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108-548: This process of serializing an object is also called marshalling an object in some situations. The opposite operation, extracting a data structure from a series of bytes, is deserialization , (also called unserialization or unmarshalling ). In networking equipment hardware, the part that is responsible for serialization and deserialization is commonly called SerDes . Uses of serialization include: For some of these features to be useful, architecture independence must be maintained. For example, for maximal use of distribution,

216-546: A String object containing all the information necessary to reconstitute objects of this class and all referenced objects up to a maximum depth given as an integer parameter (a value of -1 implies that depth checking should be disabled). The class method _load should take a String and return an object of this class. Serde is the most widely used library, or crate, for serialization in Rust . In general, non-recursive and non-sharing objects can be stored and retrieved in

324-539: A numeric character reference . Consider the Chinese character "中", whose numeric code in Unicode is hexadecimal 4E2D, or decimal 20,013. A user whose keyboard offers no method for entering this character could still insert it in an XML document encoded either as &#20013; or &#x4e2d; . Similarly, the string "I <3 Jörg" could be encoded for inclusion in an XML document as I &lt;3 J&#xF6;rg . &#0;

432-455: A computer program or from one program to another. Marshalling simplifies complex communications, because it allows using composite objects instead of being restricted to primitive objects . Marshalling is similar to or synonymous with serialization , although technically serialization is one step in the process of marshalling an object. Marshalling and serialization might thus be done differently, although some form of serialization

540-453: A markup language and file format for storing, transmitting, and reconstructing arbitrary data. It defines a set of rules for encoding documents in a format that is both human-readable and machine-readable . The World Wide Web Consortium 's XML 1.0 Specification of 1998 and several other related specifications —all of them free open standards —define XML. The design goals of XML emphasize simplicity, generality, and usability across

648-449: A Swing component, or any component which inherits it, may be serialized to a byte stream, but it is not guaranteed that this will be re-constitutable on another machine. Since ECMAScript 5.1, JavaScript has included the built-in JSON object and its methods JSON.parse() and JSON.stringify() . Although JSON is originally based on a subset of JavaScript, there are boundary cases where JSON

756-459: A byte stream. Primitives as well as non-transient, non-static referenced objects are encoded into the stream. Each object that is referenced by the serialized object via a field that is not marked as transient must also be serialized; and if any object in the complete graph of non-transient object references is not serializable, then serialization will fail. The developer can influence this behavior by marking objects as transient, or by redefining

864-455: A class serializable needs to be a deliberate design decision and not a default condition. Lastly, serialization allows access to non- transient private members of a class that are not otherwise accessible. Classes containing sensitive information (for example, a password) should not be serializable nor externalizable. The standard encoding method uses a recursive graph-based translation of the object's class descriptor and serializable fields into

972-458: A class — __sleep() and __wakeup()  — that are called from within serialize() and unserialize() , respectively, that can clean up and restore an object. For example, it may be desirable to close a database connection on serialization and restore the connection on deserialization; this functionality would be handled in these two magic methods. They also permit the object to pick which properties are serialized. Since PHP 5.1, there

1080-571: A computer running on a different hardware architecture should be able to reliably reconstruct a serialized data stream, regardless of endianness . This means that the simpler and faster procedure of directly copying the memory layout of the data structure cannot work reliably for all architectures. Serializing the data structure in an architecture-independent format means preventing the problems of byte ordering , memory layout, or simply different ways of representing data structures in different programming languages . Inherent to any serialization scheme

1188-466: A connection or a raw vector. REBOL will serialize to file ( save/all ) or to a string! ( mold/all ). Strings and files can be deserialized using the polymorphic load function. RProtoBuf provides cross-language data serialization in R, using Protocol Buffers . Ruby includes the standard module Marshal with 2 methods dump and load , akin to the standard Unix utilities dump and restore . These methods serialize to

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1296-437: A data structure, transformed by another program, then possibly executed or written out, such as in a read–eval–print loop . Not all readers/writers support cyclic, recursive or shared structures. .NET has several serializers designed by Microsoft . There are also many serializers by third parties. More than a dozen serializers are discussed and tested here . and here OCaml 's standard library provides marshalling through

1404-626: A data type tags, support for cyclic data structures, indentation-sensitive syntax, and multiple forms of scalar data quoting. YAML is an open format. Property lists are used for serialization by NeXTSTEP , GNUstep , macOS , and iOS frameworks . Property list , or p-list for short, doesn't refer to a single serialization format but instead several different variants, some human-readable and one binary. For large volume scientific datasets, such as satellite data and output of numerical climate, weather, or ocean models, specific binary serialization standards have been developed, e.g. HDF , netCDF and

1512-491: A human readable form using the storeOn: / readFrom: protocol. The storeOn: method generates the text of a Smalltalk expression which – when evaluated using readFrom: – recreates the original object. This scheme is special, in that it uses a procedural description of the object, not the data itself. It is therefore very flexible, allowing for classes to define more compact representations. However, in its original form, it does not handle cyclic data structures or preserve

