Changes for page Multipart form-data

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1		-Image Transformations
	1	+Multipart form-data

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1	1	{{container}}{{container layoutStyle="columns"}}(((
2		-In most cases, you will transform XML messages to other XML messages, or you will transform JSON or EDI messages in another of these formats. However, sometimes you want to perform an image transformation. With this image transformation you can transform images in certain formats to another format (i.e. png). This can come in handy when you want to standardize the image format before using it further downstream in your business application(s).
	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.
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4	4	Should you have any questions, please get in touch with [[academy@emagiz.com>>mailto:academy@emagiz.com]].
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9	9
10	10	== 2. Key concepts ==
11	11
12		-This microlearning focuses on performing image transformations in eMagiz.
	12	+This microlearning focuses on configuring a multipart/form-data message within eMagiz to ensure it is sent correctly to an endpoint.
13	13
14		-With image transformation, we mean transforming the raw data that represents an image to another image format.
	14	+Key aspects are:
15	15
16		-* Read the helptext of the component to understand which formats are supported
17		-* Ensure the input image is supplied in the correct format
18		-* Ensure you wrap the output image in something if you want to do additional transformations on the data further downstream
	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
19	19
20		-== 3. Image Transformation ==
	20	+== 3. Multipart form-data ==
21	21
22		-In most cases, you will transform XML messages to other XML messages, or you will transform JSON or EDI messages in another of these formats. However, sometimes you want to perform an image transformation. With this image transformation you can transform images in certain formats to another format (i.e. png). This can come in handy when you want to standardize the image format before using it further downstream in your business application(s).
	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.
23	23
24		-Before we dive into the specifics of how to configure this let us first consider the following:
	24	+Key aspects are:
25	25
26		-* Read the helptext of the component to understand which formats are supported
27		-* Ensure the input image is supplied in the correct format
28		-* Ensure you wrap the output image in something if you want to do additional transformations on the data further downstream
	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
29	29
30		-{{warning}}The focus of this microlearning lies on the image transformer component. Ensuring that the input is useful and the output fits the remainder of the process is highly depending on the use case and will therefore not be discussed in this microlearning{{/warning}}
	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}}
31	31
32		-When turning to the Create phase of eMagiz, we need to open the flow and enter "Start Editing" mode to add the component we need. For example, in the left panel, you can search for "Image". This will yield the following result.
	37	+=== 3.1 Prepare the message ===
33	33
34		-[[image:Main.Images.Microlearning.WebHome@expert-create-your-transformations-image-transformation-image-transformation-component.png]]
	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.
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36		-== 4. Assignment ==
	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.
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38		-Check out which of the XPaths we have discussed today can be found within your project.
39		-This assignment can be completed within the (Academy) project you created/used in the previous assignment.
	43	+On top of that, we need to define the contentType header.
40	40
41		-== 5. Key takeaways ==
	45	+[[image:Main.Images.Microlearning.WebHome@expert-data-handling-multipart-form-data--content-type-header-config.png]]
42	42
43		-Some of the very complex XPath options are:
	47	+=== 3.2 Construct the message ===
44	44
45		-* matches
46		-* replace
47		-* tokenize
	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	48
49		-== 6. Suggested Additional Readings ==
	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	50
51		-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:
	56	+Given all this, you can write the following SpEL expression that will yield a desirable output:
52	52
53		-* http://www.xsltfunctions.com/xsl/fn_matches.html
54		-* http://www.xsltfunctions.com/xsl/fn_replace.html
55		-* http://www.xsltfunctions.com/xsl/fn_tokenize.html
	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}}
56	56
57		-== 7. Silent demonstration video ==
	60	+Putting this in a standard transformation gives you the following solution in the flow.
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59		-As this is more of theoretical microlearning, there is no video accompanying the microlearning.)))((({{toc/}}))){{/container}}{{/container}}
	62	+[[image:Main.Images.Microlearning.WebHome@expert-data-handling-multipart-form-data--standard-transformer-config.png]]
	63	+
	64	+=== 3.3 Calling the endpoint ===
	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.
	67	+
	68	+== 4. Key takeaways ==
	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
	74	+
	75	+== 5. Suggested Additional Readings ==
	76	+
	77	+If you are interested in this topic, please read the help texts on the platform and read the following link:
	78	+
	79	+* [[Multipart form-data explained>>https://www.sobyte.net/post/2021-12/learn-about-http-multipart-form-data/||target="blank"]]
	80	+
	81	+)))((({{toc/}}))){{/container}}{{/container}}