Patent Publication Number: US-8984397-B2

Title: Architecture for arbitrary extensible markup language processing engine

Description:
BACKGROUND 
     Encoding documents for digital printing is conventionally done in a document or image processing device that is typically separate from the printing device. The processing device may be a personal computer or other document/image processing/generation device. The processing device, typically, has a generic print driver application that encodes and sends documents for reproduction by a particular printer connected thereto, through a communication channel or network. 
     The generation of standard document types is a growing trend. Such standards have been greatly encouraged and facilitated by the use of the standard extensible markup language. However, the reproduction of standard extensible markup language is not an easy task as the standard extensible markup language has been, conventionally, converted by the user into some type of format that is readily acceptable to a printing device. 
     Moreover, most conventional extensible markup language processing systems have been designed to handle specific processing with respect to specific extensible markup language vocabularies. Although a few conventional extensible markup language platforms have been created for the development of different processing sequences in support of different vocabularies and workflows, these conventional platforms are still fixed and static. 
     Thus, it is desirable to provide an extensible markup language processing system that can efficiently print any submitted arbitrary sequence of extensible markup language vocabularies. Moreover, it is desirable to provide an extensible markup language processing system that can efficiently perform the diverse processing that submitted arbitrary sequence of extensible markup language vocabularies may require. 
     A processing system includes an extensible markup language processing engine and a workflow selection engine. The workflow selection engine receives workflow specifications and document fragments to be processed and outputs workflow specifications and document fragments to the extensible markup language processing engine. The extensible markup language processing engine produces a new workflow specification and a modified document fragment. The extensible markup language processing engine outputs the new workflow specification and modified document fragment to the workflow selection engine. 
     A workflow selection engine for an extensible markup language processing system includes an initial fragment generator to break the initial document up into document fragments and workflow specifications; a workflow specification pool operatively connected to the initial fragment generator; a document fragment pool operatively connected to the initial fragment generator; a workflow selector, operatively connected to the workflow specification pool and the document fragment pool, to determine whether resources required to support extensible markup language processing are available; and a processed fragment and workflow separator operatively connected to the workflow specification pool and the document fragment pool, to separate extensible markup language process data into processed fragments and workflow specifications. The workflow selector outputs appropriate document fragments and workflow specifications to an extensible markup language processing engine. 
     A method for an extensible markup language processing breaks up an initial document into document fragments and workflow specifications; pools workflow specifications; pools document fragments; determines whether resources required to support extensible markup language processing are available; processes a document fragment in accordance with an associated workflow specification to produce a new workflow specification and modified document fragment; processes a document fragment in accordance with an associated workflow specification to produce a modified document fragment; processes appropriate modified document fragments and associated new workflow specifications; and outputs appropriate modified document fragments as a final document. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The drawings are only for purposes of illustrating an embodiment and is not to be construed as limiting, wherein: 
         FIG. 1  illustrates the architecture of a device with an embedded extensible markup language processor; 
         FIG. 2  illustrates a block diagram of an extensible markup language processing system; and 
         FIG. 3  illustrates a block diagram of another example of a workflow selection engine for an extensible markup language processor. 
     
    
    
     DETAILED DESCRIPTION 
     For a general understanding, reference is made to the drawings. In the drawings, like references have been used throughout to designate identical or equivalent elements. It is also noted that the drawings may not have been drawn to scale and that certain regions have been purposely drawn disproportionately so that the features and concepts could be properly illustrated. 
       FIG. 1  illustrates an overall system architecture that includes a print engine  55 , a user interface  50 , a memory  204 , a network interface  205 , a controller  206 , an extensible markup language processor  300 , and a bus  207 . 
     The print engine  55  converts digital signals representing an image into a hardcopy of that image on a recording medium. A central bus  207  provides interconnections and intercommunications between the various modules and devices connected thereto. A memory  204  store a variety of information such as machine fault information, machine history information, images to be processed at a later time, instruction sets for the machine, job instruction sets, etc. 
     The user interface  50  allows the user to select the various functions of the digital printing device, program various job attributes for the particularly selected function, provide other input to the digital printing device, as well as, display informational data from the digital printing device. The controller  206  controls all the functions within the digital printing device so as to coordinate all the interactions between the various modules and devices. 
     The extensible markup language processor  300  receives extensible markup language data and converts this data into a page description language, rasterized image or other form, which can readily utilized by the controller  206  and print engine  55  to generate the appropriate document or image for printing or for display or for archival and storage. The details of this process will be explained in more detail below. 
     The following descriptions will useful in understanding the operations of the extensible markup language processor. 
     Extensible markup language is a conventional standards-based way of organizing data and metadata in the same document. More specifically, extensible markup language is not a fixed format, but rather a meta language that enables the design of customized markup languages for different types of documents. Extensible markup language is a markup language because every structural element is marked by a start tag and an end tag giving the name of the element. In other words, the metadata of the extensible markup language is enclosed within tags. With respect to the input stream of the document, a tag may be delimited by the symbols “&lt;” and “&gt;”. In one implementation, extensible markup language can be used as the format for receiving input data and metadata. 
