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    5.3 - Retrieving Full-text Articles

    Documents are available from the ADS article server in different formats and at different resolutions to accomodate our users' needs. The high resolution documents (600 dpi) are considerably slower to print than the low resolution versions (200 dpi), but will give superior results, especially on plots and plates. In addition, the high resolution files are larger than the corresponding low resolution ones, and some display programs or printers may not have a large enough spooling area or physical memory to handle them. In order to decide which version of the article you should select for viewing and printing, you need to take into account the capabilities of your system and the network bandwidth available to you.

    The Printing Options are located at the bottom of the scanned article page. If your browser works with HTTP persistent cookies, a single printing option will be displayed, with a selection to print either the whole paper or individual pages. Clicking on this print button will return the article in the format that the user has specified in the article service user preferences. If the browser does not handle cookies, several of the more commonly used print options are made available here.

    All possible printing options can be accessed through the next link called "More Article Retrieval Options" (see for example this link ). This page allows the user to select among all available document formats and retrieval options.



    5.3.1 - Document Formats

    The two most popular formats available for downloading full-text articles from the ADS are:

    • Postscript: Postscript level 2 files can be printed on any modern postscript printer, or displayed by a postscript viewer such as Ghostview or GSview. For compatibility with older printers, there is also an option to retrieve a low-resolution version of the document in Postscript Level 1 format, but please avoid this format if at all possible, since these files are very large and often require large resources of printer memory and spooling space to successfully print.

      The PostScript page description language was also developed by Adobe Systems, and can be considered a precursor to PDF in many respects. The advantage that Postscript files have over PDF is that most department-size printers today are capable of printing postscript files quite efficiently, so there is no need for an external viewer or printer drivers when hardcopy output is desired. These files should successfully print on any of the modern printers supporting the Adobe PostScript level 2 language features, but some problems have been observed with print engines that don't use the Adobe PostScript interpreter. Postscript level 2 supports the same compression schemes that are used in PDF files, but since it requires ASCII rather than binary encoding of the image data, these files are approximately 20% bigger than their corresponding PDF files.

    • PDF (Portable Document Format): PDF can be viewed using freely available applications such as Adobe Acrobat Reader, GSview, or Ghostview. The document can then be printed using the "Print" menu from any of the above applications. Because of the advanced compression schemes and binary support built into PDF, documents in this format will yield the highest compression.

    Please note: if you use Adobe Acrobat Reader on a UNIX machine to view your PDF files and your printer supports PostScript level 2 (most modern printers do), then you should make sure that you select the following Postscript options in Acrobat's printing menu (which pops up when you click on the "Print" button):

    • Download Fonts Once
    • Use Printer's Halftone Screen
    • Level 2 only

    When in doubt about Postscript level 2 support for your printer, please ask your system administrator or just try and print to see if the file makes it through the printer. Enabling this feature when printing ADS articles can reduce the file size by an order of magnitude or more.

    Two other formats for full-text documents are currently available, although we strongly reccommend avoiding them if at all possible:

    • PCL (Printer Control Language): This printer language is used by printers such as HP deskjets and compatibles. Printing documents in this format may actually be difficult since you need to make sure that the entire document is sent to the printer device as a binary file, bypassing any formatting that the driver may want to perform. Also, the maximum resolution provided for PCL files is 300dpi, so you won't get the same sharpness that you would get from printing a high-resolution Postscript or PDF file.

    • TIFF (Tagged Image File Format): The original TIFF images can be retrieved for local processing or display. This format may be appropriate to further process a scanned page image in order to extract sub-images or to perform Optical Character Recognition (OCR) on it. Please note that only single-page TIFF documents are returned by our system.



    5.3.2 - Retrieval Options

    The retrieval options described below are available from both the article service preferences and from the "More Article Retrieval Options" page found at the bottom of a scanned page. The first set of options control the destination of the full text document. The possible choices are:

    • Send data to viewer: the full-text article will be sent back directly to the browser which will delegate the display to the appropriate program. For instance, a PDF file will be handed off to the PDF viewer available on the local system (usually Acrobat Reader).

    • Send data direct to printer: the full-text article will be sent back with a signature indicating that it is destined for printing (see section below "Automatic Printing of Articles" for more information). If the browser has been configured to properly handle this media type, the article will be sent directly to the printer, otherwise the user will be prompted for what should be done with the document.

    • Save file on local disk: the browser will prompt the user for a filename to save the document to.

