Classifications

• • G—PHYSICS
  • G06—COMPUTING OR CALCULATING; COUNTING
  • G06F—ELECTRIC DIGITAL DATA PROCESSING
  • G06F11/00—Error detection; Error correction; Monitoring
  • G06F11/07—Responding to the occurrence of a fault, e.g. fault tolerance
  • G06F11/14—Error detection or correction of the data by redundancy in operation
  • G06F11/1402—Saving, restoring, recovering or retrying
  • G06F11/1415—Saving, restoring, recovering or retrying at system level
  • G06F11/1433—Saving, restoring, recovering or retrying at system level during software upgrading
• • G—PHYSICS
  • G06—COMPUTING OR CALCULATING; COUNTING
  • G06F—ELECTRIC DIGITAL DATA PROCESSING
  • G06F8/00—Arrangements for software engineering
  • G06F8/60—Software deployment
  • G06F8/61—Installation
  • G06F8/62—Uninstallation
• • G—PHYSICS
  • G06—COMPUTING OR CALCULATING; COUNTING
  • G06F—ELECTRIC DIGITAL DATA PROCESSING
  • G06F8/00—Arrangements for software engineering
  • G06F8/60—Software deployment
  • G06F8/65—Updates
  • G06F8/654—Updates using techniques specially adapted for alterable solid state memories, e.g. for EEPROM or flash memories
• • G—PHYSICS
  • G06—COMPUTING OR CALCULATING; COUNTING
  • G06F—ELECTRIC DIGITAL DATA PROCESSING
  • G06F8/00—Arrangements for software engineering
  • G06F8/60—Software deployment
  • G06F8/65—Updates
  • G06F8/658—Incremental updates; Differential updates
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10S707/00—Data processing: database and file management or data structures
  • Y10S707/99951—File or database maintenance
  • Y10S707/99952—Coherency, e.g. same view to multiple users
  • Y10S707/99953—Recoverability
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10S707/00—Data processing: database and file management or data structures
  • Y10S707/99951—File or database maintenance
  • Y10S707/99952—Coherency, e.g. same view to multiple users
  • Y10S707/99954—Version management

Definitions

• This invention relates to updating a stored version of content stored in a storage device using an update package. More specifically, this invention relates to in-place updating.
• BACKGROUND OF THE INVENTION Sometimes it is required to update content stored in a storage device. For example, if the content is a software (such as an executable file), it is sometimes required to upgrade the software. However, it should be noted that sometimes other types of content also require updates, such as text or data stored in a database, etc.
• old version or “original version” refers to content before update
• new version or “updated version” refers to the content after it was updated.
• An “update package”, sometimes referred to also as a “difference”, a “difference result” or a “delta” includes data provided as input for an update process, wherein the update process updates the old version to the new version in accordance with the update package.
• US 6,546,552 (“Difference extraction between two versions of data-tables containing intra-references" , published 2003) discloses a method for generating a compact difference result between an old program and a new program.
• Each program includes reference entries that contain references that refer to other entries in the program.
• the old program is scanned and for each reference entry, the reference is replaced by a distinct label mark, whereby a modified old program is generated.
• the new program is scanned and for each reference entry, the reference is replaced by a distinct label mark, whereby a modified new program is generated.
• WO 2004/114130 discloses a system and method for generating a compact update package between an old version of content and a new version of content.
• the system of WO 2004/114130 includes a conversion element generator for generating a conversion element associated with the old version and new version. It also includes a modified version generator for generating a modified version, and an update package generator for generating the compact update package.
• the compact update package includes the conversion element and a modified delta based on the modified version and the new version.
• WO 2005/003963 (“Method and system for updating versions of content stored in a storage device ' ", published 2005) discloses a system and method for updating versions of content stored in a storage device.
• the system of WO 2005/003963 includes an update module for obtaining a conversion element and a small delta. It also includes a converted old items generator for generating converted old items by applying the conversion element to items of an old version, a data entries generator for generating data entries based on the modified data entries and on the converted old item, and a new version generator for generating a new version of content by applying the commands and the data entries to the old version.
• US 6,832,373 (“System and method for updating and distributing information", published 2004) discloses devices, systems and ,methods for updating digital information sequences that are comprised by software, devices, and data. In addition, these digital information sequences may be stored and used in various forms, including, but not limited to files, memory locations, and/or embedded storage locations. Furthermore, the devices, systems, and methods described in US 6,832,373 provide a developer skilled in the art with an ability to generate update information as needed and, additionally, allow users to proceed through a simplified update path, which is not error-prone, and may be performed more quickly than through the use of technologies existing when US 6,832,373 was filed.
• in-place update or "updating in-place”.
• an update process can process the blocks of the old version in an order which does not necessarily correspond to the sequential order of the blocks within the file.
• the order, in accordance with which blocks of the old version are updated, is referred to as an "update sequence" or "update order”.
• update sequence or "update order”.
• the storage device can store content which is partly original and partly updated version.
• the old content is sometimes required for the update process, such as in a delta update method. Therefore, if the update process is interrupted through the course of its running, before the creation of the new version is completed and when the stored content (or stored version) is partly old version and partly new version, the in-place update process cannot be repeated from start anymore.
• in-place updating can be sensitive to interruptions. When the process of in-place updating tries to resume from the point where it was interrupted (the resume location), it requires information that allows calculation of the location of interruption.
• the update process may also need to restore other information, which was available to the interrupted process at the time of interruption.
