Changes for page Communication between models

Last modified by Erik Bakker on 2026/01/02 10:29

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edited by Erik Bakker
on 2026/01/02 10:29

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edited by Erik Bakker
on 2022/07/26 09:05

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--Communication between models
++expert-create-your-transformations-xpath-expert

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  {{container}}{{container layoutStyle="columns"}}(((
--In this microlearning explains about sharing data across systems in a multi-model environment using event streaming and web services. It discusses the processes, best practices, and considerations for implementing these concepts. Take a look to gain a deeper understanding of how communication between systems in different models can be achieved effectively.
++Within the crash course, we already explained XPath conceptually. In that same microlearning, we looked at some more uncomplicated cases of using XPath within your transformation. If you need to brush up on that knowledge, please check out this [[microlearning>>doc:Main.eMagiz Academy.Microlearnings.Crash Course.Crash Course Platform.crashcourse-platform-create-transformation-xpath-basic.WebHome||target="blank"]]. In the intermediate microlearning on this subject, we built upon that knowledge. Please check out this [[microlearning>>doc:Main.eMagiz Academy.Microlearnings.Intermediate Level.Create your transformations.intermediate-create-your-transformations-xpath-intermediate.WebHome||target="blank"]] if you need a refresher on that. In the [[microlearning>>doc:Main.eMagiz Academy.Microlearnings.Advanced Level.Create your transformations.advanced-create-your-transformations-xpath-advanced.WebHome||target="blank"]] that followed, we built upon that knowledge and looked at some concrete, practical examples that could be useful in your project. In this microlearning, we will wrap the concept of XPath by looking at three complex XPath alternatives that are sometimes needed when dealing with messages in eMagiz.
  Should you have any questions, please get in touch with [[academy@emagiz.com>>mailto:academy@emagiz.com]].
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  == 1. Prerequisites ==
  * Expert knowledge of the eMagiz platform
--* Fundamental [[eMagiz Multi-model>>doc:Main.eMagiz Academy.Fundamentals.fundamental-emagiz-multi-model-explained.WebHome||target="blank"]]
--* Fundamental [[eMagiz Event Streaming>>doc:Main.eMagiz Academy.Fundamentals.fundamental-event-streaming-introduction||target="blank"]]
--* Fundamental [[eMagiz API Gateway>>doc:Main.eMagiz Academy.Fundamentals.fundamental-api-gateway-introduction||target="blank"]]
--* Fundamental [[eMagiz Messaging>>doc:Main.eMagiz Academy.Fundamentals.fundamental-messaging-introduction||target="blank"]]
++* [[XPath Basic>>doc:Main.eMagiz Academy.Microlearnings.Crash Course.Crash Course Platform.crashcourse-platform-create-transformation-xpath-basic.WebHome||target="blank"]]
++* [[XPath Intermediate>>doc:Main.eMagiz Academy.Microlearnings.Intermediate Level.Create your transformations.intermediate-create-your-transformations-xpath-intermediate.WebHome||target="blank"]]
++* [[XPath Advanced>>doc:Main.eMagiz Academy.Microlearnings.Advanced Level.Create your transformations.advanced-create-your-transformations-xpath-advanced.WebHome||target="blank"]]
++
  == 2. Key concepts ==
--* Model - the integration model of a client that runs on a specific cloud slot of eMagiz
--* Multi-model - several integration models of a single client
++This microlearning focuses on very complex XPath operations.
--When selecting a method to communicate between models always consider the following concepts:
--* Security
--* Loose coupling
--* Maintainability
--* Clarity
++With XPath Expert, we mean learning that XPath options are sometimes very complex but could benefit you in specific cases in your daily work.
--== 3. Main Multi-Model Integration Patterns ==
++Some of the very complex XPath options are:
--Most users would think that communication via queues to connect two separate eMagiz models is a bright idea. However, this is something that we do not encourage. We discourage this for several practical and technical reasons alike.
++* matches
++* replace
++* tokenize
--When looking at the practical side of things getting it configured correctly is time-consuming and an error-prone action (as is evident by the question). Furthermore, it can lead to unexpected situations where you make a typo to listen to a queue on which no messages are provided. This queue will, however, be registered on the JMS level (when you activate the flow in question with the custom configuration), which can lead to confusing queue statistics and even more troublesome false-positive alerting based on missing queue metrics or missing consumers.
++== 3. XPath Expert ==
--On top of that, when you allow one model to write and read from queues registered in another model, maintaining both models will become very complex. This holds for the ones working on the project at the moment but also for those working on it at a later stage and does that need to provide (incidental) support on the environments.
