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1		-Multipart form-data
	1	+expert-create-your-transformations-xpath-expert

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1	1	{{container}}{{container layoutStyle="columns"}}(((
2		-Sometimes when you call an external REST endpoint, they require you to send meta information and one or more "attachments" in one call to the REST endpoint. To make this possible, you need to send the information with the contentType called multipart/form-data. In this microlearning, we will discuss how you can configure a valid message within the eMagiz platform that allows you to send out messages with this contentType and have them accepted by the endpoint in question.
	2	+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.
3	3
4	4	Should you have any questions, please get in touch with [[academy@emagiz.com>>mailto:academy@emagiz.com]].
5	5
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6	6	== 1. Prerequisites ==
7	7
8	8	* Expert knowledge of the eMagiz platform
	9	+* [[XPath Basic>>doc:Main.eMagiz Academy.Microlearnings.Crash Course.Crash Course Platform.crashcourse-platform-create-transformation-xpath-basic.WebHome||target="blank"]]
	10	+* [[XPath Intermediate>>doc:Main.eMagiz Academy.Microlearnings.Intermediate Level.Create your transformations.intermediate-create-your-transformations-xpath-intermediate.WebHome||target="blank"]]
	11	+* [[XPath Advanced>>doc:Main.eMagiz Academy.Microlearnings.Advanced Level.Create your transformations.advanced-create-your-transformations-xpath-advanced.WebHome||target="blank"]]
9	9
	13	+
10	10	== 2. Key concepts ==
11	11
12		-This microlearning focuses on configuring a multipart/form-data message within eMagiz to ensure it is sent correctly to an endpoint.
	16	+This microlearning focuses on very complex XPath operations.
13	13
14		-Key aspects are:
	18	+With XPath Expert, we mean learning that XPath options are sometimes very complex but could benefit you in specific cases in your daily work.
15	15
16		-* Defining the boundary that separates the parts of the message
17		-* Defining the content types of each part of the message
18		-* Construction of the complete message according to the specification
	20	+Some of the very complex XPath options are:
19	19
20		-== 3. Multipart form-data ==
	22	+* matches
	23	+* replace
	24	+* tokenize
21	21
22		-Sometimes when you call an external REST endpoint, they require you to send meta information and one or more "attachments" in one call to the REST endpoint. To make this possible, you need to send the information with the contentType called multipart/form-data. In this microlearning, we will discuss how you can configure a valid message within the eMagiz platform that allows you to send out messages with this contentType and have them accepted by the endpoint in question.
	26	+== 3. XPath Expert ==
23	23
24		-Key aspects are:
	28	+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.
25	25
26		-* Defining the boundary that separates the parts of the message
27		-* Defining the content types of each part of the message
28		-* Construction of the complete message according to the specification
	30	+Some of the very complex XPath options are:
29	29
30		-{{info}}
31		-The following criteria apply when utilizing the boundary functionality within the multipart/form-data construction:
32		-* The value of the Boundary must begin with a double horizontal bar –, this is called a leading hyphen
33		-* The value of the Boundary must not contain more than 70 characters in addition to the leading hyphen.
34		-* The value of the Boundary must not contain characters that are disabled by the HTTP protocol or the URL, such as the colon: etc.
35		-* A boundary within the request body must always be preceeded by a CRLF line. This means that when the request body **ends** with a CRLF line an **additional** CRLF line is needed **before** the boundary doubling the CRLF lines in that part of the request body.{{/info}}
	32	+* matches
	33	+* replace
	34	+* tokenize
36	36
37		-=== 3.1 Prepare the message ===
	36	+=== 3.1 matches ===
38	38
39		-To construct the message, several steps are needed to make it work. Luckily, most of the steps necessary have to do with concepts we have already discussed in previous microlearnings. As you can imagine, based on what multipart/form-data entails, we need a way to both store the meta information and the file(s) we want to send to the external party. For example, put the metadata in one (or multiple) header(s) and use the file content as a payload. This you can achieve with a header enricher and standard transformer.
	38	+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.
40	40
41		-Once the file content is your payload, you must ensure that the data is "raw." So when you have a base64 encoded string, you should decode it before sending it to the endpoint.
	40	+matches(OrderID,'^\d{7}$')
42	42
43		-On top of that, we need to define the contentType header.