• a record referred to hereinafter as "state record” is commonly used for storing results of calculations calculated before the interruption.
• the results, together with the identification of the current updated block form a "state" of the in-place update process. For example, if the update package is compressed and it is being decompressed on-the-fly during the update process for reading just the necessary parts for updating each old block, and were the amount of data decompressed from the update package, depends on old contents of updated blocks, then this amount cannot be re-computed again once blocks were actually updated. As mentioned already above, the process cannot restart from its beginning.
• state recording Using state recording enables the resumption of an in-place update process by re-constructing the state of the process as it was at the last successful update operation, and to continue the process towards its completion.
• the information stored during state recording cannot be part of the contents being updated and must be separated to another area of storage.
• State recording takes time since it involves read & write operations from and to the storage device.
• the time required for the whole process is doubled - for each updated block there is another block to update - the one holding the state's recording.
• the present invention provides a method for updating a stored version of content stored in a storage device using an update package, wherein the update package is adapted for updating an original version of content to an updated version, wherein the update package includes update commands and wherein the updating is carried out in accordance with an update sequence, the method comprising: determining direction of the updating including: if the direction is indicative of forward then forward-updating the stored version to the updated version in accordance with the update sequence; if the direction is indicative of roll-back generating a roll-back update sequence opposite to the update sequence and rolling-back the stored version to the original version in accordance with the roll-back update sequence.
• the present invention further provides a method for reversing an update process, the update process is adapted for updating a stored version of content stored in a storage device to one of a group including an updated version and an original version using an update package, the method comprising: reversing update commands in the update package that were previously performed during updating.
• a method for in-place updating a stored version of content stored in a storage device using an update package wherein the update package is adapted for updating an original version of content to an updated version, the method comprising: determining direction of the updating; if the direction is indicative of forward then forward-updating the stored version to the updated version; otherwise rolling-back the stored version to the original version.
• a method for providing an update process of a stored version comprising: providing a forward update for updating the stored version to a first version; providing a roll-back update for updating the stored version to a second version; applying a first update operation being either of said forward update and said roll-back update; and applying a second update operation being either of said forward update and said roll-back update and being other than said first update operations.
• a method for providing an update process of a stored version comprising: applying a roll-back update for updating the stored version to an original version.
• a system for updating a stored version of content stored in a storage device using an update package wherein the update package is adapted for updating an original version of content to an updated version, wherein the update package includes update commands and wherein the updating is carried out in accordance with an update sequence
• the system comprising: a direction determination unit adapted for determining direction of the updating, a forward updating processor coupled to the direction determination unit for forward-updating the stored version to the updated version in accordance with the update sequence when the direction of the updating is indicative of forward; a roll-back sequence generator coupled to the direction determination unit for generating a roll-back update sequence opposite to the update sequence when the direction of the updating is indicative of roll-back; and a roll-back updating processor coupled to the roll-back sequence generator for rolling back the stored version to the original version in accordance with the roll- back update .
• the present invention provide a system for reversing an update process, the update process is adapted for updating a stored version of content stored in a storage device to one of a group including an updated version and an original version using an update package, the system comprising: an update commands reversal unit for reversing update commands in the update package that were previously performed during updating.
• a system for in-place updating a stored version of content stored in a storage device using an update package wherein the update package is adapted for updating an original version of content to an updated version
• the system comprising: a direction determination unit adapted for determining direction of the updating; a forward updating processor coupled to the direction determination unit for forward-updating the stored version to the updated version when the direction is indicative of forward; and a roll-back updating processor coupled to the direction determination unit for rolling-back the stored version to the original version when the direction is indicative of roll-back.
• FIG. 1 is a schematic illustration of a system for updating versions in a cellular network, in accordance with one embodiment of the invention
• Fig. 2 demonstrates simplified exemplary stages in updating an original version to an updated version
• Fig. 3 demonstrates an exemplary original version and a corresponding exemplary updated version
• Fig. 4 demonstrates exemplary update packages adapted to update the original version of Fig. 3 to the updated version thereof
• Fig. 1 is a schematic illustration of a system for updating versions in a cellular network, in accordance with one embodiment of the invention
• Fig. 2 demonstrates simplified exemplary stages in updating an original version to an updated version
• Fig. 3 demonstrates an exemplary original version and a corresponding exemplary updated version
• Fig. 4 demonstrates exemplary update packages adapted to update the original version of Fig. 3 to the updated version thereof
• Fig. 1 is a schematic illustration of a system for updating versions in a cellular network, in accordance with one embodiment of the invention
• Fig. 2 demonstrates simplified exemplary
• FIG. 5 is a flowchart illustrating operations performed before reversing an update process, according to an embodiment of the invention
• Fig. 6 demonstrates by way of example storing deleted content, according to one embodiment of the invention
• Fig. 7 demonstrates by way of example reducing usage of a content reserve buffer, according to one embodiment of the invention
• Fig. 8 is a flowchart illustrating the main procedures performed while updating an original version to an updated version in a reversible update process, according to one embodiment of the invention
• Fig. 9 is a flowchart illustrating in detail forward-updating a stored version, according to one embodiment of the invention
• Fig. 10 is a flowchart illustrating in detail rolling-back a stored version, according to one embodiment of the invention.
• Fig. 11 is a block diagram schematically illustrating a system for updating a stored version of content stored in a storage device, according to one embodiment of the invention.