++Within the crash course, we already explained XPath conceptually. In that same microlearning, we looked at some more uncomplicated cases of using XPath within your transformation. If you need to brush up on that knowledge, please check out this [[microlearning>>doc:Main.eMagiz Academy.Microlearnings.Crash Course.Crash Course Platform.crashcourse-platform-create-transformation-xpath-basic.WebHome||target="blank"]]. In the intermediate microlearning on this subject, we built upon that knowledge. Please check out this [[microlearning>>doc:Main.eMagiz Academy.Microlearnings.Intermediate Level.Create your transformations.intermediate-create-your-transformations-xpath-intermediate.WebHome||target="blank"]] if you need a refresher on that. In the [[microlearning>>doc:Main.eMagiz Academy.Microlearnings.Advanced Level.Create your transformations.advanced-create-your-transformations-xpath-advanced.WebHome||target="blank"]] that followed, we built upon that knowledge and looked at some concrete, practical examples that could be useful in your project. In this microlearning, we will wrap the concept of XPath by looking at three complex XPath alternatives that are sometimes needed when dealing with messages in eMagiz.
--Another practical reason for not wanting this is that we do not actively support this use case from eMagiz. This means that when we update our technical infrastructure, we will not consider this scenario. This could lead to additional work in the future and reduced stability of your solution.
++Some of the very complex XPath options are:
--From the technical point of view, the consequence of this construction is that both models need to know each other certificates and credentials, which are not considered secure. On top of that, because you, theoretically, can exchange data from any queue to any queue, you could create a situation in which updates in one model trigger changes in the other model (i.e., when using the same data model) that are unexpected (and frankly unwanted).
++* matches
++* replace
++* tokenize
--At the moment, the two most frequently used ways to provide communication between systems in a multi-model environment are event streaming and web services. This microlearning will discuss the processes of sharing data across systems in a multi-model environment using these concepts, including best practices.
--In the figure below, both processes are illustrated. The process at the top illustrates event streaming, and the process at the bottom illustrates web services. Model A and model B are two different models, where a system in model B should have access to the same data as the system in model A. For example, the systems in both models should be the same.
++=== 3.1 matches ===
--[[image:Main.Images.Fundamental.WebHome@fundamental-multi-model-best-practice--event-streaming-and-webservices.png]]
++Sometimes, you want to determine whether a specific value within your payload matches a pattern. In those cases, you can use the XPath function called matches. The function will return true if the supplied string matches a given regular expression. So, for example, if you want to check whether your OrderID contains exactly seven digits and nothing else, the following XPath expression will work for your use case.
--=== 3.1 Event Streaming ===
++matches(OrderID,'^\d{7}$')
--To understand the following section, it is necessary to have some background information about event streaming, which can be found [[here>>doc:Main.eMagiz Academy.Fundamentals.fundamental-event-streaming-introduction||target="blank"]].
--The first option is to decide the alignment of the data models between both models. Whenever data from the first model is transferred to the second model, and the topic is considered input for other systems and integrations in that other model, the data needs to be transformed to the common data model of that second model. This way, the topic can be exposed to any system and pattern in the second model. The picture below denotes this situation. These are the specific considerations when implementing this approach:
++As a result, you will get a true or false back which you can then use as a filter or within an if-then-else construction.
--* Leverage the credentials of the first eMagiz model in the second model
--* Create transparent systems with clear names and ensure to align the message type names
++=== 3.2 replace ===
--It is necessary to transform topics to allow communication between systems in different models using event streaming. This is because it is impossible to retrieve data from a topic that exists in one model through a different model. So, systems in model B cannot immediately access the topic present in model A. The topic needs to be transformed to ensure that systems in model B can use the data on the topic in model A. By changing the topic, all systems in model B can access the transformed topic.
++The replace function has many similarities with the matches function. It builds on the premise of the matches function, but instead of returning a true or false, you can state with what you want to replace the matched string. In other words, this function returns a string produced from the input string by replacing any substrings that match a given regular expression with a supplied replacement string.
--To ensure that the topic from model A can be transformed, model B needs credentials from model A. So, to allow for this pattern, credentials must be shared between models.