     An extensible markup language vocabulary is a collection of extensible markup language tags (element and attribute names) intended to be used together as a single markup language. An extensible stylesheet language transform is a set of rules for transforming a source extensible markup language document into a result extensible markup language document, using the syntax defined in extensible stylesheet language transformations. Extensible stylesheet language transformations are often used to insert styling instructions into an extensible markup language document or to convert the extensible markup language document into an extensible markup language vocabulary designed for formatting. 
     An extensible stylesheet language transform imparts style to the data and can also be a general tree transformation language. Moreover, an extensible markup language schema is the formal definition of an extensible markup language vocabulary. 
     An extensible stylesheet language transform is can be used for expressing a mapping of metadata tags and print format instructions. 
     Since an extensible stylesheet language transform and an extensible markup language schema are text based documents, the extensible stylesheet language transform and extensible markup language schema can be easily stored in a memory. Although extensible stylesheet language transforms can be written that work well in the absence of an extensible markup language schema, more expressive mappings can be written in an extensible stylesheet language transform if an extensible markup language schema for the input document is supplied. 
     The extensible stylesheet language is an extensible markup language vocabulary for specifying formatting semantics and language transformations. 
     As noted above, extensible markup language processing systems have been designed to handle specific processing on specific extensible markup language vocabularies and workflows. Vocabularies are developed for specific problems and needs. The workflows to handle those problems are generally fixed such that each extensible markup language file undergoes the same processing steps. 
     Conventional extensible markup language processing systems have also been designed for the development of different processing sequences in support of different vocabularies and workflows. However, these extensible markup language processing systems are still fixed and static. 
     More specifically, these extensible markup language processing systems assemble pipelines of processing steps so that the system has a variety of processing steps from which to choose. However, notwithstanding the variety, the extensible markup language process is defined by a fixed sequence of steps. Extensible markup language files can be processed through the pipeline, but the pipeline is not dynamic or reconfigurable. Further, if any step in the pipeline stalls (e.g. while waiting on data retrieval) all of the processing is temporarily halted. 
     Thus, it is desirable to provide an extensible markup language processing system that is able to efficiently print any arbitrary sequence of extensible markup language vocabularies that are submitted. More specifically, it is desirable to provide an extensible markup language processing system that is able to provide a printing component that can support any workflow as well as arbitrary submissions. 
     Extensible markup language files differ from traditional page description language files in the degree of document completion. While some vocabularies (such as scalable vector graphics) may be laid out and ready for printing, other vocabularies require more processing before printing can be attempted. The processing can include retrieval of information and insertion of files, conducting database queries, performing transformations, styling, formatting, and layout. Different vocabularies and even different jobs using the same vocabulary can require different processing specifications. 
       FIG. 2  illustrates a system and architecture for extensible markup language document processing engine  300  that addresses the various problems discussed above. The extensible markup language document processing engine  300  is suitable for parallel processing of dynamically determined workflows. 
     As illustrated in  FIG. 2 , the extensible markup language document processing system  300  receives two basic data element types  420 , a document fragment and a workflow specification. There are many options for how these two data elements are implemented 
     For example, in an object oriented implementation, document fragment objects and workflow specification objects could be defined. Alternatively, in another system, a document fragment could be defined as a uniform resource locator, and the processing in a workflow specification might be defined as the selection of a predefined pipeline. Another option might be to represent document fragments as files and workflow specifications as scripts. Each workflow specification has a corresponding document fragment. It is noted that a document fragment and its workflow specification might be combined into a single object. 
     A document fragment&#39;s workflow specification describes the processing that should be carried out on that document fragment. The conventional extensible markup language document processing system typically results in one or more new or revised document fragments. However, the extensible markup language document processing engine  300  differs from the conventional systems in that the extensible markup language document processing engine  300  also generates new workflow specifications. 
     The extensible markup language document processing system  300  deciphers the workflow specification in the workflow selection engine  310 . The extensible markup language document processing system  300  also performs the processing on a document fragment in the extensible markup language engine  320 . The extensible markup language engine  320  receives workflow specifications and document fragments to be processed  410 . Upon receiving this data, extensible markup language engine  320  decides which pipeline is specified for the document fragment and runs that document fragment through the pipeline. However, as noted above, in this architecture, the pipelines of the extensible markup language engine  320  produce new workflow specifications as well as modified fragments  400 . 
     The results  400  of the processing operations of the extensible markup language engine  320  are fed back to the workflow selection engine  310 . The workflow selection engine  310  determines if the received results  400  are a final output  430  or require further processing  410 . 
     A workflow specification may indicate processing that requires or integrates additional information beyond the fragment itself. For example, the workflow specification might require the insertion of data from a file or other fragment. Also, the workflow specification might transform the fragment using an additional style sheet or validate the fragment using an additional schema. The workflow specification might include a list of the required resources. 
     Moreover, a workflow specification may indicate processing that produces more than one fragment-workflow specification pair as its result. For example, the workflow specification might subdivide the fragment into smaller fragments. In that case, the process would result in a set of sub-fragments, each sub-fragment having a workflow specification, and, optionally, a fragment that references the set of sub-fragments and a workflow specification that reintegrates the processed sub-fragments. 