• Fig. 12 is a block diagram schematically illustrating a system for reversing an update process, according to one embodiment of the invention.
• Fig. 13 is a block diagram schematically illustrating a system for updating a stored version of content stored in a storage device, according to another embodiment of the invention.
• FIG. 1 is a schematic illustration of a system 101 for updating versions in a cellular network, in accordance with one embodiment of the invention.
• Cellular telephones 102 that are coupled to or include storage devices 103, execute programs that enable their operation. Programs are normally stored in files.
• the version of the program currently executing in the cellular telephones is referred to, hereinafter, as an "old version” or as an "original version”.
• storage devices such as the storage devices 103, are sometimes referred to also as “storage devices” or “memory units”.
• update process operates in accordance with an update package (constituting a "delta file") that the cellular telephone receives.
• an update package is generated in an update package generator 104, operating, for example, in a personal computer (PC) or in any other type of computer.
• the update package is stored in an update server 105 and transmitted, via a transmitter 106 to the cellular telephones 102.
• the invention is not limited to updating programs.
• Many other types of content stored in storage devices require update, such as data stored in databases, files stored in the storage device etc. Therefore, hereinafter the term “content” will be used instead of "program”.
• the invention is not limited to cellular networks and/or to cellular telephones 102.
• cellular telephones belong to a group referred to as embedded devices.
• embedded devices such as Personal Digital Assistants (PDAs), set-top boxes and other consumer electronic devices that are coupled to storage devices for storing content, and sometimes it is required to update the content stored therein.
• PDAs Personal Digital Assistants
• set-top boxes and other consumer electronic devices that are coupled to storage devices for storing content, and sometimes it is required to update the content stored therein.
• the storage devices 103 can be, for example, hard-disk drives, Flash-memory devices or any other storage device.
• a PC or any other computer, can store files that include data required for its operation or for operation of programs executing therein (such as
• update devices can refer to any device that is coupled to a storage device and allows updating content stored therein. It was previously explained that in order to update content stored in the storage devices, update packages are generated, stored in the update server 105 and conveyed to the storage devices or to other devices coupled therewith (such as the cellular telephones 102).
• an update package without storing it first in an update server 105.
• the update package is conveyed via the transmitter 106.
• This is also non-binding and any other way applicable for conveying the update package can be used.
• a cellular telephone 102 When a cellular telephone 102 receives an update package, it can operate an update process in accordance with the update package, wherein the update process updates the original version for generating another version referred to as an "updated version" or as a "new version". It should be noted that the cellular telephone 102 can operate the update process immediately after receiving the update package. Alternatively, it can store the update package in a non-volatile memory, such as in the storage device 103, and operate the update process in some later time (such as on the next time the telephone reboots). It is noted that a storage device can store content of original and/or updated versions. Those versed in the art would appreciate that content is normally stored in files, while a file, or the content stored therein is subject to updates by an update process.
• a file is constituted of logically sequential content.
• a file that includes text wherein the text is "123456789”
• the character '2' is logically consecutive to the character 'T
• the character '3' is logically consecutive to the character '2' etc.
• a logically sequential content is not necessarily stored in a physically sequential manner in the storage device.
• many storage devices include discrete areas in them. For example, hard drives include sectors and so do flash memory modules.
• a discrete area in a storage device is referred to as a "storage block", or shortly as “block”.
• storage block or shortly as “block”.
• RAM Random Access Memory
• a logically sequential content is not necessarily stored in a physically sequential manner in the storage device, it should be appreciated that sequential content can be spread over several storage blocks.
• one storage block can include content belonging to several logically sequential contents (such as several files).
• segments are logically sequential segments of content that perform uniform behavior during update.
• the segment "123” is logically sequential and it informally stays unmodified in the updated version.
• the segment "7” is also logically sequential (a sequence of 1 character is a valid sequence), and it is uniformly moved to occupy the position formerly occupied by "4", etc.
• the previous example of the "123456789” text and the update thereof to the updated version "123756489”, wherein each segment includes logically sequential content and performs uniform behavior during update is a simplified example. In other examples it is possible to divide the content into segments that are logically sequential, perform uniform behavior during update and occupy physically sequential area in one or more physical block.
• an alternative embodiment can limit a segment to occupy physically sequential area in one physical block (unlike “one or more” in the previous example).
• “12" is sequentially stored in two sequential blocks it must be further divided into two segments (one is “1” and the second is "2").
• content of a segment in the updated version corresponds to content of a segment in the original version (an "original segment)
• these segments are considered as “corresponding segments” or "matched segments”.
• Correspondence refers to any logical connection between the segments, wherein the updated segment can be a copy of the original segment, it can be a modified copy of the original segment (e.g., in large segments it is sometimes preferred to copy a whole segment and then modify part of the copied content), or it can include content received by performing a calculation using content stored in the original segment etc. It is noted that sometimes there may be more than one updated segment corresponding to a certain original segment (e.g., the content of the original segment is copied twice, thus generating two updated segments corresponding thereto). The opposite is also true: Sometimes there may be more than one original segment corresponding to a single updated segment (e.g., in order to calculate the content of a single updated segment, it is possible to use content stored in two distinct original segments).
• the update package includes update commands (shortly "commands"), wherein each command corresponds to one segment in the original and/or updated versions.
• An update command can include a code indicative of an update operation and it is appreciated that the codes can be, e.g., a numerical code, bit-mask, a string code or any other code applicable to the case.
