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The Hidden Terminal Problem

Nishtha Thakur
Answered 30m 22s ago

In wireless LANs ( wireless local area networks), the hidden terminal problem is a transmission problem that arises when two or more stations who are out of range of each other transmit simultaneously to a common recipient. This is prevalent in decentralised systems where there aren’t any entity for controlling ... Read More

The Exposed Terminal Problem

Smita Kapse
Answered 33m 48s ago

In wireless LANs (wireless local area networks), the exposed terminal problem is a transmission problem that arises when a transmitting station is prevented from sending frames due to interference with another transmitting station. This is prevalent in decentralised systems where there aren’t any entity for controlling transmissions. This occurs when ... Read More

Python and multi-threading. Is it a good idea?

Sri
Sri
Answered 34m 55s ago

No its not a good idea, actually.Python doesn't allow multi-threading ,but if you want to run your program speed that needs to wait for something like IO then it use a lot. Where as the threading package couldnt let you to use extra CPU cores python doesn't support multi-threading because ... Read More

Wireless LAN Protocols

Anvi Jain
Answered 36m 34s ago

Wireless LANs refer to LANs (Local Area Networks) that use high frequency radio waves instead of cables for connecting the devices. It can be conceived as a set of laptops and other wireless devices communicating by radio signals. Users connected by WLANs can move around within the area of network ... Read More

The Adaptive Tree Walk Protocol

Nishtha Thakur
Answered 40m 11s ago

Adaptive Tree Walk Protocol is a technique for transmitting data over shared channels that combines the advantages of collision based protocols and collision free protocols.In computer networks, when more than one station tries to transmit simultaneously via a shared channel, the transmitted data is garbled, an event called collision. In ... Read More

Limited-Contention Protocols

Smita Kapse
Answered 42m 55s ago

Limited Contention Protocols are the media access control (MAC) protocols that combines the advantages of collision based protocols and collision free protocols. They behave like slotted ALOHA under light loads and bitmap protocols under heavy loads.ConceptIn computer networks, when more than one station tries to transmit simultaneously via a shared ... Read More

What is the difference between .py and .pyc files ?

Sri
Sri
Answered 1h 3m ago

Python compliles the .py files and save it as .pyc fileThe .pyc contain the compiled bytecode of Python source files, A .pyc is not created for your main program file that you execute (only for imported modules).The .pyc file contains encoded python bytecode.If We Want to import module.The Module calculate ... Read More

What are the different steps involved to execute a Java program?

raja ramesh
Answered 2h 2m ago

Java program execution follows 5 majors stepsEdit - Here the programmer uses a simple editor or a notepad application to write the java program and in the end give it a ".java" extension.Compile - In this step, the programmer gives the javac command and the .java files are converted into ... Read More

Scope and lifetime of variables in Java?

raja ramesh
Answered 2h 17m ago

Instance Variables :A variable which is declared inside a class and outside all the methods and blocks is an instance variable. The general scope of an instance variable is throughout the class except in static methods. The lifetime of an instance variable is until the object stays in memory.Class Variables ... Read More

Get documents expired before today in MongoDB?

Smita Kapse
Answered 3h 19m ago

You can use $lte operator along with Date() for this. Let us first create a collection with documents. Here, we have set the date 2019-05-11, which is the current date −> db.getDocumentsExpiredDemo.insertOne({"ArrivalDate":new ISODate("2019-05-11")}); {    "acknowledged" : true,    "insertedId" : ObjectId("5cd563b17924bb85b3f4893b") } > db.getDocumentsExpiredDemo.insertOne({"ArrivalDate":new ISODate("2019-01-01")}); {    "acknowledged" : ... Read More

Update array in MongoDB document by variable index?

Anvi Jain
Answered 3h 23m ago

To update array in MongoDB document by variable index, use the below syntax. Here, yourIndexValue in the index value, where yourIndexVariableName is the variable name for index −var yourIndexVariableName= yourIndexValue, anyVariableName= { "$set": {} }; yourVariableName["$set"]["yourFieldName."+yourIndexVariableName] = "yourValue"; db.yourCollectionName.update({ "_id":  yourObjectId}, yourVariableName);Let us first create a collection with documents −> ... Read More

Delete partial data in MongoDB?

Nishtha Thakur
Answered 3h 26m ago

You can use map() for this. Let us first create a collection with documents −> db.deleteDemo.insertOne({"Name":"John"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5cd550492cba06f46efe9f06") } > db.deleteDemo.insertOne({"Name":"Carol"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5cd5504d2cba06f46efe9f07") } > db.deleteDemo.insertOne({"Name":"Sam"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5cd550512cba06f46efe9f08") } ... Read More

Selecting only a single field from MongoDB?

Smita Kapse
Answered 3h 29m ago

You can use $and operator. Let us first create a collection with documents −>db.selectingASingleFieldDemo.insertOne({"StudentFirstName":"John", "StudentAge":23, "StudentCountryName":"US"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5cd547142cba06f46efe9f02") } >db.selectingASingleFieldDemo.insertOne({"StudentFirstName":"Carol", "StudentAge":21, "StudentCountryName":"UK"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5cd5471f2cba06f46efe9f03") } >db.selectingASingleFieldDemo.insertOne({"StudentFirstName":"David", "StudentAge":24, "StudentCountryName":"AUS"}); {    "acknowledged" : true,    "insertedId" : ... Read More

MongoDB divide aggregation operator?

Anvi Jain
Answered 3h 31m ago

You can use aggregate framework for this. Let us first create a collection with documents −>db.aggregationOperatorDemo.insertOne({"FirstValue":392883, "SecondValue":10000000000}); {    "acknowledged" : true,    "insertedId" : ObjectId("5cd541452cba06f46efe9f01") }Following is the query to display all documents from a collection with the help of find() method −> db.aggregationOperatorDemo.find().pretty();This will produce the following output ... Read More

Search an array of hashes in MongoDB?

Nishtha Thakur
Answered 3h 33m ago

Let us first create a collection with documents −> db.searchAnArrayDemo.insertOne({_id:1, "TechnicalDetails":[{"Language":"MongoDB"}]}); { "acknowledged" : true, "insertedId" : 1 } > db.searchAnArrayDemo.insertOne({_id:2, "TechnicalDetails":[{"Language":"MySQL"}]}); { "acknowledged" : true, "insertedId" : 2 } > db.searchAnArrayDemo.insertOne({_id:3, "TechnicalDetails":[{"Language":"MongoDB"}]}); { "acknowledged" : true, "insertedId" : 3 } > db.searchAnArrayDemo.insertOne({_id:4, "TechnicalDetails":[{"Language":"MongoDB"}]}); { "acknowledged" : true, "insertedId" : ... Read More

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