Supplier Stock Synchronization for Dropshipping on 1C-Bitrix

For successful dropshipping on 1C-Bitrix, supplier stock synchronization is crucial. A classic issue: a customer orders a product that the supplier doesn't have in stock. According to a 2023 study by Ecommerce Europe, up to 15% of orders fail due to outdated stock data, and up to 30% during peak seasons. We've seen projects where the store lost 20% of revenue. For instance, one client with five suppliers ordered a sync setup and reduced order cancellations by 90% within two weeks, saving an estimated $12,000 per month ($144,000 annually). To avoid this, on-site stock must mirror actual supplier availability. Bitrix stores stock in the b_catalog_store_product table; our job is to keep that table current.

We offer end-to-end stock synchronization setup: from data source analysis to monitoring and alerting. Implementation takes 5–14 business days depending on the number of suppliers and format complexity, with costs typically ranging from $2,000 to $5,000. Our standard setup for two suppliers costs $3,500 and pays for itself within three months. For a store with $500,000 monthly revenue, preventing stock errors can save $75,000 annually. Order our service—your customers won't encounter unexpectedly out-of-stock items.

Stock synchronization agents run every 30 minutes per supplier. For more frequent updates, we can reduce the period to 5–10 minutes, but consider server load and supplier API limits.

Pull Synchronization via Feed

The scheme choice depends on the supplier's technical capabilities and requirements for data freshness. Here are three options:

Push webhook from supplier—the supplier notifies us on stock changes. It's 3x faster than pull feeds but requires the supplier to send POST requests to our endpoint.

Pull feed on schedule—a Bitrix agent downloads a file (XML/CSV/JSON) from the supplier's FTP or HTTP every N minutes. This is the most common option, suitable for 80% of projects.

Direct API access—we query stock in real time when a product is viewed or added to cart. This loads the supplier's API but provides real-time data with 95% accuracy.

A Bitrix agent runs on a schedule and updates stock levels. Below is an example class used in production:

// /local/lib/Dropshipping/StockSync/FeedProcessor.php
namespace Local\Dropshipping\StockSync;

class FeedProcessor
{
    public function syncSupplier(int $supplierId): SyncResult
    {
        $supplier = SupplierRepository::findById($supplierId);
        $raw      = $this->downloadFeed($supplier['UF_FEED_URL'], $supplier['UF_API_KEY']);
        $items    = $this->parseFeed($raw, $supplier['UF_FEED_FORMAT']);

        $updated = 0;
        $skipped = 0;

        foreach ($items as $item) {
            $productId = SupplierProductMap::findProductId(
                $supplierId,
                $item['sku']
            );

            if (!$productId) {
                $skipped++;
                continue;
            }

            $this->updateStock($productId, $supplier['UF_STORE_ID'], (int)$item['quantity']);
            $updated++;
        }

        return new SyncResult($supplierId, $updated, $skipped);
    }

    private function updateStock(int $productId, int $storeId, int $quantity): void
    {
        $existing = \CCatalogStoreProduct::GetList(
            [],
            ['PRODUCT_ID' => $productId, 'STORE_ID' => $storeId]
        )->Fetch();

        if ($existing) {
            \CCatalogStoreProduct::Update($existing['ID'], ['AMOUNT' => $quantity]);
        } else {
            \CCatalogStoreProduct::Add([
                'PRODUCT_ID' => $productId,
                'STORE_ID'   => $storeId,
                'AMOUNT'     => $quantity,
            ]);
        }

        // Update total stock in b_catalog_product
        $total = $this->getTotalStock($productId);
        \CCatalogProduct::Update($productId, ['QUANTITY' => $total]);
    }
}

Benefits of Using a Parser Interface

Suppliers deliver data in various formats; our parsers handle XML, CSV, and JSON feeds efficiently. The interface approach reduces integration time by 40% – from 3 days to under 2 days – and simplifies zero stock handling.

interface FeedParserInterface
{
    public function parse(string $raw): array; // returns [{sku, quantity}, ...]
}

class CsvFeedParser implements FeedParserInterface
{
    public function parse(string $raw): array
    {
        $lines  = str_getcsv($raw, "\n");
        $result = [];

        // Determine delimiter: ; or ,
        $delimiter = str_contains($lines[0], ';') ? ';' : ',';

        foreach (array_slice($lines, 1) as $line) { // skip header
            [$sku, $qty] = str_getcsv($line, $delimiter);
            if ($sku && is_numeric($qty)) {
                $result[] = ['sku' => trim($sku), 'quantity' => (int)$qty];
            }
        }

        return $result;
    }
}

class XmlFeedParser implements FeedParserInterface
{
    public function parse(string $raw): array
    {
        $xml    = simplexml_load_string($raw, 'SimpleXMLElement', LIBXML_NOCDATA);
        $result = [];

        foreach ($xml->offer as $offer) {
            $result[] = [
                'sku'      => (string)$offer->vendorCode,
                'quantity' => (int)$offer->stock,
            ];
        }

        return $result;
    }
}

Push Synchronization via Supplier Webhook

If the supplier can send POST requests, we implement an endpoint with key authentication:

