Changes for page Multipart form-data
Last modified by Erik Bakker on 2024/06/17 11:39
From version 6.1
edited by Erik Bakker
on 2022/07/26 08:31
on 2022/07/26 08:31
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To version 18.1
edited by Erik Bakker
on 2022/08/05 14:24
on 2022/08/05 14:24
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... ... @@ -1,1 +1,1 @@ 1 - expert-create-your-transformations-xpath-expert1 +Multipart form-data - Default language
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... ... @@ -1,5 +1,5 @@ 1 1 {{container}}{{container layoutStyle="columns"}}((( 2 - Withinthecrash course,wealready explainedXPath conceptually.Inthat samemicrolearning,we looked atsomemorencomplicatedcasesofusingXPathwithinyour transformation.Ifyouneedtobrushuponthatknowledge, pleasecheck outthis[[microlearning>>doc:Main.eMagizAcademy.Microlearnings.CrashCourse.CrashCourse Platform.crashcourse-platform-create-transformation-xpath-basic.WebHome||target="blank"]]. In theintermediate microlearning on this subject,we builtuponthat knowledge.Please check outthis[[microlearning>>doc:Main.eMagizAcademy.Microlearnings.IntermediateLevel.Create your transformations.intermediate-create-your-transformations-xpath-intermediate.WebHome||target="blank"]] ifyou needrefresher onthat. In the[[microlearning>>doc:Main.eMagizAcademy.Microlearnings.AdvancedLevel.Createyourtransformations.advanced-create-your-transformations-xpath-advanced.WebHome||target="blank"]]that followed, we builtupon thatknowledgeandlookedatsomeconcrete, practicalexamplesthat couldbeuseful inyour project.In thismicrolearning, we will wraptheconceptof XPathby looking atthree complexXPathalternativesthataresometimes neededwhendealing withmessagesin eMagiz.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. 3 3 4 4 Should you have any questions, please get in touch with [[academy@emagiz.com>>mailto:academy@emagiz.com]]. 5 5 ... ... @@ -6,85 +6,67 @@ 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"]] 12 12 13 - 14 14 == 2. Key concepts == 15 15 16 -This microlearning focuses on morecomplexXPath operations.12 +This microlearning focuses on configuring a multipart/form-data message within eMagiz to ensure it is sent correctly to an endpoint. 17 17 18 - With XPath Advanced,we mean learning that XPath optionsare complex butcould benefityou in your daily work.14 +Key aspects are: 19 19 20 -Some of the more complex XPath options are: 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 21 21 22 -* dateTime calculation 23 -* Filter list 24 -* XPath on JSON 25 -* SpEL notation for XPath 20 +== 3. Multipart form-data == 26 26 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. 27 27 24 +Key aspects are: 28 28 29 -== 3. XPath Advanced == 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 30 31 - Withinthe crashcourse, wealreadyexplained XPathconceptually.Inthatsamemicrolearning,weolookedatsomemoreuncomplicatedcasesofusing XPathwithin your transformation.If youneed tobrush uponthatknowledge,pleasecheckoutthis[[microlearning>>doc:Main.eMagizAcademy.Microlearnings.CrashCourse.CrashCoursePlatform.crashcourse-platform-create-transformation-xpath-basic.WebHome||target="blank"]].In theintermediatemicrolearningonthissubject,webuiltuponthat knowledge.Pleasecheckout this [[microlearning>>doc:Main.eMagizAcademy.Microlearnings.Intermediate Level.Createyourtransformations.intermediate-create-your-transformations-xpath-intermediate.WebHome||target="blank"]]ifyouneedarefresheron that. Inthismicrolearning,wewillbuild uponhatknowledgeandlookatsomeconcrete,practicalexamplesthatcouldbeusefulinyourproject.30 +To actually construct the message there a several steps needed to make it work. Luckily, most of the steps needed have to do with concepts we have already discussed in previous microlearnings. As you can imagine based on what mulipart/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. To do so it is advisable to put the metadata in one (or multiple) header(s) and use the file content as payload. This you can achieve with a header enricher and standard transformer. 32 32 33 - Someof themorecomplexXPathoptionsare:32 +Once the file content is your payload you need to make sure that the data is "raw" in nature. So when you have a base64 encoded string you should decode the string before sending it to the endpoint. 34 34 35 -* dateTime calculation 36 -* Filter list 37 -* XPath on JSON 38 -* SpEL notation for XPath 34 +On top of that we need to define the contentType header as follows. 39 39 40 - ===3.1dateTime calculation===36 +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. 