     The extensible markup language document processing engine  300  also determines, configures, and performs diverse processing which various jobs may require. In addition, the extensible markup language document processing engine  300  can separate the processing into multiple independent threads, where appropriate, so that if one thread is blocked or delayed, processing can still continue on other threads. 
     As noted before, the workflow specification indicates the processing to be done on a document fragment. However, processing, from time to time, may involve requiring the use of additional information or resources, as illustrated in  FIG. 2 . In these instances, the workflow specification may list the resources. This is particularly desirable when the resources are other processed document fragments. The information involving the use of additional information or resources is used by a workflow selection engine. 
     An example of a workflow selection engine is illustrated in  FIG. 3 . As illustrated in  FIG. 3 , an initial document  420  is received by an initial fragment generator  3120  which breaks the initial document  420  up into document fragments and workflow specifications. It is noted often the document will be handled as a single fragment and workflow. 
     The initial fragment generator  3120  send the workflow specifications to a workflow specification pool  3130  and sends the document fragments to a document fragment pool  3140 . A workflow selector  3150  examines the workflow specifications to determine whether the resources required to support the processing are available to process the initial document  420 . 
     For example, if the workflow specification indicates the aggregation of previously processed sub-fragments, a workflow selector  3150  determines if the processing of these sub-fragments has been completed. The workflow selector  3150  decides which fragments are ready for processing and submits the fragments  410  to the extensible markup language processing engine  320  of  FIG. 2 . The workflow selector  3150  also determines when all processing on the document is complete and outputs the final result  430 . 
     A processed fragment and workflow separator  3110  collects the results  400  from the extensible markup language processing engine  320  of  FIG. 2  and stores the separated results in the document fragment pool  3140  and workflow specification pool  3130 . 
     One possible implementation of the workflow selection engine  3100  is as a web service that interacts with other services. Alternatively, the workflow selection engine  3100  might be implemented as a method that operates on a workflow pool object in a more direct programming approach. 
     While the workflow pool and workflow selection engine, as described, provide the ability to select and process some fragments, even when the processing of other fragments is delayed, simpler implementations are possible. One could, for example, use a simple queue as the workflow pool and a straightforward sequential model for the workflow selection. 
     In operations, the workflow selection engine  3100  accepts a document  420  for processing. Using the initial fragment generator  3120 , the document and associated job information are separated into an initial fragment and workflow specification. The initial fragment and workflow specification  410  is then submitted to the extensible markup language processing engine  320  of  FIG. 2  and the results  400  returned. For simple jobs, this may be all that is necessary and the processed fragment would be output. 
     However, some processing options might be analyzers that decide what additional processing is needed. The analyzers result in new workflow specifications, not just modified documents. 
     For example, a document may be transformed in such a way as to generate file inclusions, database queries, or additional transformations. In the workflow selection engine  3100 , an analyzer detects the transformation and specifies the appropriate additional processing, thereby avoiding the anticipating of such possibilities in advance and predefining the processing pipeline. 
     The workflow selection engine  3100  may also detect processing that requires external resources. If the workflow selection engine  3100  detects the requirement for external resources, the workflow selection engine  3100  separates the external resource processing into its own fragment and workflow specification. In this way, delays in resource acquisition need not block other processing. 
     It is noted that there is no requirement that the document fragment pool  3140  and workflow specification pool  3130  contain elements from only one document. The workflow selection engine  3100  may allow multiple documents as well as multiple parts of a document to be processed in parallel. 
     Moreover, workflow selection engine  3100  might construct workflows dynamically. On the other hand, workflow selection engine  3100  may select from a set of basic predefined workflows, such as: check the syntax of a fragment to see if it is well-formed; examine the namespaces of a fragment and separate into sub-fragments by namespace, including a fragment for reintegration; examine the fragment for special namespaces (e.g. scalable vector graphics, extensible stylesheet language formatting objects, extensible hypertext markup language, personalized print markup language template) and assign a matching workflow specification; examine a fragment and determine what style transformation if any should be applied and assign a workflow to apply the transformation; separate file inclusions as sub-fragments and specify workflows to retrieve and insert the files, also constructing a fragment for the reintegration; insert files specified by a fragment and assign a workflow to analyze the result for further processing; and/or apply a transformation to a fragment and assign a workflow to analyze the result for further processing. 
     In summary, the extensible markup language document processing engine performs arbitrary processing on extensible markup language documents. The processing sequence of the extensible markup language document processing engine is not fixed, but rather can depend upon the information submitted with the job and upon determinations and analysis during the actual job processing. The extensible markup language document processing engine can also segment the document processing so that different fragments of the document are handled differently, thereby providing parallel processing capabilities. Moreover, the extensible markup language document processing engine can segment the document processing so that different fragments of the document are handled differently so that not all processing is blocked when a fragment requires a slow action, such as retrieval of information from the web. 
     It will be appreciated that various of the above-disclosed and other features and functions, or alternatives thereof, may be desirably combined into many other different systems or applications. Also that various presently unforeseen or unanticipated alternatives, modifications, variations or improvements therein may be subsequently made by those skilled in the art which are also intended to be encompassed by the following claims.