CN113723059A - Method and system for converting HTML (hypertext markup language) into PDF (Portable document Format) based on block chain - Google Patents

Abstract

The application relates to a method and a system for converting HTML into PDF based on a block chain, wherein the method comprises the following steps: receiving a transaction request initiated by a target transaction, wherein the transaction request comprises HTML information, XML information and XSLT information; verifying the validity of the transaction request through an intelligent contract arranged on a blockchain; if the legality is verified to be passed, the corresponding HTML content is converted into the PDF file through the intelligent contract according to the transaction request, through the method and the device, the problems that a file format conversion mode is complicated, file information is easy to leak and difficult to monitor are solved, time related to processing of the file information is shortened, cost and risk that the file information is easy to leak are reduced, and meanwhile reliability and visibility are improved.

Description

Method and system for converting HTML (hypertext markup language) into PDF (Portable document Format) based on block chain

Technical Field

The present application relates to the field of electronic documents, and in particular, to a method and system for converting HTML into PDF based on a block chain.

Background

Currently, PDF, which is a digital format for representing documents that enables users to easily and reliably exchange and view electronic documents without depending on any document creation, viewing, or printing environment, has been widely used for electronic form exchange of documents; the user can combine the PDF with software that creates, views, prints, and processes the PDF in various ways to meet the making, exchanging, and usage requirements of various electronic documents.

The conventional PDF mainly adopts software such as Microsoft Word or WPS Office to edit the content and then outputs the content as a PDF file through format conversion. Generally, tool software like Adobe Acrobat Pro can efficiently process PDF on any device at any time and any place.

However, with the popularization of electronic products such as electronic invoices, electronic insurance policies, electronic medical records, and electronic contracts, users are more and more not to independently create or edit a PDF file through software, but to create, edit, and circulate PDF in a service flow.

For example, a part of electronic labor contract-making platforms cannot provide online editing and electronic labor contract generation methods for human units and workers, and still rely on that the electronic labor contracts are edited by software such as Microsoft Word or WPS Office, converted into PDF, and uploaded to the electronic labor contract-making platforms, which obviously increases the use cost of the human units and workers. Furthermore, the existing centralized electronic labor contract-making platform is difficult to establish a sound electronic labor contract information protection system so as to ensure that the electronic labor contract information is not illegally collected, used, processed, transmitted, provided and disclosed, and also difficult to supervise whether the electronic labor contract-making platform illegally provides services such as electronic labor contract searching, calling and the like for others.

At present, an effective solution is not provided aiming at the problems of complicated file format conversion mode, easy leakage of file information and difficult supervision in the related technology.

Disclosure of Invention

The embodiment of the application provides a method and a system for converting HTML (hypertext markup language) into PDF (Portable document Format) based on a block chain, so as to at least solve the problems that in the related art, the file format conversion mode is complicated, the file information is easy to leak and difficult to monitor.

In a first aspect, an embodiment of the present application provides a method for converting an HTML into a PDF based on a block chain, where the method includes:

receiving a transaction request initiated by a target transaction, wherein the transaction request comprises HTML information, XML information and/or XSLT information;

verifying the validity of the transaction request through an intelligent contract deployed on a blockchain;

and if the legality passes, the legality passes through the verification, and the corresponding HTML content is converted into a PDF file through the intelligent contract according to the transaction request.

In some of these embodiments, the validity of the transaction request is verified by a smart contract deployed on the blockchain; if the validity check is passed, converting the HTML content into a PDF file according to the transaction request by the intelligent contract comprises the following steps:

calling a checking logic through an intelligent contract arranged on a block chain, and checking the legality of an HTML (hypertext markup language) character string in the transaction request, wherein the HTML information comprises the HTML character string;

and converting the corresponding HTML content into a PDF file through the intelligent contract.

In some embodiments, before converting the corresponding HTML content into a PDF file by the intelligent contract, the method further comprises:

if the tags in the HTML character string are not closed, calling tag processing logic through the intelligent contract to perform closing processing on the unclosed tags.

In some of these embodiments, the validity of the transaction request is verified by a smart contract deployed on the blockchain; if the validity check is passed, converting the corresponding HTML content into a PDF file according to the transaction request by the intelligent contract comprises the following steps:

calling a checking logic through an intelligent contract arranged on a block chain, and checking the legality of an HTML file path in the transaction request, wherein the HTML information comprises the HTML file path;

acquiring a corresponding HTML file through the intelligent contract according to the HTML file path;

and converting the HTML content into a PDF file through the intelligent contract.

In some of these embodiments, the validity of the transaction request is verified by a smart contract deployed on the blockchain; if the validity check is passed, converting the corresponding HTML content into a PDF file according to the transaction request by the intelligent contract comprises the following steps:

calling a checking logic through an intelligent contract arranged on a block chain, and checking an XML file path and an XSL file path in the transaction request, wherein the XML information comprises the XML file path, and the XSLT information comprises the XSL file path;

converting the XML file corresponding to the XML file path into an HTML file through the intelligent contract according to the XSL parameters corresponding to the XSL file path;

and converting the HTML content into a PDF file through the intelligent contract.

