Package com.snowbound.contenthandler.interfaces

Interface VirtualViewerContentHandlerInterface

  • All Known Implementing Classes:
    FileContentHandler, RestfulHttpContentHandler
    public interface VirtualViewerContentHandlerInterface
    The base required interface which defines methods for retrieving and saving document content. Every content handler must implement this interface.

    • Field Detail

      • PERM_HIDDEN

        @Deprecated
static final java.lang.Integer PERM_HIDDEN
        Deprecated.
        Use com.snowbound.common.transport.PermissionLevel.HIDDEN instead.

      • PERM_REDACTION

        @Deprecated
static final java.lang.Integer PERM_REDACTION
        Deprecated.
        Use com.snowbound.common.transport.PermissionLevel.REDACTION instead.

      • PERM_PRINT_WATERMARK

        @Deprecated
static final java.lang.Integer PERM_PRINT_WATERMARK
        Deprecated.
        Use com.snowbound.common.transport.PermissionLevel.PRINT_WATERMARK instead.

      • PERM_VIEW_WATERMARK

        @Deprecated
static final java.lang.Integer PERM_VIEW_WATERMARK
        Deprecated.
        Use com.snowbound.common.transport.PermissionLevel.VIEW_WATERMARK instead.

      • PERM_VIEW

        @Deprecated
static final java.lang.Integer PERM_VIEW
        Deprecated.
        Use com.snowbound.common.transport.PermissionLevel.VIEW instead.

      • PERM_PRINT

        @Deprecated
static final java.lang.Integer PERM_PRINT
        Deprecated.
        Use com.snowbound.common.transport.PermissionLevel.PRINT instead.

      • PERM_CREATE

        @Deprecated
static final java.lang.Integer PERM_CREATE
        Deprecated.
        Use com.snowbound.common.transport.PermissionLevel.CREATE instead.

      • PERM_EDIT

        @Deprecated
static final java.lang.Integer PERM_EDIT
        Deprecated.
        Use com.snowbound.common.transport.PermissionLevel.EDIT instead.

      • PERM_DELETE

        @Deprecated
static final java.lang.Integer PERM_DELETE
        Deprecated.
        Use com.snowbound.common.transport.PermissionLevel.DELETE instead.

    • Method Detail

      • init

        void init​(javax.servlet.ServletConfig config)
   throws VirtualViewerAPIException
        Used to set up each content handler instance before any methods are called.
        Parameters:
        config - The ServletConfig object for the VirtualViewer server. Can be used to retrieve web.xml parameters.
        Throws:
        VirtualViewerAPIException - if content handler throws exception

      • getDocumentContent

        ContentHandlerResult getDocumentContent​(ContentHandlerInput input)
                                 throws VirtualViewerAPIException

        Returns the content for the specified document key. The content is usually returned as a byte array, but it can also be a stream or a File object; it can also be a list of byte arrays, streams, or File objects to represent a document made of multiple parts. (VirtualViewer refers to these parts as "content elements").

        VirtualViewer is entirely agnostic about the source of document content. It can come from the local file system, a remote system, a database, or any other source as long as your content handler can provide data to VirtualViewer in any of its supported forms.

        Another note is that the content handler does not need to be consistent between documents. Any individual document should be returned in the same form each request, but different documents do not need to use the same form. The same content handler can return one document as a byte array, a second as a stream, a third as several components, and yet another in sparse form.

        Single-content element return

        This is the most common use case - a single file represents a single document. This file can be returned as a byte array, InputStream, or File object - although the first two forms are recommended.

         
 // This example retrieves the document content from a specific directory in the local filesystem.
 public ContentHandlerResult getDocumentContent(ContentHandlerInput input)
     throws VirtualViewerAPIException
 {
     String clientInstanceId = input.getClientInstanceId();
     String documentKey = input.getDocumentId();
     String fullFilePath = gFilePath + URLDecoder.decode(documentKey);
     File file = new File(fullFilePath);
     byte[] fileBytes = com.snowbound.common.utils.ClientServerIO.getFileBytes(file);
 
     ContentHandlerResult result = new ContentHandlerResult();
     result.put(ContentHandlerResult.KEY_DOCUMENT_CONTENT, fileBytes);
     return result;
 }
        Compound documents

        Using compound documents, you can make a single VirtualViewer document composed of multiple files of different formats. For example, if you provide a PDF and an image file in that order, VirtualViewer will treat it as one document with the image file as the last page.