1620-593: A list of arrays would be printed by (print foo) . Similarly an object can be read from a stream named s by (read s) . These two parts of the Lisp implementation are called the Printer and the Reader. The output of " print " is human readable; it uses lists demarked by parentheses, for example: ( 4 2.9 "x" y ) . In many types of Lisp, including Common Lisp , the printer cannot represent every type of data because it

1728-448: A list of syntax rules provided in the specification. Some key points in the fairly lengthy list include: The definition of an XML document excludes texts that contain violations of well-formedness rules; they are simply not XML. An XML processor that encounters such a violation is required to report such errors and to cease normal processing. This policy, occasionally referred to as " draconian error handling", stands in notable contrast to

1836-522: A mechanism whereby an XML processor can reliably, without any prior knowledge, determine which encoding is being used. Encodings other than UTF-8 and UTF-16 are not necessarily recognized by every XML parser (and in some cases not even UTF-16, even though the standard mandates it to also be recognized). XML provides escape facilities for including characters that are problematic to include directly. For example: There are five predefined entities : All permitted Unicode characters may be represented with

1944-653: A method), because executable code in functions cannot be transmitted across different programs. (There is a flag to marshal the code position of a function but it can only be unmarshalled in exactly the same program). The standard marshalling functions can preserve sharing and handle cyclic data, which can be configured by a flag. Several Perl modules available from CPAN provide serialization mechanisms, including Storable , JSON::XS and FreezeThaw . Storable includes functions to serialize and deserialize Perl data structures to and from files or Perl scalars. In addition to serializing directly to files, Storable includes

2052-546: A more compact non-XML syntax; the two syntaxes are isomorphic and James Clark 's conversion tool— Trang —can convert between them without loss of information. RELAX NG has a simpler definition and validation framework than XML Schema, making it easier to use and implement. It also has the ability to use datatype framework plug-ins ; a RELAX NG schema author, for example, can require values in an XML document to conform to definitions in XML Schema Datatypes. Schematron

2160-587: A more complex, non-linear storage organization. Even on a single machine, primitive pointer objects are too fragile to save because the objects to which they point may be reloaded to a different location in memory. To deal with this, the serialization process includes a step called unswizzling or pointer unswizzling , where direct pointer references are converted to references based on name or position. The deserialization process includes an inverse step called pointer swizzling . Since both serializing and deserializing can be driven from common code (for example,

2268-506: A rich datatyping system and allow for more detailed constraints on an XML document's logical structure. XSDs also use an XML-based format, which makes it possible to use ordinary XML tools to help process them. xs:schema element that defines a schema: RELAX NG (Regular Language for XML Next Generation) was initially specified by OASIS and is now a standard (Part 2: Regular-grammar-based validation of ISO/IEC 19757 – DSDL ). RELAX NG schemas may be written in either an XML based syntax or

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2376-964: A serialized object created in Squeak Smalltalk cannot be restored in Ambrai Smalltalk . Consequently, various applications that do work on multiple Smalltalk implementations that rely on object serialization cannot share data between these different implementations. These applications include the MinneStore object database and some RPC packages. A solution to this problem is SIXX, which is a package for multiple Smalltalks that uses an XML -based format for serialization. The Swift standard library provides two protocols, Encodable and Decodable (composed together as Codable ), which allow instances of conforming types to be serialized to or deserialized from JSON , property lists , or other formats. Default implementations of these protocols can be generated by

2484-418: A serialized state. For example, a Thread object is tied to the state of the current JVM . There is no context in which a deserialized Thread object would maintain useful semantics. Secondly, the serialized state of an object forms part of its class' compatibility contract. Maintaining compatibility between versions of serializable classes requires additional effort and consideration. Therefore, making

2592-500: A slow operation, taking on the order of microseconds to complete. During this time, the CPU is unable to perform any operations. As such, minimizing the number of times this switching operation must be performed would optimize performance to a substantive degree. Linux OpenGL drivers are split in two: a kernel-driver and a user-space driver. The user-space driver does all the translation of OpenGL commands into machine code to be submitted to

2700-440: A so-called "binary-object storage framework", which support serialization into and retrieval from a compact binary form. Both handle cyclic, recursive and shared structures, storage/retrieval of class and metaclass info and include mechanisms for "on the fly" object migration (i.e. to convert instances which were written by an older version of a class with a different object layout). The APIs are similar (storeBinary/readBinary), but

2808-616: A specific data format to be chosen as the serialization target. XML is one such format and means of transferring data between systems. Microsoft, for example, uses it as the basis of the file formats of the various components (Word, Excel, Access, PowerPoint, etc.) of the Microsoft Office suite (see Office Open XML ). While this typically results in a verbose wire format, XML's fully-bracketed "start-tag", "end-tag" syntax allows provision of more accurate diagnostics and easier recovery from transmission or disk errors. In addition, because