In some embodiments, after converting the corresponding HTML content into a PDF file according to the transaction request by the intelligent contract if the validity check passes, the method further includes:

encoding the PDF file by BASE64 through the intelligent contract;

and transmitting the coded character string to an initiator of the target transaction.

In some embodiments, and transmitting the encoded string to the initiator of the target transaction comprises:

dividing all the coded character strings or dividing the coded character strings according to a preset proportion, and storing the divided character strings in an account book of the block chain;

transmitting the stored transaction hash to an initiator of the target transaction.

In some embodiments, after converting the corresponding HTML content into a PDF file according to the transaction request by the intelligent contract if the validity check passes, the method further includes:

storing the PDF file into a file server, storing an index and/or a storage address of the PDF file stored by the file server, and transmitting the index and/or the storage address to an initiator of the target transaction;

and acquiring the PDF file according to the index and/or the storage address.

In some embodiments, after converting the corresponding HTML content into a PDF file according to the transaction request by the intelligent contract if the validity check passes, the method further includes:

and converting the PDF file into an OFD file through the intelligent contract.

In a second aspect, an embodiment of the present application provides a system for converting HTML into PDF based on a blockchain, where the system includes an intelligent contract, a blockchain network, and an SDK where the blockchain interacts with an application, where the intelligent contract includes a request receiving module, a validity checking module, and an HTML conversion module, and the blockchain network includes a P2P network, a consensus algorithm, a chained ledger storage, and MSP identity management;

the request receiving module receives a transaction request initiated by the SDK or other intelligent contracts, wherein the transaction request comprises HTML information, XML information and/or XSLT information;

the validity checking module checks the validity of the transaction request;

the HTML conversion module converts the corresponding HTML content into a PDF file according to the transaction request;

and the SDK interacted between the block chain and the application end is used for storing the identity certificate interacted between the user and the block chain.

Compared with the related art, the method and the system for converting the HTML into the PDF based on the block chain provided by the embodiment of the application receive the transaction request initiated by the target transaction, wherein the transaction request comprises HTML information, XML information and XSLT information; verifying the validity of the transaction request through an intelligent contract arranged on a blockchain; if the validity is verified to be passed, the corresponding HTML content is converted into the PDF file through the intelligent contract according to the transaction request, the problems that the file format conversion mode is complicated, the file information is easy to leak and difficult to monitor are solved, the time related to processing the file information is reduced, the cost and the risk of easy leakage of the file information are reduced, and meanwhile, the reliability and the visibility are improved.

Drawings

The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the application and together with the description serve to explain the application and not to limit the application. In the drawings:

FIG. 1 is a flowchart of the steps for contracting an electronic labor in the related art;

FIG. 2 is a schematic diagram of a method of creating an intelligent contract;

FIG. 3 is a schematic diagram of a method for invoking an intelligent contract;

FIG. 4 is a schematic diagram of a method of creating an intelligent contract and invoking the intelligent contract;

FIG. 5 is a flow chart of steps of a method for converting HTML to PDF based on blockchains according to an embodiment of the present application;

FIG. 6 is a timing diagram of an intelligent contract converting an HTML string to a PDF, as shown in FIG. 6;

FIG. 7 is a timing diagram of an intelligent contract converting HTML to PDF according to an HTML file path;

FIG. 8 is a flowchart illustrating steps of a method for converting HTML to PDF based on blockchains according to an embodiment of the present application;

fig. 9 is an internal structural diagram of an electronic device according to an embodiment of the present application.

Description of the drawings: 80. an intelligent contract; 81. a block chain network; 82. the block chain and the application terminal are interacted with each other through the SDK; 83. a request receiving module; 84. a validity checking module; 85. an HTML conversion module; 86. a P2P network; 87. a consensus algorithm; 88. storing the chained account book; 89. MSP identity management.

Detailed Description

In order to make the objects, technical solutions and advantages of the present application more apparent, the present application will be described and illustrated below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present application and are not intended to limit the present application. All other embodiments obtained by a person of ordinary skill in the art based on the embodiments provided in the present application without any inventive step are within the scope of protection of the present application.

It is obvious that the drawings in the following description are only examples or embodiments of the present application, and that it is also possible for a person skilled in the art to apply the present application to other similar contexts on the basis of these drawings without inventive effort. Moreover, it should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions must be made to achieve the developers' specific goals, such as compliance with system-related and business-related constraints, which may vary from one implementation to another.

Reference in the specification to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the specification. The appearances of the phrase in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. Those of ordinary skill in the art will explicitly and implicitly appreciate that the embodiments described herein may be combined with other embodiments without conflict.

Unless defined otherwise, technical or scientific terms referred to herein shall have the ordinary meaning as understood by those of ordinary skill in the art to which this application belongs. Reference to "a," "an," "the," and similar words throughout this application are not to be construed as limiting in number, and may refer to the singular or the plural. The present application is directed to the use of the terms "including," "comprising," "having," and any variations thereof, which are intended to cover non-exclusive inclusions; for example, a process, method, system, article, or apparatus that comprises a list of steps or modules (elements) is not limited to the listed steps or elements, but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus. Reference to "connected," "coupled," and the like in this application is not intended to be limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. The term "plurality" as referred to herein means two or more. "and/or" describes an association relationship of associated objects, meaning that three relationships may exist, for example, "A and/or B" may mean: a exists alone, A and B exist simultaneously, and B exists alone. The character "/" generally indicates that the former and latter associated objects are in an "or" relationship. Reference herein to the terms "first," "second," "third," and the like, are merely to distinguish similar objects and do not denote a particular ordering for the objects.

