docs/www/files/nds-oracle.txt template file).
Localizable text must be handled in ADP files, in TCL files, and in APM Parameters. OpenACS provides two approaches, message keys and localized ADP files. For ADP pages which are mostly code, replacing the message text with message key placeholders is simpler. This approach also allows new translation in the database, without affecting the file system. For ADP pages which are static and mostly text, it may be easier to create a new ADP page for each language. In this case, the pages are distinguished by a file naming convention.
If the request processor finds a file named filename.locale.adp, where locale matches the user's locale, it will process that file instead of filename.adp. For example, for a user with locale tl_PH, the file index.tl_PH.adp, if found, will be used instead of index.adp. The locale-specific file should thus contain text in the language appropriate for that locale. The code in the page, however, should still be in English. Message keys are still processed.
Internationalizing templates is about replacing human readable text in a certain language with internal message keys, which can then be dynamically replaced with real human language in the desired locale. Message keys themselves should be in ASCII English, as should all code. Three different syntaxes are possible for message keys.
"Short" syntax is the recommended syntax and should be used for new development. When internationalizing an existing package, you can use the "temporary" syntax, which the APM can use to auto-generate missing keys and automatically translate to the short syntax. The "verbose" syntax is useful while developing, because it allows default text so that the page is usable before you have done localization.
The short: #package_key.message_key#
The advantage of the short syntax is that it's short. It's as simple as inserting the value of a variable. Example: #forum.title#
The verbose: <trn key="package_key.message_key" locale="locale">default text</trn>
The verbose syntax allows you to specify a default text in a certain language. This syntax is not recommended anymore, but it can be convenient for development, because it still works even if you haven't created the message in the message catalog yet, because what it'll do is create the message key with the default text from the tag as the localized message. Example: <trn key="forum.title" locale="en_US">Title</trn>
The temporary: <#message_key original text#>
This syntax has been designed to make it easy to internationalize existing pages. This is not a syntax that stays in the page. As you'll see later, it'll be replaced with the short syntax by a special feature of the APM. You may leave out the message_key by writing an underscore (_) character instead, in which case a message key will be auto-generated by the APM. Example: <_ Title>
We recommend the short notation for new package development.
In adp files message lookups are typically done with the syntax \#package_key.message_key\#. In Tcl files all message lookups *must* be on either of the following formats:
Translatable texts in page TCL scripts are often found in page titles, context bars, and form labels and options. Many times the texts are enclosed in double quotes. The following is an example of grep commands that can be used on Linux to highlight translatable text in TCL files:
# Find text in double quotes find -iname '*.tcl'|xargs egrep -i '"[a-z]' # Find untranslated text in form labels, options and values find -iname '*.tcl'|xargs egrep -i '\-(options|label|value)'|egrep -v '<#'|egrep -v '\-(value|label|options)[[:space:]]+\$[a-zA-Z_]+[[:space:]]*\\?[[:space:]]*$' # Find text in page titles and context bars find -iname '*.tcl'|xargs egrep -i 'set (title|page_title|context_bar) '|egrep -v '<#' # Find text in error messages find -iname '*.tcl'|xargs egrep -i '(ad_complain|ad_return_error)'|egrep -v '<#'You may mark up translatable text in TCL library files and TCL pages with temporary tags on the <#key text#> syntax. If you have a sentence or paragraph of text with variables and or procedure calls in it you should in most cases try to turn the whole text into one message in the catalog (remember that translators is made easier the longer the phrases to translate are). In those cases, follow these steps:
The variable values in the message are usually fetched with upvar, here is an example from dotlrn:
ad_return_complaint 1 "Error: A [parameter::get -parameter classes_pretty_name] must have <em>no</em>[parameter::get -parameter class_instances_pretty_plural] to be deleted"was replaced by:
set subject [parameter::get -localize -parameter classes_pretty_name] set class_instances [parameter::get -localize -parameter class_instances_pretty_plural] ad_return_complaint 1 [_ dotlrn.class_may_not_be_deleted]This kind of interpolation also works in adp files where adp variable values will be inserted into the message.
Alternatively, you may pass in an array list of the variable values to be interpolated into the message so that our example becomes:
set msg_subst_list [list subject [parameter::get -localize -parameter classes_pretty_name] class_instances [parameter::get -localize -parameter class_instances_pretty_plural]] ad_return_complaint 1 [_ dotlrn.class_may_not_be_deleted $msg_subst_list]When we were done going through the tcl files we ran the following commands to check for mistakes:
# Message tags should usually not be in curly braces since then the message lookup may not be # executed then (you can usually replace curly braces with the list command). Find message tags # in curly braces (should return nothing, or possibly a few lines for inspection) find -iname '*.tcl'|xargs egrep -i '\{.*<#' # Check if you've forgotten space between default key and text in message tags (should return nothing) find -iname '*.tcl'|xargs egrep -i '<#_[^ ]' # Review the list of tcl files with no message lookups for tcl_file in $(find -iname '*.tcl'); do egrep -L '(<#|\[_)' $tcl_file; doneWhen you feel ready you may vist your package in the package manager and run the action "Replace tags with keys and insert into catalog" on the TCL files that you've edited to replace the temporary tags with calls to the message lookup procedure.
