prtg overview

module, the stronger the cohesion, the less the external, the better the module independence.Cohesion: That is, the inside of the module is designed to be more single, better. This change, the responsibility is clear.Outreach: The less the connection between the modules, the better, the connection means dependence, the lack of connectivity, the independence of the module is good, independence means that the module can be modified independently of the outside world. Reducing the outreach also in

more slowly than memory, disk I/O can become a bottleneck for the system if you wait for disk I/O to complete before doing anything else in the program. 2. Network operation: Due to the uncertainty of the network environment, if you want to read and write network data, it may be slower than disk I/O. 3.CPU: If the program is heavily consuming CPU resources for a long time, the contention for the CPU will cause performance problems, and the program needs to be rewritten to improve the situation.

: From inheritance, the simple point is that the parent class refers to the object of the subclass, the runtime still shows the behavior characteristics of the subclass, that is, the same type of object execution of the same method, may show a variety of behavior characteristics; In addition, abstraction is also an important feature, abstract is that we only need to focus on the current topic related aspects and ignore irrelevant aspects, such as the display, we said that the properties are

transaction is changed after another matter.The official document says that meeting the four characteristics of the above-mentioned business is calledACIDtransactions, wherea:atomicity,C:Consistency,I:Isolation,D:Durability). But in satisfyingACIDattributes, people take into account that performance issues are a flexible strategy. such as the isolation level of data, people can prescribe more lenient or stricter rules than before. (Refer to Wikipedia's "transaction isolation" entry for details.

on the anchor Point and coordinate point to split the image, get the 0/1 value within each point, and construct a new QR code image.However, from the image to establish a coordinate system, you can find that the picture is actually not a real square, and even a rectangle is not up, can not be scaled to restore the square, from the two-dimensional code left and right side length and the length of the red box to be seen, the left segment length is shorter than the side line, So it's not even a pa

The C language was invented in 1972 and was first used to rewrite the Uinx operating system (Unix was written primarily in assembly language, which laid the foundation of the operating system) With the success of Unix operating system, C language has been greatly promoted, has been used in large, medium and small, micro-host, is still the world's most popular, the most widely used high-level programming language One C language is a process-oriented language, non-object-or

(repeatable, can be found by index, similar List Collection "Difference: here is Key index instead of a numeric index ") Iv. How to access the elements? Set , depending on the element itself List , depending on the index of the element Map , according to Key to access the corresponding value Related articles:a big wave of Java Strikes (vi) collection and iterator interface of the--java collectiona big wave of Java Attack (vii) set interface of--java seta big wave of Java At

1. JavaScript is a scripting language based on objects and events.2. Features:1) Security (does not allow direct access to local hard disks). What he can do is the dynamic interaction of information.2) Cross-platform (as long as the browser can interpret JS can be executed, and platform-independent.) ）3. JavaScript is different from Java1) JS is the product of Netscape Company, Java is the product of sun company.2) JS is Object-based and Java is object-oriented.3) JS just need to explain to run,

the SMB type is confirmed, the client sends the session Setup command packet, submits the account number, the password, and requests a connection to the Samba server. If the client is authenticated, the Samba server responds to the session setup message and assigns the user a unique UID to communicate with the client.(3) Access to shared resources: When a client accesses a Samba shared resource, it sends a Tree Connect command packet, notifies the server of the shared resource name that it need

(typically:/user directory/.vnc/xstartup) file to 755 (rwxr-xr-x).After that, kill all the VNC clients that have started:Vncserver-kill:1Vncserver-kill:2 (Note:-kill with: 1 or: 2 with a space in the middle)Finally restart the Vncserver service! #/etc/init.d/vncserver RestartNote: Vncserver can only be turned off by the user who initiated it, and instant root cannot turn off the vncserver that other users have opened.Kill the process unless you use kill to order the violence.B. How to log into

. Get VIM:If the operating system is a unix-like operating system, VIM may already be installed. If your operating system does not have VIM installed, you will need to manually install vim yourself. get vim in Unix and gnu/linux environments:A certain version of Vim is now attached to many UNIX environments, and most gnu/linux distributions link the default VI location "/BIN/VI" to the Vim executable file. But there are many variants of Unix, and Gnu/linux has many distributions, if your unix-li