PDF, which is a digital format for representing documents, has been widely used for electronic form exchange of documents because it enables users to easily and reliably exchange and view electronic documents without depending on any document creation, viewing, or printing environment. The user can combine the PDF with software that creates, views, prints and processes the PDF in various ways to meet the making, exchanging and using requirements of various electronic documents, including:

preserving the fidelity of the document independent of the device, platform and software;

merging the contents of different sources (websites, word processing and spreadsheet software, scanned documents, photographs and graphics) into one independent document while maintaining the integrity of all original source documents;

collaboratively editing a document from multiple locations or platforms;

verifying authenticity by a digital signature;

setting security and permissions to enable creators to maintain control over documents and associated permissions;

for the disabled, the content is accessible;

with other file formats and applications, extraction and reuse of content is feasible;

data is collected using electronic forms and integrated into a business system.

The conventional PDF mainly adopts software such as Microsoft Word or WPS Office to edit the content and then outputs the content as a PDF file through format conversion. Generally, tool software like Adobe Acrobat Pro can efficiently process PDF on any device at any time and any place.

However, with the popularization of electronic products such as electronic invoices, electronic insurance policies, electronic medical records, and electronic contracts, users need to create, edit, and circulate PDF in a service flow instead of independently creating or editing a PDF file through software.

While modern technology has evolved from stone tablets and paper folders to hard drives and cloud platforms, the underlying structure is the same. Because there is no unified system for managing the identities of network participants, tracing is very laborious and the information of each database in the system is isolated, which also means a single point of failure. Even if the requirements for visibility and trust are clear, it is difficult to construct a recording system across the service network under the current approach of separating fragmented information and process sharing.

In the related art, taking the electronic labor contract as an example, fig. 1 is a flowchart of the steps of the related art for making the electronic labor contract, and the flow of the operation steps is as follows:

step S102, accessing an electronic labor contract-making platform;

step S104, uploading a labor contract text by a method provided by an electronic labor contract binding platform;

step S106, generating an electronic file of the labor contract through a creating service provided by an electronic labor contract binding platform;

step S108, signing the electronic labor contract by using reliable electronic signatures by a human unit and a worker respectively;

and step S110, prompting the laborer to download and store the electronic labor contract text in time by a human unit, and informing the laborer of a method for checking and downloading the electronic labor contract.

Through steps S102 to S110, the electronic labor contracting platform cannot provide a method for online editing and generating an electronic labor contract for a human consumption unit and a worker, and still relies on that the electronic labor contract is edited by software such as Microsoft Word or WPS Office, converted into PDF, and uploaded to the electronic labor contracting platform, which obviously increases the use cost of the human consumption unit and the worker. Furthermore, the existing centralized electronic labor contract-making platform is difficult to establish a sound electronic labor contract information protection system so as to ensure that the electronic labor contract information is not illegally collected, used, processed, transmitted, provided and disclosed, and also difficult to supervise whether the electronic labor contract-making platform illegally provides services such as electronic labor contract searching, calling and the like for others.

The inventor researches and discovers that the block chain is an important component of a new-generation information technology, is novel database software integrated by multiple technologies such as a distributed network, an encryption technology, an intelligent contract and the like, has the characteristics of traceability, supervision, data credibility and information disclosure based on the technical characteristics of a distributed consensus mechanism, the intelligent contract, data transparency, non-falsification and the like, can provide technical support for the promotion and increase of the efficiency, the value circulation and the multi-party cooperation of entity economy and public service, reduces the time, the cost and the risk related to the processing of private information, improves the trust and the visibility, and is a natural and credible basic technology.

The block chain-based protection technology is accelerated, the development of technical products such as multi-party consensus and trusted data sharing is promoted, and the establishment of a trusted digital society is facilitated.

The invention provides a method and a system for converting HTML (hypertext markup language) into PDF (Portable document Format) based on a block chain, which aim to solve the problems and provide low-cost and high-credibility support for block chain electronic contracts or block chain document applications such as other files, documents and the like.

Blockchains are generally divided into three types: public chain (Public Blockchain), Private chain (Private Blockchain) and alliance chain (Consortium Blockchain). Furthermore, there may be a combination of the above types, such as private chain + federation chain, federation chain + public chain, and so on.

Among them, the most decentralized is the public chain. The public chain is represented by bitcoin and ether house, and participants (also called nodes in the block chain) joining the public chain can read data records on the chain, participate in transactions, compete for accounting rights of new blocks, and the like. Moreover, each node can freely join or leave the network and perform related operations.

Private chains are the opposite, with the network's write rights controlled by an organization or organization and the data read rights specified by the organization. Briefly, a private chain may be a weakly centralized system with strict restrictions on nodes and a small number of nodes. This type of blockchain is more suitable for use within a particular establishment.