41 41 42 - SometimesweseethatateTimecalculation isneededwithin atransformationtodetermineaspecificaction.Asthese calculationsarenotnatively supported within theeMagizplatform,youneedto useXPath's functionalityto calculatethenewvaliddate(ordateTime).38 +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. 43 43 44 - TheXPathstandardoffersseveralfunctionstocalculatewithdateTimevalues. The twomost usedoptionsare dayTimeDurationandyearMonthDuration.With thehelpof thedayTimeDuration,you canadd, subtract,multiple,ordivideseconds, minutes, hours,and days regardingtheoriginal value. The yearMonthDurationworkssimilarlybut then formonthsand years.An exampleof suchan XPathis:<xsl:value-of xmlns:xs="http://www.w3.org/2001/XMLSchema" select="CDM:StartDate + xs:dayTimeDuration('P1D') * xs:yearMonthDuration('P1M')"/>.Inthisexample,XPath addsoneday andsubtractsonemonthfromtheinputdate.Notethatmakingthiswork requirestheadditionalnamespace tobe defined. Thereforeyou need a customsnippetwithin yourtransformation ora customtransformationto makethis work.Furthermore,note thatthe P1D andP1M couldalsobe filledwith thehelpofparameterstomakethemdynamic inature.40 +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. 45 45 46 - Someexamples that we saw duringtheyears:42 +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. 47 47 48 -* https://my.emagiz.com/p/question/172825635700358186 49 -* https://my.emagiz.com/p/question/172825635700352588 44 +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). 50 50 51 -=== 3.2 Filter list === 46 +We advise using functionality that makes it explicit that both models function independently of each other. From eMagiz, we consider two valid alternatives for this: 47 +- Using a web service as a communication layer between the two models. This web service can be REST or SOAP and has been implemented before 48 +- Using the Event Streaming functionality of eMagiz to write and read from topics. 52 52 53 - Sometimesyouhavea largemessagewhich containsa certain listwithinit. However, logic dictates thatyoucanonly sendthe messageif atleast oneentry in thelist for which attributeAis filledand attribute B equals typeC. Tomakethathappen in XPath, wefirstneedto navigatetotheistwithin the message.As we previously learned,there aretwo optionsto do so. Oneistose //to navigate tothe entitysomewherein thetree directly. The otheris tostartattherootwalk the treefrom there. Inhis example,weusethe latter. Thatresults in thefollowing XPath example: /root/list[attributeB= 'typeC']/attributeA !=''. Withthis XPath, you filterthe list onthe specified checkandsubsequentlycheck whetheroneofthoseentriesthatremainshasanattributeA which is filledin.50 +Both alternatives have the benefit that the security can be tight and explicit (i.e., only model A can write/post data to model B). Furthermore, managing the solution becomes much easier as it uses the standard functionality within the platform. Therefore, we have no plans to support this approach in the product. 54 54 55 -=== 3.3 XPath on JSON === 56 - 57 -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): 58 - 59 -* XPath header enricher 60 -* XPath transformer 61 -* XPath router 62 - 63 -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. 64 - 65 -=== 3.4 SpEL notation for XPath === 66 - 67 -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') 68 - 69 69 == 4. Assignment == 70 70 71 -C heckoutwhichoftheXPathswe havediscussed todaycan befoundwithinyourproject.72 -This assignment can be completed with inthe (Academy) project you created/used in the previous assignment.54 +Consider what your criteria are when communicating between models and compare them to our criteria. 55 +This assignment can be completed with the help of the (Academy) project you created/used in the previous assignment. 73 73 74 74 == 5. Key takeaways == 75 75 76 -Some of the more complex XPath options are: 59 +* Consider the following when communication between two models 60 +** Security 61 +** Loose coupling 62 +** Maintainability 63 +** Clarity 77 77 78 -* dateTime calculation 79 -* Filter list 80 -* XPath on JSON 81 -* SpEL notation for XPath 82 - 83 83 == 6. Suggested Additional Readings == 84 84 85 -If you are interested in this topic and want more information on it,please read the helpprovidedbyeMagizand readmore information on the following link:67 +If you are interested in this topic please read the helptexts in the platform and read the following link: 86 86 87 -* https://www. w3schools.com/xml/xpath_intro.asp69 +* https://www.sobyte.net/post/2021-12/learn-about-http-multipart-form-data/ 88 88 89 89 == 7. Silent demonstration video == 90 90