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Definition of an index for the FINDORDERHISTORY A QUERY

This table definition allows primary key-based reads as well as writes of Orders. It doesn’t however allow a query like findOrderHistory() which results multiple matches of orders sortable by age. This is due to the fact that as you’ll see later in this article this query makes use of it’s DynamoDB query() operation that requires a table to be equipped with an uncomposed primary key composed of two attributes that are scalar. The primary attribute is a parti-tion key. The partition key is known because DynamoDB’s Z axis scale (described in Chapter 1) utilizes it to choose the storage partition of an item. The other attribute is the sort key. An query() operation returns items with the partition key specified and an associated sort key within the range specified and also match the optional filter expression. The query() operation returns the items according to order indicated through the key to sort. bUAE Phone number address lists

FindOrderHistory() query function will return the consumer’s order history ordered by age. This means that it requires an initial key that contains the consumerID as the par-tition key and the orderCreationDate being the key to sort. It’s not logical to have (consumerId and the orderCreationDate) as the key in the ftgo-order-history tablesince it’s not unique. buy UAE Phone number database online

The answer is to use findOrderHistory() to access the database DynamoDB refers to as an additional index of the ftgo order-history table. This index contains (consumerId or orderCreationDate) as its key that is not unique. As with an RDBMS index it is also the DynamoDB index is automatically updated every time its table is changed. However, unlike an RDBMS index however, an DynamoDB index could contain non-key attributes. Non-key attributes boost performance because they are returned by the query which means that the application does not have to pull these attributes from the database. Additionally, as you’ll discover, they can be used to filter data. Figure 7.14 depicts the layout of the table, as well as the index. UAE Phone number database

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INTRODUCING THE FINDORDERHISTORY QUALITY

This findorderhistory() query operation comes with one parameter for filtering that defines the criteria for searching. One criteria is the age of the returned orders. This is simple to set up because the DynamoDB Query’s key condition expression can be used to restrict the range in the kind key. The other criteria for filtering correspond to non-key attributes, and can be achieved with a filter expression which is an Boolean expression. A DynamoDB Query operation only returns those items that meet this filtering expression. For example, to find Orders that are CANCELLED, the OrderHistoryDao-DynamoDb uses a query expression orderStatus = :orderStatus, where :orderStatus is a placeholder parameter. buy UAE Phone number database online

Keyword filter criteria are more difficult to implement. It is used to select customers whose restaurant’s names or menu items correspond to one of the keywords specified. The OrderHistoryDaoDynamoDb enables the keyword search by tokenizing the restaurant name and menu items and storing the set of keywords in a set-valued attribute called keywords. It identifies the items that are in line with the keywords applying a filter expression that makes use of the() function which, for instance, contains(keywords, keyword1) OR contains(keywordskeywords keywords, :keyword2) keyword1, where keyword2 are placeholders for the keyword you have specified. UAE Phone number database

AFFECTING THE QUERY’S RESULTS PAGINATING

Certain customers will be able to place an abundance of orders. This is why it makes sense for to use the FindOrderHistory() query to make use of pagination. The DynamoDB Query operation has an operation parameter pageSize which defines what the max number of items it can return. When there’s more data than that, the output of the query will have an attribute called Last-EvaluatedKey that is non-null. A DAO is able to retrieve an additional page data when it invokes the query by using an exclusiveStartKey setting to LastEvaluatedKey. UAE Phone number database providers

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As you will observe, DynamoDB doesn’t support position-based pagination. Therefore, Order History Service returns an opaque pagination token to its clients. Clients use this token to seek out another page in the results. UAE Phone number address lists

After having explained the procedure for querying DynamoDB in order to get orders from customers, lets examine how to add and update them. buy UAE Phone number database online

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Updating ORDERS

DynamoDB provides two options for updating and adding items The PutItem() as well as UpdateItem(). Its PutItem() operation creates or replaces an entire item with it’s primary key. In theory, OrderHistoryDaoDynamoDb could use this operation to insert and update orders. The main issue when the use of putItem() is making sure that updates for multiple items on the same item are correctly handled. UAE Phone number database