A federation chain is a block chain between a public chain and a private chain, and "partial decentralization" can be achieved. Each node in a federation chain typically has a physical organization or organization corresponding to it; the nodes are authorized to join the network and form a benefit-related alliance, and block chain operation is maintained together.

Based on the basic characteristics of a blockchain, a blockchain is usually composed of several blocks. The time stamps corresponding to the creation time of the block are recorded in the blocks respectively, and all the blocks form a time-ordered data chain according to the time stamps recorded in the blocks strictly.

The real data generated by the physical world can be constructed into a standard transaction (transaction) format supported by a block chain, then is issued to the block chain, the node equipment in the block chain performs consensus processing on the received transaction, and after the consensus is achieved, the node equipment serving as an accounting node in the block chain packs the transaction into a block and performs persistent evidence storage in the block chain.

The consensus algorithm supported in the blockchain may include:

the first kind of consensus algorithm, namely the consensus algorithm that the node device needs to contend for the accounting right of each round of accounting period; consensus algorithms such as Proof of Work (POW), Proof of equity (POS), Proof of commission rights (DPOS), etc.;

the second kind of consensus algorithm, namely the consensus algorithm which elects accounting nodes in advance for each accounting period (without competing for accounting right); for example, a consensus algorithm such as a Practical Byzantine Fault Tolerance (PBFT) is used.

In a blockchain network employing a first type of consensus algorithm, node devices competing for billing rights can execute a transaction upon receipt. One of the node devices competing for the accounting right may win in the process of competing for the accounting right in the current round, and become an accounting node. The accounting node may package the received transaction with other transactions to generate a latest block and send the generated latest block or a block header of the latest block to other node devices for consensus.

In the block chain network adopting the second type of consensus algorithm, the node equipment with the accounting right is agreed before accounting in the current round. Thus, the node device, after receiving the transaction, may send the transaction to the accounting node if it is not the accounting node of its own round. For the accounting node of the current round, the transaction may be performed during or before packaging the transaction with other transactions to generate the latest block. After generating the latest block, the accounting node may send the latest block or a block header of the latest block to other node devices for consensus.

As described above, regardless of which consensus algorithm is used by the blockchain, the accounting node of the current round may pack the received transaction to generate the latest block, and send the generated latest block or the block header of the latest block to other node devices for consensus verification. If no problem is verified after other node equipment receives the latest block or the block header of the latest block, the latest block can be added to the tail of the original block chain, so that the accounting process of the block chain is completed. The transaction contained in the block may also be performed by other nodes in verifying the new block or block header sent by the accounting node.

In the field of blockchain, an important concept is Account (Account); taking an ether house as an example, the ether house generally divides an account into an external account and a contract account; the external account is an account directly controlled by the user and is also called as a user account; and the contract account is created by the user through an external account, the account containing the contract code (i.e. the smart contract). Of course, for some blockchain items derived from the ethernet-based architecture (such as ant blockchains), the account types supported by the blockchain may be further expanded, and are not particularly limited in this specification.

For accounts in a blockchain, the account status of the account is usually maintained through a structure. When a transaction in a block is executed, the status of the account associated with the transaction in the block chain is also typically changed.

Taking etherhouses as an example, the structure of an account usually includes fields such as Balance, Nonce, Code and Storage. Wherein:

a Balance field for maintaining the current account Balance of the account;

a Nonce field for maintaining a number of transactions for the account; the counter is used for guaranteeing that each transaction can be processed only once, and replay attack is effectively avoided;

a Code field for maintaining a contract Code for the account; in practical applications, only the hash value of the contract Code is typically maintained in the Code field; thus, the Code field is also commonly referred to as the Codhash field.

A Storage field for maintaining the Storage contents of the account (default field value is null); for a contract account, a separate storage space is usually allocated to store the storage content of the contract account; this separate storage space is often referred to as the account storage of the contract account. The storage content of the contract account is generally constructed into a data structure of an MPT (MerklePatriceitie) tree and stored in the independent storage space; in which, the Storage content based on the contract account is constructed into an MPT tree, which is also commonly referred to as a Storage tree. Whereas the Storage field typically maintains only the root node of the Storage tree; thus, the Storage field is also commonly referred to as the Storage root field.

Wherein, for the external account, the field values of the Code field and the Storage field shown above are both null values.

In addition, in practical applications, whether public, private, or alliance, it is possible to provide the functionality of a Smart contract (Smart contract). An intelligent contract on a blockchain is a contract on a blockchain that can be executed triggered by a transaction. An intelligent contract may be defined in the form of code.

Taking an Etherhouse as an example, a user is supported to create and call some complex logic in the Etherhouse network. The ethernet workshop is used as a programmable block chain, and the core of the ethernet workshop is an ethernet workshop virtual machine (EVM), and each ethernet workshop node can run the EVM. The EVM is a well-behaved virtual machine through which various complex logic can be implemented. The user issuing and invoking smart contracts in the etherhouse is running on the EVM. In fact, the EVM directly runs virtual machine code (virtual machine bytecode, hereinafter referred to as "bytecode"), so the intelligent contract deployed on the blockchain may be bytecode.