	42	+As a result, you will get a true or false back which you can then use as a filter or within an if-then-else construction.
44	44
45		-[[image:Main.Images.Microlearning.WebHome@expert-data-handling-multipart-form-data--content-type-header-config.png]]
	44	+=== 3.2 replace ===
46	46
47		-=== 3.2 Construct the message ===
	46	+The replace function has many similarities with the matches function. It builds on the premise of the matches function, but instead of returning a true or false, you can state with what you want to replace the matched string. In other words, this function returns a string produced from the input string by replacing any substrings that match a given regular expression with a supplied replacement string.
48	48
49		-After you have set the stage, you can use a standard transformer component to build your message correctly. To create it correctly, you need to take the following into account:
	48	+When we apply this to our earlier example, we can state that when the OrderID contains any non-digit, we will replace this value with nothing. This will lead to the following XPath expression.
50	50
51		-* Each part of the message needs to be separated by a boundary
52		-* The message needs to start with a boundary and finish with a boundary
53		-* Line breaks are needed to differentiate between the boundary and the text content
54		-* No line break is needed when the content is not text-based
	50	+replace(OrderID,'\D','')
55	55
56		-Given all this, you can write the following SpEL expression that will yield a desirable output:
	52	+With a given input string of 12C34A567, the returned result will be 1234567.
57	57
58		-{{code}}'${multi-part-form-data.data-handling.boundary}' + headers.metaInfo + T(com.emagiz.util.Newline).CRLF.characters + '${multi-part-form-data.data-handling.boundary}' + T(com.emagiz.util.Newline).CRLF.characters + 'Content-Disposition: form-data; name="file"; filename="' + headers.filename + '"' + T(com.emagiz.util.Newline).CRLF.characters + 'Content-Type: application/pdf' + T(com.emagiz.util.Newline).CRLF.characters + T(com.emagiz.util.Newline).CRLF.characters + payload + '${multi-part-form-data.data-handling.boundary}'{{/code}}
	54	+=== 3.3 tokenize ===
59	59
60		-Putting this in a standard transformation gives you the following solution in the flow.
	56	+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.
61	61
62		-[[image:Main.Images.Microlearning.WebHome@expert-data-handling-multipart-form-data--standard-transformer-config.png]]
	58	+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.
63	63
64		-=== 3.3 Calling the endpoint ===
	60	+tokenize(AddressID,',')
65	65
66		-Now that we have constructed our message correctly, the last thing to do is call the endpoint in question. Since we have prepared our message and accurately defined our contentType calling the endpoint does not require any additional configurations compared to what you are already used to when dealing with REST endpoints.
	62	+The given input detailed above will result in the following output: street housenumber housenumberaddition.
67	67
68		-== 4. Key takeaways ==
	64	+== 4. Assignment ==
69	69
70		-* Make sure to define the boundary that separates the parts of the message
71		-* Make sure to define the content types of each part of the message
72		-* Make sure to define the content type that matches the specification for multipart/form-data
73		-* Construct the complete message according to the specification
	66	+Check out which of the XPaths we have discussed today can be found within your project.
	67	+This assignment can be completed within the (Academy) project you created/used in the previous assignment.
74	74
75		-== 5. Suggested Additional Readings ==
	69	+== 5. Key takeaways ==
76	76
77		-If you are interested in this topic, please read the help texts on the platform and read the following link:
	71	+Some of the very complex XPath options are:
78	78
79		-* [[Multipart form-data explained>>https://www.sobyte.net/post/2021-12/learn-about-http-multipart-form-data/||target="blank"]]
	73	+* matches
	74	+* replace
	75	+* tokenize
80	80
81		-)))((({{toc/}}))){{/container}}{{/container}}
	77	+== 6. Suggested Additional Readings ==
	78	+
	79	+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:
	80	+
	81	+* http://www.xsltfunctions.com/xsl/fn_matches.html
	82	+* http://www.xsltfunctions.com/xsl/fn_replace.html
	83	+* http://www.xsltfunctions.com/xsl/fn_tokenize.html
	84	+
	85	+== 7. Silent demonstration video ==
	86	+
	87	+As this is more of theoretical microlearning, there is no video accompanying the microlearning.)))((({{toc/}}))){{/container}}{{/container}}