IRIS EDUCATION

Spring wolf documentation

2025-06-04T13:55:00.003+05:30

Springwolf documentation for managing the Kafka based communication between microservices.

In this video, we'll show you how to auto-generate AsyncAPI documentation for your Kafka-based Event-Driven Microservices using SpringWolf + Spring Boot – with almost zero configuration! ✅ What is SpringWolf and how it helps to developer community ✅ How SpringWolf integrates with Spring Boot ✅ Auto-generating AsyncAPI YAML/JSON docs ✅ Kafka event listener mapping ✅ Debugging and visualizing event flows

Microservice communication with kafka broker

2025-06-04T13:52:00.002+05:30

Microservice communication with kafka broker in Event driven architecture

This article display how the communication takes place between two or more microservice. For communicating between the microservice you can use any message broker here in this example we are using the Kafka broker. For communication with the microservice we have created two topics TOPIC 1 and TOPIC 2.

TOPIC 1 will be produced by the MS_1 and will be consumed by the MS_2 and TOPIC 2 will be produced by the MS_2 and will be consumed by the MS_1.

For detailed explanation follow the below video link.

java 8 setup

2023-11-16T17:18:00.001+05:30

java 8 setup file click here

Thymeleaf function on button click with multiple parameter

2023-03-15T19:37:00.001+05:30

how you can write the onclick attribute using Thymeleaf syntax:

<button type="button" th:onclick="|rejectSalaryPayment('${response.uuid}', ${dto.id})|">Reject Salary Payment</button>

This assumes that the response.uuid and dto.id variables are available in the current Thymeleaf context. If they are not, you will need to provide the appropriate values or expressions to evaluate them.

Also note that the onclick attribute is written using the Thymeleaf expression syntax (|...|), which allows you to include string literals and variable expressions within the same attribute value.

Why jar file or application takes lot of time to execute

2023-03-10T12:30:00.002+05:30

There could be several reasons why your system is taking a lot of time to execute a jar file or application. Here are a few possible causes and solutions:

Insufficient hardware resources: If your system does not have enough hardware resources such as RAM, CPU or storage, it can take longer for the jar file or application to execute. To resolve this issue, you can upgrade your hardware or try closing any unnecessary applications that are running in the background.
Network issues: If the jar file or application relies on network resources, slow network connectivity can lead to delays in execution. To resolve this issue, you can try checking your network connectivity, ensure that your internet connection is stable and that the network is not congested.
Large file size: If the jar file or application is large, it can take longer to load and execute. To resolve this issue, you can try compressing the file or splitting it into smaller files.
Compatibility issues: If the jar file or application is not compatible with your system, it can lead to delays in execution. Ensure that you have installed all the necessary software dependencies for the jar file or application to run.
Anti-virus or security software: Anti-virus or security software can slow down the execution of jar files or applications. You can try disabling them temporarily to see if it improves the performance.

6. Overall, it's important to identify the specific cause of the slow execution of your jar file or application, so you can take the appropriate steps to resolve it.

Java Reflection Example

2023-03-01T13:18:00.000+05:30

Document

Filter an array by comparing another array

Create Composite Key in SQL

2023-02-27T10:51:00.003+05:30

What is a composite key?

A composite key in SQL can be defined as a combination of multiple columns, which are used to identify all the rows involved uniquely. Even though a single column can't identify any row uniquely, a combination of over one column can uniquely specify any record.

How to create a composite key?

EG:

Access remote branch git

2023-02-21T16:42:00.002+05:30

$ git branch -v -a

main 99557ef source code

remotes/origin/HEAD -> origin/main

remotes/origin/NewDesign ced7cac New Design

remotes/origin/main 99557ef source code

$ git switch -c NewDesign origin/NewDesign

This will create NewDesign branch in your local machine

Intl.RelativeTimeFormat in JavaScript

2022-12-10T20:22:00.001+05:30

Generate credit card last 4 digit with masked number

Generate credit card last 4 digit with masked number in Typescript

2022-12-10T19:36:00.002+05:30

Generate credit card last 4 digit with masked number

How to insert foreign key on column when data is present in table

2022-10-25T14:33:00.008+05:30

SET FOREIGN_KEY_CHECKS=0;

ALTER TABLE <TABLE_NAME> ADD FOREIGN KEY (COLUMN_NAME) REFERENCES TABLE_NAME(id)

