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Last modified by Erik Bakker on 2024/08/26 12:38
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edited by Erik Bakker
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1 -Annotations
1 +Header line
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1 1  {{container}}{{container layoutStyle="columns"}}(((
2 -In this microlearning, we will focus on using annotations to clarify your thought process. In the annotation, you either describe a best practice everyone should follow when they change that flow (i.e. within the asynchronous routing), describe how the (more complex) parts of the flow work or describe (parts of) of your message definitions (i.e. CDM, API Gateway Data model, system message, etc.). This will help yourself and others every time changes are needed.
2 +In this microlearning, we will learn how you can define a header line in which you specify the naming of the various columns. Some external systems require a header line when you supply them with data via a flat file that is placed somewhere.
3 3  
4 4  Should you have any questions, please contact [[academy@emagiz.com>>mailto:academy@emagiz.com]].
5 5  
6 -* Last update: May 9th, 2021
6 +* Last update: May 28th, 2021
7 7  * Required reading time: 5 minutes
8 8  
9 9  == 1. Prerequisites ==
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12 12  
13 13  == 2. Key concepts ==
14 14  
15 -This microlearning centers around using annotations.
16 -With annotations, we mean: A piece of text to explain something to yourself and others
15 +This microlearning centers around learning how to place a header line on a flat-file output.
17 17  
18 -Annotations can be used for:
17 +By header line we mean: A line in the output that defines the naming of the various columns
19 19  
20 -* Describing a best practice everyone should follow
21 -* Describing (more complex) parts of the flow
22 -* Describe (parts of) your message definitions
19 +Some external parties require that the first line in the flat file output (i.e. CSV) is filled with column names (i.e. headers). In eMagiz, we call this line a header line.
23 23  
24 -== 3. Annotations ==
21 +== 3. Header line ==
25 25  
26 -In this microlearning, we will focus on using annotations on the flow level to clarify our thought process. In the annotation, you either describe a best practice everyone should follow when they change that flow (i.e. within the asynchronous routing) or describe how the (more complex) parts of the flow work. This will help yourself and others every time changes are needed within the flow.
23 +In this microlearning, we will learn how you can define a header line in which you specify the naming of the various columns. Some external systems require a header line when you supply them with data via a flat file that is placed somewhere. The header line is the first line in the flat file output. Within this line, the various column names are specified for clarity.
27 27  
28 -Annotations can be used for:
25 +To add such a header line in eMagiz you need to navigate to the Create phase of eMagiz and open the exit flow in which you want to drop the file to a certain location. Within the context of this flow, we need to add functionality that will ensure that a header line is written to the output before any functional lines are added. To do so first enter "Start Editing" mode on flow level. After you have done so please add a file outbound channel adapter to the flow including an input channel. We will use this component to write our header line to the flat file output.
29 29  
30 -* Describing a best practice everyone should follow
31 -* Describing (more complex) parts of the flow
32 -* Describe (parts of) your message definitions
27 +Ensure that the directory to which you reference is the same as in your functional file outbound channel adapter.
33 33  
34 -To clarify the use cases let us take a look at how annotations can be added within the eMagiz platform. In our first example, we will take a look at asynchronous routing. In many eMagiz projects, a best practice is followed on how to add something to the asynchronous routing (or change something within the asynchronous routing). Because the best practice contains multiple steps it makes sense to use the annotation functionality of eMagiz to define all these steps and register them at the place you need them (i.e. the asynchronous routing). Having done so will result in something like this:
29 +[[image:Main.Images.Microlearning.WebHome@novice-file-based-connectivity-header-line--file-outbound-channel-header-line.png]]
35 35  
36 -[[image:Main.Images.Microlearning.WebHome@novice-devops-perspectives-annotations--annotation-best-practice-async-routing.png]]
31 +Now it is time to turn our attention to the Advanced tab. For the Mode select Ignore. Select this option to ensure that the header line is only written down once when there is no output created yet and not somewhere in the middle, in the end, or every time. Furthermore, select the option Append New Line to ensure that the remainder of the information is not appended to the same line.