++When we apply this to our earlier example, we can state that when the OrderID contains any non-digit, we will replace this value with nothing. This will lead to the following XPath expression.
--An advantage of this pattern is that there is no dependency across models. If the system in model A breaks down, the system in model B can still work. A disadvantage of this pattern is that there may be struggles with the setup since no direct accessibility can be achieved. Moreover, as mentioned above, credentials have to be shared, which may threaten security.
++replace(OrderID,'\D','')
--=== 3.2 Webservices ===
++With a given input string of 12C34A567, the returned result will be 1234567.
--Web services can also be used to communicate between systems in different models. This means that model A has a web service in place, and model B has a web service in place, between which data can be exchanged.
--An advantage of this pattern is that it is easy to keep an overview. Setting it up does not involve many unclarities. A disadvantage is that there is much dependency across models. If the web service in model A crashes, the system in model B cannot receive data anymore.
++=== 3.3 tokenize ===
--=== 3.3 Naming Conventions ===
++The tokenize function can split a string into multiple entries for you. This is particularly useful when you want to match an input string to a list of possible values that are valid for that string. For example, the function returns a sequence of strings constructed by splitting the input wherever a separator is found; the separator is any substring that matches a given regular expression.
--For clarity purposes, it is advised to give the systems that are the same across models the same name and the name of the other model in which the system is present. So, as illustrated in the figure, the system names in model A and B are partly the same (‘SYS’) and indicate which model also holds the system (model B in model A, model A in model B). This way, it remains clear which models have the same systems, and systems can be found more easily.
++So, for example, when the input string for AddressID is "street,housenumber,housenumberaddition" and you want to tokenize this with the help of the separator, you could use, in this example, the comma between the values as the separator. This will lead to the following XPath expression.
--== 4. Key takeaways ==
++tokenize(AddressID,',')
--* Event streaming and webervices are mainly used to communicate between systems across models.
--* To allow communication between systems in different models using event streaming, it is needed to transform topics.
--* Communication between systems in different models can also directly be achieved using web services.
--* For clarity purposes, it is advised to give the systems that are the same across models the same name, as well as the name of the other model in which the system is present.
--* Both patterns have their advantages and disadvantages.
++The given input detailed above will result in the following output: street housenumber housenumberaddition.
--* Consider the following when communication between two models
--** Security
--** Loose coupling
--** Maintainability
--** Clarity
++== 4. Assignment ==
--== 5. Suggested Additional Readings ==
++Check out which of the XPaths we have discussed today can be found within your project.
++This assignment can be completed within the (Academy) project you created/used in the previous assignment.
--* [[Fundamentals (Navigation)>>doc:Main.eMagiz Academy.Fundamentals.WebHome||target="blank"]]
--** [[eMagiz Security Guide (Explanation)>>doc:Main.eMagiz Academy.Fundamentals.fundamental-emagiz-security-guide||target="blank"]]
--** [[Multi-Model Explained (Explanation)>>doc:Main.eMagiz Academy.Fundamentals.fundamental-emagiz-multi-model-explained.WebHome||target="blank"]]
--* [[Advanced (Menu)>>doc:Main.eMagiz Academy.Microlearnings.Advanced Level.WebHome||target="blank"]]
--** [[Solution Architecture (Navigation)>>doc:Main.eMagiz Academy.Microlearnings.Advanced Level.Solution Architecture.WebHome||target="blank"]]
--*** [[Checklist for Splitting Models (Explanation)>>doc:Main.eMagiz Academy.Microlearnings.Advanced Level.Solution Architecture.Checklist for Splitting Models.WebHome||target="blank"]]
--* [[Communication between models (Search Result)>>url:https://docs.emagiz.com/bin/view/Main/Search?sort=score&sortOrder=desc&highlight=true&facet=true&r=1&f_space_facet=0%2FMain.&f_type=DOCUMENT&f_locale=en&f_locale=&f_locale=en&text=communication+between+models||target="blank"]]
--)))((({{toc/}}))){{/container}}{{/container}}
++== 5. Key takeaways ==
++
++Some of the very complex XPath options are:
++
++* matches
++* replace
++* tokenize
++
++== 6. Suggested Additional Readings ==
++
++If you are interested in this topic and want more information on it, please read the help text provided by eMagiz and read more information on the following links:
++
++* http://www.xsltfunctions.com/xsl/fn_matches.html
++* http://www.xsltfunctions.com/xsl/fn_replace.html
++* http://www.xsltfunctions.com/xsl/fn_tokenize.html
++
++== 7. Silent demonstration video ==
++
++As this is more of theoretical microlearning, there is no video accompanying the microlearning.)))((({{toc/}}))){{/container}}{{/container}}