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π¦Why is ODBC not a standard feature of Linux?
T.me/UndercodeTesting
1) Years ago, Microsoft announced a technology strategy called Windows Open Services Architecture (WOSA). The essence of WOSA is Open Database Connectivity (ODBC), which is a model of a universal database access service provided by the Windows platform, and database vendors provide adapters for their products.
2) Therefore, Windows applications can avoid the work of adapters written for data sources, and instead use the standardized ODBC framework to access data and concentrate on doing useful things.
3) The same idea is working elsewhere in Windows. For example, unified printer and modem access. And Microsoft did an excellent job to offset the differences between various networks. Windows network services can be run in the same way on TCP / IP, IPX / SPX and NetBEUI, because the platform abstracts the differences between these protocols on a middle layer.
4) "Microsoft is just a commercial company," the Linux community likes to think so. This statement has a lot of truth, but the true story is much more complicated. When Microsoft introduced WOSA-style abstractions into core services, it appeared as a reformer, and Unix / Linux was more like a hobble primitive.
written by undercode
β β β ο½ππ»βΊπ«Δπ¬πβ β β β
π¦Why is ODBC not a standard feature of Linux?
T.me/UndercodeTesting
1) Years ago, Microsoft announced a technology strategy called Windows Open Services Architecture (WOSA). The essence of WOSA is Open Database Connectivity (ODBC), which is a model of a universal database access service provided by the Windows platform, and database vendors provide adapters for their products.
2) Therefore, Windows applications can avoid the work of adapters written for data sources, and instead use the standardized ODBC framework to access data and concentrate on doing useful things.
3) The same idea is working elsewhere in Windows. For example, unified printer and modem access. And Microsoft did an excellent job to offset the differences between various networks. Windows network services can be run in the same way on TCP / IP, IPX / SPX and NetBEUI, because the platform abstracts the differences between these protocols on a middle layer.
4) "Microsoft is just a commercial company," the Linux community likes to think so. This statement has a lot of truth, but the true story is much more complicated. When Microsoft introduced WOSA-style abstractions into core services, it appeared as a reformer, and Unix / Linux was more like a hobble primitive.
written by undercode
β β β ο½ππ»βΊπ«Δπ¬πβ β β β
β β β ο½ππ»βΊπ«Δπ¬πβ β β β
π¦ Using Linux as the CVS server1 version control concepts and the introduction of several version control tools
fb.com/UndercodeTesting
marked with version 1.1 of the concept of source files
π¦source files is the most important a component of a software unit, the management of the source file is composed of the entire software management is the most important part Is the key to efficient software development. To manage source files, you must mark the source files. It is generally considered that only the file name is needed. In fact, the labeling of source files under a version maintenance tool includes two parts: File name and version. That is: the source file can be represented by the following binary tuple {filename, version}; the
1) > so-called version, the general software developers have an intuitive understanding, but it is difficult to make an accurate definition. Version, Refers to the potential existence of a specific instance of a specific object. A specific object here refers to a software component managed by a version maintenance tool, generally refers to a source file. A specific instance refers to a software developer from the software storage room A real copy of the restored software constituent unit with certain contents and attributes.
2) The definition of the version as a potential existence is based on the following Consider: The version is used as a representation part of the source file, and the software personnel's reference to it actually wants different source files corresponding to different versions, so the version is an abstraction. It is used to define the content and attributes that a specific instance should have. That is to say, the version is a potential existence of a specific instance, an abstraction of different incarnations of the source file.
3) With the above understanding of the concept of version. Everyone has a certain understanding of the version maintenance tool: the version maintenance tool should be for developers The storage method of shielded source files is transparent to developers. Developers do not need to understand what source files are in the software repository, but only need to explain what source files are needed and what source files are to be stored.The version maintenance tool is automatically completed. All this works. The theory about version maintenance also includes: version space, dimension, version representation, storage, merge and other theories, because we mainly explain the cvs linux server here, so everything is simple, friends who are interested in this aspect can read books
5) this tut talking about cvs is such a powerful tool. we first before telling cvs Introduce several other version maintenance tools.
π¦ 1.2 Introduction to maintenance tools for several versions
1.2..1 SCCS
The full name of SCCS is Source Code Control System. Before the introduction, the concept of working file is defined. The so-called working file refers to the βwriteβ permission obtained from the software storage room. Source files.
SCCS is a basic source file version control tool, which is suitable for the version maintenance of any text file. It is based on the version control of a single file. Generally, its software storage room and the file to be maintained are in the same directory.
When SCCS works, there is a special SCCS format file that retains the encoded version of its source file, which records enough information to generate a new version, and records who has the right to modify the file and has a "lock" for that version.