• update operations and hence update commands that are allowed for updating an original version to an updated version. For example: A "delete" command corresponds to one segment in the original version, whose content is deleted when generating the updated version (hence this command does not correspond to any segment in the updated version).
• a deleted segment in the original version has no corresponding segment in the updated version.
• the delete command frees the segment in the storage device thus allowing writing other content into the segment. That is, the update process does not need to physically delete the content. It can only mark this area as free.
• An "insert" command corresponds to one segment in the update version, wherein new content is added into this segment.
• An inserted segment in the updated version has no corresponding segment in the original version. It is noted that in some embodiments, when inserted content is written in a non-free area (i.e., physical area that includes content that was not freed before, for example, by a delete command), the original content is overridden by the inserted content and therefore considered as deleted.
• such an insert command is considered as equivalent to a delete command followed by an insert command.
• a "copy" command corresponds to one segment in the original version (an “original segment”) and to one segment in the updated version (an “updated segment”), wherein content of the original segment is copied to the updated segment.
• the original and updated segments are considered as corresponding segments.
• the area previously occupied by the original segment is considered free, thus it is allowed to write other content therein. It is noted that the update process does not need to physically delete (free) the content. It can only mark this area as free.
• inserted content that is written into a non-free area i.e., physical area that includes content that was not freed before, for example, by a delete command
• a copy command is considered as equivalent to a delete command followed by a copy command.
• a "replace" command replaces content of an original segment with new content in the update version and hence it corresponds to one original segment and to one updated segment.
• the content of the original segment is deleted while supplementary data (such as data stored in the replacements supplementary data portion, 419, of Fig. 4 below) is written into the updated segment.
• bitwise XOR exclusive or
• the exemplary commands described above are non-limiting and there may be additional types of update commands (such as "backup") or fewer types of update commands in an update package.
• additional types of update commands such as "backup”
• fewer types of update commands in an update package instead of a "replace” command it is possible to use a combination of “delete” and “insert” as was previously explained.
• the commands corresponding to a single block should better be organized in groups, wherein the commands in each group correspond to one block and do not include commands corresponding to other blocks interweaved in between. Doing this the update process can access in one read operation all the original content that is required from the original block or access in one write operation all the updated content that is required to the updated block. Interweaving commands that correspond to different blocks in an update package adapted to such a storage device, whenever the update process performs an operation in accordance with a command it accesses the whole block, although it actually requires access to a segment thereof.
• the term "stored version" is used for referring to the version currently stored in the storage device.
• the stored version can be, e.g., an original version, it can be an intermediate version, as illustrated, for example, with reference to Fig. 2 below, or it can be an updated version.
• Fig. 2 illustrates simplified exemplary stages in updating an original version 201 to an updated version 202 in a storage device allowing access to whole blocks.
• the original version 201 includes four blocks, specifically these are 203, 204, 205 and 206.
• the updated version 202 also includes four blocks, namely 207, 208, 209 and 210, wherein block 207 replaces block 203, block 208 replaces block 204, block 209 replaces block 205 and block 210 replaces block 206.
• the update process first replaces block 203 with block 207.
• the stored version 211 includes a combination of the original version 201 and the updated version 202, wherein the first block is 207 (which belongs to the updated version) while the other blocks (i.e., 204, 205 and 206) still belong to the original version 201.
• the update process replaces block 204 with block 208, thus the stored version becomes 212.
• the stored version 213 is generated, and finally the stored version becomes the updated version 202.
• Versions that are partly original and partly updated e.g., versions 211, 212, 213) are referred to as "intermediate versions". It should be appreciated that the update process illustrated in Fig. 2 can terminate, normally or not, at any stage.
• the stored version stored in the storage device can be any of the versions 201, 211, 212, 213 or 202. Furthermore, since interruption may occur while storing content in an updated block, the last updated block at the point of interruption may be corrupted, that is, it may contain undefined content as is known to those versed in the art . It should be noted that the example provided with reference to Fig. 2 is by no way binding.
• Original, intermediate and/or updated versions can include any number of blocks, a block can include any applicable number of bits and the update process can perform any operation applicable to the case apart or in addition to replacing blocks (such as deleting blocks, inserting blocks, moving blocks etc.). In addition, in a storage device that allows access to portions of blocks, there can also exist original, updated and intermediate versions.
• Fig. 3 illustrates an exemplary original version 301 and a corresponding exemplary updated version 302.
• the original version is sometimes also referred to as a "source version” while the updated version is sometimes referred to as a "target version”.
• Segments 303, 304, 305, 306, 307 and 308 constitute together the original version 301
• segments 309, 310, 311, 312, 313, 314 and 315 constitute together the updated version 302.
• the original version includes fewer segments compared to the updated version (six segments in the original version compared to seven segments in the updated version).
• the update process inserted new content (segments 311 and 313 in the example) into the updated version.
• the content of segments 303, 305, 306 and 308 in the original version is identical to the content of segments 309, 312, 315 and 314 of the updated version, respectively. That is, the original content of these segments is copied into the corresponding segments in the updated version. Furthermore, the content of segment 307 of the original version is deleted thus it does not appear in the new version, while the updated content of segment 310 replaces the original content of segment 304.
• the original version 301 is stored in one block in the storage device, specifically, block 316.
• the update process is an in-place update process, that is, the updated version overrides the original version, hence the update version 302 is also stored in block 316.
