The most fundamental component of the WASD VMS Hypertext Services
environment is the HTTPd, or HyperText Protocol Transport
Daemon, or HTTP server. It has a single-process, multi-threaded, asynchronous
I/O design.
2.1 - Server Features
The package provides a complete implementation of a basic HTTP/1.0 server, including:
The HTTPd executes permanently on the server host, listening for client connection requests on TCP/IP port 80 (by default). It provides concurrent services for a (technically) unlimitted number of clients (constrained only by the server resources). When a client connects the server performs the following tasks:
For I/O intensive activities like file transfer and directory listing, the AST-driven code provides an efficient, multi-threaded environment for the concurrent serving of multiple clients.
For scripts, the technique of using multi-threaded, concurrent, spawned
subprocesses or network processes, attached to standard input/output streams,
provides a versatile, extensible, powerful scripting environment. Any DCL
procedure or image executing within the process can behave essentially as an
HTTP server. This capability is employed to easily extend the basic services
provided by the core daemon code. An HTTP script/server for this environment
does not need to concern itself with network activities, it merely reads and
writes from the standard I/O streams.
2.3 - TCP/IP Packages
The WASD server supports Digital TCP/IP Services (UCX) with a native image.
The "UCX" version is also known to work under TCPware v5.n (UCX compatibility emulation) from Process Software Corporation.
Using the excellent freeware NETLIB package from MadGoat Software (Matthew Madison), this server can also (potentially) support
NETLIB requires VAX/VMS v5.2 or later, or OpenVMS Alpha v1.5 or later.
NETLIB must be obtained and installed separately. This is not a difficult undertaking for there is a familiar VMSINSTAL-driven installation and configuration.
The WASD NETLIB support was developed using v2.1, which may be obtained from
http://www.madgoat.com/netlib.html
NETLIB support within the WASD server is tested in-house using the
Digital TCP/IP Services package. Other TCP/IP packages may or may not perform
as tested.
2.4 - International Features
As of version 4.4 the HTTP server has undergone a limited degree of internationalization. The impetus for this development was the use of the package in some European countries where English is not the first language.
As this was not within the original critera while building the server it
has meant an extensive rewrite of some functionality within the code (I hope
it's appreciated ;^) The objective is to provide users of the server with a
more familiar and therefore more comfortable environment. Unfortunately the
server administrators are still confronted by an English-language interface
and documentation, but then the package doesn't pretend to be
international software!
Aspects
The international features only apply to the server, not to scripts!
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 7 - Message 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.
Mapping rules map requested URL paths to physical or other paths (see 8 - Mapping Rules). 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 example, requests originating with a language preference of "en, fr" from ".au" can receive an English version, whilst requests prefering "de, se, en" from ".de" and ".se" receive German and Swedish versions respectively.
For conditional mapping information see 8.5 - Conditional Mapping.
This section describes WASD-specific characteristics of the available
HTTP/1.0 request methods.
2.5.1 - GET
Of course, the GET method is used to access documents supplied by the
server. There is nothing WASD server-specific about this method.
2.5.2 - POST & PUT
The WASD HTTPd does not differentiate between POST and PUT methods, both
are handled identically.
Script Handling
The "normal" usage of the POST method is to return data from a <FORM>..</FORM> construct to a script running on the server. In this regard WASD is no different to other any web server; the form data is delivered to the script's standard input as a stream of URL-encoded text. For example:
name=Fred+Nurk&address=Fred%27s+House%0D%0A0+Nowhere+Lane&submit=Submit
Note that WWW_CONTENT_LENGTH will be the length of the form data. See
12 - Scripting for further information.
File Creation/Upload
If the client sends data back to the server using either the POST or the PUT methods, without a script being mapped to be executed in response to that data, the WASD HTTPd will create a file corresponding to the specified path. The data stream may be text or binary.
Of course, for the server to accept POST and PUT data in this manner, authentication and authorization must be enabled and allow such access to the request path.
The data stream is processed according to MIME content-type:
The server specially processes "application/x-www-form-urlencoded" POSTS (i.e. those generated by <FORM>...</FORM>, allowing files to be created directly from HTML forms. The processing eliminates any field names from the URL-encoded data stream, placing only field values into the file. This capability can be quite useful and is demonstrated in the Update HTTPd module (UPD.C).
This server can process a request body according to RFC-1867, "Form-based File Upload in HTML". As yet it is not a full implementation. It will not process "multipart/mixed" subsections. The implementation is basic, providing a facility to allow the upload of a file into the server administered file system. The ACTION= parameter of the <FORM> tag must specify the directory (as a URL path) in which the uploaded file will be created.
The following example HTML illustrates how a form may be used to upload a file from the browser host file system:
<FORM METHOD=POST ACTION="/web/directory/" ENCTYPE="multipart/form-data"> <INPUT TYPE=submit VALUE=" Upload document ... "> <INPUT TYPE=file SIZE=50 NAME=uploadfile> </FORM>
Again, the Update module (UPD.C) illustrates the use of this facility.
NOTE: This capability has only been tested against Netscape Navigator versions 2 and 3. VMS Netscape Navigator 3.0b5 hangs if an upload of a variable-record format file is attempted. Stick to STREAM-LF or fixed, or convert the file to STREAM-LF.
Text file created according to the path, VMS record type is STREAM-LF.
Any other MIME type is considered binary and the created file is made an UNDEFINED record type.
A directory will be created by the HTTPd if a directory path is provided with the POST or PUT methods. For example:
/dir1/dir2/dir-to-be-created/
A file will be deleted by the HTTPd if the file path ending with a wildard version specification is provided with the POST or PUT methods. For example:
/dir1/dir2/file-to-be.deleted;*
A directory will be deleted by the HTTPd if a directory path ending with a wildard version specification is provided with the POST or PUT methods. For example:
/dir1/dir2/dir-to-be-deleted/;*
The DELETE method should delete the file or directory corresponding to the supplied path.