Fig. 2 is a schematic diagram of a method for creating a smart contract, as shown in fig. 2, after Bob sends a Transaction (Transaction) containing information for creating a smart contract to the ethernet network, each node can execute the Transaction in the EVM. In fig. 1, the From field of the transaction is used To record the address of the account initiating the creation of the intelligent contract, the contract code stored in the field value of the Data field of the transaction may be bytecode, and the field value of the To field of the transaction is a null account. After the nodes reach the agreement through the consensus mechanism, the intelligent contract is successfully created, and the follow-up user can call the intelligent contract.

After the intelligent contract is established, a contract account corresponding to the intelligent contract appears on the block chain, and the block chain has a specific address; for example, "0 x68e12cf284 …" in each node in fig. 2 represents the address of the contract account created; the contract Code (Code) and account store (Storage) will be maintained in the account store for that contract account. The behavior of the intelligent contract is controlled by the contract code, while the account storage of the intelligent contract preserves the state of the contract. In other words, the intelligent contract causes a virtual account to be generated on the blockchain that contains the contract code and account storage.

As mentioned above, the Data field containing the transaction that created the intelligent contract may hold the byte code of the intelligent contract. A bytecode consists of a series of bytes, each of which can identify an operation. Based on the multiple considerations of development efficiency, readability and the like, a developer can select a high-level language to write intelligent contract codes instead of directly writing byte codes. For example, the high-level language may employ a language such as Solidity, Serpent, LLL, and the like. For intelligent contract code written in a high-level language, the intelligent contract code can be compiled by a compiler to generate byte codes which can be deployed on a blockchain.

Taking the Solidity language as an example, the contract code written by it is very similar to a Class (Class) in the object-oriented programming language, and various members including state variables, functions, function modifiers, events, etc. can be declared in one contract. A state variable is a value permanently stored in an account Storage (Storage) field of an intelligent contract to save the state of the contract.

Fig. 3 is a schematic diagram of a method for invoking an intelligent contract, as shown in fig. 3, and still taking an ethernet shop as an example, after Bob sends a transaction including information of invoking the intelligent contract to the ethernet shop network, each node may execute the transaction in the EVM. In fig. 3, the From field of the transaction is used To record the address of the account initiating the invocation of the smart contract, the To field is used To record the address of the invoked smart contract, and the Data field of the transaction is used To record the method and parameters of the invocation of the smart contract. After invoking the smart contract, the account status of the contract account may change. Subsequently, a client may view the account status of the contract account through the accessed block link point (e.g., node 1 in fig. 3).

The intelligent contract can be independently executed at each node in the blockchain network in a specified mode, and all execution records and data are stored on the blockchain, so that after the transaction is executed, transaction certificates which cannot be tampered and lost are stored on the blockchain.

FIG. 4 is a schematic diagram of a method for creating an intelligent contract and invoking the intelligent contract, as shown in FIG. 4. An intelligent contract is created in an Ethernet workshop and needs to be subjected to the processes of compiling the intelligent contract, changing the intelligent contract into byte codes, deploying the intelligent contract to a block chain and the like. The intelligent contract is called in the Ethernet workshop, a transaction pointing to the intelligent contract address is initiated, the EVM of each node can respectively execute the transaction, and the intelligent contract code is distributed and operated in the virtual machine of each node in the Ethernet workshop network.

The invention converts HTML and CSS into PDFs meeting the standard through a block chain intelligent contract, the PDFs can be accessed, searched and used for indexing, and the related conversion behaviors can be traced and audited.

The implementation process of the invention mainly calls a PDF conversion engine through a block chain intelligent contract, and uses structural information from HTML to create PDF/A, PDF/UA or PDF with tags. The method fully utilizes semantic and structural information existing in the HTML and the CSS, maps the semantic and structural information to the associated objects and styles, and converts HTML content into a rich and intelligent PDF document.

HTML (hypertext markup language) is mainly used to construct hypertext documents and to place an application pointing to another document into one document.

XML (extensible markup language) is a source language that allows users to define their own markup language, which provides a uniform way to describe and exchange structured data independent of the application or vendor.

XSL (extended stylesheet language) is primarily based on a stylesheet language for XML.

XSLT refers to XSL transformation, i.e., the transformation of an XML document into another document, such as HTML.

PDF (portable document format) is mainly used for a file format developed by file exchanges in a manner independent of an application program, an operating system, and hardware. A PDF file is a data presentation form of an electronic document based on a PostScript language image model, enabling users to exchange and view electronic documents without relying on the context of creation, viewing, or printing of the document.

The OFD (open format document) mainly adopts a two-dimensional vector imaging model to describe any primitive object subjected to typesetting, including characters, graphics, images and the like, and generates an output result irrelevant to equipment, which is used for executing a program and transmitting the output result to output equipment.

It should be noted that, in the embodiment of the present invention, a hyper-hedger Fabric block chain network is adopted, an intelligent contract is written using Java language, and iText and pdfHTML components are used in the intelligent contract, but the block chain network, the intelligent contract programming language, and the introduced components do not affect the method of the present invention, and other public chains, alliance chains, and private chains are also applicable. The programming language for writing the intelligent contract is not limited to Java, and may be GoLang, node. js, identity, etc. When the programming language is used, components with mature corresponding languages can be introduced, so that the workload of coding is reduced, and the stability and reliability of the intelligent contract are improved.