2916-421: A validity error must be able to report it, but may continue normal processing. A DTD is an example of a schema or grammar . Since the initial publication of XML 1.0, there has been substantial work in the area of schema languages for XML. Such schema languages typically constrain the set of elements that may be used in a document, which attributes may be applied to them, the order in which they may appear, and

3024-527: A vocabulary to refer to the constructs within an XML document, but does not provide any guidance on how to access this information. A variety of APIs for accessing XML have been developed and used, and some have been standardized. Existing APIs for XML processing tend to fall into these categories: Stream-oriented facilities require less memory and, for certain tasks based on a linear traversal of an XML document, are faster and simpler than other alternatives. Tree-traversal and data-binding APIs typically require

3132-458: Is a lexical , event-driven API in which a document is read serially and its contents are reported as callbacks to various methods on a handler object of the user's design. SAX is fast and efficient to implement, but difficult to use for extracting information at random from the XML, since it tends to burden the application author with keeping track of what part of the document is being processed. It

3240-726: Is a language for making assertions about the presence or absence of patterns in an XML document. It typically uses XPath expressions. Schematron is now a standard (Part 3: Rule-based validation of ISO/IEC 19757 – DSDL ). DSDL (Document Schema Definition Languages) is a multi-part ISO/IEC standard (ISO/IEC 19757) that brings together a comprehensive set of small schema languages, each targeted at specific problems. DSDL includes RELAX NG full and compact syntax, Schematron assertion language, and languages for defining datatypes, character repertoire constraints, renaming and entity expansion, and namespace-based routing of document fragments to different validators. DSDL schema languages do not have

3348-436: Is a lightweight plain-text alternative to XML, and is also commonly used for client-server communication in web applications. JSON is based on JavaScript syntax , but is independent of JavaScript and supported in many other programming languages. JSON is an open format, standardized as STD 90 ( RFC   8259 ), ECMA-404 , and ISO/IEC 21778:2017 . YAML is a strict superset of JSON and includes additional features such as

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3456-447: Is a member of the Read type class defines a function that will extract the data from the string representation of the dumped data. The Show type class, in turn, contains the show function from which a string representation of the object can be generated. The programmer need not define the functions explicitly—merely declaring a type to be deriving Read or deriving Show, or both, can make

3564-570: Is an XML industry data standard. XML is used extensively to underpin various publishing formats. One of the applications of XML is in the transfer of Operational meteorology (OPMET) information based on IWXXM standards. The material in this section is based on the XML Specification . This is not an exhaustive list of all the constructs that appear in XML; it provides an introduction to the key constructs most often encountered in day-to-day use. XML documents consist entirely of characters from

3672-466: Is an object-oriented serialization mechanism for objects, the Serializable interface. Prolog 's term structure, which is the only data structure of the language, can be serialized out through the built-in predicate write_term/3 and serialized-in through the built-in predicates read/1 and read_term/2 . The resulting stream is uncompressed text (in some encoding determined by configuration of

3780-498: Is better suited to situations in which certain types of information are always handled the same way, no matter where they occur in the document. Pull parsing treats the document as a series of items read in sequence using the iterator design pattern . This allows for writing of recursive descent parsers in which the structure of the code performing the parsing mirrors the structure of the XML being parsed, and intermediate parsed results can be used and accessed as local variables within

3888-458: Is fully integrated with its IDE . The component's contents are saved to a DFM file and reloaded on-the-fly. Go natively supports unmarshalling/marshalling of JSON and XML data. There are also third-party modules that support YAML and Protocol Buffers . Go also supports Gobs . In Haskell, serialization is supported for types that are members of the Read and Show type classes . Every type that

3996-476: Is generally used in the receiver end of the implementations of Remote Method Invocation (RMI) and Remote procedure call (RPC) mechanisms to unmarshal transmitted objects in an executable form. JAXB or Java Architecture for XML Binding is the most common framework used by developers to marshal and unmarshal Java objects. JAXB provides for the interconversion between fundamental data types supported by Java and standard XML schema data types. XmlSerializer

4104-455: Is globally declared, these methods utilize the JAXBContext's mapping of XML root elements to JAXB mapped classes to initiate the unmarshalling. If the mappings are not sufficient and the root elements are declared locally, the unmarshal methods use declaredType methods for the unmarshalling process. These two approaches can be understood below. The unmarshal method uses JAXBContext to unmarshal

4212-555: Is not clear how to do so. In Common Lisp for example the printer cannot print CLOS objects. Instead the programmer may write a method on the generic function print-object , this will be invoked when the object is printed. This is somewhat similar to the method used in Ruby. Lisp code itself is written in the syntax of the reader, called read syntax. Most languages use separate and different parsers to deal with code and data, Lisp only uses one. A file containing lisp code may be read into memory as

