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1		-Command Queue
	1	+ XPath Advanced

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1	1	{{container}}{{container layoutStyle="columns"}}(((
2		-Within the platform of eMagiz, sometimes you need to send a particular command from the eMagiz portal to retrieve information or execute a specific action. These commands can happen from the Deploy and the Manage phase. The two most noteworthy examples of the triggered command queue are the runtime dashboard functionalities and the message redelivery actions.
	2	+Within the crash course, we already explained XPath conceptually. In that same microlearning, we also 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](crashcourse-platform-create-transformation-xpath-basic.md). In the intermediate microlearning on this subject, we built upon that knowledge. Please check out this [microlearning](intermediate-create-your-transformations-xpath-intermediate.md) if you need a refresher on that. In this microlearning, we will build upon that knowledge and look at some concrete, practical examples that could be useful in your project.
3	3
4	4	Should you have any questions, please get in touch with [[academy@emagiz.com>>mailto:academy@emagiz.com]].
5	5
	6	+* Last update: October 25th, 2021
	7	+* Required reading time: 6 minutes
	8	+
6	6	== 1. Prerequisites ==
7	7
8		-* Expert knowledge of the eMagiz platform
	11	+* Advanced knowledge of the eMagiz platform
	12	+* [XPath Basic](crashcourse-platform-create-transformation-xpath-basic.md)
	13	+* [XPath Intermediate](intermediate-create-your-transformations-xpath-intermediate.md)
9	9
	15	+crashcourse-platform-create-transformation-xpath-basic
	16	+crashcourse-platform-create-transformation-XPath-basic
	17	+
10	10	== 2. Key concepts ==
11	11
12		-This microlearning focuses on the command queue. The command queue communicates between the eMagiz portal and an eMagiz runtime.
	20	+This microlearning focuses on more complex XPath operations.
13	13
14		-* Commands towards a runtime, for example, to retrieve runtime information in the runtime dashboard, are sent via the command queue
15		-* You can monitor the command queue the same way as any other queue within your model
16		-* The command queue is prominently used when accessing the [[Runtime Dashboard>>doc:Main.eMagiz Academy.Microlearnings.Crash Course.Crash Course Platform.crashcourse-platform-deploy-runtime-dashboard.WebHome||target="blank"]] and when using [[Message Redelivery>>doc:Main.eMagiz Academy.Microlearnings.Intermediate Level.Message Redelivery.WebHome||target="blank"]]
	22	+With XPath Advanced, we mean learning that XPath options are complex but could benefit you in your daily work.
17	17
18		-== 3. Command queue ==
	24	+Some of the more complex XPath options are:
19	19
20		-Within the platform of eMagiz, sometimes you need to send a particular command from the eMagiz portal to retrieve information or execute a specific action. These commands can happen from the Deploy and the Manage phase. The two most noteworthy examples of the triggered command queue are the runtime dashboard functionalities and the message redelivery actions.
	26	+* dateTime calculation
	27	+* Filter list
	28	+* XPath on JSON
	29	+* SpEL notation for XPath
21	21
22		-For example, when you navigate the Runtime Dashboard and click on a runtime, the eMagiz portal will send a command to the runtime via the command queue to retrieve the runtime state. So, for example, the same logic applies when you select a flow and stop it.
23	23
24		-For Message redelivery, the command queue retrieves all messages in the dead letter queue and resends messages via the command queue.
25	25
26		-{{info}}When all commands sent from the eMagiz portal are not working across models, something is probably broken in the backend of the eMagiz platform. In these cases, please contact us at [[support@emagiz.com>>mailto:support@emagiz.com]]{{/info}}
	33	+== 3. XPath Advanced ==
27	27
	35	+Within the crash course, we already explained XPath conceptually. In that same microlearning, we also 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](crashcourse-platform-create-transformation-xpath-basic.md). In the intermediate microlearning on this subject, we built upon that knowledge. Please check out this [microlearning](intermediate-create-your-transformations-xpath-intermediate.md) if you need a refresher on that. In this microlearning, we will build upon that knowledge and look at some concrete, practical examples that could be useful in your project.
	36	+
	37	+Some of the more complex XPath options are:
	38	+
	39	+* dateTime calculation
	40	+* Filter list
	41	+* XPath on JSON
	42	+* SpEL notation for XPath
	43	+
	44	+=== 3.1 dateTime calculation ===
	45	+
	46	+Sometimes we see that a dateTime calculation is needed within a transformation to determine a specific action. As these calculations are not natively supported within the eMagiz platform, you need to use XPath's functionality to calculate the new valid date (or dateTime).
