| 2.1Server Behaviour |
| 2.2VMS Versions |
| 2.3TCP/IP Packages |
| 2.4International Features |
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The most fundamental component of the WASD VMS Web Services environment is the HTTP server (HyperText Transport Protocol Daemon, or HTTPd). WASD has a single-process, multi-threaded, asynchronous I/O design.
The following bullet-points summarise the features and facilities, many of which are described in significant detail in following chapters.
The technical aspects of server design and behaviour are described in WASD_ROOT:[SRC.HTTPD]READMORE.TXT
The WASD server is supported on any VMS version from V7.0 upwards, on Alpha, Itanium and VAX architectures. The current version (as of 2019), V8.4 Alpha and Itanium, as is commonly the case on VMS platforms, required nothing more than relinking. Obviously no guarantees can be made for yet-to-be-released versions but at a worst-case these should only require the same.
Up until v10.1 WASD was supported on VMS V6.0 and later. Eventually it had to be dragged kicking and screaming into the mid-1990s!
The WASD distribution and package organisation fully supports mixed-architecture clusters (Alpha, Itanium and/or VAX in the one cluster) as one integrated installation.
The WASD server uses the TCP/IP Services (UCX) BG $QIO interface. The following packages support this interface and may be used.
To deploy IPv6 services this package must support IPv6.
WASD provides a number of features that assist in the support of non-English and multi-language sites. These "international" features only apply to the server, not necessarily to any scripts!
A directory may contain language-specific variants of a basic document. When requesting the basic document name these variants are automatically and transparently provided as the response if one matches preferences expresses in the request's "Accept-Language:" request header field. Both text and non-text documents (e.g. images) may be provided using this mechanism.
Configuration information is provided in section Language Variants of WASD Configuration.
Generally the default character set for documents on the Web is ISO-8859-1 (Latin-1). The server allows the specification of any character set as a default for text document responses (plain and HTML). In addition, text document file types may be modified or additional ones specified that have a different character set associated with that type. Furthermore, specific character sets may be associated with mapping paths. A site can therefore relatively easily support multiple character set document resources.
In addition the server may be configured to dynamically convert one character set to another during request processing. This is supported using the VMS standard NCS character set conversion library.
For further information see [CharsetDefault], [CharsetConvert] and [AddType] in Alphabetic Listing of WASD Configuration.
The server uses an administrator-customizable database of messages that can contain multiple language instances of some or all messages, using the Latin-1 character set (ISO8859-1). Although the base English messages can be completely changed and/or translated to provide any message text required or desired, a more convenient approach is to supplement this base set with a language-specific one.
One language is designated the prefered language. This would most commonly be the language appropriate to the geographical location and/or clientele of the server. Another language is designated the base language. This must have a complete set of messages and is a fall-back for any messages not configured for the additional language. Of course this base language would most commonly be the original English version.
More than just two languages can be supported. If the browser has prefered languages set the server will attempt to match a message with a language in this preference list. If not, then the server-prefered and then the base language message would be issued, in that order. In this way it would be possible to simultaneously provide for English, French, German and Swedish audiences, just for example.
For message configuration information see Message Configuration of WASD Configuration.
Dates appearing in server-generated, non-administrative content (e.g. directory listings, not META-tags, which use Web-standard time formats) will use the natural language specified by any SYS$LANGUAGE environment in use on the system or specifically created for the server.
Virtual-server-associated mapping, authorization and character-sets allow for easy multiple language and environment sites. Further per-request tailoring may be deployed using conditional rule mapping described below. Single server can support multi-homed (host name) and multiple port services.
For virtual services information see Configuration Considerations of WASD Configuration.
Mapping rules map requested URL paths to physical or other paths (see Request Processing Configuration of WASD Configuration). Conditional rules are only applied if the request matches criteria such as prefered language, host address (hence geographical location to a certain extent), etc. This allows requests for generic documents (e.g. home pages) to be mapped to language versions appropriate to the above criteria.
For conditional mapping information see Conditional Configuration of WASD Configuration.
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