4320-442: Is not permitted because the null character is one of the control characters excluded from XML, even when using a numeric character reference. An alternative encoding mechanism such as Base64 is needed to represent such characters. Comments may appear anywhere in a document outside other markup. Comments cannot appear before the XML declaration. Comments begin with <!-- and end with --> . For compatibility with SGML ,

4428-482: Is not valid JavaScript. Specifically, JSON allows the Unicode line terminators U+2028 LINE SEPARATOR and U+2029 PARAGRAPH SEPARATOR to appear unescaped in quoted strings, while ECMAScript 2018 and older does not. See the main article on JSON . Julia implements serialization through the serialize() / deserialize() modules, intended to work within the same version of Julia, and/or instance of

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4536-462: Is that, because the encoding of the data is by definition serial, extracting one part of the serialized data structure requires that the entire object be read from start to end, and reconstructed. In many applications, this linearity is an asset, because it enables simple, common I/O interfaces to be utilized to hold and pass on the state of an object. In applications where higher performance is an issue, it can make sense to expend more effort to deal with

4644-424: Is the framework used by C# developers to marshal and unmarshal C# objects. One of the advantages of C# over Java is that C# natively supports marshalling due to the inclusion of XmlSerializer class. Java, on the other hand requires a non-native glue code in the form of JAXB to support marshalling. An example of unmarshalling is the conversion of an XML representation of an object to the default representation of

4752-552: Is useful in the programming of user interfaces whose contents are time-varying — graphical objects can be created, removed, altered, or made to handle input events without necessarily having to write separate code to do those things. Serialization breaks the opacity of an abstract data type by potentially exposing private implementation details. Trivial implementations which serialize all data members may violate encapsulation . To discourage competitors from making compatible products, publishers of proprietary software often keep

4860-422: Is usually used to do marshalling. The term deserialization is somewhat similar to un -marshalling a dry object "on the server side", i.e., demarshalling (or unmarshalling) to get a live object back: the serialized object is transformed into an internal data structure, i.e., a live object within the target runtime. It usually corresponds to the exact inverse process of marshalling, although sometimes both ends of

4968-523: The Marshal module and the Pervasives functions output_value and input_value . While OCaml programming is statically type-checked, uses of the Marshal module may break type guarantees, as there is no way to check whether an unmarshalled stream represents objects of the expected type. In OCaml it is difficult to marshal a function or a data structure which contains a function (e.g. an object which contains

5076-538: The freeze function to return a serialized copy of the data packed into a scalar, and thaw to deserialize such a scalar. This is useful for sending a complex data structure over a network socket or storing it in a database. When serializing structures with Storable , there are network safe functions that always store their data in a format that is readable on any computer at a small cost of speed. These functions are named nstore , nfreeze , etc. There are no "n" functions for deserializing these structures —

5184-581: The Boost Framework , the S11n framework, and Cereal. MFC framework (Microsoft) also provides serialization methodology as part of its Document-View architecture. CFML allows data structures to be serialized to WDDX with the <cfwddx> tag and to JSON with the SerializeJSON() function. Delphi provides a built-in mechanism for serialization of components (also called persistent objects), which

5292-580: The GPU . To reduce the number of system calls, the user-space driver implements marshalling. If the GPU's command buffer is full of rendering data, the API could simply store the requested rendering call in a temporary buffer and, when the command buffer is close to being empty, it can perform a switch to kernel-mode and add a number of stored commands all at once. Marshalling data requires some kind of data transfer, which leverages

5400-504: The Internet . It is a textual data format with strong support via Unicode for different human languages . Although the design of XML focuses on documents, the language is widely used for the representation of arbitrary data structures , such as those used in web services . Several schema systems exist to aid in the definition of XML-based languages, while programmers have developed many application programming interfaces (APIs) to aid

5508-598: The Microsoft Windows family of operating systems the entire set of device drivers for Direct3D are kernel-mode drivers. The user-mode portion of the API is handled by the DirectX runtime provided by Microsoft. This is an issue because calling kernel-mode operations from user-mode requires performing a system call , and this inevitably forces the CPU to switch to "kernel mode". This is

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5616-601: The P/Invoke process, is also an example of an action that requires marshalling to take place. Additionally, marshalling is used extensively within scripts and applications that use the XPCOM technologies provided within the Mozilla application framework . The Mozilla Firefox browser is a popular application built with this framework, that additionally allows scripting languages to use XPCOM through XPConnect (Cross-Platform Connect). In

5724-542: The Serialize function in Microsoft Foundation Classes ), it is possible for the common code to do both at the same time, and thus, 1) detect differences between the objects being serialized and their prior copies, and 2) provide the input for the next such detection. It is not necessary to actually build the prior copy because differences can be detected on the fly, a technique called differential execution. This