An embodiment of the present application provides a method for converting HTML into PDF based on a block chain, and fig. 5 is a flowchart illustrating steps of the method for converting HTML into PDF based on a block chain according to an embodiment of the present application, as shown in fig. 5, the method includes the following steps:

step S502, receiving a transaction request initiated by a target transaction, wherein the transaction request comprises HTML information, XML information and/or XSLT information;

step S504, the validity of the transaction request is checked through the intelligent contracts deployed on the blockchain;

and step S506, if the validity check is passed, converting the corresponding HTML content into a PDF file through an intelligent contract according to the transaction request.

Through steps S502 to S506 in the embodiment of the application, the problems of complicated file format conversion mode, easy leakage of file information and difficult supervision are solved, the time related to processing the file information is reduced, the cost and the risk of easy leakage of the file information are reduced, and meanwhile, the reliability and the visibility are improved.

In some embodiments, step S504 and step S506, the validity of the transaction request is checked by the intelligent contract deployed on the blockchain; if the validity check is passed, converting the HTML content into a PDF file through an intelligent contract according to the transaction request, wherein the PDF file comprises the following steps:

calling a checking logic through an intelligent contract arranged on a block chain, and checking the legality of an HTML (hypertext markup language) character string in a transaction request, wherein the HTML information comprises the HTML character string;

and converting the corresponding HTML content into a PDF file through an intelligent contract.

Specifically, fig. 6 is a timing diagram of an intelligent contract converting an HTML string into a PDF, as shown in fig. 6;

the SDK or other block chains initiate a transaction request to the block chain in a chain-crossing mode, wherein the transaction request comprises a character string of HTML to be converted;

responding a transaction request by an intelligent contract arranged on the block chain, and verifying the legality of an HTML (hypertext markup language) character string in the transaction request by the intelligent contract calling a verification logic;

the HTML character string is verified to be legal, and the intelligent contract calls a convertToPdf () method in the HtmlConverter object to convert the HTML into PDF;

optionally, the HTML tag in the transaction request is not closed, and the intelligent contract calls the tag processing logic to perform closing processing on the unclosed tag.

In some embodiments, step S504 and step S506, the validity of the transaction request is checked by the intelligent contract deployed on the blockchain; if the validity check is passed, converting the corresponding HTML content into a PDF file through an intelligent contract according to the transaction request, wherein the PDF file comprises the following steps:

calling a checking logic through an intelligent contract arranged on a block chain, and checking the legality of an HTML file path in a transaction request, wherein HTML information comprises the HTML file path;

acquiring a corresponding HTML file through an intelligent contract according to the HTML file path;

the HTML content is converted to a PDF file by means of an intelligent contract.

Specifically, FIG. 7 is a timing diagram of an intelligent contract converting HTML to PDF according to an HTML file path, as shown in FIG. 7;

the SDK or other block chains initiate a transaction request to the block chain in a chain crossing mode, wherein the transaction request comprises a path of an HTML file to be converted;

responding a transaction request by an intelligent contract arranged on the block chain, and verifying the legality of an HTML file path in the transaction request by the intelligent contract calling a verification logic;

and when the path of the HTML file is verified to be legal, the intelligent contract calls a convertToPdf () method in the HtmlConverter object to convert the source HTML content pointed by the path of the HTML file into a PDF file.

The convertttopdf () method creates a complete PDF file. Once the input is parsed and converted to PDF, any File, OutputStream, PdfWriter, or Pdfdocument passed to the convertToPdf () method will close.

In some cases, an intelligent contract may wish to add some extra information to the Document, or may simply not want to convert HTML to a PDF file, but rather convert it to a series of objects that may be used for different purposes.

Optionally, the intelligent contract calls the convertToDocument () method to return a Document instance, and may further add some additional content using this Document instance.

Optionally, the smart contract calls the coverToElements () method to create a list of IEement objects.

In some embodiments, step S504 and step S506, the validity of the transaction request is checked by the intelligent contract deployed on the blockchain; if the validity check is passed, converting the corresponding HTML content into a PDF file through an intelligent contract according to the transaction request, wherein the PDF file comprises the following steps:

calling a checking logic through an intelligent contract arranged on a block chain, and checking an XML file path and an XSL file path in a transaction request, wherein XML information comprises the XML file path, and XSLT information comprises the XSL file path;

converting the XML file corresponding to the XML file path into an HTML file through an intelligent contract according to the XSL parameter corresponding to the XSL file path;

the HTML content is converted to a PDF file by means of an intelligent contract.

Specifically, the SDK or other block chains initiate a transaction request to the block chain in a cross-chain mode, wherein the transaction request comprises a path of an XML file to be converted and a path of an XSL file;

responding a transaction request by an intelligent contract arranged on the block chain, and verifying the legality of an XML file path and an XSL file path in the transaction request by the intelligent contract calling a verification logic;

and when the paths of the XML files and the XSL files are verified to be legal, the intelligent contract calls a newTransformer () method of the Transformer factory to acquire a Transformer object of the XSL parameters. The smart contract then calls the transform () method of the transform object to complete the XML to HTML conversion. And finally, the intelligent contract calls a convertToPdf () method of the HtmlConverter to complete the conversion of the PDF file.