The version of SCCS is a good four-tuple, namely: release number, level number, branch number, sequence number (release, level, banch, sequence)
1.2.2 RCS
π¦ WHAT IS RCS
π¦ Using Linux as the CVS server1 version control concepts and the introduction of several version control tools
fb.com/UndercodeTesting
marked with version 1.1 of the concept of source files
π¦source files is the most important a component of a software unit, the management of the source file is composed of the entire software management is the most important part Is the key to efficient software development. To manage source files, you must mark the source files. It is generally considered that only the file name is needed. In fact, the labeling of source files under a version maintenance tool includes two parts: File name and version. That is: the source file can be represented by the following binary tuple {filename, version}; the
1) > so-called version, the general software developers have an intuitive understanding, but it is difficult to make an accurate definition. Version, Refers to the potential existence of a specific instance of a specific object. A specific object here refers to a software component managed by a version maintenance tool, generally refers to a source file. A specific instance refers to a software developer from the software storage room A real copy of the restored software constituent unit with certain contents and attributes.
2) The definition of the version as a potential existence is based on the following Consider: The version is used as a representation part of the source file, and the software personnel's reference to it actually wants different source files corresponding to different versions, so the version is an abstraction. It is used to define the content and attributes that a specific instance should have. That is to say, the version is a potential existence of a specific instance, an abstraction of different incarnations of the source file.
3) With the above understanding of the concept of version. Everyone has a certain understanding of the version maintenance tool: the version maintenance tool should be for developers The storage method of shielded source files is transparent to developers. Developers do not need to understand what source files are in the software repository, but only need to explain what source files are needed and what source files are to be stored.The version maintenance tool is automatically completed. All this works. The theory about version maintenance also includes: version space, dimension, version representation, storage, merge and other theories, because we mainly explain the cvs linux server here, so everything is simple, friends who are interested in this aspect can read books
5) this tut talking about cvs is such a powerful tool. we first before telling cvs Introduce several other version maintenance tools.
π¦ 1.2 Introduction to maintenance tools for several versions
1.2..1 SCCS
The full name of SCCS is Source Code Control System. Before the introduction, the concept of working file is defined. The so-called working file refers to the βwriteβ permission obtained from the software storage room. Source files.
SCCS is a basic source file version control tool, which is suitable for the version maintenance of any text file. It is based on the version control of a single file. Generally, its software storage room and the file to be maintained are in the same directory.
When SCCS works, there is a special SCCS format file that retains the encoded version of its source file, which records enough information to generate a new version, and records who has the right to modify the file and has a "lock" for that version.
The version of SCCS is a good four-tuple, namely: release number, level number, branch number, sequence number (release, level, banch, sequence)
1.2.2 RCS
π¦ WHAT IS RCS
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1) > is another basic source code management tool, which is WALTER.f .Tichy was developed at Purdue University in Indina in 1980. RCS is similar to SCCS and is also a version maintenance system based on a single file. RSC manages files through RSC files; the maintenance process using RCS is similar to SCCS. It is also carried out according to the recovery submission
2) mode.It is not a detailed description of the RCS file. It is a storage room for source files in the RCS system. It is a special encoding file that contains sufficient information for developers to restore the old version of the source file for development. it usually .V suffix
3) as its structure:
? RCS head, the portion of the recording head corresponding to the version number of the file tree,
the version? description: this section describes the nature of the attribute of each node of the tree RCS
? initial Information: One part is what was expressed when creating the first RCS version
? File content
RCS is similar to SCCS. RCS organizes the maintained versions into a tree structure. However, RCS allows multiple branches, that is, the version number of RCS is not a quadruple like SCCS. The form is: issue number, level number, ( Branch number, serial number].
written by undercode
β β β ο½ππ»βΊπ«Δπ¬πβ β β β
The two versions of maintenance tools have in common: the "lock" method is adopted, and users who insist on having a "lock" to the current question have the right to modify the file. . mechanisms they used the so-called "lock-modify-unlock". With this well-known that only a weakness, that is not so far a multi-user concurrent use.
2 build cvs server under Linux
2.1 Introduction and rationale CVS
CVS The full name is Current Version Control. CVS is a GNU software package. Developed by Intersolv, the latest version is 1.10.8. It is a maintenance tool based on the RCS system. It explicitly stores the source files and the user βs The working space is independent, and it has expanded the recovery submission function of RCS in a certain mode. It makes it advantageous and parallel development.
CVS concentrates the RCS files of source files under a directory according to the hierarchy of its source tree. Absolute path by environment CVSROOT defined amount of
γ
visible The directory can be divided into two parts: part of the $ {CVSROOT} / CVSROOT, which contains some of the desired CVS RCS file management file as another part formed a source file, software development in accordance source tree structure . constitutedγ
on files in the CVSROOT, in later sections, to explain in detail the structure ,, and the workspace in the source code directoryγ
CVS source control is performed has the following characteristics:
1, the source separation space and user space.