        Document modifications, such as rotating or inserting/deleting pages, cannot be done to a compound document without converting it to a single-file document (either a PDF or a TIF, depending on if the first content element was a text or image file).

        To return a compound document, return several content elements in the KEY_DOCUMENT_CONTENT_ELEMENTS parameter. These can be either a byte array, input stream or File and the items in the list do not have to all match. If only one content element is returned it will functionally be the same as a single-content element document described above.

         
 // This example retrieves document content from the local file system and adds the same cover page to every 
 // requested document by returning them as a compound document.
 public ContentHandlerResult getDocumentContent(ContentHandlerInput input)
     throws VirtualViewerAPIException
 {
     String clientInstanceId = input.getClientInstanceId();
     String documentKey = input.getDocumentId();
     List<Object> contentElements = new List<Object>();
 
     //Adding the cover page first will make it the first page(s) of the document
     InputStream coverPage = getCoverPageStream();
     contentElements.put(coverPage);
 
     //Add the file content from the local system next
     String fullFilePath = gFilePath + URLDecoder.decode(documentKey);
     File file = new File(fullFilePath);
     byte[] fileBytes = com.snowbound.common.utils.ClientServerIO.getFileBytes(file);
     contentElements.put(fileBytes);
 
     ContentHandlerResult result = new ContentHandlerResult(); 
     result.put(ContentHandlerResult.KEY_DOCUMENT_CONTENT_ELEMENTS, contentElements);
     return result;
 }
        Sparse documents

        Sparse documents are a special case of compound document. In this case, every content element represents a single page, and each page/content element can be requested and returned in separate chunks as needed. The ideal use case for sparse documents is when a) the document is already split up into single-page files and b) retrieving each page is relatively time-expensive, making retrieving the whole document prohibitive. An example use case could be if a physical document was scanned and converted to a series of large image files, one for each page, and those files were stored on a remote server with a poor connection. Retrieving all of those image files at once may be prohibitive; the document could be represented in sparse form to avoid that cost.

        To implement sparse documents you will need to read the KEY_SPARSE_PAGE_INDEX value from input and return at least that page. The index is zero-based. Several additional pages around that page can also be returned - VirtualViewer will cache each page as it retrieves it, so returning additional pages will help limit future requests from VirtualViewer. VirtualViewer suggests an amount of pages to return with KEY_SPARSE_PAGE_COUNT but the suggestion is not required.

        Note: if KEY_SPARSE_PAGE_INDEX's value is null then all sparse page elements must be returned. This is for operations that require the entire document, such as emailing or printing. All page elements should be returned in the same way as a partial sparse document: using KEY_DOCUMENT_SPARSE_ELEMENTS.

        When returning a sparse document, four values should be returned: the list of sparse content elements, the zero-based page index the returned pages start at, the number of pages being returned, and the total number of pages in the document.

        Note: sparse document content elements do not support the File object. Each content element should be a byte array or input stream.

         
  // This example assumes the existence of a function that returns a single page of the document. To fit the best
  // use case of sparse documents, this function should be relatively expensive, so calling it for each page of 
  // the document is not ideal.
  public ContentHandlerResult getDocumentContent(ContentHandlerInput input)
      throws VirtualViewerAPIException
  {
      String clientInstanceId = input.getClientInstanceId();
      String documentKey = input.getDocumentId();
      Integer requestedPageIndex = input.get(ContentHandlerInput.KEY_SPARSE_PAGE_INDEX);
      List<byte[]> sparseElements = new List<byte[]>();
           
      int documentPageCount = getDocumentPageCount(documentKey);
 
      int startPageIndex = 0;
      int returnPageCount = documentPageCount;
 