• a version (an original and/or updated version) can be stored in more than one block as was previously explained, with reference to the "123456789” example.
• 301 and 302 as part of larger original and updated versions.
• original version 301 and updated version 302 refer to the versions as a whole, or to one block there from. While looking at the figure it is illustrated that there are two free segments padding the original version 301 on both sides. Specifically, these are segments 318 and 319. There are also two free segments, 320 and 321 padding the updated version 302.
• the free segments 318, 319, 320 and 321 are not part of the original or updated versions, instead they are unused spaces in the block 316, when occupied by the original or updated version. Theses free segments can sometimes be used for storing content which is part of other files. It is further noted that according to the example, the free segment 320 is smaller than the free segment 318, while the free segment 321 is smaller than the free segment 319. That is, the space occupied by the original version 301 is smaller than the size occupied by the updated version 302.
• the segments 303 and 309 are corresponding segments. Similarly are 304 and 310; 305 and 312; 306 and 315; and 308 and 314. Fig.
• the update package 401 includes update commands for updating the version.
• the command 403 instructs the update process to copy the original content of segment 303 to the updated segment 309.
• the update command 404 instructs the update process to replace the original content of segment 304 with the "replaced data", thus yielding the updated content of the updated segment 310.
• a transforming function such as XOR in order to replace data, as was previously explained. In such an embodiment the "replaced data" would store the transforming data.
• Command 405 is in charge for deleting the original content of segment 307; command 306 copies the original content of segment 308 to the updated segment 314; command 407 copies the original content of segment 306 to the updated segment 315; command 408 instructs the update process to insert the "inserted data" into the updated segment 313; command 409 instructs it to copy the original content of segment 305 to the updated segment 312; and command 410 is in charge of inserting the inserted data as the updated content of segment 311. It is noted that data provided to the update process, such as inserted and/or replaced data, are interweaved with the update commands of the update package 401.
• Such an update package where data are interweaved with the update command is referred to as a "data indistinct update package” or “data interweaved update package”.
• the order by which the update commands appear in the update package is not necessarily equivalent to the order of the respective segments in the original and/or updated versions.
• the update package includes additional commands, for updating additional segments of additional blocks.
• 401 is part of an update package.
• data such as "inserted data” and "replaced data” that are required for some update commands are generally referenced as "supplementary data”.
• An update command that requires supplementary data is referenced as a "data consuming update command”.
• the update package 402 is an alternative update package (or a part thereof) that generates the updated version 302 from the original version 301.
• the update commands in the update package 402 are equivalent to the update commands of the update package 401, and ordered in the same order as they appear therein: command 411 is equivalent to command 403; command 412 is equivalent to command 404; command 413 is equivalent to command 405; command 414 is equivalent to command 406; command 415 is equivalent to command 407; command 416 is equivalent to command 408; command 417 is equivalent to command 409; and command 418 is equivalent to command 409.
• command 411 is equivalent to command 403
• command 412 is equivalent to command 404
• command 413 is equivalent to command 405
• command 414 is equivalent to command 406
• command 415 is equivalent to command 407
• command 416 is equivalent to command 408
• command 417 is equivalent to command 409
• command 418 is equivalent to command 409.
• the update package 402 unlike the update package 401, all the supplementary
• the portion 419 of the update package is used for storing supplementary data required for replace commands (hence it is referred to as a "replacements supplementary data portion”), while the portion 420 of the update package is used for storing data required for insert commands (hence it is referred to as an "insertions supplementary data portion").
• Such an update package, where supplementary data are stored in supplementary data portions is referred to as a "data distinct update package”.
• each supplementary data portion (such as portions 419 and 420) can include supplementary data items that correspond to more than one data consuming update command.
• the insertions supplementary data portion 420 includes supplementary data of the update commands 416 and 418.
• a data consuming update command can include a pointer to the respective supplementary data item that is stored in the update package, e.g., a pointer to the beginning of supplementary data item included in one of the portions 419 and 420.
• each update command that requires supplementary data can include the size of the respective data, thus allows computing the position where the respective supplementary data item begins. This is non-binding and other embodiments are allowed as well.
• the supplementary data portion can associate with each supplementary data item the size of this item.
• Such a reverse is sometimes desired, for example, when the forward update process fails in the middle, thus yielding a stored version that is an intermediate version.
• a cellular operator may wish to return to the previous version (the original version) when such failure occurs.
• an update process starts operating it can present a message to the user such as "the handheld is not updating software. The update is expected to last for 30 minutes during which the telephone will be inoperable". If the user must use his telephone within the coming 30 minutes he is given the option to cancel the update process (thus postponing it to some later time). However, the update process can perform part of the update task before the user presses cancel, which results in an intermediate version.
• a rolling back update process can operate in accordance with the update package used for forward updating this original version, but in a reversed direction (i.e., from its end toward the beginning) as will further be explained in detail.
• the examples provided are by no way limiting and other examples and reasons for roll-back exist as well.
• a cellular operator successfully updates an original version to an updated version
• the updated version is found non-satisfactory and therefore the operator would rather return (roll-back) to the previously operating original version. That is, roll-back does not require that the stored version would be an intermediate version; it can occur also when the stored version is an updated version.
• 421 is a "direction indication", constituting "update attribute bits”.
• the direction indication is used to indicate the direction by which the update process should operate, and/or the reason for this operation. For example, there can be different codes for the different directions and/or reasons of operation. However, this is non-limiting and other embodiments can store the direction indication in other storage areas which are not necessarily part of the update package.