    Other retrieval options are:

    • Email: articles can be retrieved through email instead of through a WWW browser. If this option is selected, the document will be sent to the specified email address as a MIME (Multipurpose Internet Mail Extension) document. MIME-aware email systems should be able to send the retrieved images directly to the printer, to a file, or to a viewer, depending on what destination option was selected by the user.

    • Compression: for most of the retrieval options, the data can optionally be compressed before they are sent to the user. Unix compress and GNU gzip are the supported compression algorithms.

    Please note that the high resolution version of an article may be considerably slower to print than the low resolution version but will give superior results, especially on plots and plates. In additon, the high resolution files are larger than the corresponding low resolution pages, and some printers may not have a large enough spooling area or physical memory required during the printing process.



    5.3.3 - Advanced Features

    If you find yourself retrieving, viewing and printing full-text documents from the ADS all the time, you may consider setting up your browser so that downloading an article and saving it to disk or printing it take place automatically and efficiently.

    5.3.3.1 - Enabling Document Compression

    To make efficient use of disk space and network bandwidth, we give our users the option to retrieve articles in a compressed format. The two compression schemes supported are UNIX compress and the superior GNU gzip format. Well-behaved browsers will recognize the compressed data stream (without confusing it with the content-type of the data being transmitted) and will uncompress it before launching the appropriate helper application.

    Unfortunately, many MS-Windows based Web browsers (including Netscape Navigator 3.x and Microsoft Explorer 3.x) ignore the compression information when retrieving these files, requiring the user to uncompress the files by hand before launching a viewer or printing them. Recent versions of both browsers are rumored to have fixed this problem. In case you are still plagued by this problem, you may want to consider installing GSview as your Postscript and PDF viewer.

    Please note that all the full-text documents retrieved from our site are already internally compressed, so further compression of the data with an application such as gzip usually only yields a marginal decrease in file size. For PDF and Postscript level 2 files we typically see an reduction in size of 5-6%.

    5.3.3.2 - Automatic Printing of Articles

    In order to automatically print a full-text document you will need to make sure that the article destination specified in article service preferences is set to "Send data direct to printer" (or that you select that option by hand when using the "More Article Retrieval Options" form).

    Next you should configure your browser to map the MIME type of the data returned by our server to the local printing program on your system. This sounds more complicated than it really is: most browsers (including Netscape Navigator and MicroSoft Internet Explorer ) provide menus that allow the user to define the application to be run for each given MIME type. For Netscape 4.x, the menu is available under "Edit" -> "Preferences" -> "Navigator" -> "Applications." Once you have found the proper menu for your browser you can create (or modify) the following entry for the MIME content type application/remote-printing:

        Description:    Remote Printing
        MIME Type:      application/remote-printing
        File extension: .prn
        Application:    (select "Save to File" or enter OS-specific application)
    
    
    Selecting the Save to file option in the menu above will cause all article documents dowloaded from our site to be saved to disk first. You can then view them or print them using the appropriate program depending on the document format as explained in the section "Document Formats" above. Alternatively, you may choose to have a helper application execute automatically when a document of this MIME type is downloaded. In this case, you should select Application from the above menu and then fill in the proper command depending on the computer platform you are using. This command typically is a procedure that feeds the data downloaded from our server to your local printing command, and in general depends on the operating system of your computer. Some examples of popular operating systems and relative printing applications are:

    • System V-based UNIX systems (e.g. Solaris):
          lp -c %s
      
      
    • BSD-based UNIX (e.g. Linux):
          lpr %s
      
      
    • Microsoft Windows (9x, 2K, NT): download and install one of the shareware printing packages gsprint or prfile and then use this entry in as your helper application:
          gsprint %s    (or prfile32 %s)
      
      
      
      
    5.3.4 - Troubleshooting

    If you are having trouble printing articles, please make sure you have checked the following:

    • If you have downloaded an article into a file and can't decipher what kind of data is contained in it, it is probably a gzipped postscript or PDF file, but gunzip or winzip won't uncompress it unless the file name extension is .gz. Try renaming the file to whatever.gz, then uncompress it, and then view/print the resulting file.

    • If Acrobat Reader complains about a PDF file being corrupted, it may be that the file did not download completely because of lack of local disk space or a timeout from the server. In the first case, please check and make sure you do have enough local disk space to handle full-text articles. In the second case, please attempt to download smaller documents by selecting only a small range of pages at a time for download.

    • If you have just changed your article preference settings but your changes don't seem to have had any effect on the full-text articles, you probably need to force a reload of the pages in the web browser in order for it to pick up the new settings. This can be done by clicking on SHIFT + ``Reload (Netscape) or ``Refresh (Internet Explorer).

    You may also want to read our Frequently Asked Questions.



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