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Document upload (remote publishing)
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| bet | 5/9 | | Sana | 22.07.2021 | | Hajmi | 34,45 Kb. | | #15603 |
3.1 Document upload (remote publishing)
An important aspect of the BSCW system with respect to current Web technology is the ability to upload documents to the central server where they can then be accessed by others. Direct support for document uploading was originally part of the HTTP protocol (HTTP ÔPUTÕ) but today a variety of methods exist with no standard approach implemented by all Web browsers and servers. The BSCW system supports two of the current methods; MIME multipart as described in IETF RFC 1867 (Nebel and Masinter, 1995) and supported by recent Netscape Web browsers, and HTTP PUT as implemented by HTML editors like America Online AOLpress.
3.1.1 RFC 1867 file uploading
RFC 1867 decribes a format for transmitting the contents of multiple files, plus details such as file names, MIME-types etc., as a single MIME multipart message sent as one HTTP request to a Web server. Web servers must be extended with code to decode the multipart message; some servers provide this as part of the server functionality and CGI solutions are widely available for others. Browser support is also required to allow users to select files for upload from their local machines and to construct the multipart message format.
For users of Web browsers which do support this method of upload such as Netscape Navigator, BSCW supports document upload to a shared workspace with no additional client-side software required. Clicking the Ôadd docÕ button shown in Figure 1 returns a HTML form allowing users to select a document to upload and specify information such as the name to give the document in the workspace. The BSCW server software decodes the transmitted documents independently of the Web server. However, not everyone uses the Netscape browser, and those that do may use older versions that do not support the uploading feature. This method also has a number of other deficiencies including a lack of progress reporting; there is no way to distinguish a server crash from a partially-complete upload.
To address these problems we have built a number of small ÔhelperÕ applications which augment a standard Web browser. These helpers, versions of which run on Macintosh, PC and Unix platforms, also use the MIME multipart method to transmit documents to a BSCW server, but provide a much richer user interface than is possible using HTML. For example, the helper for Windows 95/NT users supports drag and drop of files to the Web browser to upload multiple documents to the currently displayed workspace folder (Figure 2), full integration with the Windows registry for document type identification, and a Ôpercentage doneÕ indicator to give feedback on the status of the upload. Users can also tailor their preferences profile to use this method of uploading rather than the Netscape method, so that clicking on the Ôadd documentÕ button automatically launches the helper applicationÕs multiple file selection dialogue.
3.1.2 HTTP ÔPUTÕ document publishing
The mechanism described above is a general method for uploading documents to a BSCW server. From user feedback following the release of an earlier version of the system to the public domain, we discovered a more specific requirement for ÔpublishingÕ (HTML) documents to a shared workspace. This need arose when a number of user groups perceived BSCW as a tool for the management of a Web site. It is clear that in many organizations maintenance of the Web site is a group rather than an individual activity, and the features provided by BSCW suggested to some that the system might assist with this task. This parallels a clear trend for the development of tools to support Web site construction and management and an increase in the richness and complexity of Web sites in general.
We have therefore extended BSCW with support for document publishing from remote editors like Netscape Composer and America Online AOLpress (Figure 3). Such editors support browsing and downloading HTML/plain text documents from a Web server, WYSIWYG document editing, and publishing back to the server using a HTTP ÔPUTÕ request. Implementations of the PUT method vary across editors and, as with RFC 1867 file uploading described above, servers must be extended with code to handle extracting and storing the new (version of the) document; the protocols as implemented currently provide no support for version management themselves. In addition, current implementations of browser/editors are generally feature-poor with respect to traditional word processors and a number of common problems exist, such as not remembering where an edited document was downloaded from forcing users to re-type the URL location when updating the document.
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