Eg - Alter table vivagame11.matches add foreign key (leagueid) references vivagame11.league(id)

Last record and Last 10 records using JpaHibernate

2022-10-25T13:19:00.007+05:30

View the last 10 records

List<User> findFirst10ByUsername(String username);

`View last record using JpaHibernate`

User findFirstByOrderByIdDesc()

Round two decimal places in Java

2022-08-29T19:55:00.002+05:30

Filter an array by comparing another array

Convert Array to list in java

2022-08-24T19:11:00.004+05:30

Convert Array to list in java

Remove duplicate objects from array Typescript

2022-08-02T19:20:00.002+05:30

Filter an array by comparing another array

Remove duplicate objects from array Typescript

Filter an array by comparing another array

2022-07-29T11:32:00.004+05:30

Filter an array by comparing another array

Java stream filter with map and distinct

2022-07-29T11:18:00.012+05:30

OptimizeMixedDistinctAggregations$AggregateInfo.getOriginalNonDistinctAggregateArgs()

Having clause in sql server query

2022-06-02T00:49:00.001+05:30

JsonFactory, ObjectMapper and JsonNode

2022-04-28T16:31:00.002+05:30

Insert a line break in th:text thymeleaf

2022-04-26T21:22:00.004+05:30

Concatenate Text in date fromat in thymeleaf

2022-02-24T16:41:00.006+05:30

Difference between set, hashset and treeset in java

2022-02-16T05:18:00.001+05:30

A Set is a generic set of values with no duplicate elements. A TreeSet is a set where the elements are sorted.

A HashSet is a set where the elements are not sorted or ordered. It is faster than a TreeSet. The HashSet is an implementation of a Set.

Set is a parent interface of all set classes like TreeSet, HashSet, etc.

JQuery Datatable

2022-01-14T12:58:00.013+05:30

Aggregate identifier must be non-null

2022-01-13T08:55:00.001+05:30

Aggregate identifier must be non-null after applying an event. Make sure the aggregate identifier is initialized at the latest when handling the creation event.

For this I have force fully passed a random variable to CreateRemarkCommand() which is given below: Users.kt class CreateRemarkEvent(val id: Int, val remarkDto: RemarkDto) : BaseEvent(); class CreateRemarkCommand(val id: Int, val remarkDto: RemarkDto) : BaseCommand(); RemarksController: public BaseResponseDto storeRemarks(@RequestBody RemarkDto remarkDto){ remarkDto.setRemarkDate(new Date()); remarkDto.setUserType(UserType.SUBSCRIBER); int remarkAggregate = Integer.parseInt(RandomStringUtils.randomNumeric(6).toString()); CreateRemarkCommand remarkCommand = new CreateRemarkCommand(remarkAggregate, remarkDto); commandBus.dispatch(new GenericCommandMessage<>(remarkCommand)); log.info("Dispatched command"); return BaseResponseDto.builder() .statusCode(StatusCode.SUCCESS) .message("Remarks Created.") .build(); } EventSourcingHandler: @EventSourcingHandler public void on(CreateRemarkEvent event) { RemarkDto remarkDto = event.getRemarkDto(); this.id = event.getId(); this.adminId = remarkDto.getAdminId(); this.userId = remarkDto.getUserId(); this.userType = remarkDto.getUserType(); this.remark = remarkDto.getRemark(); this.remarkDate = remarkDto.getRemarkDate(); } @EventHandler: @EventHandler public void handle(CreateRemarkEvent event) { RemarkDto remarkDto = event.getRemarkDto(); UserRemarks remarks = new UserRemarks(); remarks.setUserId(remarkDto.getUserId()); remarks.setAdminId(remarkDto.getAdminId()); remarks.setUserType(remarkDto.getUserType()); remarks.setRemark(remarkDto.getRemark()); remarks.setRemarkDate(remarkDto.getRemarkDate()); remarksQueryRepository.save(remarks); log.info("Successfully saved remarks of user Id" + remarkDto.getUserId()); } @CommandHandler: @CommandHandler public void handle(CreateRemarkCommand command) throws Exception { remarksRepository.newInstance(() -> new UserRemarks(command.getId(), command.getRemarkDto())); } RemarkAggregate: public class UserRemarks { @AggregateIdentifier private Integer id; private String remark; private Integer adminId; private Integer userId; private UserType userType; private Date remarkDate; public UserRemarks(int id, RemarkDto remarkDto) { apply(new CreateRemarkEvent(id, remarkDto)); }