5832-404: The Unicode repertoire. Except for a small number of specifically excluded control characters , any character defined by Unicode may appear within the content of an XML document. XML includes facilities for identifying the encoding of the Unicode characters that make up the document, and for expressing characters that, for one reason or another, cannot be used directly. Unicode code points in

5940-410: The infoset augmentation facility and attribute defaults. RELAX NG and Schematron intentionally do not provide these. A cluster of specifications closely related to XML have been developed, starting soon after the initial publication of XML 1.0. It is frequently the case that the term "XML" is used to refer to XML together with one or more of these other technologies that have come to be seen as part of

6048-558: The External Data Representation (XDR) standard as described in RFC 1014). Finally, it is recommended that an object's __repr__ be evaluable in the right environment, making it a rough match for Common Lisp's print-object . Not all object types can be pickled automatically, especially ones that hold operating system resources like file handles , but users can register custom "reduction" and construction functions to support

6156-429: The XML core. Some other specifications conceived as part of the "XML Core" have failed to find wide adoption, including XInclude , XLink , and XPointer . The design goals of XML include, "It shall be easy to write programs which process XML documents." Despite this, the XML specification contains almost no information about how programmers might go about doing such processing. The XML Infoset specification provides

6264-447: The XML data, when the root element is globally declared. The JAXBContext object always maintains a mapping of the globally declared XML element and its name to a JAXB mapped class. If the XML element name or its @xsi:type attribute matches the JAXB mapped class, the unmarshal method transforms the XML data using the appropriate JAXB mapped class. However, if the XML element name has no match,

6372-549: The XML processor inserts in the DTD itself and in the XML document wherever they are referenced, like character escapes. DTD technology is still used in many applications because of its ubiquity. A newer schema language, described by the W3C as the successor of DTDs, is XML Schema , often referred to by the initialism for XML Schema instances, XSD (XML Schema Definition). XSDs are far more powerful than DTDs in describing XML languages. They use

6480-437: The accelerated version and falls back to the pure Python version. R has the function dput which writes an ASCII text representation of an R object to a file or connection. A representation can be read from a file using dget . More specific, the function serialize serializes an R object to a connection, the output being a raw vector coded in hexadecimal format. The unserialize function allows to read an object from

6588-434: The allowable parent/child relationships. The oldest schema language for XML is the document type definition (DTD), inherited from SGML. DTDs have the following benefits: DTDs have the following limitations: Two peculiar features that distinguish DTDs from other schema types are the syntactic support for embedding a DTD within XML documents and for defining entities , which are arbitrary fragments of text or markup that

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6696-598: The base language for communication protocols such as SOAP and XMPP . It is one of the message exchange formats used in the Asynchronous JavaScript and XML (AJAX) programming technique. Many industry data standards, such as Health Level 7 , OpenTravel Alliance , FpML , MISMO , and National Information Exchange Model are based on XML and the rich features of the XML schema specification. In publishing, Darwin Information Typing Architecture

6804-401: The behavior of programs that process HTML , which are designed to produce a reasonable result even in the presence of severe markup errors. XML's policy in this area has been criticized as a violation of Postel's law ("Be conservative in what you send; be liberal in what you accept"). The XML specification defines a valid XML document as a well-formed XML document which also conforms to

6912-493: The built-in data types , as well as plain old data structs , as binary data. As such, it is usually trivial to write custom serialization functions. Moreover, compiler-based solutions, such as the ODB ORM system for C++ and the gSOAP toolkit for C and C++, are capable of automatically producing serialization code with few or no modifications to class declarations. Other popular serialization frameworks are Boost.Serialization from

7020-416: The built-in cmdlets Import-CSV and Export-CSV . Marshalling (computer science) In computer science , marshalling or marshaling ( US spelling ) is the process of transforming the memory representation of an object into a data format suitable for storage or transmission , especially between different runtimes . It is typically used when data must be moved between different parts of

7128-423: The case of C1 characters, this restriction is a backwards incompatibility; it was introduced to allow common encoding errors to be detected. The code point U+0000 (Null) is the only character that is not permitted in any XML 1.1 document. The Unicode character set can be encoded into bytes for storage or transmission in a variety of different ways, called "encodings". Unicode itself defines encodings that cover

7236-705: The compiler for types whose stored properties are also Decodable or Encodable . PowerShell implements serialization through the built-in cmdlet Export-CliXML . Export-CliXML serializes .NET objects and stores the resulting XML in a file. To reconstitute the objects, use the Import-CliXML cmdlet, which generates a deserialized object from the XML in the exported file. Deserialized objects, often known as "property bags" are not live objects; they are snapshots that have properties, but no methods. Two dimensional data structures can also be (de)serialized in CSV format using

7344-529: The compiler generate the appropriate functions for many cases (but not all: function types, for example, cannot automatically derive Show or Read). The auto-generated instance for Show also produces valid source code, so the same Haskell value can be generated by running the code produced by show in, for example, a Haskell interpreter. For more efficient serialization, there are haskell libraries that allow high-speed serialization in binary format, e.g. binary . Java provides automatic serialization which requires that