      //If KEY_SPARSE_PAGE_INDEX is null, all pages should be returned. If it is set then we will return the requested
      //page and the two next pages.
      if(requestedPageIndex != null) {
          startPageIndex = requestedPageIndex;
          returnPageCount = 3;
 
          //Make sure not to request more pages than the document has
          if(startPageIndex + returnPageCount > documentPageCount) {
              returnPageCount = documentPageCount - startPageIndex;
          }
      }
 
      for(int index = startPageIndex; index < startPageIndex + returnPageCount; index++) {
          byte[] documentPage = getSingleDocumentPage(documentKey, index);
          sparseElements.put(documentPage);
      }
 
      ContentHandlerResult result = new ContentHandlerResult(); 
      result.put(ContentHandlerResult.KEY_DOCUMENT_SPARSE_ELEMENTs, sparseElements);
      result.put(ContentHandlerResult.KEY_DOCUMENT_SPARSE_PAGE_INDEX, startPageIndex);
      result.put(ContentHandlerResult.KEY_DOCUMENT_SPARSE_RETURN_PAGE_COUNT, returnPageCount);
      // For this example we are assuming each document is exactly 10 pages long.
      // In actual code the real length should be returned.
      result.put(ContentHandlerResult.KEY_DOCUMENT_SPARSE_TOTAL_PAGE_COUNT, 10);
      return result;
  }
        Media documents

        VirtualViewer supports video and audio files. Most media files that are supported by modern browsers are supported by VirtualViewer. Not all browsers support the same media types and encodings: see the compatibility chart at https://developer.mozilla.org/en-US/docs/Web/HTML/Supported_media_formats for more details.

        If the media format and specific file support streaming, VirtualViewer will stream the media to the browser. In addition, the media file can be streamed from this method to avoid a long initial delay while loading the full media file from the end content store. To stream from this method, return an InputStream that is progressively loading from the end content store. VirtualViewer will read from and cache the stream's data in the background while streaming the file to the client browser as soon as there is enough data to do so. 

         
  // This is an example of one way to return a progressively-loading InputStream by using Java's basic URL library 
  // to download a video file over HTTP.
 
  InputStream mediaStream = new URL("http://example.com/MyMedia.mp4").openStream();
  // VirtualViewer will continously read data from this stream until the file is downloaded,
  // while also streaming the media to the requesting client browser.
  result.put(ContentHandlerResult.KEY_DOCUMENT_INPUT_STREAM, mediaStream);
  result.put(ContentHandlerResult.KEY_DOCUMENT_DISPLAY_NAME, "My Media");

  // We should not close the stream in getDocumentContent: VirtualViewer will close the stream once it is completed.
  return result;

        Note: VirtualViewer uses a thread pool to read from the document InputStreams that are returned from this function. This thread pool is configurable via the "asyncStreamBuffer" web.xml init-params. It is strongly recommended that you configure this thread pool to fit your needs and system specifications.

        Note: media documents do not support compound documents,multiple content elements or the File content element. Media documents should always be returned as a single byte[] or an InputStream. Media files cannot be included as part of a separate compound document.

        CAD/DWG files - including external references

        VirtualViewer supports external references for CAD/DWG files. The external reference files must be returned as a list of ExternalReference objects.

        Note: This feature is currently only supported when running the VirtualViewer server on Windows.