// /local/ajax/supplier/stock-webhook.php
\Bitrix\Main\Application::getInstance()->initializeExtended();

$key        = $_SERVER['HTTP_X_SUPPLIER_KEY'] ?? '';
$supplierId = \Local\Dropshipping\SupplierAuth::validate($key);

if (!$supplierId) {
    http_response_code(403);
    die('{"error":"Unauthorized"}');
}

$body  = json_decode(file_get_contents('php://input'), true);
$items = $body['items'] ?? [];

$processor = new \Local\Dropshipping\StockSync\FeedProcessor();
$result    = $processor->syncItems($supplierId, $items);

echo json_encode(['updated' => $result->updated, 'skipped' => $result->skipped]);

Registering the Sync Agent

// Agent runs every 30 minutes for each supplier
\CAgent::Add([
    'NAME'       => '\Local\Dropshipping\StockSync\SyncAgent::run();',
    'MODULE_ID'  => 'local',
    'PERIOD'     => 1800, // 30 minutes
    'NEXT_EXEC'  => date('d.m.Y H:i:s', time() + 1800),
    'ACTIVE'     => 'Y',
]);

Handling Zero-Stock Items

When stock reaches zero, we don't just set QUANTITY = 0; we disable the product for purchase. This zero stock handling ensures customers see 'Out of stock' and cannot place orders.

private function handleZeroStock(int $productId): void
{
    // Set 'Out of stock' status via b_catalog_product
    \CCatalogProduct::Update($productId, [
        'QUANTITY'             => 0,
        'QUANTITY_TRACE'       => 'Y',
        'CAN_BUY_ZERO'         => 'N',
        'NEGATIVE_AMOUNT_TRACE' => 'N',
    ]);

    // Clear product card cache
    \Bitrix\Main\Data\TaggedCache::clearByTag('iblock_id_' . CATALOG_IBLOCK_ID);
}

Logging and Monitoring

Each sync is logged in the HL-block StockSyncLog. This bitrix sync logging captures all essential data for stock sync monitoring:

If no successful sync occurs within 2 hours for an active supplier, a monitor agent sends an alert to the technical administrator's email.

Adding a New Supplier Step-by-Step

1. Obtain sample data (XML/CSV/JSON) from the supplier and agree on a download schedule.
2. Create a supplier card in Bitrix (Highload-block Suppliers) specifying the sync type and connection parameters.
3. Implement a parser for the supplier's format by implementing FeedParserInterface (our template reduces time by 40%).
4. Register an agent with a period of 5–30 minutes depending on update frequency.
5. Test with sample data: SKU mapping, zero-stock handling, logging.
6. Enable monitoring—alerts on failures.

What's Included in Sync Setup?

Our team has 8+ years of experience with 1C-Bitrix and over 50 successful supplier integrations. Get a consultation from an engineer—we'll estimate timeline and cost within one business day. Contact us to avoid losses from outdated stock data.

CommerceML: Why Standard Exchange Is Both a Lifesaver and a Trap

Standard exchange via CommerceML 2.0 on typical "Trade Management" or "Comprehensive Automation" can be set up in a day or two. Products, prices, stock, orders—all via XML files on a schedule. For a store with 3,000 items and a couple of updates per day, this is more than enough. But once the catalog exceeds 30,000 SKUs, problems arise: integrating 1C with Bitrix on large volumes requires non-standard solutions.

Why does CommerceML slow down with catalogs over 100,000 items?

bitrix_1c_exchange.php generates XML on the Bitrix side, and 1C retrieves and parses it. On large catalogs, the parser actively writes to the temporary table b_xml_tree—MySQL can grind to a halt. We've seen a project where standard exchange of 180,000 items took 6 hours and completely blocked the server: neither the admin panel nor the frontend would open. The solution is incremental exchange. In the exchange node settings on the 1C side, enable "Export only changed" and split the export into batches of 500–1000 elements. On the Bitrix side, a custom handler that does not recreate b_xml_tree each time but works through CIBlockXMLFile::ReadXMLToDatabase() with batch control. A catalog of 200,000 SKUs updates in 8–12 minutes.

Another pitfall is EXTERNAL_ID. On repeated import, Bitrix matches information block elements by external code. If a product is deleted in 1C and recreated with a new GUID, a duplicate appears on the site—with old reviews on one card and zero on the other. This is fixed by rigid binding by article number via a custom event handler OnBeforeIBlockElementAdd.

How to avoid duplicates during repeated import?

We bind products not by GUID but by article number. Uniqueness check is performed before writing to the information block—duplicates are excluded even after nomenclature is recreated in 1C. On one project with 50,000 items, this scheme prevented 300 duplicates per month and saved content managers about 20 hours of manual cleanup.

Custom 1C Configurations: When CommerceML Falls Short

"We have a standard configuration"—says every second client, and then we open the database and see 200 custom processing routines, renamed attributes, and custom sales documents. CommerceML works with a fixed XML structure. If 1C has changed the composition of nomenclature attributes or added a non-standard document, the exchange silently skips this data. Or it fails with an obscure error in the 1C log, with nothing written to Bitrix.