• the direction of the update is one of two directions. Specifically, the direction is one of forward and roll-back. This is non-limiting and other embodiments can have any direction applicable to the case.
• an update process operating in accordance with one embodiment of the invention starts operating, it needs to identify the direction of operation and the start position. It is noted that when a forward update initially begins, the stored version is normally the original version, the start position is the beginning of the original version and the beginning of the update package, and the direction is forward (as was already noted). However, if the stored version is an intermediate version, the start position would be somewhere along the intermediate version and along the update package.
• the direction can be either forward or roll-back.
• a signature for example, can be a known er se checksum computed for the specific block. The signatures can be stored together with their corresponding blocks.
• a stored version can be either an original version, an intermediate version or an updated version (see, for example, Fig. 2), a person versed in the art would appreciate that by calculating signatures of blocks in the stored version and comparing them with the blocks' original signatures and with the blocks' updated signatures it is possible to determine the identity of the stored version. Furthermore, if the stored version is determined to be an intermediate version, it is possible to determine the position of interruption of the previously running update process. Then it is possible to locate the update command in the update package that corresponds to the position of interruption. In storage devices that allow access to content that occupies part of a block it is further possible to compare segments' signatures, in order to determine the segment where interruption of the previously running update process occurred.
• state records it is possible to associate with the update package records referenced as "state records". According to one embodiment it is possible to associate a state record with commands corresponding to each block, wherein the state record reflects the state of the update process, as it should be after the update of the corresponding block is completed.
• the state-record can include a copy of the block in RAM used by the update process to hold variables that maintain the process, such as known er se local variables.
• 5 is a flowchart illustrating operations performed before reversing an update process, according to an embodiment of the invention.
• the update sequence is determined in accordance with the update package and in 502 the update process reads the first block of the stored version in accordance with the update sequence.
• the signature corresponding to the read block is accessed (e.g., by reading it from the update package) and a corresponding signature is calculated in 504, based on content read in 502. If in 505 the update process identifies that the two signatures match and as long as there are other, un- examined blocks (see 506), the signature corresponding to the next block in accordance with the update sequence is accessed in 507 and in 508 the block is read in order to calculate its corresponding signature in 504.
• the update process can access the state record that corresponds to the read block, as done in 509, in order to restore the process state in 510. Once the state has been restored, the process reverses in 511 in order to return to the original version. It is noted that according to one example, while updating a block the update process stores its original content in a backup buffer to allow restoring its content if the update process fails before the block's update is complete ('backup-first').
• a different example can store the updated block's content in the backup buffer ('update-first') without incurring changes to the block itself, instead of the original content, and then copy the updated content from the backup buffer to the block.
• the backup-first case when locating the point of interruption it is possible that the content of this block is corrupted. In this case the content can be recovered from the backup buffer.
• the new content already exists in the backup buffer.
• Fig. 5 is non-binding.
• the signatures in the update package can correspond to blocks in the original version instead of the updated version.
• the stored version that exists before the update process (forward-update or roll-back) starts operating is generally referred to as source version, while the stored version that the update process is generally referred to as a "target version".
• the source version can be an original version, an updated version or an intermediate version.
• the target version can be either an original version or an updated version.
• Fig. 6 illustrates by way of example storing deleted content during a pre-reversal update process, according to one embodiment of the invention.
• FIG. 3 there is illustrated one segment 307 of the original version 301 (see Fig. 3), which is the source version in this example.
• a portion of the update package 402 of Fig. 4 wherein the illustrated portion includes the delete update command 413, in charge for deleting segment 307.
• the portion also includes the replacements supplementary data portion 419, the insertions supplementary data portion 420 and the direction indication 421.
• a "content reserve buffer” 601 is illustrated.
• the content reserve buffer constituting a "save buffer” is an area in the storage device 103 accessible to the update process, that is specially allocated in order to allow reserving deleted content.
• the content reserve buffer 601 can be allocated temporarily only for the duration of the update process and be reused afterwards for any other task. Before deleting content during the update process, it is possible to reserve (602) a copy thereof in the content reserve buffer. Alternatively, it is possible to dedicate space in the update package for the content reserve buffer, thus ensuring that there is enough space in the storage device 103 for this buffer, in the cost of a larger update package (which requires more bandwidth and/or more time to transmit, compared to a smaller update package). It is noted that Fig. 6 illustrates reserving content during a delete operation.
• reserving should occur whenever the update process performs an operation that overrides content, such as "replace", in order to allow for a later reversal of the advancing update process.
• embodiments operating a transforming function while performing a "replace” operation can avoid reserving the stored content before overriding it with the replacing content, because the transforming data can be re-applied to the replacing content in order to re-transform it back to content identical to the stored content.
• the embodiment of Fig. 6 is non-binding and alternative embodiments are allowed as well. For example, it is possible to include a copy of the deleted data in the update package.
• FIG. 7 illustrates by way of example reducing usage of a content reserve buffer, according to one embodiment of the invention. It is noted that supplementary data items used for insertion and replacement commands in the pre-reversal update process are not required after performing their respective update commands as their supplementary data is already written into the target version. Yet, it was already explained that content deleted during the advancing update process is reserved, e.g., in the content reserve buffer.
• the content stored in the content reserve buffer can be copied (701) into the update package, in-place of the already used supplementary data 420, allowing to free (and/or re-use) the content reserve buffer thereby.