        Parameters:
        input - ContentHandlerInput containing the following values:
        Every row is an expected value in the ContentHandlerInput. The first column is the string key for the value. The second column is the type of the value. The third column is the detailed description of the value.
        KeyTypeDescription
        KEY_DOCUMENT_ID java.lang.String The key representing the document. Can be retrieved with String documentId = input.getDocumentId(); .
        KEY_CLIENT_INSTANCE_ID java.lang.String Custom configurable value used to pass data from client to content handler. If not set then will be the session ID. Can be retrieved with String clientInstanceId = input.getClientInstanceId();
        KEY_HTTP_SERVLET_REQUEST javax.servlet.http.HttpServletRequest Request that called this method. Can be retrieved with HttpServletRequest request = input.getHttpServletRequest();
        KEY_SPARSE_PAGE_INDEX Integer The specific page index being requested. This parameter is used only for sparse documents. If this parameter is null, the entire document should be returned, even for sparse documents. (For sparse documents this should be in the form of a complete KEY_DOCUMENT_SPARSE_ELEMENTS list). Can be retrieved with int pageIndex = input.getSparseRequestedPageNumber();
        KEY_SPARSE_PAGE_COUNT int Suggested number of pages to return for a sparse document. This does not have to be respected. Can be retrieved with int pageCount = input.getSparseRequestedPageCount();
        Returns:
        ContentHandlerResult with the following values:
        Every row is an expected value in the ContentHandlerResult. The first column is the string key for the value. The second column is the type of the value. The third column is the detailed description of the value.
        KeyTypeDescription
        KEY_DOCUMENT_DISPLAY_NAME String The name VirtualViewer should display for this document. If omitted VirtualViewer will display the document key instead.
        KEY_DOCUMENT_CONTENT byte[] A byte array of the document content. Only one document content return parameter should be set.
        KEY_DOCUMENT_INPUT_STREAM java.io.InputStream An input stream of the document content. Only one document content return parameter should be set.
        KEY_DOCUMENT_FILE java.io.File A File object referencing the document content file. Using KEY_DOCUMENT_CONTENT or KEY_DOCUMENT_INPUT_STREAM is recommended for efficiency. Only one document content return parameter should be set.
        KEY_DOCUMENT_CONTENT_ELEMENTS java.util.List

        A list of content elements - byte arrays, input streams or File objects. They do not have to be in the same form, nor do the original files need to be the same image or document format (a content element list consisting of a JPEG byte array and a PDF input stream is acceptable). VirtualViewer will treat all of the content elements as if they formed one contiguous document.

        If a list containing only one content element is returned, it will behave exactly as the single-content element cases above.

        Only one document content return parameter should be set.
        KEY_DOCUMENT_SPARSE_ELEMENTS java.util.List

        A parameter required for sparse documents. A list of single-page content elements - byte arrays or input streams only. File objects are not supported.

        If one of the content elements is of a format that supports multiple pages, such as PDF, it must be one page. Any pages beyond the first will be ignored by VirtualViewer.

        Only one document content return parameter should be set.
        KEY_DOCUMENT_SPARSE_PAGE_INDEX java.util.List A parameter required for sparse documents. The zero-based page index at which the collection of returned pages start. For example, if page index 5 is requested and you are returning pages 5-8, this should equal 5.
        KEY_DOCUMENT_SPARSE_RETURN_PAGE_COUNT java.util.List A parameter required for sparse documents. The number of pages you are returning with this method. For example, if page index 5 is requested and you are returning pages 5-8, this should return 4.
        KEY_DOCUMENT_SPARSE_TOTAL_PAGE_COUNT java.util.List A parameter required for sparse documents. The total number of pages in the sparse document. This should be the same in each request for a given document. For example, when a 300-page-long document is requested, this should be 300 - regardless of how many pages are being returned for the request.
        KEY_EXTERNAL_REFERENCE_CONTENT_ELEMENTS java.util.List<ExternalReference> A list of external references for CAD/DWG files.
        Throws:
        VirtualViewerAPIException - if content handler throws exception