Pagination in Java

2022-01-13T00:19:00.006+05:30

Remark Controller:

PageRequest pageRequest = new PageRequest(remarkDto.getPageNumber(), Constants.REPORT_ITEM_PER_PAGE); Page<UserRemarks> remarksList = remarksQueryRepository.findAll(pageRequest); remarksList.getContent().stream().sorted((Comparator.comparing(UserRemarks::getRemarkDate) .reversed())).collect(Collectors.toList()); RemarkDtoPaginationResponse response = getRemarkDtoPaginationResponse(remarkDto, remarksList); return response; <br><br> @NotNull private RemarkDtoPaginationResponse getRemarkDtoPaginationResponse(RemarkDto remarkDto, Page<UserRemarks> remarksList) { List<RemarkDto> remarkDtos = mapperFactory.getMapperFacade().mapAsList(remarksList.getContent(), RemarkDto.class); RemarkDtoPaginationResponse response = new RemarkDtoPaginationResponse(); response.setContent(remarkDtos); response.setLast(remarksList.isLast()); response.setTotalElements((int) remarksList.getNumberOfElements()); response.setSize(remarksList.getSize()); response.setNumber(remarkDto.getPageNumber()); response.setFirst(remarksList.isFirst()); response.setTotalPages(remarksList.getTotalPages()); response.setNumberOfElements(remarksList.getNumberOfElements()); return response; }

Remark repository

@Query("select d from UserRemarks d order by d.remarkDate desc") Page findAllByOrderByDatesDesc(Pageable pageable);

Web Client

@RequestMapping(value = "/subscriber-remarks-list", method = RequestMethod.GET) @PreAuthorize("@permissionService.check('VIEW_USER_REMARKS')") public String listAllRemarks(@RequestParam(name = "remarkStartDate", required = false) String remarkStartDate, @RequestParam(name = "remarkEndDate", required = false) String remarkEndDate, @RequestParam(name = "name", required = false) String adminName, @RequestParam(name = "page", required = false) String page, HttpServletRequest request, Model model){ String url = apiGatewayAddress + "/user/get-remark-info"; int pageNumber = (page != null && !page.isEmpty()) ? Integer.parseInt(page) : 0; RemarkDto allRemarks = RemarkDto.builder() .adminFullName(adminName) .pageNumber(pageNumber) .build(); if (!StringUtils.isEmpty(remarkStartDate) && !StringUtils.isEmpty(remarkEndDate)) { Date createdAtStartDate = MfsUtils.stringToDate(remarkStartDate, "MMM dd yyyy"); Date createdAtEndDate = MfsUtils.stringToDate(remarkEndDate, "MMM dd yyyy"); allRemarks.setRemarkStartDate(createdAtStartDate); allRemarks.setRemarkEndDate(MfsUtils.getDayEndTime(createdAtEndDate)); } String queryString = request.getQueryString(); HashMap<String, String> parameterKeyValuePair = mfsUtils.getUrlParameterToKeyValuePair(queryString); List<SearchCriteria> searchCriteriaList = getRemarksCriteria(parameterKeyValuePair); RemarkDtoPaginationResponse remarkDto = restTemplate.postForObject(url, allRemarks, RemarkDtoPaginationResponse.class); List<RemarkDto> listDto = remarkDto.getContent(); RemarkDto[] remarkArray = new RemarkDto[listDto.size()]; for (int i = 0; i < listDto.size(); i++) { remarkArray[i] = listDto.get(i); } for (int i = 0; i < remarkArray.length; i++) { AdminDto adminDto = userService.getAdminInfo(remarkArray[i].getAdminId()); UserDto userDto = userService.getSubscriberInfo(remarkArray[i].getUserId()); listDto.get(i).setAdminFullName(adminDto.getFullName()); listDto.get(i).setAdminType(adminDto.getAdminType()); listDto.get(i).setUserFullName(userDto.getFullName()); } // RemarkDtoPaginationResponse remarks = new RemarkDtoPaginationResponse(); remarkDto.setContent(listDto); // model.addAttribute("remarks", remarks.getContent()); model.addAttribute("remarks", remarkDto); model.addAttribute("searchCriteriaList", searchCriteriaList); return "admin/subscriber/subscriber-remarks-list"; }