1. Configure Web. XML to start SPRINGMVC2, the XML----------------is obsolete "not recommended use"1), configure handlermapping, request map to Controller2), configuration Handleradapter, support multi-type processorSee more:/org/springframework/web/servlet/dispatcherservlet.properties file pieces4, the implementation of the ControllerImplements the Controller class and its subclasses. Implement the appropriate method.5. Contextual relationship (Spring-spring MVC)Spring MVC inherits the spring c

Applicationobjectsupport. Description: Abstract class Applicationobjectsupport provides the Getapplicationcontext () method, which can be easily obtained to ApplicationContext. When spring initializes, the ApplicationContext object is injected through the Setapplicationcontext (Applicationcontextcontext) method of the abstract class. inherits from the abstract class Webapplicationobjectsupport. Description: Similar to the above method, call Getwebapplicationcontext () to get Webapplicat

for this: There is no C language for some time, the basic grammar of C language is a little rusty. Write some examples of C language to review C language. Some instances use algorithms that are a bit rusty after a long time. Review these algorithms by writing some examples of C language. Used to write examples on Windows, this time write an example on Linux, I want to add some Linux elements in the instance. Previously written program is a student version of the program, pe

, but the customer can always get the loan in a limited time. (4) When the customer receives all the necessary funds, they will be able to return all the funds in a limited time.The problem of dining philosophersFive philosophers in a round table dining, everyone must pick up two forks to eat;The solution to the problem of dining philosophers: (1) Waiter solution: The waiter as a manager, the philosopher in the fork before the need to obtain the waiter's consent; (2) a maximum of 4 philosophers;

group Youuser inside user to execute sudo command (need to enter password).Line three: Allow the user to execute the sudo command youuser, and do not enter a password at the time of execution.Line four: Allow user group Youuser inside user to execute sudo command, and do not enter password at execution time.4. Revoke sudoers file Write permission, command:chmod u-w/etc/sudoersThis makes it possible for ordinary users to use sudo.------------------------------------------------------------------

) + = Scsi_ proc.oscsi_mod-y+= scsi_trace.oscsi_mod-$ (config_pm) + = SCSI_PM.OSg.cScsi_transport_fc.cScsi_transport_iscsi.cScsi_debug.cFC Initiator Driver obj-$ (CONFIG_SCSI_QLA_FC) + = qla2xxx/ configscsi_qla_fctristate "Qlogicqla2xxxfibrechannelsupport" Dependson pciscsiselectscsi_fc_attrsselectfw_loader---help---Thisqla2xxx driversupportsallQLogicFibreChannelPCIandPCIehost Adapters. Bydefault,firmwarefortheisppartswillbeloadedviathe firmwareloaderinterface. ispfirmware Filename------------

storage medium for data sharing between servers, such as storing data in the SSO system as a single-point login, which can be saved in memcached and shared by multiple applications.　　Applications because memcache are distributed, you can provide shared resources for different servers in a Web project. Because memcache is storing data directly in memory, in order to reduce the pressure of the database, you can add a layer of memcache cache between the Web and the database. And in Memcache, the d

iterator. In the above block diagram, enumeration can only be used in Hashtable, Vector, and stack.5, finally, see Arrays and collections. These are the two tool classes that manipulate arrays and collections.Third, collection interface and Abstractcollection class1, Introduction: Collection interface is the root interface of processing object collection. The Abstractcollection class is a convenient class that provides a partial implementation of the Collegetion interface."interface" boolean

1. Java Web resources are divided into static web (HTML, CSS, JS, Flash) and Dynamic Web resources (ASP PHP JSP, is a small program that can be accessed)2. Dynamic Web Resources Use the database to implement additions and deletions to change the operation.3. Using JDBC to control the databasec/S and B/s controversyC/SQQ, net DiskPros: Achieve brilliant effects and special features, just download the client, rely on the weak network speedCons: First use requires download of client, update, all cl