	47	+
	48	+The XPath standard offers several functions to calculate with dateTime values. The two most used options are dayTimeDuration and yearMonthDuration. With the help of the dayTimeDuration, you can add, subtract, multiple, or divide seconds, minutes, hours, and days regarding the original value. The yearMonthDuration works similarly but then for months and years. An example of such an XPath is: <xsl:value-of xmlns:xs="http://www.w3.org/2001/XMLSchema" select="CDM:StartDate + xs:dayTimeDuration('P1D') * xs:yearMonthDuration('P1M')"/>. In this example, XPath adds one day and subtracts one month from the input date. Note that making this work requires the additional namespace to be defined. Therefore you need a custom snippet within your transformation or a custom transformation to make this work. Furthermore, note that the P1D and P1M could also be filled with the help of parameters to make them dynamic in nature.
	49	+
	50	+Some examples that we saw during the years:
	51	+
	52	+* https://my.emagiz.com/p/question/172825635700358186
	53	+* https://my.emagiz.com/p/question/172825635700352588
	54	+
	55	+=== 3.2 Filter list ===
	56	+
	57	+Sometimes you have a large message which contains a certain list within it. However, logic dictates that you can only send the message if at least one entry in the list for which attribute A is filled and attribute B equals type C. To make that happen in XPath, we first need to navigate to the list within the message. As we previously learned, there are two options to do so. One is to use // to navigate to the entity somewhere in the tree directly. The other is to start at the root and walk the tree from there. In this example, we use the latter. That results in the following XPath example: /root/list[attributeB = 'type C']/attributeA !=''. With this XPath, you filter the list on the specified check and subsequently check whether one of those entries that remains has an attributeA which is filled in.
	58	+
	59	+=== 3.3 XPath on JSON ===
	60	+
	61	+With the release of build number .50, we expanded our offering on JSON messages to resemble much of the functionality we previously offered for XML messages. As a result, you can use XPath expressions on JSON messages within the following components (related to XPath):
	62	+
	63	+* XPath header enricher
	64	+* XPath transformer
	65	+* XPath router
	66	+
	67	+To activate the functionality, simply link the JSON source factory support object to one of these components to achieve the desired result. For more information, check out: https://emagiz.github.io/docs/release-notes/build50.
	68	+
	69	+=== 3.4 SpEL notation for XPath ===
	70	+
	71	+Sometimes you want to perform an XPath operation but store the header via a standard message header enricher component. As a result, you need a valid SpEL expression to help you in this cause. To do so, you need to know the correct notation for an XPath expression when using the SpEL language. An example of the correct notation is: #xpath(payload,'/root/entity/attribute')
	72	+
	73	+
	74	+
28	28	== 4. Assignment ==
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30		-There is no assignment for this microlearning.
	77	+Check out which of the XPaths we have discussed today can be found within your project.
	78	+This assignment can be completed within the (Academy) project you created/used in the previous assignment.
31	31
32	32	== 5. Key takeaways ==
33	33
34		-* Commands towards a runtime, for example, to retrieve runtime information in the runtime dashboard, are sent via the command queue
35		-* You can monitor the command queue the same way as any other queue within your model
36		-* The command queue is prominently used when accessing the [[Runtime Dashboard>>doc:Main.eMagiz Academy.Microlearnings.Crash Course.Crash Course Platform.crashcourse-platform-deploy-runtime-dashboard.WebHome||target="blank"]] and when using [[Message Redelivery>>doc:Main.eMagiz Academy.Microlearnings.Intermediate Level.Message Redelivery.WebHome||target="blank"]]
	82	+Some of the more complex XPath options are:
37	37
	84	+* dateTime calculation
	85	+* Filter list
	86	+* XPath on JSON
	87	+* SpEL notation for XPath
	88	+
	89	+
	90	+
38	38	== 6. Suggested Additional Readings ==
39	39
40		-There are no suggested additional readings.
	93	+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 link:
41	41
	95	+* https://www.w3schools.com/xml/xpath_intro.asp
	96	+
42	42	== 7. Silent demonstration video ==
43	43
44	44	As this is more of theoretical microlearning, there is no video accompanying the microlearning.)))((({{toc/}}))){{/container}}{{/container}}