37 37  
38 -The second example is about using annotations on the flow level to describe parts of the flow. In this example, we will use the annotation to describe that we use a filter to determine which messages are picked up from a local directory and how we filter. That way anyway opening the flow has to merely read the annotation to get the context. Having done so will result in something like this:
33 +[[image:Main.Images.Microlearning.WebHome@novice-file-based-connectivity-header-line--file-outbound-channel-header-line-advanced.png]]
39 39  
40 -[[image:Main.Images.Microlearning.WebHome@novice-devops-perspectives-annotations--describe-parts-of-flow.png]]
35 +After you have done so we need to add a standard transformer that defines the various column names to be written to the flat file output. To do so add the standard transformer component to the canvas including an input channel. After you have done so define the relevant SpEL expression. In this case, we advise using a property value that represents a string of column names. The value of the property should be something as follows:
41 41  
42 -The third example does not take place on the flow level but the message definition level. Therefore instead of going to Create, we go to Design. In Design when you navigate to the CDM, API Gateway Data model, Event Streaming Data model, message definitions, etc. you have the option to add annotations to the canvas. In this example, we want to make clear to all that make changes that a certain part of our CDM is used by a lot of integrations within eMagiz and therefore everyone should be careful and think twice before adjusting anything related to that part. Having done so will result in something like this:
37 +'Header1;Header2;Header3;Header4'
43 43  
44 -[[image:Main.Images.Microlearning.WebHome@novice-devops-perspectives-annotations--describe-crucial-part-of-cdm.png]]
39 +Do note that the separator, in this case, needs to match the requirements of the external system. At the flow configuration level, the standard transformer should look as follows.
45 45  
46 -Now that we saw some examples let us turn our attention to the how. How can I add an annotation and how can I link it. Adding the annotation is simple. You drag the annotation icon from the left context menu onto the canvas. As a result, an empty annotation will be shown on the canvas. By double-clicking on it you can type whatever you want. Note that you need to be in "Start Editing" mode to change anything, including annotations.
41 +[[image:Main.Images.Microlearning.WebHome@novice-file-based-connectivity-header-line--define-columns-names.png]]
47 47  
48 -[[image:Main.Images.Microlearning.WebHome@novice-devops-perspectives-annotations--annotation-icon-context-menu.png]]
43 +Our last step is to ensure that this piece of logic is tied to the main flow and is executed before writing the functional line(s) to the output file. To make that happen we need to add a wiretap to the flow. With the help of this functionality, you can define which part of the logic takes precedence over another part of the logic. To do so double click on the channel on which you want to place a wiretap, select the option wiretap and select the correct wiretap channel. After you have done this the result should be something as follows:
49 49  
50 -When you are satisfied with what you have written down you can press the Save button. After you have done so you can rescale the annotation to ensure that the complete text is visible. To link the annotation to a component (on flow level) or an entity (on message definition level) you hover over the annotation until your mouse indicator changes to a + icon, execute a right-click and drag from the annotation to the component in question.
45 +[[image:Main.Images.Microlearning.WebHome@novice-file-based-connectivity-header-line--wiretap-result.png]]
51 51  
52 -Now you know what annotations are good for and how you can add them within the eMagiz platform.
47 +With these couple of steps, you have now successfully added logic to your flow that will ensure that a header line is added before any functional line(s) are written to the output file.
53 53  
54 54  == 4. Assignment ==
55 55  
56 -Add annotation on the flow level that describes how (a part of) a flow works.
51 +Configure an exit in which you define and write a header line to a flat-file output before adding functional lines.
57 57  This assignment can be completed with the help of the (Academy) project that you have created/used in the previous assignment.
58 58  
59 59  == 5. Key takeaways ==
60 60  
61 -* Annotations can be used for:
62 - * Describing a best practice everyone should follow
63 - * Describing (more complex) parts of the flow
64 - * Describe (parts of) your message definitions
65 -* You can add annotations by dragging and dropping the annotation icon on the canvas.
56 +* The header line contains the names of the columns of the flat file output
57 +* Use the Ignore mode to ensure the header line is created once
58 +* Use the wiretap to ensure the header line is created first
66 66  
67 67  == 6. Suggested Additional Readings ==
68 68  
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72 72  
73 73  This video demonstrates how you could have handled the assignment and gives you some context on what you have just learned.
74 74  
75 -{{video attachment="novice-devops-perspectives-annotations.mp4" reference="Main.Videos.Microlearning.WebHome"/}}
68 +{{video attachment="novice-file-based-connectivity-header-line.mp4" reference="Main.Videos.Microlearning.WebHome"/}}
76 76  
77 77  )))((({{toc/}}))){{/container}}{{/container}}
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