• the update package itself can be updated in-place, which may require a reliable modification method for modifying its storage area in case the update process is interrupted.
• Reliable in- place modification of the update package can use any reliability technique, such as using a backup buffer, package signatures and state records as was previously explained.
• the supplementary data items it is possible to replace the supplementary data items at a later time, e.g., upon termination of the update process. It should be appreciated that sometimes there are two or more deleted segments, whose content (or al least part of their content) is similar or shared. According to an alternative embodiment, when two or more segments share content, this content can be reserved only once, while the other occurrences can reserve an indication as to where the reserved content is stored or how to retrieve it.
• the direction indication 421 is set to indicate which direction should a preceding update process operate, if such an update process initiates.
• the pre-reversal update process fails, or stopped in the middle, it also sets the direction indication 421, to indicate whether the preceding update process (if initiated) should operate in a forward or roll-back mode (such as in Fig. 5, 511).
• reversing a forward update process is performed by undoing each of the update commands performed by the forward update process but in a reversed order, starting from the last update command performed by the forward update process, and terminating with the first update command in the update package.
• reversing a rolling-back update process is performed by redoing each of the update commands, whose reversing command was performed by the rolling-back update process, starting from the last reversed-update command performed by the rolling-back update sequence.
• the forward update process operated successfully and yielded the updated version 302 by updating the original version 301 in accordance with the update package 402. It is noted that following this successful forward update the direction indicator 421 indicates that the update process direction should be reversed (i.e., the preceding update process, if initiated, will operate as roll-back).
• the rolling-back update process undoes the update operations done by its preceding forward update process, but in a reversed order: starting from the last update command executed before the advancing process terminated and terminating with the first update command 411.
• the first update command to be undone by during roll-back is 418.
• the supplementary data portions (420 and 421 in the figure) are also accessed in a reversed order.
• the supplementary data portions include reserved content written thereto while deleting content during the forward update. Understanding that a rolling-back update behaves like a forward update (apart from the reversed direction of progress and the reversal of the commands), it should be appreciated that whenever the rolling-back update process deletes content from the stored version, a copy of the deleted content is written into the supplementary data portions (or into the content reserve buffer).
• each of the exemplary update commands can be undone by performing an appropriate operation (a "reversing update command” or "reverting operation”), which reverses the original operation's result:
• a "delete” operation can be undone (or rolled-back, reversed) by an insert operation.
• the content previously deleted by the delete command is the supplementary data for the insertion command.
• the delete operation performed by the command delete 307 (see, for example, command 413) is reversed by insert 307 supplementary-data (wherein the supplementary data can be store in the supplementary data portion or in the content reserve buffer).
• An "insert" operation performed in accordance with an "insert” command can be undone by a delete operation.
• command 418 can be undone by performing delete 311. It is noted that when deleting content while performing the reversing command, the deleted content should be reserved, e.g. in the content reserve buffer or in the insert supplementary data portion.
• a "copy” operation can be undone by copying the updated segment back to its original position.
• the command 417 (copy 305 ⁇ 312) can be reversed by the command copy 312 ⁇ 305.
• a "replace” operation can be undone by deleting content inserted by the pre-reversal update process and writing instead data stored in the replacements supplementary data portion 419 or in the content reserve buffer. In other words, a replace operation can be undone by another, reversed, replace operation.
• a transforming function such as bitwise XOR
• Fig. 8 is a flowchart illustrating the main procedures performed while updating a source version to a target version in a reversible update process, according to one embodiment of the invention. It is noted that the direction of the update process is determined in 801 in accordance with the value of the direction indicator 419.
• the update process will operate in 802 in accordance with the update package in a forward direction.
• the update process will set the direction indicator to indicate that a preceding update process, if initiated, should perform roll-back,.
• the update process determines in 801 that the update process should operate to perform roll-back, then it will operate in 804 in accordance with the update package in roll-back direction.
• the update process will set the direction indicator to indicate that a preceding update process, if initiated, should perform forward-update.
• Fig. 9 is a flowchart illustrating in detail a forward update process, according to one embodiment of the invention.
• the update process Upon start, in 901, the update process has to locate the position in the stored version where it should start updating. It is appreciated that if the stored version is the original version then the start position is the beginning of the version, if the stored version is the updated version then the start position is the end of the version (hence the forward update process will terminate without performing any update operation), and if the stored version is an intermediate version then the start position is in the termination point of the previously running update process (see, for example, Fig. 5). In 902 the update process initiates the process' state. If the stored version is an intermediate version then the state would be initiated in accordance with the state record. However, if the stored version is an original or updated version then the state would be initiated as new.
• the update process locates the update command from where it should start reading, and it determines pointer positions such as in the replacements supplementary data portion 419, the insertions supplementary data portion 420 and the content reserve buffer 601, thus allowing it to access (for reading and/or writing) the correct data items stored therein. It is illustrated in 903 that if the stored version is an updated version, and remembering that the update process is a forward update process, then there are no more update commands in accordance with the update sequence, and therefore the update process terminates without performing any update command. However, if the stored version is an original version or an intermediate version then the update process reads from the update package the next update command in accordance with the update sequence and operates accordingly.