7452-501: The corresponding manual pages for SWI-Prolog, SICStus Prolog, GNU Prolog. Whether and how serialized terms received over the network are checked against a specification (after deserialization from the character stream has happened) is left to the implementer. Prolog's built-in Definite Clause Grammars can be applied at that stage. The core general serialization mechanism is the pickle standard library module, alluding to

7560-429: The data structure and contain metadata . What is within the tags is data, encoded in the way the XML standard specifies. An additional XML schema (XSD) defines the necessary metadata for interpreting and validating XML. (This is also referred to as the canonical schema.) An XML document that adheres to basic XML rules is "well-formed"; one that adheres to its schema is "valid." IETF RFC 7303 (which supersedes

7668-798: The database systems term pickling to describe data serialization ( unpickling for deserializing ). Pickle uses a simple stack -based virtual machine that records the instructions used to reconstruct the object. It is a cross-version customisable but unsafe (not secure against erroneous or malicious data) serialization format. Malformed or maliciously constructed data, may cause the deserializer to import arbitrary modules and instantiate any object. The standard library also includes modules serializing to standard data formats: json (with built-in support for basic scalar and collection types and able to support arbitrary types via encoding and decoding hooks ). plistlib (with support for both binary and XML property list formats). xdrlib (with support for

7776-612: The details of their programs' serialization formats a trade secret . Some deliberately obfuscate or even encrypt the serialized data. Yet, interoperability requires that applications be able to understand each other's serialization formats. Therefore, remote method call architectures such as CORBA define their serialization formats in detail. Many institutions, such as archives and libraries, attempt to future proof their backup archives—in particular, database dumps —by storing them in some relatively human-readable serialized format. The Xerox Network Systems Courier technology in

7884-442: The direct use of almost any Unicode character in element names, attributes, comments, character data, and processing instructions (other than the ones that have special symbolic meaning in XML itself, such as the less-than sign, "<"). The following is a well-formed XML document including Chinese , Armenian and Cyrillic characters: The XML specification defines an XML document as a well-formed text, meaning that it satisfies

7992-456: The disadvantage of losing the more compact, byte-stream-based encoding, but by this point larger storage and transmission capacities made file size less of a concern than in the early days of computing. In the 2000s, XML was often used for asynchronous transfer of structured data between client and server in Ajax web applications. XML is an open format, and standardized as a W3C recommendation . JSON

8100-450: The distinction between the two concepts. A few examples: In Python , the term "marshal" is used for a specific type of "serialization" in the Python standard library – storing internal python objects: The marshal module exists mainly to support reading and writing the “pseudo-compiled” code for Python modules of .pyc files. … If you’re serializing and de-serializing Python objects, use

8208-637: The early 1980s influenced the first widely adopted standard. Sun Microsystems published the External Data Representation (XDR) in 1987. XDR is an open format , and standardized as STD 67 (RFC 4506). In the late 1990s, a push to provide an alternative to the standard serialization protocols started: XML , an SGML subset, was used to produce a human-readable text-based encoding . Such an encoding can be useful for persistent objects that may be read and understood by humans, or communicated to other systems regardless of programming language. It has

8316-530: The encoding details are different, making these two formats incompatible. However, the Smalltalk/X code is open source and free and can be loaded into other Smalltalks to allow for cross-dialect object interchange. Object serialization is not part of the ANSI Smalltalk specification. As a result, the code to serialize an object varies by Smalltalk implementation. The resulting binary data also varies. For instance,

8424-516: The entire repertoire; well-known ones include UTF-8 (which the XML standard recommends using, without a BOM ) and UTF-16 . There are many other text encodings that predate Unicode, such as ASCII and various ISO/IEC 8859 ; their character repertoires are in every case subsets of the Unicode character set. XML allows the use of any of the Unicode-defined encodings and any other encodings whose characters also appear in Unicode. XML also provides

8532-498: The following ranges are valid in XML 1.0 documents: XML 1.1 extends the set of allowed characters to include all the above, plus the remaining characters in the range U+0001–U+001F. At the same time, however, it restricts the use of C0 and C1 control characters other than U+0009 (Horizontal Tab), U+000A (Line Feed), U+000D (Carriage Return), and U+0085 (Next Line) by requiring them to be written in escaped form (for example U+0001 must be written as &#x01; or its equivalent). In

8640-685: The functions performing the parsing, or passed down (as function parameters) into lower-level functions, or returned (as function return values) to higher-level functions. Examples of pull parsers include Data::Edit::Xml in Perl , StAX in the Java programming language, XMLPullParser in Smalltalk , XMLReader in PHP , ElementTree.iterparse in Python , SmartXML in Red , System.Xml.XmlReader in