In some embodiments, in step S506, after converting the corresponding HTML content into a PDF file by the smart contract according to the transaction request, the method further includes:

carrying out BASE64 encoding on the PDF file through an intelligent contract;

and transmitting the encoded character string to an initiator of the target transaction.

In some of these embodiments, and transmitting the encoded string to the initiator of the target transaction includes:

dividing all the coded character strings or dividing the coded character strings according to a preset proportion, and storing the divided character strings in an account book of a block chain;

the stored transaction hash is transmitted to the initiator of the target transaction.

In some embodiments, in step S506, after converting the corresponding HTML content into the PDF file according to the transaction request by the intelligent contract if the validity check passes, the method further includes:

storing the PDF file into a file server, and transmitting an index and/or a storage address of the PDF file stored by the file server to an initiator of the target transaction;

and acquiring the PDF file according to the index and/or the storage address.

In some embodiments, in step S506, after converting the corresponding HTML content into the PDF file according to the transaction request by the intelligent contract if the validity check passes, the method further includes:

and converting the PDF file into an OFD file through an intelligent contract.

It should be noted that the steps illustrated in the above-described flow diagrams or in the flow diagrams of the figures may be performed in a computer system, such as a set of computer-executable instructions, and that, although a logical order is illustrated in the flow diagrams, in some cases, the steps illustrated or described may be performed in an order different than here.

The embodiment of the present application provides a system for converting HTML into PDF based on a blockchain, and fig. 8 is a flowchart illustrating steps of a method for converting HTML into PDF based on a blockchain according to an embodiment of the present application, where, as shown in fig. 8, the system includes an intelligent contract 80, a blockchain network 81, and an SDK82 where the blockchain interacts with an application end, where the intelligent contract 80 includes a request receiving module 83, a validity checking module 84, and an HTML conversion module 85, and the blockchain network 81 includes a P2P network 86, a consensus algorithm 87, a chained ledger store 88, and MSP identity management 89;

the request receiving module 83 receives a transaction request initiated by an SDK or other intelligent contracts, wherein the transaction request includes HTML information, XML information, and/or XSLT information;

the validity check module 84 checks the validity of the transaction request;

the HTML conversion module 85 converts the corresponding HTML content into a PDF file according to the transaction request;

the SDK82 of the blockchain interacting with the application is used to store the identity credentials of the user interacting with the blockchain.

By the aid of the system, the problems that file format conversion modes are complex, file information is easy to leak and difficult to monitor are solved, time related to processing the file information is shortened, cost and risk of easy leakage of the file information are reduced, and meanwhile reliability and visibility are improved.

The above modules may be functional modules or program modules, and may be implemented by software or hardware. For a module implemented by hardware, the modules may be located in the same processor; or the modules can be respectively positioned in different processors in any combination.

In one embodiment, a computer device is provided, which may be a terminal. The computer device includes a processor, a memory, a network interface, a display screen, and an input device connected by a system bus. Wherein the processor of the computer device is configured to provide computing and control capabilities. The memory of the computer device comprises a nonvolatile storage medium and an internal memory. The non-volatile storage medium stores an operating system and a computer program. The internal memory provides an environment for the operation of an operating system and computer programs in the non-volatile storage medium. The network interface of the computer device is used for communicating with an external terminal through a network connection. The computer program is executed by a processor to implement a method of converting HTML to PDF based on a blockchain. The display screen of the computer equipment can be a liquid crystal display screen or an electronic ink display screen, and the input device of the computer equipment can be a touch layer covered on the display screen, a key, a track ball or a touch pad arranged on the shell of the computer equipment, an external keyboard, a touch pad or a mouse and the like.

In an embodiment, fig. 9 is a schematic internal structure diagram of an electronic device according to an embodiment of the present application, and as shown in fig. 9, there is provided an electronic device, which may be a server, and its internal structure diagram may be as shown in fig. 9. The electronic device comprises a processor, a network interface, an internal memory and a non-volatile memory connected by an internal bus, wherein the non-volatile memory stores an operating system, a computer program and a database. The processor is used for providing calculation and control capability, the network interface is used for communicating with an external terminal through network connection, the internal memory is used for providing an environment for an operating system and the running of a computer program, the computer program is executed by the processor to realize a method for converting HTML into PDF based on a block chain, and the database is used for storing data.

Those skilled in the art will appreciate that the configuration shown in fig. 9 is a block diagram of only a portion of the configuration relevant to the present application, and does not constitute a limitation on the electronic device to which the present application is applied, and a particular electronic device may include more or less components than those shown in the drawings, or combine certain components, or have a different arrangement of components.

