Programmer Help

Tuples are another important sequence structure in Python. Similar to lists, tuples are also composed of a series of elements sorted in a specific order. Unlike a list, a list can operate on any element and is a variable sequence, while a tuple is an immutable sequence, that is, the elements in the tuple cannot be modified separately. Tuples c ...

button drive A key driver written by Jay himself supports single double click, continuous press and long press; callback is used to handle key events (custom buffeting time), which only takes three steps to create keys, link mapping between key events and callback processing functions, and periodic check of keys. Source address: https://github. ...

JSON is a lightweight data interaction format, easy for people to read and write, but also easy for machine analysis and generation, and effectively improve the efficiency of network transmission. It is often used in practical projects. Compared with xml, JSON has many advantages, such as asking duniang, a lot of advantages. Third party Library ...

In the process of learning MQTT, the following contents help me https://www.runoob.com/w3cnote/mqtt-intro.html is a basic introduction to MQTT Https://mosquito.org/api/files/mosquito-h.html this website records almost all the mosquito interfaces you want to know. They all have function profiles. Maybe they can't see any points. Look at the deta ...

The creation mode is divided into the following types. Singleton mode: a class can only generate one instance. The class provides a global access point for external access to the instance. Its extension is the limited multiple instance mode. Prototype pattern: an object is used as a prototype, and multiple new instances similar to the proto ...

In Kubernetes, the IP address of the service and Pod can only be used inside the cluster network, and it is not visible for applications outside the cluster. In order to enable external applications to access the services in the cluster, the following schemes are provided in Kubernetes: NodePort LoadBalancer Ingress This section mainly introd ...

Overview of ACL (access control list) Access control list is a list of instructions applied to the router interface, which are used to tell the router which packets can be received and which packets need to be rejected. Access control is the main strategy of network security prevention and protection. Its main task is to ensure that netwo ...

The topology of this experiment is as follows: Objective: Complete the establishment of extended ACL on R1 route, and achieve the experimental requirements: Allow PC1 to access Linux web services; Allow PC2 to access the ftp service of Linux; PC1 and PC2 are forbidden to access other Linux services; Allow PC1 to connect PC2 Experimental st ...

Experimental topology Physical topology Logical topology 172.24.4.8 is the fip of pod 100.60.0.31. step Get ready Create logical router ovn cluster ovn-nbctl lr-add ovn-cluster ovn-nbctl lrp-add ovn-cluster ovn-cluster-fip-ns1 00:00:00:65:77:09 100.69.0.1/16 Create logical switch fip-ns1 and connect to ovn cluster ovn-nbctl ls-add fip-ns1 ovn ...

Enumeration (enum) Enumerations (enums) are just a way of naming constants. It is a basic data type in C language and a set of named integer constants. The specification defines "constants" such as states, options, and so on in the code. Does not participate in memory occupation and release. The purpose of using enumeration in develo ...