      • saveDocumentContent

        ContentHandlerResult saveDocumentContent​(ContentHandlerInput input)
                                  throws VirtualViewerAPIException
        This method is used to update document data only.
        Parameters:
        input - ContentHandlerInput containing the following values:
        Every row is an expected value in the ContentHandlerInput. The first column is the string key for the value. The second column is the type of the value. The third column is the detailed description of the value.
        KeyTypeDescription
        KEY_DOCUMENT_CONTENT byte[] The document file content. Can be retrieved with byte[] documentContent= input.getDocumentContent(); .
        KEY_DOCUMENT_ID java.lang.String The key representing the document. Can be retrieved with String documentId = input.getDocumentId(); .
        KEY_CLIENT_INSTANCE_ID java.lang.String Custom configurable value used to pass data from client to content handler. If not set then will be the session ID. Can be retrieved with String clientInstanceId = input.getClientInstanceId();
        KEY_HTTP_SERVLET_REQUEST javax.servlet.http.HttpServletRequest Request that called this method. Can be retrieved with HttpServletRequest request = input.getHttpServletRequest();
        Returns:
        ContentHandlerResult with the following values:
        Every row is an expected value in the ContentHandlerResult. The first column is the string key for the value. The second column is the type of the value. The third column is the detailed description of the value.
        KeyTypeDescription
        DOCUMENT_ID_TO_RELOAD String Optional return used to alert the client that the document key has been changed when saving. This could be used if the content handler decided to create a new document under a new key instead of updating the original document.
        Throws:
        VirtualViewerAPIException - if content handler throws exception

      • saveDocumentComponents

        ContentHandlerResult saveDocumentComponents​(ContentHandlerInput input)
                                     throws VirtualViewerAPIException
        This method is used to save or update an existing document and sub-components of the document, such as annotations, bookmarks, document notes and watermarks. In earlier versions, VirtualViewer would pass null to signal that a component should be deleted. Currently, VirtualViewer will pass null to signal that no change should be made to a component.
        Parameters:
        input - ContentHandlerInput containing the following values:
        Every row is an expected value in the ContentHandlerInput. The first column is the string key for the value. The second column is the type of the value. The third column is the detailed description of the value.
        KeyTypeDescription
        KEY_DOCUMENT_CONTENT byte[] The document file content. If null no changes need to be saved to the document. Can be retrieved with byte[] documentContent= input.getDocumentContent(); .
        KEY_ANNOTATION_LAYERS com.snowbound.common.transport.AnnotationLayer[] All of the annotation layers for the document. Each layer should be updated if it layer.isNew() or isModified() is true. If a layer has been saved but is no longer present in the array it may be deleted; if a layer name is present in KEY_DELETED_ANNOTATION_LAYERS but absent from this list of layers, the layer was deleted by the user. If a layer name is absent from both this list of layers and from KEY_DELETED_ANNOTATION_LAYERS, that may indicate that the user never loaded or viewed the layer during their session. Can be retrieved with AnnotationLayer[] annotationLayers= input.getAnnotationLayers(); .
        KEY_DELETED_ANNOTATION_LAYERS String[] Any annotation layers that were removed during the user's session. This item is present for extra information and validation. If a layer name is present in this array but absent from the list in KEY_ANNOTATION_LAYERS, the layer was deleted by the user. If a layer name is absent from both this array and from KEY_ANNOTATION_LAYERS, that may indicate that the user never loaded or viewed the layer during their session. Can be retrieved with String[] layersDeletedInSession = input.getDeletedAnnotationLayers(); .
        KEY_BOOKMARK_CONTENT byte[] The bookmark file content. If null no changes need to be saved to the bookmark file. Can be retrieved with byte[] bookmarkContent= input.getBookmarkContent(); .
        KEY_NOTES_CONTENT byte[] The notes file content. If null no changes need to be saved to the notes file. Can be retrieved with byte[] notesContent = input.getNotesContent(); .
        KEY_WATERMARK_CONTENT byte[] The watermark file content. If null no changes need to be saved to the watermark file. Can be retrieved with byte[] watermarkContent = input.getWatermarkContent(); .
        KEY_PAGE_COUNT int The number of pages in the document. Can be retrieved with int pageCount = input.getDocumentPageCount(); .
        KEY_DOCUMENT_FORMAT int An integer code representing the document format. Can be retrieved along with a format information object with the following code: 
        