• the update command is a 'copy' command (905) the content of the original segment is copied into the updated segment in 906. It is noted that when the target segment is not free, there are some embodiments that require reserving the content stored therein in the content reserve buffer (or in the insertions supplementary data portion 420), as if there is a delete command before the copy command. If the command is an 'insert' command (907) then in 908 data is copied from the insertions supplementary data portion 420 into the updated segment and in 909 the pointer in the insertions supplementary data portion is advanced to the next data item.
• content stored therein is reserved in the content reserve buffer (or in the insertions supplementary data portion 420), as if there is a delete command before the copy command. If the command is a 'delete' command (910) then in 911 the content stored in the original segment is copied into the content reserve buffer (or into the insertions supplementary data portion 420), and in 912 the pointer to in the content reserve buffer is advanced to the next available space.
• Fig. 10 is a flowchart illustrating in detail rolling-back a stored version, according to one embodiment of the invention.
• the update process has to locate the position in the stored version where it should start updating. It is appreciated that if the stored version is the original version then the start position is the beginning of the version (hence the rolling-back update process will terminate without performing any update operation), if the stored version is the updated version then the start position is the end of the version, and if the stored version is an intermediate version then the start position is in the termination point of the previously running update process (see, for example, Fig. 5).
• the update process initiates the process' state. If the stored version is an intermediate version then the state would be initiated in accordance with the state record. However, if the stored version is an original or updated version then the state would be initiated as new.
• the update process locates the update command from where it should start reading, and it determines pointer positions such as in the replacements supplementary data portion 419, the insertions supplementary data portion 420 and the content reserve buffer 601, thus allowing it to access (for reading and/or writing) the correct data items stored therein.
• the rolling-back update process operates in accordance with a roll- back update sequence, which is opposite to the update sequence of the update package. It is illustrated in 1003 that if the stored version is an original version, and remembering that the update process is a rolling- back update process, then there are no more update commands in accordance with the roll-back update sequence, and therefore the update process terminates without performing any update command.
• the roll-back update process reads from the update package the next update command in accordance with the reversed update sequence (or in other words: the previous update command in accordance with the update sequence) and performs the update operation reversely corresponding to the update command.
• the update command is a 'copy' command (1005) the content of the updated segment is copied into the original segment in 1006, which is the update command reversely corresponding to the 'insert' command.
• the command is a 'delete' command (1010) then in 1011 data is copied from the insertions supplementary data portion 420 (or from the content reserve buffer) into the original segment, and in 1012 the pointer in the insertions supplementary data portion is retreated to the previous data item.
• the command is a 'delete' command (1010) then in 1011 data is copied from the insertions supplementary data portion 420 (or from the content reserve buffer) into the original segment, and in 1012 the pointer in the insertions supplementary data portion is retreated to the previous data item.
• content stored therein is reserved in the content reserve buffer (or in the insertions supplementary data portion 420), as if there is an insert command before the delete command, in accordance with the roll-back update sequence).
• the invention provides for a method for providing an update process of a stored version.
• the method comprising: providing a forward update for updating the stored version to a first version; providing a roll-back update for updating the stored version to a second version; applying a first update operation being either of said forward update and said roll-back update; and applying a second update operation being either of said forward update and said roll-back update and being other than said first update operations.
• the first version can be one of several versions, including original version and updated version. However, this is non-limiting and other embodiments may have a different version being the first version, such as an intermediate version.
• the second version can be one of several versions, including original version and updated version.
• Fig. 11 is a block diagram schematically illustrating a system 1101 for updating a stored version of content stored in a storage device, according to one embodiment of the invention.
• the system 1101 includes a direction determination unit 1102 adapted for determining direction of the updating, for example, in accordance with the direction indication 421.
• the system 1101 also includes a forward updating processor 1103 coupled to the direction determination unit 1102.
• the forward updating processor 1103 forward- updates the stored version to the updated version in accordance with the update sequence. This is done, for example, in accordance with the flowchart of Fig. 9.
• a roll-back sequence generator 1104 that is coupled to the direction determination unit 1102 generates a roll-back update sequence opposite to the update sequence.
• the roll-back sequence generator 1104 can follow the update sequence in a reversed order, one command at a time. Alternatively it can follow the update sequence altogether, thus generating and storing the roll-back update sequence in the storage device, e.g., as a list.
• the system 1101 also includes a roll-back updating processor 1105 coupled to the roll-back sequence generator 1104.
• the roll-back updating processor 1105 rolls-back the stored version to the original version in accordance with the roll-back update. This is done, for example, in accordance with the flowchart of Fig. 10.
• Fig. 12 is block diagram schematically illustrating a system for reversing an update process, according to one embodiment of the invention.
• the system 1201 includes an update commands reversal unit 1202.
• Fig. 13 is a block diagram schematically illustrating a system 1301 for updating a stored version of content stored in a storage device.
• the system 1301 includes a direction determination unit 1302.
• the direction determination unit 1302 uses the direction indication in order to determine direction.
• a forward updating processor 1303 is coupled to the direction determination unit 1302. When the direction is indicative of forward, the forward updating processor 1303 forward-updates the stored version to the updated version, e.g., in accordance with the flowchart of Fig. 9.
• the system 1301 also includes a roll-back update processor 1304.
• the roll-back update processor 1304 rolls-back the stored version to the original version, e.g., in accordance with the flowchart of Fig. 10.
• the system according to the invention may be a suitably programmed computer.
• the invention contemplates a computer program being readable by a computer for executing the method of the invention.
• the invention further contemplates a machine-readable memory tangibly embodying a program of instructions executable by the machine for executing the method of the invention.

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