The CVS system places the source code files under the repository.Users must modify the files to make a copy of the files under the repository before they can modify it.2
. Concurrent access to the
CVS system allows multiple developers to obtain the same version of the source file of the same file at the same time. Of course, this is also the main reason why CVS is widely used. When a developer extracts a file, he will create a copy in his workspace that is independent of other developers. The version number of this file is the same as the "header" version of the file, unless he uses the commit command to complete the permanent upgrade of the version. At this time, other users can use the undate command to match their version number with the "latest header version number.": If the user finds that the header version has changed after checkout, a new file can be formed using the rcsmerge command of the RCS system. This new file and including the original content, but also includes content modified by the user. this weakness and other conflicts occur simultaneously on the same file modification developers, can notify them manually modify
2) mode.It is not a detailed description of the RCS file. It is a storage room for source files in the RCS system. It is a special encoding file that contains sufficient information for developers to restore the old version of the source file for development. it usually .V suffix
3) as its structure:
? RCS head, the portion of the recording head corresponding to the version number of the file tree,
the version? description: this section describes the nature of the attribute of each node of the tree RCS
? initial Information: One part is what was expressed when creating the first RCS version
? File content
RCS is similar to SCCS. RCS organizes the maintained versions into a tree structure. However, RCS allows multiple branches, that is, the version number of RCS is not a quadruple like SCCS. The form is: issue number, level number, ( Branch number, serial number].
written by undercode
β β β ο½ππ»βΊπ«Δπ¬πβ β β β
The two versions of maintenance tools have in common: the "lock" method is adopted, and users who insist on having a "lock" to the current question have the right to modify the file. . mechanisms they used the so-called "lock-modify-unlock". With this well-known that only a weakness, that is not so far a multi-user concurrent use.
2 build cvs server under Linux
2.1 Introduction and rationale CVS
CVS The full name is Current Version Control. CVS is a GNU software package. Developed by Intersolv, the latest version is 1.10.8. It is a maintenance tool based on the RCS system. It explicitly stores the source files and the user βs The working space is independent, and it has expanded the recovery submission function of RCS in a certain mode. It makes it advantageous and parallel development.
CVS concentrates the RCS files of source files under a directory according to the hierarchy of its source tree. Absolute path by environment CVSROOT defined amount of
γ
visible The directory can be divided into two parts: part of the $ {CVSROOT} / CVSROOT, which contains some of the desired CVS RCS file management file as another part formed a source file, software development in accordance source tree structure . constitutedγ
on files in the CVSROOT, in later sections, to explain in detail the structure ,, and the workspace in the source code directoryγ
CVS source control is performed has the following characteristics:
1, the source separation space and user space.
The CVS system places the source code files under the repository.Users must modify the files to make a copy of the files under the repository before they can modify it.2
. Concurrent access to the
CVS system allows multiple developers to obtain the same version of the source file of the same file at the same time. Of course, this is also the main reason why CVS is widely used. When a developer extracts a file, he will create a copy in his workspace that is independent of other developers. The version number of this file is the same as the "header" version of the file, unless he uses the commit command to complete the permanent upgrade of the version. At this time, other users can use the undate command to match their version number with the "latest header version number.": If the user finds that the header version has changed after checkout, a new file can be formed using the rcsmerge command of the RCS system. This new file and including the original content, but also includes content modified by the user. this weakness and other conflicts occur simultaneously on the same file modification developers, can notify them manually modify
Therefore, CVS system is a Copy-modify-Merge algorithm and The advantage of this algorithm that is not the lock-modify-unlockj mechanism used by the two systems mentioned above is that software developers can get a copy of the source file (Copy) and will not lock the file. ", Thus providing the possibility for parallel development. After getting the copy, developers can modify it in their own development environment (Modify ), Then submit your modified file and merge it with the source file to form a new version.
3. The source file sharing
CVS uses $ {CVSROOT} for different users. Users can copy different templates according to their needs. after modifying the carrier to $ {CVSROOT}. in this way users can share source files. this is of course we have established the necessary CVS server
4, independent work environment
users make changes to develop in their own work environment, it is natural to work independently The environment is worth saying. CVS also supports a "lock" mechanism. Allows users to lock the template copy they have obtained
5, numerals
CVS To facilitate the introduction of a tag file located in the working directory of the user, and the CVS directory is a file operation he labeled specific tag file, i.e., the operation of the respective version, even if the The version has been modified.
2.2. Obtaining and installing
CVS CVS has a default installation in general Linux distributions. If your system is not installed, it does not matter, CVS can be easily obtained on the Internet. Its source code is in ftp : //202.113.29.4/pub1/unix/cvs It's documentation is at ftp://202.113.29.4/doc/cvs. Anyone can download it easily. At present his latest version is 2.10.8.