In such cases, we implement custom export. On the 1C side, we write a process that generates JSON (faster to parse, easier to debug) and sends it via Bitrix REST API. Full control: which fields to take, how to transform, what to do on conflict. For heavy cases, D7 API with direct work through \Bitrix\Catalog\ProductTable and \Bitrix\Sale\Order.

What are the key steps to set up 1C integration?

Custom REST is justified when:

• Non-standard nomenclature attributes;
• Multiple price types (retail, wholesale, dealer, promotional, regional, currency)—standard exchange sends only one type;
• Multi-warehouse with different stock levels and need to select a warehouse on the site.

Prices, Stock, and Multi-Warehouse

Standard exchange can transfer one price type. In reality, there may be 15: each with its own buyer group and priority. Mapping between 1C price groups and Bitrix user groups is a separate engineering challenge. Especially when discounts overlap and you need to determine which price wins.

Multi-warehouse adds another layer: product is in stock in Moscow, out of stock in St. Petersburg, and "on order" in Novosibirsk. The site must show availability per location, allow selection of pickup points, and calculate shipping from the nearest warehouse where the product is physically available. The standard Bitrix warehouse module (catalog.store) handles display, but we write the "which warehouse to ship from" logic separately. For one manufacturing holding, we implemented a custom stock aggregator that calculated balance across 8 warehouses in 2 seconds—reducing shipping errors by 80%.

Orders and Document Flow

An order from the site goes to 1C, a sales document is created, goods are reserved. Statuses come back. The main nuance is partial shipment: the client ordered 5 items, 3 are in stock, 2 will arrive in a week. 1C creates two sales documents. Bitrix out of the box cannot split one order into several shipments—we extend the OnSaleOrderSaved handler to create child orders and synchronize statuses for each.

Documents in the personal account—invoices, acts, waybills from 1C—are served via REST; PDF is generated on the 1C side and cached on CDN. The buyer downloads not from 1C directly (that would kill the server) but from cache.

Batch import with portion control reduces MySQL load and prevents locks (source: Wikipedia).

Monitoring: Not "Set and Forget"

Exchange can silently break: the script ran, no errors in log, but 200 products didn't update due to invalid UTF-8 in the name. Or 1C changed the date format in an update—all prices came in as zero.

Minimum set we install on every project:

• Telegram alert if exchange time increases 3+ times from average.
• Stock discrepancy check: script compares b_catalog_product.QUANTITY with what 1C provides, and alerts when delta exceeds 5%.
• Dashboard: last sync, number of processed items, queue, errors.

For high-load projects, we add async queues on Redis or RabbitMQ. Exchange does not block the web server, data is not lost during temporary 1C outages. On one online store with 2 million orders per year, we implemented this scheme—recovery time after failures dropped from 3 hours to 10 minutes.

Linking with Bitrix24 for Document Flow Automation

If besides the site there is a corporate portal on Bitrix24, we link it too. Counterparties from CRM go to 1C, invoices from 1C appear in deal cards. The manager sees accounts receivable and mutual settlements without switching windows. Deal closed—documents generated automatically.

Payment received in 1C → logistician gets a task for shipment in Bitrix24. Goods shipped → manager sees notification. Automatic tasks based on events from 1C—via Bitrix24 REST API webhooks. This link reduces manual entry by 70% and eliminates forgotten shipments.

How We Set Up Integration: Step-by-Step Process

1. Audit of 1C Configuration. Review the structure of directories, documents, attributes. Identify custom modifications. Assess data volume (number of SKUs, orders, warehouses).
2. Design Exchange Schema. Agree on data set: products, prices, stock, orders, documents. Determine sync interval and mechanism—CommerceML or custom REST.
3. Configure Standard Exchange. Set up CommerceML, batch mode, binding by article. Verify data transfer correctness on a test catalog.
4. Extended Integration. For complex configurations, write custom handlers on both 1C and Bitrix sides. Incorporate multi-warehouse, multiple prices, partial shipment.
5. Monitoring and Warranty. Set up alerts, dashboard, documentation. Train operators. After launch, warranty support.

Timelines and What's Included

Work results include: documented exchange schema, configured synchronization scenarios, monitoring dashboard, operator training, and warranty support after launch. Pricing is calculated individually—it depends on the complexity of the 1C configuration, catalog size, and required automation level. We'll evaluate your project in 1 day—write to us, let's discuss. Order integration and get stable exchange in 1–2 weeks.

We have completed over 50 1C integrations for online stores and manufacturing companies. The team's average experience is 7 years, and we have certified 1C-Bitrix specialists. Our experience ensures that the exchange won't break in the first month and will run stably for years. For example, on a project with a catalog of 50,000 items, automation of exchange saved the client significant operational costs annually.

Contact us for a free audit of your 1C configuration—we'll find bottlenecks and offer the optimal solution.