Back-End Developers and Full-Stack Developers who work with Java are often involved in multiple projects, and they rely on Maven to help them manage everything.

But what is Maven exactly, and why is it so popular with developers? Ahead, we’ll walk you through what Maven is, what it does, how it works, and when you should use it.

What is Maven?

Maven is an open-source build tool that Software Developers use to build, publish, and deploy several projects at once. It’s written in Java and is mainly used for Java-based projects, but you can also use it to build and manage projects in other languages like C#, Ruby, and Scala.

To better understand Maven and what it does, it’s important to understand two key terms: build tools and JAR files.

What is a build tool?

A build tool compiles code and packages it into a form that can be executed. Dev teams rely on building tools to automate the process of turning source code into an actual application. A build tool typically does the following things:

• Create source code
• Create documentation from the source code
• Compile source code and bundle it into a package file format such as JAR

What is a JAR file?

A Java Archive (JAR) file is a package file that aggregates many files into a single one. JAR files are based on the ZIP file format and contain Java class files (a type of code file) and resources like text, images, and associated metadata.

Java developers use JAR files for packaging everything needed to run a Java library or software package. In fact, many JAR files work like fully executable files — all you need to do is double-click to run it.

A software project can involve many JAR files, and Maven helps developers track, manage, and download libraries and source code packages that the project needs to run. When the software is ready to deploy, Maven packages everything into its own self-contained JAR file.

What does Maven do?

Maven helps developers manage multiple projects at once by simplifying and automating the project lifecycle. The default Maven lifecycle phases are:

• Validate that the project information is correct and available.
• Compile source code.
• Test using an appropriate testing framework.
• Package code into a JAR file.
• Verify that quality assurance criteria are met.
• Install packages into a local repository that other projects can use.
• Deploy copies into a remote repository for access by other developers and projects.

How does Maven work?

Maven works through three fundamental functions or concepts:

• Maven manages dependencies by downloading libraries and JAR files required by the project and their dependencies.
• Maven helps developers manage projects with a Project Object Model (POM).
• Maven adopts a convention over configuration approach.

What is a Maven dependency?

One of the major features of Maven is dependency management. A Maven dependency is another source of code — a library, a framework, or a package file — that the project needs to run correctly.

A small project may only require a few libraries that the dev team can easily manage. But larger projects may rely on hundreds of libraries and package files, including libraries that depend on other libraries or JAR files to function. All of these dependencies might be stored in dozens of different locations.

Maven tracks everything and simplifies building a project by automatically downloading the dependencies a project needs to work independently.

What is a Maven Project Object Model?

The Project Object Model (POM) plays a central role in Maven. A POM is an XML file containing a blueprint or map of the project, including source code files, dependencies, plugins, configuration settings, and general information such as project version, project description, developers, and mailing lists.

When you run a task or goal, Maven looks for the POM, reads it, gets the needed configuration information, and performs the task.

What is convention over configuration?

Convention over configuration is a software framework design model in which the framework provides all the default values needed to run an application. This means that developers using the framework don’t need to make as many decisions about configuration (though they can always choose to override default values and manually configure the framework).

Maven’s convention over configuration approach means you don’t need to define every task like compiling, testing, and packaging a file. Instead, Maven handles them automatically using built-in defaults. All you need to do is add the file paths to the POM, and Maven takes care of the rest.

What are the pros and cons of Maven?

Like any other development tool, Maven has its pros and cons.

Pros of Maven

• Maven makes the project build process easier. While it doesn’t remove the need to understand the underlying mechanisms of a project, it takes care of a lot of the details.
• Maven promotes a standard build system. The Maven POM provides a uniform build template. Once you understand how one Maven project works, you’ll understand how to build any future Maven project.
• Maven can quickly provide useful project information. It takes information from the POM or from project sources to provide quality information including changelogs, mailing lists, dependency lists, and test reports.

Cons of Maven

• Maven comes with a learning curve. Newbies will need some initial training to understand how it works — and some devs feel that its support and documentation are limited when they run into issues.
• Maven’s dependency management system isn’t perfect. For example, if the Maven code for a dependency isn’t available, it’s impossible to add in the dependency within Maven itself.
• Maven can be slow, especially with large projects. As project size and complexity increase, so does build time.

When should you use Maven?

Given its pros and cons, we recommend using Maven in the following situations:

• When your project involves a lot of dependencies, including libraries, frameworks, and JAR files.
• When your project doesn’t involve a lot of special configurations, allowing you to make the most of Maven’s convention over configuration approach.
• When you know that your team or company can commit to using Maven on future projects, making it worthwhile to invest the time needed to learn it.

Java development teams everywhere use Maven

If you’re getting into Back-End Development or Full-Stack Development, especially in Java, learning to build tools like Maven is worthwhile. If you’re just starting out, we can help you gain the skills you need with online programming courses in Java and how to pass the Java technical interview. If you’re not sure what to learn next, our developer career paths can help guide you toward building the skills you need for success.

If you’re an aspiring Cybersecurity Specialist, Back-End Developer, or Data Scientist, then you’ll need to know about hashing. Hashing is an important tool used in data authentication and security, as well as database management. 

Never heard of hashing before? Don’t worry, we’ll break it down for you. Ahead, we’ll walk you through everything you need to know about hashing, including what it is, how it works, why people use it, and popular hashing algorithms.

What is hashing?

Hashing is the process of converting data — text, numbers, files, or anything, really — into a fixed-length string of letters and numbers. Data is converted into these fixed-length strings, or hash values, by using a special algorithm called a hash function.

For example, a hash function that creates 32-character hash values will always turn text input into a unique 32-character code. Whether you want to generate a hash value for the word “Codecademy” or for the entire works of Shakespeare, the hash value will always be 32 characters long.

How hashing works

Input data is key

The input data to be hashed is also known as the key. A key can be in just about any format. It could be a string of text, a list of numbers, an image, or even an application file.

The hash function

The central part of any hashing process is the hashing function, which takes the key and converts it to a fixed-length string of characters. But how exactly does that work? How is it that your name and a novel can both be condensed into the same number of characters? 

The secret is dividing the data into equal-sized blocks.

The most popular hashing algorithms work with block sizes between 160 and 512 bits. A bit is the basic unit of computer information and corresponds to either a binary 1 or 0.

Let’s suppose that we’re working with SHA-1, a popular hash function that works with block sizes of 512 bits. 512 bits is about the same as 32 words, so if we have a short message to hash, then the SHA-1 function only needs to run once to generate a final hash value.

Of course, most files and datasets are much larger than that, so the algorithm divides all of the data into 512-bit chunks. If our data is 1024 bits, then the algorithm first runs the SHA-1 function for the first chunk of data, generates a hash value, and then combines this first hash value with the second half of the data to generate a final hash value.

For larger inputs, the process repeats until all the 512-bit chunks have been processed by the hashing algorithm. A hash function might process a large dataset or file thousands or even hundreds of thousands of times before it generates the final hash value. This is why hashing algorithms need to be efficient in order to be effective.

The hash value

The final output of the hash function is the hash value, which ideally should be unique to each input. Hash values may only need to be used once for data authentication or digital signatures, or they may be stored for easy lookup in a hash table.

Properties of hashing algorithms

There are several different approaches hashing algorithms and functions use to convert data into hash values, but they all share a few common characteristics..

Deterministic

If you use the same data input and the same hashing algorithm, then the final hash value should be the same. This is a key aspect of using hash functions to authenticate data.

Ideally, no two inputs in a hashing algorithm should yield the same output hash value. This is known as a collision, and the best hashing algorithms have the fewest instances of collisions.

Quick computation

Remember that hashing algorithms process data in small chunks to generate a final hash value. An effective hashing algorithm quickly processes any data type into a unique hash value.

Irreversible

Hash functions are designed to make it impossible to regenerate a message or file from the hash value. In fact, if the hashing function can be reversed to recreate the original input, it’s considered to be compromised. This is one thing that distinguishes hashing from encryption, which is designed to be reversible.

Why is hashing used?

Hashing is used in a variety of applications, from cybersecurity to blockchain to data privacy. Here are a few ways that people use hashing every day.

Message and data authentication

Hashing helps Cybersecurity Specialists ensure that data isn’t intercepted between the sender and the recipient.

Let’s pretend that we’re both spies. We’re working in different cities, doing spy stuff, and since we don’t have a secure internet connection, the only trusted way for us to communicate with each other is by sending hand-delivered notes.

But if I send a note to you, how can we make sure that no one’s tampered with my message? I can encrypt the message, but if someone else has figured out the encryption, how do we know they haven’t intercepted my message and replaced it with another one?

One solution is to use a hashing algorithm to turn the contents of my message into a series of characters. If we can both turn my message into the same string of characters with the hashing algorithm, we’ll know no one tampered with my message while on its way to you.

In other words, hashing is a way to authenticate data or show that the data received wasn’t somehow changed along the way. When you’re downloading software, hashing helps ensure that what you’re installing is the original code and not compromised by a virus, trojan, or other malware.

Detecting changes in data

Even when you’re working with non-sensitive data, hashing is an effective way to compare two sets of data and see if they’re different.

Let’s look at two messages and their hash values using a popular hash function called MD5:

“Meet me at Codecademy HQ on Broadway”

942206fffceea95d4c8393c77ea617ab

“Meet me at Codecadamy HQ on Broadway”

aad9085d26114958742098b18348414e

What did you notice first: the different hash values or the differences between the messages?

If you read through each message, you’ll notice that the word “Codecademy” is spelled differently in the second message. Now, imagine that you want to find out whether two versions of a novel are different. Even a computer would need some time to go through thousands of words, but with hashing, all it takes is comparing a few characters to determine whether two sets of data are different.

Data privacy

Sometimes, you want to be able to store and retrieve sensitive information. For example, many websites don’t store your actual password in a database but rather your password’s hash value instead. That way, if someone does hack into the database, all they’ll find are hash values that can’t be directly used by themselves.

This is especially useful for the health and financial industries. Instead of storing directly identifiable information such as name or social security number, a health or bank database can store the hash value of this information instead.

Blockchain

One of the most publicized applications of hashing is blockchain, specifically with cryptocurrencies like Bitcoin. We go more into blockchain here, but as a quick review, it’s a digital collection of transactions or records about something. Since everyone has access to the same data in a blockchain, how can everyone be sure that no one has altered any of the past transactions? That’s where hashing comes in.

In a blockchain, every new record or transaction is known as a block. In the case of Bitcoin, a block includes the transfer amount, the timestamp, and  the hash value for the data in the previous block. So If someone tried to alter the transaction history for a unit of Bitcoin, the hash values would change, and the transaction would be invalid. Hashing is how blockchains can ensure data authenticity and integrity when everyone has access to the same data.

Database management

When you’re working with large databases, combing through all the different entries to find the data you need can be exhausting — but hashing can make it easier. Instead of relying on index structure, hashing allows you to search for a data record using a search key and hash function.

Hash files store data in buckets, and each bucket can hold multiple records. Hash functions are used to map search keys to the location of a record within a bucket.

There are two hashing methods you can use in a database management system (DBMS): Static hashing and dynamic hashing.

• With static hashing, a search key and hash function always lead to the same address, and the number of buckets remains fixed. When you need to add a new record to the database, you can use a hash key to automatically generate an address for the record and store it. Then, you can use the same key to locate the record when you need to access, update, or delete it.
• Unlike static hashing, dynamic hashing (AKA extendible hashing) allows for data buckets to be created and removed as needed. This helps prevent bucket overflow, which occurs when a bucket doesn’t have enough space for a new record. 

Popular hashing algorithms

Since the early days of digital computing, various hashing algorithms have been developed, each with its own methods, advantages, and disadvantages. Here are three popular hashing algorithms used today.

Message Digest 5 (MD5)

MD5 was once the most common hashing algorithm in the early days of computer cryptography. But, the algorithm suffered from frequent collisions, and while it’s still widely used around the world, it’s no longer used for sensitive or confidential data.

MD5 is also significantly slower than the algorithms listed below, and while using it, there’s a greater chance of ending up with the same hash value for two different inputs.

Secure Hash Algorithm (SHA)

SHA actually refers to a group of hashing algorithms. The SHA-2 family of hash functions was originally developed by the US National Security Agency (NSA) and is the standard for hashing private data. It’s currently used by cryptocurrencies and the CIA.

CRC32

When the primary purpose of hashing is simply to detect errors and changes in data, then most people work with a cyclic redundancy check (CRC) code. Hashing with CRC32 is also a quick and easy way to check file integrity, particularly with ZIP files and files downloaded from FTP servers.

Hashing is a valuable tool in cybersecurity and database management

If you’re pursuing a career in cybersecurity, you’ll need to understand hashing’s role in data security, integrity, and privacy. It’s also a valuable tool for Back-End Engineers and Data Scientists.

Still, you’ll need more than hashing to excel in any of the careers listed above. Try taking online programming courses to keep building your skills — for example, learning how to implement User Authentication and Authorization in Express.