> For the complete documentation index, see [llms.txt](https://hanfak.gitbook.io/workspace/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://hanfak.gitbook.io/workspace/integration/comms.md).

# Communications between apps

## Inter app communications

### Http

#### REST

**Contents**

* XML
* Json

#### GraphQL

#### Webservice/SOAP

* Envelopes

### Files

#### FTP/SFTP

### Database

### Messaging

* jms
  * <https://dzone.com/articles/java-message-service-jms>
* Hessian

## how it gets the data

* pulling from the app/intermediary(message broker)
  * Making a request
    * on demand
    * scheduled (quartz)
  * <https://en.wikipedia.org/wiki/Pull_technology>
* Pushed from app/intermediary(message broker)
  * subscribed to it and when updates occurs (ie to database  or event or in flow) it will send a request to who needs it
    * Can do this on a schdule
    * if receiving app  is down, then it will not lose the request as it will still be on message broker. So when back up it can start to get these messages/data and process them. This prevents lost messages/data.
      * If app has high availability (ie via kubernetes), then can expect all messages to be sent and received, without losing any. Thus can rely on http as a means to communciate.
  * <https://en.wikipedia.org/wiki/Publish%E2%80%93subscribe_pattern>
  * observer pattern
* Sockets

## sync or async

* request - response
* async req-response
* fire and forget
* publish subscribe
* message routing

-3 Message Exchange Patterns in Application Integration To Know About

## Intra app communications

* Sending messages to objects
  * Delegating to dependencies