8748-642: The identity of shared references (i.e. two references a single object will be restored as references to two equal, but not identical copies). For this, various portable and non-portable alternatives exist. Some of them are specific to a particular Smalltalk implementation or class library. There are several ways in Squeak Smalltalk to serialize and store objects. The easiest and most used are storeOn:/readFrom: and binary storage formats based on SmartRefStream serializers. In addition, bundled objects can be stored and retrieved using ImageSegments . Both provide

8856-438: The java.rmi.Remote interface. When such an object is invoked, its arguments are marshalled and sent from the local virtual machine to the remote one, where the arguments are unmarshalled and used. In .NET , marshalling is also used to refer to serialization when using remote calls : When you marshal an object by value, a copy of the object is created and serialized to the server. Any method calls made on that object are done on

8964-399: The mapping. However, if the @xsi:type attribute of the XML data has a mapping to an appropriate JAXB class, then this takes precedence over declaredType parameter. The unmarshal methods by declaredType parameters always return a JAXBElement<declaredType> instance. The properties of this JAXBElement instance are set as follows: XML Extensible Markup Language ( XML ) is

9072-413: The marshalled data containing codebase(s) into an executable Java object in JAXB. Any object that can be deserialized can be unmarshalled. However, the converse need not be true. To "marshal" an object means to record its state and codebase(s) in such a way that when the marshalled object is "unmarshalled," a copy of the original object is obtained, possibly by automatically loading the class definitions of

9180-415: The object be marked by implementing the java.io.Serializable interface . Implementing the interface marks the class as "okay to serialize", and Java then handles serialization internally. There are no serialization methods defined on the Serializable interface, but a serializable class can optionally define methods with certain special names and signatures that if defined, will be called as part of

9288-424: The object in any programming language. Consider the following class: Unmarshalling is the process of converting the XML representation of Code Snippet 1 to the default executable Java representation of Code Snippet 2, and running that very code to get a consistent, live object back. Had a different format been chosen, the unmarshalling process would have been different, but the end result in the target runtime would be

9396-408: The object. You can marshal any object that is serializable or remote (that is, implements the java.rmi.Remote interface). Marshalling is like serialization, except marshalling also records codebases. Marshalling is different from serialization in that marshalling treats remote objects specially. … Any object whose methods can be invoked [on an object in another Java virtual machine] must implement

9504-595: The older GRIB . Several object-oriented programming languages directly support object serialization (or object archival ), either by syntactic sugar elements or providing a standard interface for doing so. The languages which do so include Ruby , Smalltalk , Python , PHP , Objective-C , Delphi , Java , and the .NET family of languages. There are also libraries available that add serialization support to languages that lack native support for it. C and C++ do not provide serialization as any sort of high-level construct, but both languages support writing any of

9612-550: The older RFC 3023 ), provides rules for the construction of media types for use in XML message. It defines three media types: application/xml ( text/xml is an alias), application/xml-external-parsed-entity ( text/xml-external-parsed-entity is an alias) and application/xml-dtd . They are used for transmitting raw XML files without exposing their internal semantics . RFC 7303 further recommends that XML-based languages be given media types ending in +xml , for example, image/svg+xml for SVG . Further guidelines for

9720-482: The pickle module instead In the Java -related RFC   2713 , marshalling is used when serializing objects for remote invocation . An object that is marshalled records the state of the original object and it contains the codebase ( codebase here refers to a list of URLs where the object code can be loaded from, and not source code). Hence, in order to convert the object state and codebase(s), unmarshalling must be done. The unmarshaller interface automatically converts

9828-464: The pickling and unpickling of arbitrary types. Pickle was originally implemented as the pure Python pickle module, but, in versions of Python prior to 3.0, the cPickle module (also a built-in) offers improved performance (up to 1000 times faster). The cPickle was adapted from the Unladen Swallow project. In Python 3, users should always import the standard version, which attempts to import

9936-478: The process trigger specific business logic. The accurate definition of marshalling differs across programming languages such as Python , Java , and .NET , and in some contexts, is used interchangeably with serialization. To " serialize " an object means to convert its state into a byte stream in such a way that the byte stream may be converted back into a copy of the object, which is unmarshalling in essence. Different programming languages either make or don’t make

10044-449: The processing of XML data. The main purpose of XML is serialization , i.e. storing, transmitting, and reconstructing arbitrary data. For two disparate systems to exchange information, they need to agree upon a file format. XML standardizes this process. It is therefore analogous to a lingua franca for representing information. As a markup language , XML labels, categorizes, and structurally organizes information. XML tags represent

10152-517: The regular thaw and retrieve deserialize structures serialized with the " n " functions and their machine-specific equivalents. PHP originally implemented serialization through the built-in serialize() and unserialize() functions. PHP can serialize any of its data types except resources (file pointers, sockets, etc.). The built-in unserialize() function is often dangerous when used on completely untrusted data. For objects, there are two " magic methods" that can be implemented within