Take, for instance an instance when two event handlers at the same time try to modify the identical item. Each event handler calls OrderHistoryDaoDynamoDb to load the item from DynamoDB, change it in memory, and update it in DynamoDB using PutItem(). The event handler that handles one event could alter the changes that was made by the other handler. OrderHistoryDaoDynamoDb can prevent lost updates by using DynamoDB’s optimistic locking mechanism. A less complicated and efficient method is to utilize UpdateItem(). UpdateItem() method. UAE Phone number id list

This updateItem() operation changes the each attribute on the object, and creates the item, if needed. Since various event handlers update the different attributes of the item, the use of UpdateItem is logical. This is also more efficient since there’s no requirement to extract the order from the table. UAE Phone number database

One issue that comes with updating the database to respond an event is as we mentioned earlier, the process of identifying and eliminating duplicate events. Let’s take a look at how you can accomplish this using DynamoDB.

DETECTING DUPLICATE EVENTS

All the event handlers of Order History Service are independant. Each of them determines the attributes for the item in the order. Order History Service could, thus, simply avoid the issue of duplicate events. The disadvantage of ignoring the issue is that an Order item can sometimes become out-of-date. This is since an event processor which receives duplicate events will change the attributes of an Order item to their previous values. The order item won’t have the correct attributes until events later on are delivered. UAE Phone number id list

As mentioned earlier One way to stop the data from getting out of date is to identify and eliminate duplicate events. OrderHistoryDaoDynamoDb can detect duplicate events by recording in each item the events that have caused it to be updated. Then, it can use it’s UpdateItem() procedure’s conditional updating mechanism, which will update an item only when an event isn’t duplicate. UAE Phone number database

A conditional update can only be executed if a conditional expression is real. A condition expression determines if an attribute exists or is assigned an exact value. The Order-HistoryDaoDynamoDb DAO can track events received from each aggregate instance using an attribute called <><> whose value is the highest received event ID. A duplicate event occurs when the attribute is present and its value is lower than or equivalent to the ID of the event. The OrderHistoryDaoDynamoDb DAO uses this condi-tion expression: UAE Phone number id list

attribute_not_exists(<><>)

OR <><> < :eventId

The condition expression will only allow the update only if the attribute doesn’t exist , or the eventID is greater than the event ID that was processed the last time. ID.

For example, suppose an event handler receives a DeliveryPickup event whose ID is 123323-343434 from a Delivery aggregate whose ID is 3949384394-039434903. The name of the tracking attribute is Delivery3949384394-039434903. The event handler will take the event as duplicated when the value of the attribute is higher that or equivalent to 123323 343434. A operation called query() operation that is invoked in the event handler changes the Order item with this expression of condition: UAE Phone number database providers

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attribute_not_exists(Delivery3949384394-039434903)

OR Delivery3949384394-039434903 < :eventId UAE Phone number address lists

Now that I’ve described the DynamoDB data model and query design, let’s take a look at OrderHistoryDaoDynamoDb, which defines the methods that update and query the

ftgo-order-history table.

The OrderHistoryDaoDynamoDb class

The OrderHistoryDaoDynamoDb class implements methods that read and write items in the ftgo-order-history table. Its update methods are invoked by OrderHistory-EventHandlers, and its query methods are invoked by OrderHistoryQuery API. Let’s look at the various methods that are available, beginning at the addingOrder() procedure. buy UAE Phone number database

A SYSTEM FOR ADDORDER() ADDORDER() Method

AddOrder() method as shown in Listing 7.2 adds an order to the ftgo’s order-history table. It is a method that has two parameters: sourceEvent and order. The order parameter refers to that of the Order to add, which is derived by analyzing the OrderCreated event. The sourceEvent parameter includes the eventId as well as the ID and type of the aggregate that generated the event. It is used to implement conditionsal updates. UAE Phone number database

