3. Defining data model Items

the purpose of the sheet items is to define the items, which includes their name and data type, as well as to which device and tag combination they belong note the sequence of steps shown in this guide is a recommendation, as it felt the most natural for the author but users are free to follow their own preferred sequence defining the item names items are the part of a data model which provides a meaning and context to a value and make it possible for users to understand what the recorded value means users will define the names for these items in the column labeled item name the users enters the name into the next empty cell in this column important do not leave blank rows between entries or at the start a blank row will be seen as the end of the configuration and the configurator will not process any entry past the blank row the configurator will verify the item name for invalid ascii characters to learn more about which ascii characters are allowed, review the section restrictions on ascii characters allowed to be used the configurator also validates the length of the string invalid ascii characters if an invalid character is found, a prompt is shown to the user invalid characters are marked in red as spaces are not a visible character, they can't be marked in red, so the user can make use of the comment added to the cell as well invalid string length to allow for the most efficient storage of the configuration as well as practicality when using an item name in a query, the maximum length of an item name can not exceed 50 characters if an item name is longer 50 characters, the user will be prompted note names of items which exceed the 50 character limit, will by default be trimmed to 50 characters if no action is taken by the user setting default values for other columns if a user enters a value into the column labeled item name , the configurator will prefill the columns labeled device/tag as well as is meta data? this is done to ensure that these columns are not forgotten for the column labeled device/tag , the value is the first combination from the drop down menu used by this column for the column is meta data? the value is set to yes this is done on purpose, as users are mostly interested in process data, so they will be encourage to pay attention to each item to ensure the setup is correct tip while a very common way of filling in spreadsheet style lists is to do it row by row, it has been observed that it can be beneficial to fill in all items first, especially if items are repeated throughout the data model hierarchy this can be achieved through the use of copy & paste cell content as well as make use of the ms excel autocomplete feature, where it does try to recognize what the user may want to enter as a repeat making use of these fast forms of duplication, can make it very quick to fill in all the names for the items filling in the example below was done in less than 1 minute adding an item description (optional) users are able to provide a description for an item to provide some context for colleagues about the purpose of the item and what it is used for the configurator will verify the item description for invalid ascii characters to learn more about which ascii characters are allowed, review the section restrictions on ascii characters allowed to be used the configurator also validates the length of the string invalid ascii characters if an invalid character is found, a prompt is shown to the user invalid characters are marked in red invalid string length to allow for the most efficient storage the maximum length of an item description can not exceed 256 characters if an item description is longer 256 characters, the user will be prompted note descriptions for items which exceed the 256 character limit, will by default be trimmed to 256 characters if no action is taken by the user defining the device and tag to assign an item to its respective device and tag, users select a string representing the device and tag from the drop down menu in the column labeled device/tag this will add the selected string into the cell note only values available through the drop down menu can be selected important do not leave blank rows between entries or at the start a blank row will be seen as the end of the configuration and the configurator will not process any entry past the blank row how to understand the strings shown by the drop down menu the column with the labeled device/tag will provide the user with a drop down menu which shows the device and tag combinations as a string representation combinations of devices and tags in the drop down menu will shown as a pipe symbol " | " separated string on how to add additional devices and tags, please review the chapter 2 defining the device(s) and tag(s) docid\ fsnu3vwyl72emowz qofb the string has to be read from the left, with the first value being the device name and the second value being the tag name they are also listed in the order as in the sheet tags tip if the user first entered all the items in the column labeled item name in the right order of their device and tag combination, the process of filling in the column labeled device/tag can be speed up making use of the different options ms excel has for duplication of values across rows for example a users selects for the first item in a hierarchy level the string through the drop down menu then they simply duplicate this value to all the other items for this device and tag combination in the picture below, the user has copied the value of row 7 shown by the interrupted green cell border and then selected rows 8 10 the user then simply pasted the value into the selected rows a second option is to make use of the ms excel autocomplete feature, where it does try to recognize what the user may want to enter as a repeat setting the value type in accordance with the eav database model, values are stored in dedicated tables which store values of a specific data type litmus production record database supports four different data types for tags value type string what data are stored example isinteger numeric values of the type integer 25 isstring alphanumerical values sap2023051001 isdecimal numeric values of the type decimal / float / real 124 457 isboolean boolean values true 0 the user sets the value type by selecting it from the drop down menu in the column labeled value type this will add the selected string into the cell tip users can speed up the process by duplication the value type set for one item to other items with the same value type making use of the different option ms excel offers in this example, the user duplicated the isdecimal value type, by first copying it shown by the interrupted green cell border and then selecting other items which are a time making use of ctrl+left click the user then pasted the value type into the selected rows a second option is to make use of the ms excel autocomplete feature, where it does try to recognize what the user may want to enter as a repeat defining if a item records process or meta data litmus production record database allows to record both process data as well as meta data for tags to learn more about the these two types of data, please review the chapter how are data for a tags stored docid\ qqkxpp3ewbdy1alf5ijoz as well as the chapter core concept behind recording process and meta data for process tags docid\ amceahd6bo48cyboguikw by default, every item will be set to the value yes this is done on purpose, as users are mostly interested in process data, so they will be encourage to pay attention to each item to ensure the setup is correct the user selects which item will record process data by selecting the value no from the drop down menu tip users can speed up the process by duplication the value type set for one item to other items with the same value type making use of the different option ms excel offers in this example, the user duplicated the no value, by first copying it shown by the interrupted green cell border and then selecting other items which are a process values making use of ctrl+left click the user then pasted the new value for the setting into the selected rows a second option is to make use of the ms excel autocomplete feature, where it does try to recognize what the user may want to enter as a repeat defining an initial value for an item (optional) users are able to define an initial value for an item using the column labeled initial value this allows to make sure, that if a a user requests data for a tag, at least one value does exist this is most useful for items which have been set to be meta data the reason for this is, that process data are expected to be send on a constant base through for example litmus edge using the solution litmus production record tag message conversion flow therefore, they will get a value as soon as the communication between litmus production record database and the data source such as litmus edge has been established meta data on the other hand can be very static, being updated very infrequently or potentially never after their initial value to not have to create a special flow or use sql to provide a value for items set to be meta data, the configurator allows users to therefore provide this initial value when setting up the tag users simply enter the desired initial value into a cell note to be able to add an initial value, the value type has to be set otherwise the cell will be cleared, as the configurator can not check if the value matches the value type the configurator will verify for initial values which are of the value type isstring for invalid ascii characters to learn more about which ascii characters are allowed, review the section restrictions on ascii characters allowed to be used for items which are not of the value type isstring , the value is verified it is is of the correct value type invalid ascii characters if an invalid character is found, a prompt is shown to the user invalid characters are marked in red invalid values if value type not isstring if an invalid value is found, a prompt is shown to the user invalid values are marked in red invalid string length t he maximum length of a string value can not exceed 256 characters if an initial value for the value type isstring is longer 256 characters, the user will be prompted note initial values for items which exceed the 256 character limit, will by default be trimmed to 256 characters if no action is taken by the user tip users can speed up the process by duplication the initial value set for one item to other items with the same initial value making use of the different option ms excel offers in this example, the user duplicated the value san jose, by first copying it shown by the interrupted green cell border and then selecting other items which will have the same value the user then pasted the new value for the setting into the selected rows a second option is to make use of the ms excel autocomplete feature, where it does try to recognize what the user may want to enter as a repeat