10260-487: The rules of a Document Type Definition (DTD). In addition to being well formed, an XML document may be valid . This means that it contains a reference to a Document Type Definition (DTD), and that its elements and attributes are declared in that DTD and follow the grammatical rules for them that the DTD specifies. XML processors are classified as validating or non-validating depending on whether or not they check XML documents for validity. A processor that discovers

10368-446: The same system image. The HDF5.jl package offers a more stable alternative, using a documented format and common library with wrappers for different languages, while the default serialization format is suggested to have been designed rather with maximal performance for network communication in mind. Generally a Lisp data structure can be serialized with the functions " read " and " print ". A variable foo containing, for example,

10476-468: The same. The process of unmarshalling XML data into an executable Java object is taken care of by the in-built Unmarshaller class. The unmarshal methods defined in the Unmarshaller class are overloaded to accept XML from different types of input such as a File, FileInputStream, or URL. For example: Unmarshal methods can deserialize an entire XML document or a small part of it. When the XML root element

10584-538: The serialization for an object so that some portion of the reference graph is truncated and not serialized. Java does not use constructor to serialize objects. It is possible to serialize Java objects through JDBC and store them into a database. While Swing components do implement the Serializable interface, they are not guaranteed to be portable between different versions of the Java Virtual Machine. As such,

10692-573: The serialization/deserialization process. The language also allows the developer to override the serialization process more thoroughly by implementing another interface, the Externalizable interface, which includes two special methods that are used to save and restore the object's state. There are three primary reasons why objects are not serializable by default and must implement the Serializable interface to access Java's serialization mechanism. Firstly, not all objects capture useful semantics in

10800-414: The server Marshalling is used within implementations of different remote procedure call (RPC) mechanisms, where it is necessary to transport data between processes and/or between threads . In Microsoft's Component Object Model (COM), interface pointers must be marshalled when crossing COM apartment boundaries. In the .NET Framework , the conversion between an unmanaged type and a CLR type, as in

10908-488: The standard class String , that is, they effectively become a sequence of bytes. Some objects cannot be serialized (doing so would raise a TypeError exception): bindings, procedure objects, instances of class IO, singleton objects and interfaces. If a class requires custom serialization (for example, it requires certain cleanup actions done on dumping / restoring), it can be done by implementing 2 methods: _dump and _load . The instance method _dump should return

11016-469: The string "--" (double-hyphen) is not allowed inside comments; this means comments cannot be nested. The ampersand has no special significance within comments, so entity and character references are not recognized as such, and there is no way to represent characters outside the character set of the document encoding. An example of a valid comment: <!--no need to escape <code> & such in comments--> XML 1.0 (Fifth Edition) and XML 1.1 support

11124-478: The tags occur repeatedly, one can use standard compression methods to shrink the content—all the Office file formats are created by zipping the raw XML. Alternative formats such as JSON (JavaScript Object Notation) are more concise, but correspondingly less robust for error recovery. Once the data is transferred to a program or an application, it needs to be converted back to an object for usage. Hence, unmarshalling

11232-624: The target stream), with any free variables in the term represented by placeholder variable names. The predicate write_term/3 is standardized in the ISO Specification for Prolog (ISO/IEC 13211-1) on pages 59 ff. ("Writing a term, § 7.10.5"). Therefore it is expected that terms serialized-out by one implementation can be serialized-in by another without ambiguity or surprises. In practice, implementation-specific extensions (e.g. SWI-Prolog's dictionaries) may use non-standard term structures, so interoperability may break in edge cases. As examples, see

11340-410: The unmarshal process will abort and throw an UnmarshalException . This can be avoided by using the unmarshal by declaredType methods. When the root element is not declared globally, the application assists the unmarshaller by application-provided mapping using declaredType parameters. By an order of precedence, even if the root name has a mapping to an appropriate JAXB class, the declaredType overrides

11448-522: The use of XML in a networked context appear in RFC 3470 , also known as IETF BCP 70, a document covering many aspects of designing and deploying an XML-based language. XML has come into common use for the interchange of data over the Internet. Hundreds of document formats using XML syntax have been developed, including RSS , Atom , Office Open XML , OpenDocument , SVG , COLLADA , and XHTML . XML also provides

11556-472: The use of much more memory, but are often found more convenient for use by programmers; some include declarative retrieval of document components via the use of XPath expressions. XSLT is designed for declarative description of XML document transformations, and has been widely implemented both in server-side packages and Web browsers. XQuery overlaps XSLT in its functionality, but is designed more for searching of large XML databases . Simple API for XML (SAX)

11664-426: The vendor support of XML Schemas yet, and are to some extent a grassroots reaction of industrial publishers to the lack of utility of XML Schemas for publishing . Some schema languages not only describe the structure of a particular XML format but also offer limited facilities to influence processing of individual XML files that conform to this format. DTDs and XSDs both have this ability; they can for instance provide

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