List 7.2 AddOrder() method is used to add or edits an order

public class OrderHistoryDaoDynamoDb … The key to the
@Override Order item to be updated
public variable. Boolean addOrder(Order order Optional eventSource) {
UpdateItemSpec spec = new UpdateItemSpec()
.withPrimaryKey(“orderId”, order.getOrderId())
The update .withUpdateExpression(“SET orderStatus = :orderStatus, ” +
“creationDate = :cd, consumerId = ;consumerId lineItems =” +
expression the meaning of which buy UAE Phone number database
Updates to the ” lineItems: keywords =:keywords RestaurantName is ” + UAE Phone number database
attribute “:restaurantName”)
.withValueMap(new Maps()
The values of the .add(“:orderStatus”, order.getStatus().toString())
placeholders in .add(“:cd”, order.getCreationDate().getMillis())
the update .add(“:consumerId”, order.getConsumerId())
expression .add(“:lineItems”, mapLineItems(order.getLineItems()))
.add(“:keywords”, mapKeywords(order))
.add(“:restaurantName”, order.getRestaurantName())

.map())

.withReturnValues(ReturnValue.NONE);

return idempotentUpdate(spec, eventSource);

}

This addOrder() method generates an UpdateSpec that makes up the AWS SDK and describes the update process. When you have created the UpdateSpec it invokes idempotent-Update() which is a helper method that executes the update following the addition of an expres-sion of condition that protects from duplicate updates. buy UAE Phone number database

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The NOTEPICKEDUP() METHOD

NotePickedUp() method, as shown in listing 7.3. notePickedUp() procedure that is shown in figure 7.3 It is called through the handler of the DeliveryPickedUp event. It changes the delivery status of the order item to PICKED_UP. UAE Phone number database

The listing 7.3 NotePickedUp() method alters the status of the order to PICKED_UP

public class OrderHistoryDaoDynamoDb …

@Override UAE Phone number database providers

public void notePickedUp(String orderId, Optional eventSource) { UpdateItemSpec spec = new UpdateItemSpec()

.withPrimaryKey(“orderId”, orderId)

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.withUpdateExpression(“SET #deliveryStatus = :deliveryStatus”)

.withNameMap(Collections.singletonMap(“#deliveryStatus”, UAE Phone number database for sale

DELIVERY_STATUS_FIELD))

.withValueMap(Collections.singletonMap(“:deliveryStatus”, DeliveryStatus.PICKED_UP.toString())) email marketing database UAE Phone number

.withReturnValues(ReturnValue.NONE); idempotentUpdate(spec, eventSource); UAE Phone number database
}

The method works similarly to addingOrder(). This method generates an UpdateItemSpec, and activates IdempotentUpdate(). Let’s examine the IdempotentUpdate() method.

THE IDMOTENTUPDATE() METHOD

The following table outlines the IdempotentUpdate() method that is able to update the item by including a conditional expression in the UpdateItemSpec to guard from duplicate update. email marketing database UAE Phone number

7.4 Listing 7.4 The IdempotentUpdate() method is able to ignore duplicate events.

public class OrderHistoryDaoDynamoDb …

private boolean idempotentUpdate(UpdateItemSpec spec, Optional eventSource) { UAE Phone number database

{try You can try it.

table.updateItem(eventSource.map(es -> es.addDuplicateDetection(spec))

.orElse(spec));

Return true;

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} catch (ConditionalCheckFailedException e) {

Do not make any false claims;
}

}

If the sourceEvent is supplied, idempotentUpdate() invokes SourceEvent.add-DuplicateDetection() to add to UpdateItemSpec the condition expression that was described earlier. The idempotentUpdate() method catches and ignores the ConditionalCheckFailedException, which is thrown by updateItem() if the event was a duplicate. email marketing database UAE Phone number

After we’ve looked at the code used to update tables, we can take a look into the method used to query.

The FINDORDERHISTORY() Method

The findOrderHistory() method, shown in listing 7.5, retrieves the consumer’s orders by querying the ftgo-order-history table using the ftgo-order-history-by-consumer-id-and-creation-time secondary index. It is a two-part method: the consumerId is the identifier for the customer while filter specifies the criteria for searching. This method generates Query-Spec, which is, just like UpdateSpec forms part of AWS SDK. It takes its parameters it queries the index and then transforms the results to an order history object. UAE Phone number consumer database

Listing 7.5 The findOrderHistory() method locates the orders of a consumer that are matched

public class OrderHistoryDaoDynamoDb …

@Override

public OrderHistory findOrderHistory(String consumerId, OrderHistoryFilter filter) { UAE Phone number database
The query must be completed
querySpec spec = new queryspec() returns the order of orders UAE Phone number database providers
of advancing of
.withScanIndexForward(false)
.withHashKey(“consumerId”, consumerId)

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.withRangeKeyCondition(new RangeKeyCondition(“creationDate”)

.gt(filter.getSince().getMillis())); UAE Phone number database for sale

filter.getStartKeyToken().ifPresent(token -> The maximum
spec.withExclusiveStartKey(toStartingPrimaryKey(token))); age of the UAE Phone number consumer database
Orders to
Map valuesMap = to create a new HashMap <>(); returns

String filterExpression = Expressions.and( keywordFilterExpression(valuesMap, filter.getKeywords()),

statusFilterExpression(valuesMap, filter.getStatus()));

if (!valuesMap.isEmpty()) Construct a filter expression
spec.withValueMap(valuesMap); and placeholder value map
From the OrderHistoryFilter.
if (StringUtils.isNotBlank(filterExpression)) {
spec.withFilterExpression(filterExpression);
}

Limit the number of people
of outcomes if
filter.getPageSize().ifPresent(spec::withMaxResultSize);
The caller has indicated
A page size.
ItemCollection The result is index.query(spec);

Return to the new OrderHistory( UAE Phone number consumer database

StreamSupport.stream(result.spliterator(), false)

.map(this::toOrder)

.collect(toList()),

Optional.ofNullable(result

.getLastLowLevelResult()

.getQueryResult().getLastEvaluatedKey())

.map(this::toStartKeyToken));

}

Create an Order using the results of the query.

After constructing the QuerySpec This method runs a query and creates an Order-History that contains the Orders list by analyzing the returned items.

The findOrderHistory() method implements pagination by serializing the value returned by getLastEvaluatedKey() into a JSON token. If a client specifies a start token in OrderHistoryFilter, then findOrderHistory() serializes it and invokes withExclusiveStartKey() to set the start key. UAE Phone number database

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As you will see, you need to tackle a variety of issues when you implement the CQRS view, such as selecting an appropriate database, creating a data model that effectively implements the updates as well as queries. It is also about managing simultaneous updates, and handling duplicate events. The most complex component in the program is called the DAO as it has to effectively handle concurrency and make sure that updates are irresistible. UAE Phone number database free

Summary

The implementation of queries to pull data from multiple sources is difficult since the data from each service is confidential.

There are two options to create these kinds of queries using API composition pattern and API composition pattern, and the Command query responsibility segregation (CQRS) pattern.

It is the API composition model, that collects information from multiple sources, provides the most efficient method to implement queries. It should be utilized whenever it is possible. UAE Phone number database free

A drawback to an API structure is the fact that some complicated queries need inefficient joins in memory of massive data sets. UAE Phone number database

The CQRS pattern that implements queries with the view database, is more effective however, it is more difficult to implement.

The CQRS view module has to handle multiple updates, as well as identify and eliminate duplicate events.

CQRS helps to separate the concerns by allowing a particular service to run the ability to return information owned by a different service.

Clients have to deal with the eventuality of the CQRS views. buy UAE Phone number database online

Patterns of APIs that are external to the public

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It is the FTGO application, as well as many other applications, uses an REST API. Its clients include FTGO mobile apps, JavaScript running in the browser, as well as applications created by the partners. In a monolithic structure it is the API that is accessible for clients’ use will be an monolith’s API. However, once the FTGO team has begun to deploy microservices, it’s no longer an API as each service has their own API. Mary as well as her group have to determine which API the FTGO application should be able to expose to its customers. For instance, should customers be aware of the services and submit requests directly to them? UAE Phone number database for sale

The process of creating an API for applications is made more difficult due to the variety of its clients. Different clients usually require different information. Desktop browsers’ UI typically displays more details than mobile applications. Additionally, different clients access the services through different types of networks. Clients inside the firewall make use of a high-performance network, while those outside the firewall utilize an internet connection or mobile networks and will experience lesser performance. Therefore, as you’ll discover that it’s not always a good idea to make sense to provide an API that is a one-size-fits-all. UAE Phone number database
This chapter begins by explaining the various external API design problems. I then discuss some of the other outside API patterns. I discuss an API gateway pattern, then the API gateway pattern first, then the pattern for Back-ends that frontends. Then, I will examine the steps to design and build the API gateway. I look at the various options offered, including available API gateways off the shelf and frameworks to build your own. I explain the concept and development for an API gateway built using an Spring Cloud Gateway frame-work. I also explain how to construct an API gateway with GraphQL the framework that uses graphs to create a query language. UAE Phone number database free

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Design issues with APIs that are external to the design

To explore the different API-related issues we’ll look at one of them: the FTGO application. As Figure 8.1 illustrates, the application’s APIs are utilized by various customers. Four kinds of users use the APIs of the service:

Web-based applications, for instance consumer web applications, which provides the browser-based UI that consumers can use Restaurant web application that implements the browser-based UI for restaurants as well as Admin web app, that provides the internal administrator user interface

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Mobile applications, one specifically for customers and the other for couriers UAE Phone number database

Applications developed by third-party developers

The web-based applications are within the firewall, which means they can access the service via the high-bandwidth, low-latency network. Other clients operate without firewalls, and they can access the services via the internet with a lower bandwidth, but higher latency as well as mobile networks.

One way to approach API design is to allow clients to call the API directly. On the surface, this sounds quite straightforward–after all, that’s how clients invoke the API of a monolithic application. However, this technique is not often employed in microservice architecture due to the following issues:

The APIs for service that are fine-grained will require users to submit multiple requests to get the information they require that is not efficient and can lead to an unsatisfactory user experience. UAE Phone number business database free download

The inability to encapsulate that results from clients having knowledge of the APIs of each service makes it difficult to alter the architecture and APIs.

Services may utilize IPC mechanisms that aren’t a good fit or feasible for clients to utilize, particularly clients that aren’t part of the firewall.

API design issues related to issues with API design for FTGO mobile client UAE Phone number database

Customers use this FTGO Mobile client in order to manage and place their orders. Imagine you’re designing the clients View Order view which shows an order. In chapter 7, you will learn that the information displayed in this view contains basic information about the order, like its status, status of payment as well as the status of the purchase from the point of view of the restaurant as well as delivery information, which includes the location of the order and the estimated delivery time if it is in the process of being delivered. UAE Phone number business database free download

This monolithic edition of FTGO application comes with an API endpoint which returns the order information. The mobile client obtains the information it requires by making a single request. However, in this microservices variant of FTGO application the details of an order are like the ones previously mentioned and are scattered across a variety of services, such as: UAE Phone number database

Order Service–Basic order details including the order details, as well as status

Kitchen Service – The status of the order from the perspective of the restaurant and the estimated date it is ready for pickup

Delivery Service – The order’s delivery status as well as its estimated delivery date and the current location buy UAE Phone number database online

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Accounting Service – The order’s payment status UAE Phone number database for sale

When the client on mobile calls the services directly, it should as Figure 8.2 illustrates, make multiple calls to retrieve the data.
In this case the mobile app serves as an API composer. It calls multiple APIs and then combines the results. While this method seems to be reasonable however, it is plagued by a number of serious issues. UAE Phone number database free download

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Poor user experience due to the client’s multiple requests

The main issue is that the mobile app has to make multiple requests to get the information it wishes to show before the end user. The tense interactions between the application and its services may cause the app to appear unresponsive particularly when it is using the internet or mobile networks. The internet has lower speed and lower latency than a traditional LAN, while mobile network are more prone to issues. The latency of mobile networks (and the internet) is generally 100 times greater than that of a network. UAE Phone number database

The greater latency may not pose a problem in retrieving order information since the mobile app reduces the time delay by processing the requests simultaneously. The response time for all requests is not more than the time of one request. However, in some situations the client might need to run requests sequentially and this can cause a negative user experience. UAE Phone number database free download

Furthermore, a the poor user experience caused by latency in the network isn’t the only problem with an API that is chatty. It also requires mobile developers to write potentially complicated API writing composition codes. This is a distraction from the primary goal of creating a fantastic user experience. Additionally, since each network request requires energy, a Chatty API drains mobile’s battery quicker.

INCAPSULATION FRAUDS Front-end developers to modify their CODE IN LOCKSTEP TO WORK WITH THE BACKEND

Another disadvantage of the mobile app directly connecting to those services can be due to the absence of the encapsulation. When an application grows and develops, the creators of a service may alter an API in a manner that disrupts existing clients. They could even alter how the system is broken down into different services. Developers can introduce new services or separate or combine existing services. However, if information about the services is integrated into mobile applications it may be difficult to modify the APIs for the services. UAE Phone number database free download

As opposed to updating a server-side app it can take several hours, or possibly days to release the latest version of a mobile app. Apple or Google must be able to approve the update and then make it available to download. It is possible that users will not be able to download the upgrade right away, if ever. You may not be able to convince reluctant users to download the upgrade. The approach of exposing APIs for services to mobile devices can be a significant barrier to the development of those APIs. UAE Phone number database

Services could make use of CLIENT-UNFRIENDLY MECHANISMS

Another problem with a mobile application that calls services directly is that certain service providers might use protocols that can’t be readily accessible to a client. Applications that run without firewalls typically employ protocols like HTTP as well as WebSockets. However, as explained in Chapter 3, developers of services can choose a variety of protocols from, not only HTTP. Certain of the services offered by an application could use gRPC, while others might utilize the AMQP messaging protocol. These protocols work effectively internally, but may not be able to be used by mobile devices. Some aren’t even compatible with firewalls. buy UAE Phone number database online

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API design issues that apply to other types of clients

I decided to use the mobile client as it’s an excellent opportunity to highlight the negatives of cli-ents gaining access to services directly. However, the issues that arise from the openness of services to cli-ents isn’t exclusive to mobile clients. Other kinds of clients particularly those that aren’t protected by firewalls have the same issues. As we’ve mentioned earlier the FTGO applications’ services are used by web-based applications as well as clients that run on browsers, JavaScript applications, as well as third-party applications. Let’s examine the API design and design challenges that these buy UAE Phone number database for marketing clients face. UAE Phone number b2b database

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API DESIGN QUESTIONS REGARDING WEB Application

Traditional server-side web applications which manage HTTP queries from the browser, and then return HTML pages, operate within the firewall, and can access services via the internet. Latency and bandwidth aren’t an issue when it comes to the use of API composition within web applications. Web applications also can utilize non-web-friendly protocols for accessing the APIs. The teams who develop web applications are part the same group and typically work closely with the teams who write the backend software, therefore web applications can easily be updated when the backend services are modified. It is therefore possible for web applications to be able to connect to backend service directly. UAE Phone number database

API DESIGN QUESTIONS REGARDING JAVASCRIPT BROWSER-BASED APP

Modern browsers employ a certain proportion of JavaScript. Even if HTML is created through a server-side web app it is commonplace to use JavaScript running within the browser to call services. For example, all of the FTGO application web appli-cations–Consumer, Restaurant, and Admin–contain JavaScript that invokes the back-end services. The consumer web application is one example. It automatically refreshes the order Details page by using JavaScript which invokes the APIs of the service. UAE Phone number b2b database

On the other side the applications that run on browsers JavaScript applications are simple to update as the APIs for ser-vices are changed. However, JavaScript applications that access the internet’s services are experiencing the same issues with latency issues on networks as mobile apps. This is not the only issue. browser-based UIs particularly those designed that are designed for desktops are generally more advanced and require many more features than mobile apps. It’s probable that Consumer and Restaurant applications, that access services via the internet, will not be able to write APIs for service effectively. UAE Phone number database

SEARCHING APIS FOR APPLICATIONS BY THIRD-PART

FTGO as well as other companies, provides an API for third-party developers. The developers can utilize this API FTGO API to create applications to manage and process orders. Third-party applications are able to access APIs on the internet, and API composition is likely to be inefficient. However, this inefficiency API composition can be a minor issue when compared with the larger issue of creating an API which is utilized by third-party software. This is because third-party developers require an API that’s reliable. UAE Phone number b2b database

Only a handful of organizations can make third-party developers change to a different API. Businesses with an unstable API are at risk of losing developers to competitors. So, it is important to control the development of an API that is utilized by developers from third parties. It is common to have to keep older versions up to some time, and possibly forever.

This is a major burden on an business. It’s not practical to hold the backend developers accountable for long-term backward compatibility. Instead of providing services directly to third party developers, businesses should use an independent API public that’s created by a separate team. In the next section, API gateways are public. API is developed through an architectural component referred to by the name of the API gateway. Let’s take a look at the way an API gateway operates. UAE Phone number b2c database

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Pattern API Gateway

As you’ve already observed, there are a variety of disadvantages to services connecting to services directly. It’s not always practical for clients to execute API creation over internet. Encapsulation isn’t available, which creates a challenge for programmers to alter APIs and decomposition of services. Sometimes, services employ protocols for communication that aren’t appropriate for use outside of firewalls. Therefore, a better option is to make use of API gateways. API gateway. UAE Phone number database

The API gateway an API service that acts as the gateway to the application from outside world. It’s responsible for routing requests, API composition, and other tasks, like authentication. This section focuses on API gateways and the API gateway design pattern. I will discuss its benefits as well as drawbacks. I also discuss the design considerations you need to consider when designing the API gateway. buy UAE Phone number database online

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A brief overview of API gateway pattern buy UAE Phone number database for marketing

Section 8.1.1 discussed the disadvantages of clients, including the FTGO mobile application that makes multiple requests to provide details to users. An alternative is to allow a client to send one inquiry to an API gateway, which is a service which acts as the primary gateway for API requests to an application that is not inside the firewall. This is similar to the Facade design pattern that is part of the object-oriented design. Similar to a facade, an API gateway wraps the internal architecture of the application and offers an API for its clients. It could also be charged with additional responsibilities, like monitoring, authentication, and limit on rate. UAE Phone number database

It is the API gateway that handles requests processing, the composition and routing of API requests and also for the translation of protocols. All API requests from clients outside start with API gateway. API gateway. The gateway forwards certain requests to the right service. The API gateway manages other requests by using an API composition pattern, and also by calling multiple services before gathering the results. It can be able to translate between protocols for clients like HTTP and WebSockets as well as non-client-friendly protocols that are used by the API services. UAE Phone number b2c database

REQUEST ROUTING

One of the main purposes that the API gateway is to route requests. A API gateway performs API functions through routing request requests towards the appropriate service. When it receives a query it API gateway checks an routing map which specifies the service it will route the request. A routing map could include, for instance, mapping the HTTP method and its path towards an HTTP URL for a particular service. This is similar to the reverse proxy-ing functions that web servers offer, like NGINX. UAE Phone number database

API COMPOSITION

An API gateway usually does more than just reverse proxying. It may also facilitate certain API operations by using API composition. API composition, for instance. FTGO API gateway is an example, as it implements an API operation called the Get Order Details API operation with API composition. As the figure 8.4 illustrates the mobile application sends an API request which retrieves order information from multiple sources.

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The FTGO API gateway is an API with a coarse-grained structure that allows mobile users to access the data they require in one request. For instance, the mobile client can make only one obtainOrderDetails() call to API gateway. UAE Phone number b2c database

PROTOCOL TRANSLATION

An API gateway could also carry out the translation of protocols. It could provide a RESTful API external clients, despite the fact that the applications use various protocols internally, like REST and GRPC. In the event of need for implementation, some API operations is a translation between the external RESTful API and the internal gRPC APIs.
API GATEWAY API GATEWAY OFFERS EACH CLIENT WITH A CLIENT-SPECIFIC API UAE Phone number customers database

An API gateway can provide a single , one-size-fits-all (OSFA) API. The problem with one API is that clients may require different specifications. For example, a third-party application might need an API operation called the Get Order Details API operation to provide the entire information about the order, whereas mobile clients only require just a portion of the data. One approach to address this issue is to offer clients the option of specifying in their request which fields and objects should be returned by the server. This method is suitable for an open API that is required to support many different applications from third parties, but it doesn’t always give users the necessary control. UAE Phone number database

An alternative is to allow an API gateway to offer each client an individual API. For instance it’s possible that the FTGO API gateway could offer its FTGO mobile app with an API specifically created to meet the needs of its users. It might even offer distinct APIs for Android or iPhone mobile apps. The API gateway can also provide an API available to third-party developers to utilize. In the next post, I’ll discuss the Backends for Frontends pattern which takes the concept of an API-per-client further by creating a distinct API gateway to each of the clients.UAE Phone number customers database