It will be understood by those skilled in the art that all or part of the processes of the methods of the embodiments described above can be implemented by hardware instructions of a computer program, which can be stored in a non-volatile computer-readable storage medium, and when executed, can include the processes of the embodiments of the methods described above. Any reference to memory, storage, database, or other medium used in the embodiments provided herein may include non-volatile and/or volatile memory, among others. Non-volatile memory can include read-only memory (ROM), Programmable ROM (PROM), Electrically Programmable ROM (EPROM), Electrically Erasable Programmable ROM (EEPROM), or flash memory. Volatile memory can include Random Access Memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in a variety of forms such as Static RAM (SRAM), Dynamic RAM (DRAM), Synchronous DRAM (SDRAM), Double Data Rate SDRAM (DDRSDRAM), Enhanced SDRAM (ESDRAM), Synchronous Link DRAM (SLDRAM), Rambus Direct RAM (RDRAM), direct bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM).

It should be understood by those skilled in the art that various features of the above-described embodiments can be combined in any combination, and for the sake of brevity, all possible combinations of features in the above-described embodiments are not described in detail, but rather, all combinations of features which are not inconsistent with each other should be construed as being within the scope of the present disclosure.

The above-mentioned embodiments only express several embodiments of the present application, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the concept of the present application, which falls within the scope of protection of the present application. Therefore, the protection scope of the present patent shall be subject to the appended claims.

Claims (10)

1. A method for converting HTML to PDF based on a blockchain, the method comprising:

receiving a transaction request initiated by a target transaction, wherein the transaction request comprises HTML information, XML information and/or XSLT information;

verifying the validity of the transaction request through an intelligent contract deployed on a blockchain;

and if the validity check is passed, converting the corresponding HTML content into a PDF file through the intelligent contract according to the transaction request.

2. The method of claim 1, wherein the validity of the transaction request is verified by an intelligent contract deployed on a blockchain; if the validity check is passed, converting the HTML content into a PDF file according to the transaction request by the intelligent contract comprises the following steps:

calling a checking logic through an intelligent contract arranged on a block chain, and checking the legality of an HTML (hypertext markup language) character string in the transaction request, wherein the HTML information comprises the HTML character string;

and converting the corresponding HTML content into a PDF file through the intelligent contract.

3. The method of claim 2, wherein prior to converting corresponding HTML content to a PDF file by the smart contract, the method further comprises:

if the tags in the HTML character string are not closed, calling tag processing logic through the intelligent contract to perform closing processing on the unclosed tags.

4. The method of claim 1, wherein the validity of the transaction request is verified by an intelligent contract deployed on a blockchain; if the validity check is passed, converting the corresponding HTML content into a PDF file according to the transaction request by the intelligent contract comprises the following steps:

calling a checking logic through an intelligent contract arranged on a block chain, and checking the legality of an HTML file path in the transaction request, wherein the HTML information comprises the HTML file path;

acquiring a corresponding HTML file through the intelligent contract according to the HTML file path;

and converting the HTML content into a PDF file through the intelligent contract.

5. The method of claim 1, wherein the validity of the transaction request is verified by an intelligent contract deployed on a blockchain; if the validity check is passed, converting the corresponding HTML content into a PDF file according to the transaction request by the intelligent contract comprises the following steps:

calling a checking logic through an intelligent contract arranged on a block chain, and checking an XML file path and an XSL file path in the transaction request, wherein the XML information comprises the XML file path, and the XSLT information comprises the XSL file path;

converting the XML file corresponding to the XML file path into an HTML file through the intelligent contract according to the XSL parameters corresponding to the XSL file path;

and converting the HTML content into a PDF file through the intelligent contract.

6. The method of claim 1, wherein after converting the corresponding HTML content into a PDF file according to the transaction request if the validity check passes, the method further comprises:

encoding the PDF file by BASE64 through the intelligent contract;

and transmitting the coded character string to an initiator of the target transaction.

7. The method of claim 6, wherein transmitting the encoded string to an initiator of the target transaction comprises:

dividing all the coded character strings or dividing the coded character strings according to a preset proportion, and storing the divided character strings in an account book of the block chain;

transmitting the stored transaction hash to an initiator of the target transaction.

8. The method of claim 1, wherein after converting the corresponding HTML content into a PDF file according to the transaction request if the validity check passes, the method further comprises:

storing the PDF file into a file server, storing an index and/or a storage address of the PDF file stored by the file server, and transmitting the index and/or the storage address to an initiator of the target transaction;

and acquiring the PDF file according to the index and/or the storage address.

9. The method of claim 1, wherein after converting the corresponding HTML content into a PDF file according to the transaction request if the validity check passes, the method further comprises:

and converting the PDF file into an OFD file through the intelligent contract.

10. A system for converting HTML into PDF based on a blockchain is characterized by comprising an intelligent contract, a blockchain network and an SDK (software development kit) with the blockchain interacting with an application end, wherein the intelligent contract comprises a request receiving module, a legality checking module and an HTML conversion module, and the blockchain network comprises a P2P network, a consensus algorithm, a chained ledger storage and MSP (mixed-Signal processor) identity management;

the request receiving module receives a transaction request initiated by the SDK or other intelligent contracts, wherein the transaction request comprises HTML information, XML information and/or XSLT information;

the validity checking module checks the validity of the transaction request;

the HTML conversion module converts the corresponding HTML content into a PDF file according to the transaction request;

and the SDK interacted between the block chain and the application end is used for storing the identity certificate interacted between the user and the block chain.

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