Installation The process is roughly as follows:
1. Unzip the downloaded compressed file in any directory.
2 Use the installation tool in the file package to complete the installation (with instructions). Usually it is:
make config
make install
(unavailable version, installation method may be different, specific see, it brought their own installation documentation)
γ
installation 2.3 server to use
after installing the CVS system we can start to install CVS repository. in the linux environment, CVS is generally based on the use of the command line And there is also GUI front-end tools, such as TKCVS etc. Here we will apply the general CVS command that is cvs [cvs options] cvs-command [command options] way to complete the configuration server.
2.3.1 software repository (repository) management
1 Create CVSROOT root directory
first edit the relevant environmental variables (CVS a few important environment variables are as follows:
CVSROOT warehouse full pathname of the root directory of
CVSREAD If set, indicates that the operation at the time of checkout all files are set to read-only
CVSBIN CVS use a lot of orders RCS, RCS tool path specified music
CVSEDITOR specify the user to write the log information used to edit When the
CVS_RSH server starts a remote CVS server, the name of the shell used
CVS_SERVER determines the name of "" cvs server "", the default is the CVS
CVSWRAPPERS cvswrapper script, which is used to specify the package file name.)
The important one is CVSROOT, It indicates the location of the warehouse is located, in the creation of a new warehouse, it is essential therefore generally necessary to add the definition of the environment variable CVSROOT as add the following two lines in the / etc / bashrc file
CVSROOT = / cvsroot
Export CVSROOT
or Directly execute
$ export CVSROOT = / cvsroot on the command line
and start creating CVSROOT at the corresponding location
$ mkdir cvsroot
$ cvs init
If there is no variable CVSROOT defined, this prompt will appear:
cvs init: No CVSROOT specified! Please use the '-d' option
cvs [initn aborted]: or set the CVSROOT environemnt variable
If you do not want to define environment variables, you can use this command:
3. The source file sharing
CVS uses $ {CVSROOT} for different users. Users can copy different templates according to their needs. after modifying the carrier to $ {CVSROOT}. in this way users can share source files. this is of course we have established the necessary CVS server
4, independent work environment
users make changes to develop in their own work environment, it is natural to work independently The environment is worth saying. CVS also supports a "lock" mechanism. Allows users to lock the template copy they have obtained
5, numerals
CVS To facilitate the introduction of a tag file located in the working directory of the user, and the CVS directory is a file operation he labeled specific tag file, i.e., the operation of the respective version, even if the The version has been modified.
2.2. Obtaining and installing
CVS CVS has a default installation in general Linux distributions. If your system is not installed, it does not matter, CVS can be easily obtained on the Internet. Its source code is in ftp : //202.113.29.4/pub1/unix/cvs It's documentation is at ftp://202.113.29.4/doc/cvs. Anyone can download it easily. At present his latest version is 2.10.8.
Installation The process is roughly as follows:
1. Unzip the downloaded compressed file in any directory.
2 Use the installation tool in the file package to complete the installation (with instructions). Usually it is:
make config
make install
(unavailable version, installation method may be different, specific see, it brought their own installation documentation)
γ
installation 2.3 server to use
after installing the CVS system we can start to install CVS repository. in the linux environment, CVS is generally based on the use of the command line And there is also GUI front-end tools, such as TKCVS etc. Here we will apply the general CVS command that is cvs [cvs options] cvs-command [command options] way to complete the configuration server.
2.3.1 software repository (repository) management
1 Create CVSROOT root directory
first edit the relevant environmental variables (CVS a few important environment variables are as follows:
CVSROOT warehouse full pathname of the root directory of
CVSREAD If set, indicates that the operation at the time of checkout all files are set to read-only
CVSBIN CVS use a lot of orders RCS, RCS tool path specified music
CVSEDITOR specify the user to write the log information used to edit When the
CVS_RSH server starts a remote CVS server, the name of the shell used
CVS_SERVER determines the name of "" cvs server "", the default is the CVS
CVSWRAPPERS cvswrapper script, which is used to specify the package file name.)
The important one is CVSROOT, It indicates the location of the warehouse is located, in the creation of a new warehouse, it is essential therefore generally necessary to add the definition of the environment variable CVSROOT as add the following two lines in the / etc / bashrc file
CVSROOT = / cvsroot
Export CVSROOT
or Directly execute
$ export CVSROOT = / cvsroot on the command line
and start creating CVSROOT at the corresponding location
$ mkdir cvsroot
$ cvs init
If there is no variable CVSROOT defined, this prompt will appear:
cvs init: No CVSROOT specified! Please use the '-d' option
cvs [initn aborted]: or set the CVSROOT environemnt variable
If you do not want to define environment variables, you can use this command: