We have 13 years old monolithic java application using
Struts 2 for handling UI calls
JDBC/Spring JDBC Template for db calls
Spring DI
Tiles/JSP/Jquery for UI
Two deployables are created out of this single source code.
WAR for online application
JAR for running back-end jobs
The current UI is pretty old. Our goal is to redesign the application using microservices. We have identified modules which can run as separate microservice.
We have following questions in our mind
Which UI framework should we go for (Angular/React or a home grown one). Angular seems to be very slow and we need better performance as far as page loading is concerned.
Should UI/Javascript make call to backend web services directly or should there be a spring controller proxy in deployed WAR which kind of forwards UI calls to APIs. This will also help if a single UI calls requires getting/updating data from different microservice.
How should we cover microservice security aspect
Which load balancer should we go for if we want to have multiple instance of same microservice.
Since its a banking application, our organization does not allow using Elastic Search/Lucene for searching. So need suggestion for reporting using Oracle alone.
How should we run backend jobs?
There will also be a main payment microservice which will create payments. Since payments volume is huge hence it will require multiple instances. How will we manage user logged-in session. Should we go for in-memory distributed session store (may be memcache)
This is a very broad question. You need to get a consultant architect to understand your application in depth, because it is unlikely you will get meaningful in-depth answers here.
However as a rough guideline here are some brief answers:
Which UI framework should we go for (Angular/React or a home grown one). Angular seems to be very slow and we need better performance as far as page loading is concerned.
That depends on what the application actually needs to do. Angular is one of the leading frameworks, and is usually not slow at all. You might be doing something wrong (are you doing too many granular calls? is your backend slow?). React is also a strong contender, but seems to be losing popularity, although that is just a subjective opinion and could be wrong. Angular is a more feature complete framework, while React is more of a combination of tools. You would be just crazy if you think you can do a home grown one and bring it to the same maturity of these ready made tools.
Should UI/Javascript make call to backend web services directly or
should there be a spring controller proxy in deployed WAR which kind
of forwards UI calls to APIs. This will also help if a single UI calls
requires getting/updating data from different microservice.
A lot of larger microservice architectures often involve an API gateway. Then again it depends on your use case. You might also have an issue with CORS, so centralising calls through a proxy / API gateway, even if it is a simple reverse proxy (you don't need to develop it) might be a good idea.
How should we cover microservice security aspect.
Again no idea what your setup looks like. JWT is a common approach. I presume the authentication process itself uses some centralised LDAP / Exchange or similar process. Once you authenticate you can sign a token which you give to the client, which is then passed to the respective micro services in the HTTP authorization headers.
Which load balancer should we go for if we want to have multiple
instance of same microservice.
Depends on what you want. Are you deploying on a cloud based solution like AWS (in which case load balancing is provided by the infrastructure)? Are you going to deploy on a Kubernetes setup where load balancing and scaling is handled as part of its deployment fabric? Do you want client-side load balancing (comes part of Spring Cloud)?
Since its a banking application, our organization does not allow using
Elastic Search/Lucene for searching. So need suggestion for reporting
using Oracle alone.
Without knowledge of how the data on Oracle looks like and what the reporting requirements are, all solutions are possible.
How should we run backend jobs?
Depends on the infrastructure you choose. Everything is possible, from simple cron jobs, to cloud scheduling services, or integrated Java scheduling mechanisms like Quartz.
There will also be a main payment microservice which will create
payments. Since payments volume is huge hence it will require
multiple instances. How will we manage user logged-in session. Should
we go for in-memory distributed session store (may be memcache)
Not really. It will defeat the whole purpose of microservices. JWT tokens will be managed by the client's browser and expire automatically. You don't need to manage user logged-in session in such architectures.
As you have mentioned it's a banking site so security will be first priory. Here I have few suggestions for FE and BE.
FE : You better go with preactjs it's a react like library but much lighter and fast as compare to react. For ui you can go with styled components instead of using some heavy third party lib. This will also enhance performance and obviously CDNs for images and big files.
BE : As per your need you better go with hybrid solution node could be a good option.e.g. for sessions.
Setup an auth server and get you services validate user from there and it will be used in future for any kinda service .e.g. you will expose some kinda client API's.
User case for Auth : you can use redis for session info get user validated from auth server and add info to redis later check if user is logged in from redis this will reduce load from auth server. (I have used same strategy for a crypto exchange and went pretty well)
Load balancer : Don't have good familiarity with java but for node JS PM2 will do that for you not a big deal just one command and it will start multiple instances and will balance on it's own.
In case you have enormous traffic then you better go with some messaging service like rabbitmq this will reduce cost of servers by preventing you from scaling your servers.
BE Jobs : I have done that with node for extensive tasks and went quite well there you can use forking or spanning this will start a new instance for particular job and will be killed after completing it and you can easily generate logs along with that.
For further clarification I'm here :)
Is there a Java tool for choreographing web services that makes it easy to deal with transactions?
In my use case I want to chain 2 SOAP web services: the first will perform a debit into a client's bank account and the second will recharge his cell phone for the corresponding amount. How can I implement this sequence of web services calls transactionally?
I briefly looked at Apache Camel but it doesn't seem to be the most adequate tool.
Thanks.
If your web-services are implemented using SOAP, you can implement 2-phase commit with WS-AtomicTransaction extension. These articles go into details how it can be implemented:
Using Web Services Atomic Transactions (Java)
Coordinating Web Services Activities with WS-Coordination,
WS-AtomicTransaction, and WS-BusinessActivity (.NET, but the
concept is the same)
Is there a possible architecture that a developer can think of when it comes to extending a web application by introducing Web Services to the existing architecture or vice-verse. The main concern in this context is the data integrity and security.
The following images will suggest two approaches that a developer can think of.
This architecture indicates that all the request should be handled by an individual service layer. Therefore, only the service layer can communicate with the Data Base and satisfy request for both the web application and the gate way.
The second approach shows the web application is directly communicating with DB. For an example an Admin Portal. Meantime there can be an external web services also communicating with the DB. This approach may lead to Data Integrity Violating scenarios. However, introducing external web services might be easier than refactoring an existing Web Application to call a web service from developer end. Hence, can we still compromise for the long term consequences by having external web service and a separate web application instead of both the Web Application and the Gateway being catered with a single web service layer. Any reasonable comment on this would be appreciated.
You could build an API that has access to everything. In other word, the web application could work trough a rest/rpc api using Ajax/WebSockets.
Since everything goes through the API, data integrity shouldn't be enforced at any time. Also, you'll get a clear separation from Client, Api and Database.
This will allow you to replace the database by anything else without breaking other parts of your system.
I would personally advise to have at least a shared data access layer which handle data validation and persistence.
The best way would be however as defined in your first diagram with a shared service layer to factorize transaction management which should be defined at this level. You could so take advantage of custom transaction isolation and / or locking policy in order to ensure Data integrity. Public service layer methods could be in this case directly exposed as rest services and consumed by both mobile and web apps (gateway / API component is not necessary).
All of this will depend on the estimated time to refactor the legacy app architecture on a way and to duplicate data access logic (and business one ???) on the other. Of course the duplication will decrease maintainability and extensibility.
I've had to answer this question on several projects; there's a 3rd option which you don't mention, which is my favourite.
The problem with option 1 - "web services as persistence and business logic layer" is that it introduces a lot of additional moving parts into the design. Those moving parts are expensive - you have to write, test and maintain a lot more code, and very often the services you want from your web services to run your own application are not the ones that would make sense to a 3rd party developer.
You are also introducing a potentially significant performance and scalability risk - calling a web service which calls a database is measurably slower than just calling the database.
The second option - duplicating business logic across web app and service layer - has all the problems of duplication.
The option I prefer is to develop the business logic layer as a separate component, and have it used by both the web app and the web services; each application uses the component as a library. This means you have to have separate teams - the "library" team and the "app" teams - but you avoid duplication, and you avoid invoking a bunch of web services every time you have to render a web page.
The business logic layer is responsible for persistence - including making sure that database consistency is honoured, and managing transactions. As the business logic layer is shared between both the web app and the web services, this logic is concentrated into a single code base, and - ideally - made entirely transparent to the apps.
The web services now do far less. Their job is to handle incoming requests, translate them into method invocations on the business logic component, and returning any response data in the appropriate format (XML, JSON). They may offer "coarse grained" service requests and map them onto several more granular business logic methods. They may deal with authentication, authorization, request throttling etc. They just don't deal with the actual business logic.
I am going to make a small trade management system. I want to make a independent database service to which all the other client connect. The database will be MYSQL and I will be using Java for making the service. The client can either be a Web Application or a desktop application using Java Swing (has not decided yet). There will be another layer sit between the client and the database service to handle the business logic (I call it trade service).
The architecture is something like: Client -> Trade Service -> Database Service.
My questions is that what client/service communication technology is the best suitable one for client->Trade Service and the best suitable one for Trade service -> Database.
Shall I make it s RESTful service? SOAP? Using RPC? Or any other technologies?
Many thanks for your help. Any idea or suggestions are welcome.
Take a look at RabbitMQ, A pool messaging service
http://www.rabbitmq.com/
It's Robust, flexible, fast and scalable and you can use it to communicate in Java, PHP, or whatever technologies ou want.
Shall I make it s RESTful service? SOAP? Using RPC?
These are all very similar approaches in that they are over HTTP so - assuming that's what you want; I would recommend using RESTful. You'll have lot's of examples to work with and it will allow you flexibility in the future to do things like switching out the UI layer for a smart phone app or desktop app.
Regardless of what model you pick you should understand how it works first and build in things like security and guidelines early. Do your homework now. Trying to change the middle layer of a design like this is a pain.
There is no blanket answer to your question, there are instead options based on your skill set. Do you conceptually understand the HTTP spec completely and be able to extend it to REST, that works very closely with HTTP (common creation ancestor). Do you better understand the traditional method invocation of SOAP? Are you tied in your ecosystem to a specific language, as this can impact which tools you choose from.
If you were paying me to write a service based on the simple requirements you have given (which is nearly impossible), I would create a domain driven design service (your business layer) with a RESTful interface and Spring JDBC for data access. That is me, and what I work in most often. My partner in crime at work would probably choose SOAP and Hibernate.
I think what you're taking about is Queues, and I'm guessing you need a managed service for that. Queues can be the glue between your micro-services. Some of the vendors I know which have Queue as a Service are :
CloudBoost.io : https://www.cloudboost.io
Check out https://tutorials.cloudboost.io/en/queues/basicqueues for documentation.
Iron.io : https://www.iron.io
P.S : I work at CloudBoost
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Let's share Java based web application architectures!
There are lots of different architectures for web applications which are to be implemented using Java. The answers to this question may serve as a library of various web application designs with their pros and cons. While I realize that the answers will be subjective, let's try to be as objective as we can and motivate the pros and cons we list.
Use the detail level you prefer for describing your architecture. For your answer to be of any value you'll at least have to describe the major technologies and ideas used in the architecture you describe. And last but not least, when should we use your architecture?
I'll start...
Overview of the architecture
We use a 3-tier architecture based on open standards from Sun like Java EE, Java Persistence API, Servlet and Java Server Pages.
Persistence
Business
Presentation
The possible communication flows between the layers are represented by:
Persistence <-> Business <-> Presentation
Which for example means that the presentation layer never calls or performs persistence operations, it always does it through the business layer. This architecture is meant to fulfill the demands of a high availability web application.
Persistence
Performs create, read, update and delete (CRUD) persistence operations. In our case we are using (Java Persistence API) JPA and we currently use Hibernate as our persistence provider and use its EntityManager.
This layer is divided into multiple classes, where each class deals with a certain type of entities (i.e. entities related to a shopping cart might get handled by a single persistence class) and is used by one and only one manager.
In addition this layer also stores JPA entities which are things like Account, ShoppingCart etc.
Business
All logic which is tied to the web application functionality is located in this layer. This functionality could be initiating a money transfer for a customer who wants to pay for a product on-line using her/his credit card. It could just as well be creating a new user, deleting a user or calculating the outcome of a battle in a web based game.
This layer is divided into multiple classes and each of these classes is annotated with #Stateless to become a Stateless Session Bean (SLSB). Each SLSB is called a manager and for instance a manager could be a class annotated as mentioned called AccountManager.
When AccountManager needs to perform CRUD operations it makes the appropriate calls to an instance of AccountManagerPersistence, which is a class in the persistence layer. A rough sketch of two methods in AccountManager could be:
...
public void makeExpiredAccountsInactive() {
AccountManagerPersistence amp = new AccountManagerPersistence(...)
// Calls persistence layer
List<Account> expiredAccounts = amp.getAllExpiredAccounts();
for(Account account : expiredAccounts) {
this.makeAccountInactive(account)
}
}
public void makeAccountInactive(Account account) {
AccountManagerPersistence amp = new AccountManagerPersistence(...)
account.deactivate();
amp.storeUpdatedAccount(account); // Calls persistence layer
}
We use container manager transactions so we don't have to do transaction demarcation our self's. What basically happens under the hood is we initiate a transaction when entering the SLSB method and commit it (or rollback it) immediately before exiting the method. It's an example of convention over configuration, but we haven't had a need for anything but the default, Required, yet.
Here is how The Java EE 5 Tutorial from Sun explains the Required transaction attribute for Enterprise JavaBeans (EJB's):
If the client is running within a
transaction and invokes the enterprise
bean’s method, the method executes
within the client’s transaction. If
the client is not associated with a
transaction, the container starts a
new transaction before running the
method.
The Required attribute is the implicit
transaction attribute for all
enterprise bean methods running with
container-managed transaction
demarcation. You typically do not set
the Required attribute unless you need
to override another transaction
attribute. Because transaction
attributes are declarative, you can
easily change them later.
Presentation
Our presentation layer is in charge of... presentation! It's responsible for the user interface and shows information to the user by building HTML pages and receiving user input through GET and POST requests. We are currently using the old Servlet's + Java Server Pages (JSP) combination.
The layer calls methods in managers of the business layer to perform operations requested by the user and to receive information to show in the web page. Sometimes the information received from the business layer are less complex types as String's and integers, and at other times JPA entities.
Pros and cons with the architecture
Pros
Having everything related to a specific way of doing persistence in this layer only means we can swap from using JPA into something else, without having to re-write anything in the business layer.
It's easy for us to swap our presentation layer into something else, and it's likely that we will if we find something better.
Letting the EJB container manage transaction boundaries is nice.
Using Servlet's + JPA is easy (to begin with) and the technologies are widely used and implemented in lots of servers.
Using Java EE is supposed to make it easier for us to create a high availability system with load balancing and fail over. Both of which we feel that we must have.
Cons
Using JPA you may store often used queries as named queries by using the #NamedQuery annotation on the JPA entity class. If you have as much as possible related to persistence in the persistence classes, as in our architecture, this will spread out the locations where you may find queries to include the JPA entities as well. It will be harder to overview persistence operations and thus harder to maintain.
We have JPA entities as part of our persistence layer. But Account and ShoppingCart, aren't they really business objects? It is done this way as you have to touch these classes and turn them into entities which JPA knows how to handle.
The JPA entities, which are also our business objects, are created like Data Transfer Objects (DTO's), also known as Value Objects (VO's). This results in an anemic domain model as the business objects have no logic of their own except accessor methods. All logic is done by our managers in the business layer, which results in a more procedural programming style. It's not good object oriented design, but maybe that's not a problem? (After all object orientation isn't the only programming paradigm which has delivered results.)
Using EJB and Java EE introduces a bit of complexity. And we can't use purely Tomcat (adding an EJB micro-container isn't purely Tomcat).
There are lots of issues with using Servlet's + JPA. Use Google for more information about these issues.
As the transactions are closed when exiting the business layer we can't load any information from JPA entities which is configured to be loaded from the database when it's needed (using fetch=FetchType.LAZY) from inside the presentation layer. It will trigger an exception. Before returning an entity containing these kinds of fields we have to be sure to call the relevant getter's. Another option is to use Java Persistence Query Language (JPQL) and do a FETCH JOIN. However both of these options are a little bit cumbersome.
Ok I'll do a (shorter) one:
Frontend : Tapestry (3 for older projects, 5 for newer projects)
Business layer: Spring
DAO's : Ibatis
Database : Oracle
We use Sping transaction support, and start transactions upon entering the service layer, propagating down to the DAO call's. The Service layer has the most bussines model knowledge, and the DAO's do relatively simple CRUD work.
Some more complicated query stuff is handled by more complicated queries in the backend for performance reasons.
Advantages of using Spring in our case is that we can have country/language dependant instances, which are behind a Spring Proxy class. Based on the user in the session, the correct country/language implementation is used when doing a call.
Transaction management is nearly transparent, rollback on runtime exceptions. We use unchecked exceptions as much as possible. We used to do checked exceptions, but with the introduction of Spring I see the benefits of unchecked exceptions, only handling exceptions when you can. It avoids a lot of boilerplate "catch/rethrow" or "throws" stuff.
Sorry it's shorter than your post, hope you find this interesting...
Ideal Java Based Web Development Technologies Today.
Web Layer :
HTML+CSS+Ajax+JQuery
RESTFul Web Controller/Action/Request Processing Layer :
Play Framework
Business Logic/Service Layer:
Use Pure Java Code as long as possible. One can do fusion of web services here.
XML/JSon Data Transformation Layer :
XMLTool(Search On Google Code),JSoup,Google GSon,XStream,JOOX (Search On Google Code)
Persistence Layer :
CRUD : JPA or SienaProject or QueryDSL /
Complex Queries : JOOQ,QueryDSL
Here's my 5 cents
Presentation
Android, Angular.JS WebClient, OAUTHv2
API
REST, Jersey (JAX-RS), Jackson (JSON de-/serialisation), DTO-objects (different from business logic models)
Business Logic
Spring for DI and Event handling. DDD-ish approach of model objects. Longer running jobs are offloaded with SQS in worker-modules.
DAO
Repository model with Spring JDBC-templates to store Entities.
Redis (JEDIS) for Leaderboards, using Ordered Lists.
Memcache for Token Store.
Database
MySQL, Memcached, Redis
What we have followed in our project is :
Front end Technology
AngularJS
HTML5
css3
Javascript
Bootstrap 3
API
REST
JERSEY (JAX-RS)
REST ASSURED
SPRING BOOT
Jackson
spring security
Business Logic
SPRING DATA
SPRING data MongoDB
Data base
MongoDB
Server (For caching)
redis
We are still using the usual Struts-Spring-Hibernate stack.
For future apps, we are looking into Spring Web Flow + Spring MVC + Hibernate or
Spring + Hibernate + Web Services with Flex front end.
A distinct characteristic of our architecture is modularization. We have a number of modules, some starting with 3 to max 30 tables in the database. Most of modules consist of business and web project. Business project holds business and persistence logic while web holds presentation logic.
On logical level, there are three layers: Business, Persistence and Presentation.
Dependencies:
Presentation depends on Business and Persistence.
Persistence depends on Business.
Business does not depend on other layers.
Most of business projects have three types of interfaces (note: not GUI, it is a programatic java interface layer).
Interface that presentation is using as a client
Interface that other modules are using when they are the client of the module.
Interface that can be used for administrative purposes of the module.
Often, 1 extends 2.
This way, it is easy to replace one implementation of module with another. This helps us adopt to different clients and integrate more easily. Some clients will buy only certain modules and we need to integrate functionality they already have. Since interface and implementation layer are separated, it is easy to roll out ad-hock module implementation for that specific client without affecting dependant modules. And Spring Framework makes it easy to inject different implementation.
Our business layer is based on POJOs. One tendency I am observing is that these POJOs resemble DTOs. We suffer from anaemic domain model. I am not quite sure why is this happening but it can be due to simplicity of problem domain of many of our modules, most of the work is CRUD or due to developers preferring to place logic somewhere else.
Here is one more web architecture I have worked on:
One major requirement was the application should support mobiles/other
devices. The application should also be extensible or flexible to
changes in technology choices.
Presentation Tier:
JSP/JQuery (Client-side MVC)
Native Android
Native iPhone
Mobile web (HTML5/CSS3/Responsive design)
Spring REST Controllers (Can change to JAX-RS)
Business Service Tier:
Spring #Service (Can change to Stateless EJB)
Data Access Tier:
Spring #Repository (Can change to Stateless EJB)
Resource Tier:
Hibernate(JPA) entities (Can change to any ORM)
You can find more information on the book which follows this architecture here.
IMHO, most of us have a common denominator. Atleast in the back-end, we have some form of IOC/DI container and a persistence framework. Personally I use Guice and Mybatis for this. The differences are in how we implement the view/UI/presentation layer. There are 2 major options here (may be more) .. Action based (URLs mapped to controllers) and component based. Currently am using component based presentation layer (using wicket). It perfectly mimics a desktop environment where I use components and events as opposed to URLs and controllers. Am currently looking for a reason why I should migrate to this URL-controller kind of architecture (that's how I ended up on this page). Why the hype about RESTful and Stateless architectures.
To answer this question in short: I write stateful web applications using a component oriented framework on top of Guice IOC container and put data in relational database using Mybatis.
A bit different, and I would claim more modular java architecture here. We have:
Spring WS/Rest/JSP front end
Spring MVC for business service logic, containing presentation layer logic as well as Spring transactions
Component service communication interface, looked up through EJB by business services. EJBs set their own transaction boundaries that are able to join Spring transactions.
Component service implementations, again Spring components
Integration layer, MyBatis for database integrations, Spring WS for web service integrations, other integration techonologies for other services
Mainframes, databases, other services at other servers...
In addition to the above, we have the shared library modules which is common functionality provider for all srevices.
Use of different layers allows us full decoupling and the modularity we need. We are also able to fully utilize the power of Java EE as well as Spring. Nothing prevents us from using JSF, for example, for the front end if needed.
Compared to example architecture by OP, I think this can be described as having four main layers instead of three, albeit with a twist.
I've worked on projects that use that rigid manager pattern. Historically, I was a huge proponent of the rigid hierarchy where everything fit into a neat box. As I progress in my career I find it to be forced in a lot of cases. I believe that adopting a more agile mindset towards application design leads to a better product. What I mean by this creating a set of classes that solve the problem at hand. Rather than saying "Did you build a manager for this and that?"
The current project I'm working on is a web app with a combination of Spring MVC and RestEasy JSON/Ajax calls. On the server side embedded in our controllers is a sensible facade based data tier with JPA/Hibernate for direct Database access, some EJB access, and some SOAP based web service calls. Tying all this together is some custom java controller code that determines what to serialize as JSON and return to the client.
We spend almost no time attempting to create some unified pattern instead opting to adopt the "Worse is Better" idea of the Unix Design Philosophy. Being that its much better to color outside the lines and build something sensible, quickly than it is to build something that adheres to a bunch of strict design mandates.
The components in Web Application Architecture include :
1 : Browser : Client interaction
HTML
JavaScript
Stylesheet
2 : Internet
3 : Webserver
CSS
Image
Pages(Java render )
4 : Application Server
App Webapp (Java interaction)
Others WebApps
5 : Database Server
Oracle, SQL, MySQL
6 : Data