This section describes how to check that the set of keys used in message lookups in tcl, adp, and info files and the set of keys in the catalog file are identical. The scripts below assume that message lookups in adp and info files are on the format \#package_key.message_key\#, and that message lookups in tcl files are always is done with one of the valid lookups described above. The script further assumes that you have perl installed and in your path. Run the script like this:
acs-lang/bin/check-catalog.sh package_keywhere package_key is the key of the package that you want to test. If you don't provide the package_key argument then all packages with catalog files will be checked. The script will run its checks primarily on en_US xml catalog files.
Some parameters contain text that need to be localized. In this case, instead of storing the real text in the parameter, you should use message keys using the short notation above, i.e. #package_key.message_key#.
In order to avoid clashes with other uses of the hash character, you need to tell the APM that the parameter value needs to be localized when retrieving it. You do that by saying: parameter::get -localize.
Here are a couple of examples. Say we have the following two parameters, taken directly from the dotlrn package.
| Parameter Name | Parameter Value |
|---|---|
| class_instance_pages_csv | #dotlrn.class_page_home_title#,Simple 2-Column;#dotlrn.class_page_calendar_title#,Simple 1-Column;#dotlrn.class_page_file_storage_title#,Simple 1-Column |
| departments_pretty_name | #departments_pretty_name# |
Then, depending on how we retrieve the value, here's what we get:
| Command used to retrieve Value | Retrieved Value |
|---|---|
| parameter::get -localize -parameter class_instances_pages_csv | Kurs Startseite,Simple 2-Column;Kalender,Simple 1-Column;Dateien,Simple 1-Column |
| parameter::get -localize -parameter departments_pretty_name | Abteilung |
| parameter::get -parameter departments_pretty_name | #departments_pretty_name# |
The value in the rightmost column in the table above is the value returned by an invocation of parameter::get. Note that for localization to happen you must use the -localize flag.
The locale used for the message lookup will be the locale of the current request, i.e. lang::conn::locale or ad_conn locale.
Developers are responsible for creating the keys in the message catalog, which is available at /acs-lang/admin/
Dates and times must be converted when stored in the database, when retrieved from the database, and when displayed. All dates are stored in the database in the server's timezone, which is an APM Parameter set at /acs-lang/admin/set-system-timezone and readable at lang::system::timezone.. When retrieved from the database and displayed, dates and times must be localized to the user's locale.
Get the date in ANSI format from the database (YYYY-MM-DD HH24:MI:SS; the time portion is optional). By convention, we identify dates in ansi format by ending the column name with _ansi. Example:
select to_char(posting_date, 'YYYY-MM-DD HH24:MI:SS') as posting_date_ansi from table
Use the Tcl command lc_time_fmt to format the date in "pretty" format. Several standard formats localize automatically:
%c: Long date and time (Mon November 18, 2002 12:00 AM)
%x: Short date (11/18/02)
%X: Time (12:00 AM)
%q: Long date without weekday (November 18, 2002)
%Q: Long date with weekday (Monday November 18, 2002)
The "q" format strings are OpenACS additions; the rest follow unix standards (see man strftime).
set posting_date_pretty [lc_time_fmt $posting_date_ansi "%q"]
Use the *_pretty version in your ADP page.
To internationalize numbers, use lc_numeric $value, which formats the number using the appropriate decimal point and thousand separator for the locale.
When coding forms, remember to use message keys for each piece of text that is user-visible, including form option labels and button labels.
Acs-lang includes tools to automate some internationalization. From /acs-admin/apm/, select a package and then click on Internationalization, then Convert ADP, Tcl, and SQL files to using the message catalog..
Find datetime in .xql files. Use command line tools to find suspect SQL code:
grep -r "to_char.*H" * grep -r "to_date.*H" *
In SQL statements, replace the format string with the ANSI standard format, YYYY-MM-DD HH24:MI:SS and change the field name to *_ansi so that it cannot be confused with previous, improperly formatting fields. For example,
to_char(timestamp,'MM/DD/YYYY HH:MI:SS') as foo_date_pretty
becomes
to_char(timestamp,'YYYY-MM-DD HH24:MI:SS') as foo_date_ansi
In TCL files where the date fields are used, convert the datetime from local server timezone, which is how it's stored in the database, to the user's timezone for display. Do this with the localizing function lc_time_system_to_conn:
set foo_date_ansi [lc_time_system_to_conn $foo_date_ansi]
When a datetime will be written to the database, first convert it from the user's local time to the server's timezone with lc_time_conn_to_system.
When a datetime field will be displayed, format it using the localizing function lc_time_fmt. lc_time_fmt takes two parameters, datetime and format code. Several format codes are usable for localization; they are placeholders that format dates with the appropriate codes for the user's locale. These codes are: %x, %X, %q, %Q, and %c.
set foo_date_pretty [lc_time_fmt $foo_date_ansi "%x %X"]
User locale is a property of ad_conn, ad_conn locale. The request processor sets this by calling lang::conn::locale, which looks for the following in order of precedence:
Use user preference for this package (stored in ad_locale_user_prefs)
Use system preference for the package (stored in apm_packages)
Use user's general preference (stored in user_preferences)
Use Browser header (Accept-Language HTTP header)
Use system locale (an APM parameter for acs_lang)
default to en_US
For ADP pages, message key lookup occurs in the templating engine. For TCL pages, message key lookup happens with the _ function. In both cases, if the requested locale is not found but a locale which is the default for the language which matches your locale's language is found, then that locale is offered instead.