int formatCode = input.getDocumentFormat();
Format format = VirtualViewerFormatHash.getInstance().getFormat(outputFormat);
        KEY_DOCUMENT_ID java.lang.String The key representing the document. Can be retrieved with String documentId = input.getDocumentId(); .
        KEY_CLIENT_INSTANCE_ID java.lang.String Custom configurable value used to pass data from client to content handler. If not set then will be the session ID. Can be retrieved with String clientInstanceId = input.getClientInstanceId();
        KEY_HTTP_SERVLET_REQUEST javax.servlet.http.HttpServletRequest Request that called this method. Can be retrieved with HttpServletRequest request = input.getHttpServletRequest();
        Returns:
        ContentHandlerResult with the following values:
        Every row is an expected value in the ContentHandlerResult. The first column is the string key for the value. The second column is the type of the value. The third column is the detailed description of the value.
        KeyTypeDescription
        DOCUMENT_ID_TO_RELOAD String Optional return used to alert the client that the document key has been changed when saving. This could be used if the content handler decided to create a new document under a new key instead of updating the original document.
        Throws:
        VirtualViewerAPIException - if content handler throws exception

      • saveDocumentComponentsAs

        ContentHandlerResult saveDocumentComponentsAs​(ContentHandlerInput input)
                                       throws VirtualViewerAPIException
        This method is used to save a copy of a document under a new key, along with sub-components of the document, such as annotations, bookmarks, document notes and watermarks.
        Parameters:
        input - ContentHandlerInput containing the following values:
        Every row is an expected value in the ContentHandlerInput. The first column is the string key for the value. The second column is the type of the value. The third column is the detailed description of the value.
        KeyTypeDescription
        KEY_DOCUMENT_CONTENT byte[] The document file content. If null no changes need to be saved to the document. Can be retrieved with byte[] documentContent= input.getDocumentContent(); .
        KEY_ANNOTATION_LAYERS com.snowbound.common.transport.AnnotationLayer[] All of the annotation layers for the document. If not null all layers should be saved for the new document. Can be retrieved with AnnotationLayer[] annotationLayers= input.getAnnotationLayers(); .
        KEY_BOOKMARK_CONTENT byte[] The bookmark file content. If null no bookmark file need be saved. Can be retrieved with byte[] bookmarkContent= input.getBookmarkContent(); .
        KEY_NOTES_CONTENT byte[] The notes file content. If null no notes file need be saved. Can be retrieved with byte[] notesContent = input.getNotesContent(); .
        KEY_WATERMARK_CONTENT byte[] The watermark file content. If null no watermark file need be saved. Can be retrieved with byte[] watermarkContent = input.getWatermarkContent(); .
        KEY_PAGE_COUNT int The number of pages in the document. Can be retrieved with int pageCount = input.getDocumentPageCount(); .
        KEY_DOCUMENT_FORMAT int An integer code representing the document format. Can be retrieved along with a format information object with the following code: 
        
int formatCode = input.getDocumentFormat();
Format format = VirtualViewerFormatHash.getInstance().getFormat(outputFormat);
        KEY_DOCUMENT_ID java.lang.String A temporary key based on the original document's display name. Can be retrieved with String documentId = input.getDocumentId(); .
        KEY_CLIENT_INSTANCE_ID java.lang.String Custom configurable value used to pass data from client to content handler. If not set then will be the session ID. Can be retrieved with String clientInstanceId = input.getClientInstanceId();
        KEY_HTTP_SERVLET_REQUEST javax.servlet.http.HttpServletRequest Request that called this method. Can be retrieved with HttpServletRequest request = input.getHttpServletRequest();
        Returns:
        ContentHandlerResult with the following values:
        Every row is an expected value in the ContentHandlerResult. The first column is the string key for the value. The second column is the type of the value. The third column is the detailed description of the value.
        KeyTypeDescription
        DOCUMENT_ID_TO_RELOAD String Optional return used to alert the client that the document key has been changed when saving. VirtualViewer will send a temporary document key in the input based on the original document's display name, but if that is being changed then this return value should be set.
        Throws:
        VirtualViewerAPIException - if content handler throws exception